|Year : 1965 | Volume
| Issue : 1 | Page : 1-34
Intracranial space occupying lesions
Department of Neuro-Ophthalmology, Bombay Hospital, Bombay 1, India
|Date of Web Publication||21-Feb-2008|
Department of Neuro-Ophthalmology, Bombay Hospital, Bombay 1
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Pandit Y. Intracranial space occupying lesions. Indian J Ophthalmol 1965;13:1-34
In the very first place I have to express my extreme sense of gratefulness to the Society for the honour that has been done to me by granting me the Adenwalla award to speak on a subject very dear to me, namely Neuro-ophthalmology.
With neurological centers springing up all over the world, it has become increasingly recognised that these are centers where the paths of a neurophysician, a neuro-surgeon, an ophthalmologist and an otolaryngologist often cross. Neuro ophthalmology is now an established speciality but how close neurology and ophthalmology can overlap will be judged from an amusing incident. A new book on neuro-ophthalmology came to the library of a well-known college and hospital of Bombay. The neurologist wanted to index it under neurology, whereas the ophthalmologist claimed it under his section. In the end the ophthalmologist won because the book was written by an ophthalmologist,
This association between neurology and ophthalmology is needed never more so closely as in space occupying intracranial conditions and often the ophthalmologist is the first to detect and place his finger on the lesion. However, because of the widely differing individuality of the symptoms and signs in such cases, the task of localising the lesion and determining its nature demands the highest knowledge of the anatomy and physiology of the parts, every available new technique and improvement in clinical and extra-clinical investigations and above all a frank and free discussion between the specialists on a common platform, giving full credit to each other's contribution to the case. How far the ophthalmologist's effort can be useful to the neurologist can be judged from the extensive distance the optic pathways cover in the brain from pole to pole, and from the fact that six of the twelve cranial nerves with their nuclei are associated with the eyes besides the vagus and the sympathetic. The opportunity for such collaboration is thus very extensive. The labour of today's presentation covers the experience and interest of such happy collaboration over a number of years. You will pardon me, if during this talk, I occasionally step out from the rigid confines of today's subject.
| Anatomy and Physiology|| |
As regards anatomy and physiology there are many finer points for consideration by a specialist and I do not wish to burden you with those as they arise during the consideration of individual cases and their treatment.
Problems associated with blood vessels may however be dealt with. These fall under two heads (1) impairment of blood-supply due to a 'squeezing' action of a space-occupying lesion and ,2) Tumours in connection with blood vessels (aneurysms and angiomas).
The brain is supplied by two systems of arterial blood vessels a carotid system and a vertebral system. The two systems are interconnected by the anterior and posterior communicating arteries. Important facts about the intracranial blood vessels are their thin walls, which are unsupported and a poor anastomosis. However, Elschnig (1893), King (1941), Adson (1942) Dandy and Padget (1948) on a study of embryos, claim a rich anastomosis between ophthalmic artery-a branch of the internal carotid and branches of the external carotid. See [Figure - 27]
The pressure of blood and velocity in the cerebral vessels are constant in health and have to be maintained constant. "Life therefore is a gamble between pressure within and pressure without the vessels" (Woollard). Occlusion, total or partial of the cerebral vessels leads to softening of the convolutions they supply, with corresponding loss of function. Since space occupying lesions directly or indirectly impair circulation the functional loss is primarily a circulatory failure. It is important to remember that a physiological loss of function, which is recoverable, precedes the softening and destruction which are unrecoverable. It is important therefore to distinguish between depression and destruction of function. We shall see later, how far the ophthalmologist can help in making that distinction.
As regards aneurysms we shall deal with them along with tumours at the base of the brain.
Physiology of the Pituitary and Endocrinology
The concepts about the part played by the hypothalamus and the transport of its products have undergone a change in recent years and certain clinical observations on pituitary tumours lend support to these modern concepts.
It is now conceded that the anterior pituitary or the adenohypophysis is distinct from the neurohypophysis or the posterior part, not only developmentally or because of the histological differences and differences in the hormones secreted but also because of differences in the secretory mechanism.
The posterior pituitary itself has little secretory activity but its glia-like `pituicytes' store the two hormones ADH (antidiuretic hormone, sometimes called vasopressin) and oxytocin which are engineered by the supraoptic and paraventricular nuclei of the hypothalamus and pass down the "stalk" to this pars nervosa of the pituitary. [Figure - 1]
Evidence to this effect is afforded by the case of Rothballer and Dugger (1955) in which a small tumour of the median eminence caused a severe diabetes insipidus. At the autopsy the neurosecretion was not found in the nervous system either above or below the tumour. The tumour evidently had destroyed the neurons going from the hypothalamus to the hypophysis causing secondary degeneration of the ganglion cells of the supraoptic and paraventricular nuclei which produce ADH.
Similarly Sloper and Adams (1956) examined the hypothalamus and hypophysis in women in whom the peduncle of the hypophysis was cut to influence cancer of the breast. The neurosecretion oxytocin was found above the cut.
Both these reports prove that the hormones ADH and oxytocin are primarily produced at a higher level in the hypothalamus.
On the other hand the six and add hormones of the anterior pituitary are engineered through neurosecretory products in the hypothalamus which reach the hypophysis via the blood stream-the so called hypothalmic hypophyseal portal system. Thus the hypothalamus is the master organ for both the neuro and adenchypophyseal parts of the pituitary.
As regards the role of ophthalmologists in cerebral space-occupying lesions, their services will be required under the following conditions: (a) Headache (b) Visual disturbances (c) Changes in the ocular fundus (d) Affections of the motor-nerves of the eye (e) Displacements and involvements of the eye-balls.
The triad of headache, vomiting and papilloedema as acknowledged features of an intracranial space occupying lesion though met with in many cases are not always all present. Very often it is the type of headache alone that focuses our attention to such a lesion. At times we find papilloedema alone or a visual field-defect as the one and only sign. In other cases we come across signs and symptoms where not one of the triads is present and yet the patient has a fairly large space occupying lesion. In this connection I can recall to my mind the case of a young lady during the war. She walked into the surgery for slight instability during dancing and a detailed examination just gave a possible suggestion of a tumour which was later confirmed by X'rays. On operation it was found to be a case of glioma of the parieto occipital region. On the other hand we have in the past twenty years come across several cases of papilloedema where both angiography and air studies have failed to offer any help in the localisation of the lesion. It is therefore important that one must keep an open mind on this so-called `triad'.
| Pathology|| |
When we talk of space occupying lesions we do not only mean hyperplasias, new growths and secondary deposits but also include traumatic and vascular conditions like hoemorrhage and aneurysms, infective granulomas like tuberculoma and gumma and thrombotic conditions like cavernous sinus thrombosis [Figure - 2],[Figure - 3]
| Pathology of Cerebral Tumours|| |
Kernohan and Sayre have reassessed the pathology of tumors of the central nervous system. Microscopically, besides the tumour, the phenomenon of oedema is a prominent feature, involving all strata of the cerebrum, with loosening of the ground substance, separation of the myelin sheaths, distension of perivascular spaces and swelling and transformation of astrocytes.
In primary tumors of the nervous system metastasis outside the nervous system is extremely rare. Local extensions after a break through the pia and subarachnoid and along vascular structures is possible.
As regards the nomenclature of the various types of cerebral tumours with their gradation, they are named according to the types of neural cells predominantly seen in microscopical sections of the same, like meningioma, medulloblastoma, astrocytoma, oligodendroglioma etc. and combinations of the same. Typical instances are reproduced here. Those interested in the actual pathological classifications may refer the classical works on the subject by Kernohan and Sayre. (1953) See [Figure - 4],[Figure - 5],[Figure - 6],[Figure - 7],[Figure - 8],[Figure - 9],[Figure - 10],[Figure - 11]
As clinicians we are more concerned with their location and dangers involved when they encroach on vital structures like the visual paths, cerebral nerves and ganglia, invade dural sinuses and encircle cerebral arteries. Again, we are concerned with the operability of the condition and its prognosis.
| Localisation|| |
The matter of localising a lesion requires systematic examination in detail which is often laborious and time consuming. As ophthalmologists, we have to consider the type of headache pupillary reflexes, and the optical system in a certain order, viz. the palpebral fissure, the visual functions, pupillary reflexes, the fundi oculi, muscleparesis, cerebral functions and endocrine disturbances. X-Ray examinations, EEG, air-studies and angiography are jobs for the radiologist, neuro-physician, and neuro-surgeon but the neuro-ophthalmologist cannot plead ignorance of these forms of examination
| Headache|| |
It is one symptom for which the ophthalmologist is visited as a first or a last resort. In recognising the type of pain associated with increased intracranial tension, it is necessary to know the physiology of headache.
Wolff (1955) in a very lucid and impressive monograph on 'Headache Mechanisms', has shown that pain studied critically can be of localising value.
He has carried out his observations on Farradic stimulation of cerebral structures in conscious human volunteers undergoing cranial surgery under local anesthesia. There are quite a number of areas which are pain insensitive, for example (a) the bony skull, (b) dura everywhere except over the floor of the anterior fossa and along the margins of the occipital and transverse sinuses, (c) arteries of the cerebral cortex, (d) parenchyma of brain, (e) pia-arachnoid, (f) ependymal lining of ventricles, (g) choroid plexus.
This explains why some of the cerebral space-occupying lesions are not painful.
On the other hand there are pain-sensitive structures which on Farradic stimulation evoke pain in specific areas which thus have a somewhat localising value. For example Ferradic stimulation of (a) the sagital sinus, (b) the middle meningeal artery, (c) dura on the floor of the anterior fossa, cause pain behind and over the eye.
Similarly Wolff has worked out all the pain-sensitive areas. The pain is always referred to the same area when a particular structure is irritated in different subjects.
Among pain-sensitive structures the most sensitive are the larger blood vessels and the venous sinuses.
Generally speaking the pain is referred to the eyes and the back of the eyes when these pain-sensitive structures are situated in front of the line joining the ears across the top of the head.
Structures near about this line give rise to pain in the temples, above the ear.
Those behind this line and below the tentorium give rise to pain at the back of the ear, head and neck.
Wolff argues that the pain and headache are not due to increased intracranial pressure, because by artificially raising the spinal fluid pressure, from 6 to 8 times the normal, by injecting saline into the subarachnoid space through a spinal puncture, no headache could be produced. Besides, there is no significant difference in the incidence and degree of headache in cases of cerebral tumour with and without raised intracranial tension. Therefore headache cannot be due to the increased pressure by itself. In one case of left parietal meningioma, the headache got induced on lowering the intracranial pressure by draining a few cc of the spinal fluid whereas it got relieved by again raising the intracranial pressure.
Because of similar anatomical studies at the time of surgical removal of cerebral tumors we are led to agree with him to the inevitable conclusion that pain is due to traction or distention of pain-sensitive blood-vessels with which the tumour may be related. For example the 3rd ventricle is an insensitive structure but by placing and inflating a tiny balloon in it the vascular circle of Willis is put on the stretch and a diffuse headache follows which disappears immediately on deflation of the baloon. Farradic stimulation and cutting of the floor of the ventricle produces no pain. [Figure - 12]
Thus we come to the conclusion that headaches in intra-cranial conditions are due to (1) traction and displacement of the great venous sinuses with their immediate tributaries (2) traction on the middle meningeal art. (3) traction and displacement of the large arteries at the base of the brain (4) Pressure on the sensory 5th, 9th, 10th cranial nerves and the upper three cervical nerves. (5) Inflammation in or about any of these structures.
Since there are so many other causes of headaches, for differential diagnosis and for determining the localising value, the questioning for headaches should have a certain order and a purpose.
1. Is the headache continuous or intermittent? Where is the head ache?
2. Is there any tenderness over the area?
3. Is the pain of a throbbing or continuous nature?
4. Does it get worse on shaking the head?
5. Is it related to reading, or associated with visual disturbance? Is there any diplopia?
Continuous headaches are more likely to be of cerebral origin. If continuous, is it localised in any particular area? According to the localisation of pain further clinical examination will have to be planned.
If the pain is throbbing and localised, it may be that a cerebral tumour is closely related to a blood-vessel or it may be a localised vascular condition as in temporal arteritis.
If throbbing and generalised, particularly when it gets worse even with a slight shake of the head, it is what is called a vascular or histamin-headache, when the culprit may be an allergen or there may be a psychic cause which may need analysing as in one of our cases, where the patient came with half a dozen X-Ray plates of her head and the headache was traced, by simple questioning, to the death of her grandson whom she adored. It is necessary to remember this for most of these people imagine that they have a cerebral tumour.
Histamin-type of headache never is an isolated symptom but always is associated with some other allergic manifestation, like urticaria, asthma etc. Besides, a histamin type of headache gets relieved by vaso-constrictors of which a tight band across the head and an ice-pack on the head for a hangover are everyday examples.
Question 5 is to exclude headaches of ocular origin, in which case it should be ascertained whether the eyeball is affected or not.
| The Palpebral Fissure|| |
The palpebral fissure can be wide or narrow from various causes, among which endocrinological conditions associated with neurological conditions, especially pituitary tumours take an important part. The second condition in which a change in size of the palpebral fissure occurs and with which we are concerned is when an intracranial tumour extends into the orbit or vice-versa, an orbital condition spreads into the brain. (See [Figure - 28] on p. 23)
A word of caution against the appearance of false proptosis cannot be misplaced at this stage, however elementary it may sound, for example prominence of the eye balls due to a natural condition or high myopia, congenital glaucoma, excess of fat in the orbit, muscle imbalances and disturbances of the sympathetic nerve. A narrowing of the fissure may give the false impression of a widening of the opposite side, for example in ptosis or myasthenia gravis.
The neurological conditions in which one or both eyes may become prominent directly, or indirectly through the endocrines, are pituitary tumors, sphenoidal ridge tumors, tumours of the optic nerve and chiasma, cerebral aneurysms, infections of the cavernous sinus, cerebral abscess, hydrocephalus and haemorrhage.
An unusual instance from my personal cases I would like to present here. A girl aged 18 was travelling by a bullock cart and a sudden jerk led to proptosis of the eye.
The eye was quiet. Proptosis was 5 mm. On X-Ray examination it was found that the roof of the orbit was fractured by a calcified mass in the anterior cranial fossa. As the patient refused an operation, it was not possible to determine the nature of the calcified mass.
The non-neurological conditions giving rise to proptosis which are to be differentiated for our purpose are distensions of the nasal-accessory sinuses which give rise to proptosis and a displacement of the eyeball towards the side opposite to the offending sinuses. In this connection I recall the case of one young lady of 24 who came with sudden proptosis. slight external displacement of the eyeball and marked papilloedema on the same side. X-Ray examination revealed a suspicious infection of the posterior ethmoidal sinuses, which on draining restored the condition to normalcy rapidly.
| Visual Functions|| |
No part of the clinical examination is as important as the examination of the visual functions. Examination of the central vision not only means charting of the visual acuity, but it involves a search for central scotomas.
It is the peripheral field of vision that demands our skill and labour, in deciphering intracranial lesions.
It is a form of examination which is tedious and time consuming and so often allowed to be tricked out of our effort on some pretext or other. The pretext is either lack of a proper perimeter, the ignorance of the patient or language. It is not quite necessary to have one of the modem, high priced very impressive perimeters which are marvels in engineering and mechanical and technical skill. The wonderful monograph on perimetry by Traquair who operated mostly with nothing better than a rotating arc, should set aside any excuse on grounds of non-availability or cost. One can make quite a serviceable perimeter himself if he is a `do-it-yourself' fan.
It is surprising how with a little patience one can explain to even the simplest and silliest looking illiterate what is expected and get him to go through the test.
Language difficulty with fourteen or fifteen different official languages in India is yet an unsolved difficulty, especially in the large cosmopolitan cities of India, and so perhaps the only tangible excuse in some instances.
Field studies are of two kinds, a rough and ready method, and an extremely detailed and precise one.
Among the former class, the confrontation test is the crudest, but sometimes the only test available. In this connection I bring to my mind a case which I had seen in my very early days, of primary optic atrophy, who, inspite of a repeatedly negative Wassermann was subjected to antisyphilitic line of treatment on three different occasions. His vision when I saw him was reduced to perception of light only and when I too, spontaneously suggested a Wassermann test, he threw up his hands and said, "no more Wassermann", and then talked about his antisyphilitic courses of treatment in the absence of any syphilis. So poor was the vision that perimetry was impossible. I could not take his confrontation test as he could not see even movements of fingers. I was left with the only alternative and that was to take his projection which I used as a confrontation test. Strangely, he could perceive a faint glow on the nasal side, which would suddenly cease on crossing the midline into the temporal field. This was noticed in both the eyes. X'Ray examination was immediately suggested which revealed a huge pituitary tumour. This case was allowed to run blind because no one before me had done even a confrontation test.
Harrington's multiple object screen is quite a quick and useful test which can be handled by a non-medical assistant and in intracranial pathology, thus may sow the seeds of suspicion, worth exploring.
The extremely sensitive perimeters are more needed for physiological and clinical research. For office use even an arc with a radius of curvature of 33 cm. and which can be rotated should serve our purpose. The important things to remember are:
(1) One must chart isopters for at least two different sized objects.
(2) The test object should be moved from the periphery right upto the centre, to cover any field defect within the limits of the field of vision scotomas.
(3) Perimetry should always be done under identical conditions of luminosity and light adaptation, to be of comparative value.
There is one other way in which we see perimetry cheated out of its importance because of our reluctance to spend sufficient time over perimetry. Far too often we are presented with a field with a single isopter charted. Traquair has emphasised strongly the value of quantitative perimetry or perimetry in three dimensions, which can only be done by charting two isopters for every field. Charting with weaker retinal stimuli not only throws into relief the nature of an early lesion but by comparing it with the isopter for a stronger stimulus we can get an idea about the prognosis. Here is a typical case. [Figure - 14]. Isopters for 10/330 and 3/330 are close together and show a temporal contraction. The isopters being close together the condition is not capable of recovery beyond the limit of these isopters even on removing the cause. On the other hand if you compare it with the isopter for 2/1000, the latter shows not only a hemianopic characteristic missed by the previous isopters but the two isopters are widely separated suggesting a depression of the field. The defect is an unstable one which is capable of recovering to the limits of the higher isopters if the cause is removed or progressing if the cause remains.
In all subjective forms of perimetry a great deal of personal factor prevails, for example intelligence, attention, exhaustion etc. For this reason any form of objective perimetry would be preferable. [Figure - 15]
Copenhave and Beinhocker (1964) have brought out a device for objective visual field testing using the EEG. These authors used a computor system with EEG using occipital electrodes to chart the field. At a chosen point in the retinal locus a stimulus is given. The response given is studied and a signal light is displayed. The potentials involved are passed through the amplifiers.
The electrodes, 4 mm. each are placed at the occiput separated by a distance of two inches. The test object is a Xenon flash lamp of ten microseconds duration with approximate peak at 3.3 x 10 6 millilamberts attached on the rods.
The localising value of visual field defects are too well known and so I shall content myself by demonstrating the accompanying diagram. [Figure - 16]
| Papilloedema|| |
This is the third of the triad of symptomatology in a space occupying cerebral lesion. Experience shows that every case of a space occupying lesion is not accompanied by oedema of the nerve head. On the other hand we may find papilloedema but no increased intracranial tension. When the optic nerve and chiasma are pressed upon by a tumour there is optic atrophy of the primary type, but then we also come across cases of cerebral tumours with normal looking optic discs. As an instance, in 1958 I was asked to give an opinion on the fundus of an elderly female. Two years prior to the present check up she had become unconscious while at a hill station and was considered as a case of vascular hypertension. No change in the discs were recorded at that time. This time, examination of the discs showed an early bluish yellow atrophy. When asked if she could see her physician standing in the temporal field of one eye, she answered in the negative. It was eventually proved to be a case of pituitary tumour.
Incidence of papilloedema as given by several authors is as follows: Hartman and Guillaumat (1938) on a study of 1169 cases, found papilloedema from gliomas in 76g%,, meningiomas compressing brain 40%, tumours of the posterior fossa 71%. Pettrobelos and Henderson (1950) reported 59.5% papilloedema out of all cases of cerebral tumours. Collier (1927), Davis (1923) and Mc Alpine (1935) have described papilloedema in cases of spinal cord tumours.
In our series in 1961 out of 50 cases of all types of space occupying intracranial lesions, 21 had bilateral papilloedema, 7 oedema of the right nerve head, 6 oedema of the left nerve head while 13 cases had partial to complete optic strophy and three cases had no changes in the discs.
The Fundus in Papilloedema. The points to look for in the optic disc in papilloedema are hyperaemia, blurring of upper and lower margins, forward thrust of the lamina cribrosa, engorgement, blurring of details, surrounding oedema leading to concentric ridges, haemorrhage, exudates and a half star figure at macula.
It is most important to remember that there are clinical conditions besides new growth that can give rise to increased intracranial tension and papilloedema, because they are amenable to non-surgical treatment. Cerebral abscess, gumma and tuberculoma, the last one particularly in our country are the common causes.
A tragedy in this connection was that of a doctor's wife in 1954, who had developed papilloedema and headache and we were unable to localise any growth, by all the means we had at our disposal then. During the time preparations were being made for her to be taken abroad we thought of treating her on antituberculous line of treatment. She was making such good progress that the party was now hesitating to go abroad. Since the preparations were complete by now, they did go abroad (England) where the lesion was localised in the brain-stem. At the operation, a soft growth was seen and removed from the fourth ventricle which histologically was found to be a tuberculoma. Unfortunately the patient did not survive the operation.
Another case of papilloedema without any localising sign had improved with an antimalarial line of treatment since malarial parasistes were found on a routine blood-examination.
Where a growth is not easily localised, in our country it would be a sound principle to treat the case on antimalarial, antituberculous and antisyphilitic line of treatment on the least suspicion.
An interesting case of papilloedema which I came across during the last war, was due to fat embolism in the brain after a fractured femur. (Pandit -1954). In this case the cerebro spinal fluid was not under increased pressure. Postmortem examination showed profuse pin-point haemorrhages and extensive fat embolism in the brain. It was speculated that the cerebral petechial hemorrhages, papilloedema and even death must be due to impediment to circulation of venous blood clue to extensive fat embolism, because the cerebro-spinal fluid was not under high tension and there was no evidence of toxicity from any lipo-proteolytic process.
There are many clinical conditions besides intracranial space-occupying lesions, that give rise to an ophthalmoscopic picture resembling papilloedema, for example, optic neuritis, primary or secondary to a retinal lesion as in renal retinopathy, ancemia, blood dyscrasias and chorio-retinal disease, or sinusitis particularly of the ethmoidal and sphenoidal air-sinuses. (See case description on p. 9).
Oedema from retinal conditions is easily recognised from the macular star when it is present, because the star is a complete one in retinal conditions whereas it is a half-star between the disc and macula in papilloedema. The difficulty comes in early cases.
Cooper (1956) places great emphasis on the feathery ring surrounding the papilla [Figure - 17] not only as an early sign but also as a sign of differential diagnosis between papilloedema due to increased intracranial tension and that from other causes. He has presented a histopathological comparison between papilloedema and optic neuritis to emphasise the value of this sign. He argues that a plaque of inflammation (retrobulbar neuritis) situated at position II, [Figure - 18] should give an exact picture of papilloedema, except that the loss of vision in the neuritic condition should be unilateral, acute and very severe.
In our opinion this feathery ring though present in most cases of papilloedema, occasionally is absent and its absence should not be taken as evidence against an intracranial pathology if there is other evidence to indicate it. Nevertheless when present it is a useful sign in determining raised intracranial tension.
During recent years much experimental work on papilloedema is being done on monkeys by introducing and blowing up small rubber-balloons in selected areas of the brain and thus imitating the effects of space-occupying lesions. The most interesting of these are by an Indian anatomist Sohan Singh Hayreh (1964) working at the Institute at London, and his paper on `Pathogenesis of Papilloedema' should be read in its original form to appreciate the importance of his studies.
Another school from Japan has carried out experiments on rabbits by insertion of hard and soft paraffin pieces into the subdural spaces. The results of observations of Dr. M. Kato (1963) can be summarised as follows:
Placing the piece for a long time in the intercerebral fissure, papilloedema was produced. Pressure on the third ventricle applied continuously produced papilloedema.
Localisation: By itself papilloedema has little localising value except perhaps where it is more intense on one side than on the other. Then the lesion in all probability is on the side with greater degree of papilloedema and situated probably in the anterior fossa. Along with other signs it can be of some localizing value.
Mention has already been made about unilateral papilloedema with acute and intense loss of the whole visual field in inflammatory lesions of the optic nerve near about the entrance of the central retinal vessels into the nerve. [Figure - 18] II
Foster Kennedy syndrome: Papilloedema on one side with optic atrophy on the other, denotes a lesion at the chiasma on the side of the optic atrophy. A frontal or olfactory groove tumor would by its pressure cut off the subarachnoidal space round the ipsilateral optic nerve distal to the tumour from the cerebral subarachnoidal space and that around the opposite optic nerve and so prevent the effects of increased fluid tension on the affected side whereas pressure atrophy of the nerve will not be prevented. [Figure - 18] IV
| Ocular Paresis|| |
It is not necessary for me to repeat here the classical differences between nuclear and infra-nuclear palsies, nor describe the same.
In the study of lesions of the 3rd, 4th and 6th nerves, diplopias should be properly charted on a Hess' screen or its many improvements, to show which muscles are paralysed and which are overacting. In their interpretation we must consider the following two laws: a) Sherrington's law of reciprocal innervation and (b) Herring's law: "Cortical innervation of ocular muscles being proportionate, the movements of each eye are equal".
Sometimes no cause can be detected for an ocular palsy at all, under which condition we are forced to group them under "cranial myopathies".
The consideration of eye palsies is of interest from two points of view 1) as a localising sign, and 2) as a component of several syndromes.
As a localising sign, by itself it is of little value. As a matter of fact, the third and the sixth nerves are often involved in all kinds of space occupying lesions where the base of the brain is stretched along with the vessels there, so that the third nerve gets compressed between the posterior cerebral and superior cerebellar arteries and the sixth nerve between the internal auditory or the anterior inferior cerebellar artery and the pons. Thus they have earned the notoriety of being signs of false localising value, the tumour or cause may be situated quite a distance from these nerves. This is also called indirect paralysis. [Figure - 19] (Also see under temporal and occipital tumours).
As a component of syndromes, several syndromes have been described in which one or more of the motor nerves of the eye are involved and which have definite localizing value, e.g. Gradinigo's syndrome, Weber's, Benedict's, Interpeduncular syndrome and a host of others. We shall deal with some of them when we consider tumours in certain locations.
Cerebral paralysis. Distinction must be made between paralysis of muscles and paralysis of movements. The latter are called cerebral paralysis of muscles and are due to supranuclear lesions. They are usually bilateral and are of an acute but transient nature. They come under consideration only in acute cerebral conditions mostly vascular and so are not usually associated with space occupying lesions, but may come for consideration in a condition like rupture of an aneurysm.
There is supposed to be a supranuclear center which orientates volitional conjugate movements and for the lateral movements it is provisionally placed in the posterior part of the second frontal convolution, as experimental stimulation of this part turns the eyes to the opposite side. However there are other areas on the brain giving a similar though more feeble response. In pontine lesions the conditions are exactly reversed.
The understanding of this phenomenon is rather difficult and is further complicated when we break it up into irritative and destructive lesions.
[Figure - 20] helps in understanding the different situations. A lesion at areas 8 or 19 (cerebral) will produce an effect exactly opposite to a lesion near about VI N. (sixth nerve nucleus), that is a pontine lesion.[Figure - 52]
| Disturbances of Cerebral Functions and the Endocrines|| |
There is not sufficient time to deal with these separately but we shall deal with them along with considerations of tumours in certain locations where such disturbances become characteristic features.
| Neuroradiology|| |
Neuroradiology plays a considerable part in helping the neurosurgeon or the neurologist in localisation of the site of the lesion and in some instances even indicates the pathology of the tumour. A Plane X-Ray plate should invariably be taken before undertaking any specialised investigations. It may show evidence of increased intracranial pressure by either showing the separation of the sutures among young adults or by erosion of the posterior clinoid processes. A calcified pineal may be visualised and its displacement will localise the pathology in the opposite cerebral hemisphere. Internal auditary meatus should be carefully seen for evidence of intracranial erosion or enlargment in which case it is highly characteristic of an acoustic neuroma. Calcifications seen in the suprasellar regions in a young adult will suggest a strong possibility of a craniopharyngioma and a possibility of an aneurysm with calcification of an aneurysm in an older person. Calcification in any other region of the skull would indicate a strong possibility of a tumor at the site. [Figure - 2],[Figure - 3],[Figure - 21]
In a patient suspected of a possibility of a space occupying lesion specialised investigations should be undertaken irrespective of the plane X-Rays showing abnormality or not. About twenty per cent of the intracranial tumors show abnormality on plane X-Ray of the skull.
There are two contrast media which are utilised in localisation of the tumors-air or radio-opaque dye in the arteries supplying the brain. Air is directly introduced into the ventricles by placing burr holes in the skull or it is introduced in the ventricle by doing a lumbar puncture. In cases where there is clinical or radiological evidence of increased pressure, it would be advisable to introduce air directly into the ventricles to avoid 'coning' of the brain stem in the foramen magnum, whilst in cases where there is no increased pressure air may be introduced through the lumbar theca. It has an advantage that the patient does not require to have the head shaved which may be an important consideration in the female. After having introduced air into the ventricles the X-Rays of the skull are taken to visualise the ventricular system in various positions. Air remains uppermost in the ventricles thus allowing the frontal horns to be visualised when the head is turned up and the occipital horns to be visualised when the head is turned down. Special manoeuvres are utilised in filling the anterior or the posterior and often third ventricle, the temporal horns or the fourth ventricle. Accurate assessment of the displacement of the ventricle will help to localise the tumour at its proper site. [Figure - 22],[Figure - 23]
Radio-opaque contrast material may be injected either directly inside into the arteries supplying the brain or indirectly delivered at the origin of the arteries through a catheter introduced into the arterial system. It is commonly introduced into the common carotid artery under local anesthesia through a direct skin puncture. [Figure - 24],[Figure - 25],[Figure - 26],[Figure - 27],[Figure - 28],[Figure - 29]
Generally, three exposures are made in the lateral view and two on the antero-posterior view to show the arterial capillaries or venous plexuses of the circulation. Similarly, vertebral circulation could also be visualised by direct vertebral puncture. It usually requires considerable experience to puncture the vertebral artery and the failure rate is about 10% even in the hands of experienced persons in which case catheter may be introduced either through the axillary or the temporal artery, and guided to the origin of the vertebral artery and the dye injected.
Again, as in the case of air studies, the localisation of the tumour is done by careful visualising the displacement of the arteries. The advantage of the arteriogram is that it shows: the tumour circulation which is visualised in 20% of the cases, and need not necessarily be followed by an operation as there are no changes in intra-cranial pressure as is the case with air studies. In cases where an aneurysm or an angioma is suspected, arterial studies must always take a precedence.
Both these methods are complementary to each other. However, air studies are more accurate in localising the space occupying lesion than arteriography. A normal ventricular system would definitely exclude a space occupying lesion at the time of the examination unless it is a diffuse infiltrative tumour like a glioma.
| Electroencephalography|| |
Electroencephalography (EEG) is the method of recording brain potentials by placing electrodes on the scalp. The E.E.G. equipment comprises of electrode connections to take the electrical potentials to the E.E.G. machine which is a system of amplifiers and recording apparatus. For common use 8-channel machines are available for simultaneous recordings from different areas of the scalp. The pattern obtained varies with age and it is different in awake and sleep states. The abnormalities are noted by comparing the E.E.G. pattern with that of normal people of corresponding age group and by noting the similarity of wave forms obtained from the corresponding regions of the two halves of cerebral hemispheres. In normal adult E.E.G. in awake state alpha rhythm appears commonly at 10c/s (8-13 c/s) over the posterior regions and it disappears on eye opening. Low voltage fast activity occurs over the anterior regions. In children, slow activities in delta (½-3 c/s) and theta ranges (4.7 c/s) appear diminishing in amount as the individual reaches adolescence.
E.E.G. is useful in localisation of supratentorial space occupying lesions. In such cases there are focal abnormalities in the E.E.G. which comprise of (i) disturbance of the normal regional activity (ii) appearance of slower potentials (iii) phase reversal of the potentials indicating the site of neoplasm. [Figure - 30],[Figure - 31],[Figure - 32],[Figure - 33]
| Clinical Features|| |
Having considered all these preliminaries, we are now in a position to consider the clinical features of space-occupying lesions in certain classical situations. We shall only consider the following as they concern ophthalmologists:
- Frontal lobe tumours.
- Tumours of the Olfactory groove.
- Sphenoidal ridge tumours.
- Tumours of the middle cranial fossa.
A. Pituitary tumours.
B. Chiasmal syndrome.
C. Tumours of the median area.
D. Temporal lobe tumours.
- Occipital tumours.
- Tumours of the brain stem.
A. Midbrain tumours.
B. Pontine tumours.
C. Medullary tumours.
- Cerebello-pontine tumours.
- Cerebellar tumours.
For an ophthalmologist, for investigations of such tumours, it is necessary to follow a certain order. The order I follow is to analyse:-
- Displacement of the eyeball.
- Ocular disturbances.
- Ophthalmoscopic changes.
- Extra-ocular disturbances.
- Special Investigations.
| Frontal Lobe Tumours|| |
The type of primary tumours one comes across in this region usually are gliomas and meningiomas, vascular tumours tuberculomas rarely dermoids and terratomas.
Displacement of the eyeball occurs only when a tumour extends into the orbit through the orbital fissure. It is likely to cause some bulging of the eyeball on the side of the tumour.
(See [Figure - 3], and [Figure - 34],[Figure - 35],[Figure - 36]).
Disturbances of eye sight are not to be expected but visuo-psychic disturbances can occur, e.g. inability to recognise objects in the visual field opposite to the lesion although there is nothing wrong with perception of objects. If the tumour reaches the chiasma, a Foster-Kennedy syndrome may be expected, with loss of vision, beginning with a central scotoma on the side of the tumour. Further visual disturbances may be expected with extension of the lesion.
There is no paralysis of muscles but paralysis of movements with conjugate deviation of the eyes may occur, as explained earlier, because of the presence of a centre for conjugate lateral movements in the posterior part of the second frontal gyrus. (area 8 [Figure - 20])
The fundus picture is either of papilloedema, primary optic atrophy or a Foster-Kennedy syndrome. The fundus may not show any abnormality at all.
If there is involvement of Broca's area in the left inferior gyrus there will be motor aphasia. If the lesion invades the second frontal convolution, there will be difficulty in writing (agraphia). Similarly pressure on the olfactory tract will cause anosmia. Involvement of the fronto-pontine tract will cause cerebellar type of ataxia. Similar other neighbourhood signs will be found depending upon the transgression of the tumour.
Psychic changes are often described, like apathy and indifference, mental depression, progressive dementia, intellectual enfeeblement, failing memory, inability to express ideas, automaticity, incontinence of urine and faces with complete disregard to same.
Alteration in character and temperament are reflected in restlessness euphoria, egoism, childishness, irritability, lack of anxiety over gravity of the situation.
A special sign of localizing value is the so-called grasp reflex, which when unilateral denotes a lesion of the median part of the opposite frontal lobe. An object placed in the hand contralateral to the side of the lesion will be grasped tightly and cannot be released voluntarily.
| Tumours of the Olfactory Groove|| |
These tumours are more common in females in the ratio of 6:4. Mostly the cases are meningiomas. These may arise from the anterior, middle or posterior part of the groove. They push the frontal lobe and the optic nerve upwards or encompassing the nerve may extend posteriorly to the chiasma and sella turica, thus simulating pituitary tumours. Accordingly one can get papilloedema or optic atrophy but the classical Foster Kennedy Syndrome is not often met with.
Visual changes vary according to the way the optic nerves are involved and because there may be central scotoma and optic atrophy the condition may be mistaken for disseminated selerosis or retrobulbar neuritis.
Naturally the most characteristic feature should be anosmia or loss of sensation of smell and should distinguish true olfactory tract involvement from its encroachment by neighbourhood pathology.
Since I have not come across this comparatively rare type of tumour, I do not wish to make further comments on it.
| Sphenoidal Ridge Tumours|| |
For clinical purposes [Figure - 37] shows how the sphenoidal fissure can be divided into two parts. Through the narrow supero-lateral half no structure passes whereas through the broad infero-medial half all important structures pass in the orbit. Note that the IV, lacrimal and frontal nerves enter above the tendinous ring.
Proptosis is common however to all tumours of this ridge, because it is through the superior orbital fissure that such tumours migrate into the orbit. Before actual migration, proptosis may be due to venous and lymphatic stasis. Thus in early cases besides mere proptosis there may be nothing else to indicate a space occupying lesion in this region. With increase of tumour and the closer it is to the medial end of the fissure, the vital structures begin to get involved, as evidenced by diminished vision and optic atrophy or papilloedema on the same side spreading gradually backwards to the chiasma and affecting the opposite optic nerve. Finally one or the other motor nerves of the eye gets involved and one can expect any variety of peripheral lesion of the sixth, third and fourth cranial nerves in that order of frequency. The ophthalmic nerve can also get involved since its branches pass through the same fissure.
Other symptoms will depend on pressure on neighbouring structures. The tumours in this region are mostly meningiomas. [Figure - 38], A
| Tumours of the Middle Cranial Fossa|| |
A. Pituitary Tumours
These tumours are the type of cerebral tumours in which opthalmologists are most concerned. They are often first diagnosed by the ophthalmologist. One need not dwell long on the obvious cases with pituitary dysfunction such as acromegaly, gigantism, Frolich's syndrome and dwarfism. They are the types of tumours made glamorous by the endocrinal disturbances they characterise.
The intra sellar tumours are mostly adenomas where the ocular signs are combined with signs of pituitary dysfunction depending upon the cell-structure of such tumours. Thus the chromophil variety is associated with hypopituitarism, the chromophobe variety with acromegaly of a progressive type. Rarely we get basophil adenomas [Figure - 39] and secondary malignant metastasis. Jafferson (1955) records a case of primary adenocarcinoma.
Tumours from the surrounding areas can invade the area and the picture then becomes complicated. Thus invasion may come from the frontal lobe, the olfactory lobe, the third ventricle, chiasma and from the nasopharynx.
One of the rare cases in our opinion was the case of a man 60 years old, whom we saw in 1956. He complained of foggy vision and was prescribed vitamins by his physician. On examination there was loss of colour vision, pupils were moderately dilated but not reacting to light, and loss of knee jerks. X'Ray of the skull revealed a large erosion of the sella turcica. The case comes under "pseudo tabes pituitario". Since he had hypertension and emphysema an operation was not advised.
Ocular Findings: Generally speaking the vision is gradually lost. Though papilloedema may be present the general picture is that of ischoemia of the optic nerves followed by atrophy. The colour of the atrophy is rather typical being slightly bluish yellow and the blood vessels are normal. As vision gradually deteriorates the patient may read letters only on the nasal side of the test chart, and miss those on the temporal side. This has been found in three of our cases and thus gave an early clue to the diagnosis.
Visual Fields: Bitemporal hemianopia is typically associated with pituitary tumours; but a great variety of fields may be encountered. Our cases usually come at a late stage and an early quadrantic anopsia is not encountered.
The colour fields do give us an early clue but very often colour defects are difficult to demonstrate as the subjective phenomenon is varied and response is directly related to the intelligence of the patient, Much depends on the pre-fixed and post-fixed state of the chiasma. If the chiasma is directly above the sella the defect is mostly a bitemporal hemianopia. If prefixed, that is the chiasma is in front of the pituitary, the latter will press on one or both optic tracts leading to fields corresponding with tract lesions -a homonymous hemianopia. If the chiasma lies behind the tumour (post-fixed), one or both optic nerves may be involved the field defect being more on one side than the other, with or without junction scotomas, and may be confused with retrobulbar neuritis.
An interesting case was that of a bus driver in the B.E.S.T. Organisation of Bombay who was first examined on 2-6-1952 when he was first recruited, when nothing abnormal was detected. In yearly check-ups in February 1954 his fields showed slight temporal contraction on both the sides. In April 1955 he was found defective for green colour. Perimetry with coloured objects showed marked contraction. An X-Ray examination of the skull at this time showed "Enlarged deepened sella destruction, displacement of posterior clinoids and lifting of anterior clinoids; appearance suggests a pituitary tumour."
Thereafter X-Rays examination showed a progressive lesion of the sella turcica. In 1955 his blood-sugar and urine-sugar were normal. By September 1961 he had become totally red and green blind. The fields did not show any further deterioration but X-Rays showed a further enlargement and erosion of the sella. His blood sugar on 2-8-63 was 260 mgm. % fasting and 390 mgm. % two hours after glucose.
This case is most interesting in the sense that within a period of ten years he had developed red and green blindness, severe diabetes and progressive enlargement and erosion of the sella turcica because of a pituitary tumour. The association of red-green blindness with pituitary enlargement has not so far been recorded according to our knowledge.
Just as a neighbouring tumour may extend and reach the pituitary region, pituitary tumours may extend into the neighbouring regions, e.g. upwards into the hypothalamic region, downwards into the sphenoidal and ethmoidal sinuses and pharynx, laterally to the carvernous sinus leading to nerve palsies and to the temporal lobe or may even have a posterior subtentorial extension. In one of our cases at the Goculdas Tejpal Hospital such an invasion led to a bilateral oculomotor paralysis. Weinberger, Grant and Adler (1940) cite cases of ocular muscle palsies through extension of the tumour to the cavernous sinus. In one of our cases Hodgkins disease was associated with pituitary tumour. There was calcification in the skull and rarefaction at the end of the long hones. [Figure - 41], A
Rathke s pouch tumours: Craniopharyngioma and adamantinoma. Frazier and Alpers were the first to suggest the term Rathke's pouch tumours (1934). These may be solid or semicystic and arise from the embryonic remains of craniopharyngeal ducts. Often there are areas of calcification.
Much depends on the size of the tumour and pressure on the adjacent structures like the infundibulum, the third ventricle, thalamus, cerebral peduncles and the optic tracts. Headache is a prominent symptom, patients show obesity, spontaneous pains, infantilism, and diabetes insipidus.
The ocular signs are progressive loss of vision, diplopia, pallor of the optic disc or papilloedema when there is pressure on the third ventricle. Bitemporal hemianopia is common but homonumous hemianopia is rare.
Radiologically the wall shows a cyst. Supra sellar tumours may show a normal sella turcica but the anterior and posterior clinoids may get eroded. They are slow growing. They give rise to Cushing's (1930) "chiasmal syndrome". The bitemporal hemianopsias are not congruous and the other signs will depend upon the pressure on neighbouring structures.
B. The Chiasmal Syndrome
Cushing described the importance of bitemporal field defects with optic atrophy as a sure indication of chiasmal pathology particularly of a tumour at the sella turcica, even in the absence of any evidence from X-Ray or EEG examination and air-studies. Sometimes the discs may not appear at all abnormal in which case visual field defects may be the only indication for an exploration of the chiasmatic region by a craniotomy.
Again it need not always be a tumour in connection with the pituitary fossa, for example this syndrome has been observed in suprasellar meningiomas, craniopharyngiomas, gliomas of the chiasma, aneurysm from the anterior part of the circle of Willis. Opticochiasmatic arachnoiditis, disseminated sclerois and neuromyelitis optica may affect the chiasma and may simulate this syndrome.
In this connection, we were recently asked to give an opinion on a case of bitemporal hemianopsia, with no other clinical sign. The surgeons were hesitant to explore because the EEG was normal and on X-Ray examination the sella was perfectly normal. We strongly recommended a craniotomy but now the patient became hesitant as he could carry on with his work without any trouble. Eventually he drifted to Vellore where he was operated upon and a cyst was seen at the cisterna chiasmaticus which was removed.
C. Median Area Tumours
The two main types of tumours here are meningiomas and aneurysms. Being the site of origin of the roots of the motor nerves of the eyes, besides the usual features of intracranial tumours, it is but natural to expect oculomotor palsies of the peripheral type to be associated with such tumours as a special and distinguishing feature. The third, fourth and sixth cranial nerves have almost an equal part to play in this drama, soliloquically or simultaneously. The location of such tumours being more opposite the optic tract, the visual field defects will be of the homonymous hemianopic type. The fifth nerve though a close relation, seldom seems to be affected.
The other type of tumour at the base of the brain is aneurysm. There the arterial tree is very much in contact with the optic nerves, the chiasma: corpora mammilaria and stalk of the hypophysis. Although this type of tumour is rare, one has to be on the look out for the same.
Aneurysms are classified into three types:-(1) Saccular which is congenital in origin. (2) Arterio sclerotic which is the commonest, and (3) Mycotic which according to Duke Elder is a diffuse angiomatosis.
The clinical symptomatology is practically the same as that of the meningiomas, just described because the pressure effects will be on the same group of structures, namely the visual paths--optic nerve, chiasma and tracts -motor nerves and the V nerve. Headache and papilloedema will be the non-specific manifestations of space occupying lesions.
It is extremely difficult to clinically differentiate a cerebral aneurysm except for the fact that these tumours may give rise to transient obscuration of vision and retinal haemorrhages in certain cases. The clinching part in the diagnosis will be afforded by an angiogram, examples of which are presented herewith. [Figure - 43]
D. Temporal Lobe Tumours:
They are mostly gliomas and meningiomas and are of frequent occurrence among cerebral tumours. Although the temporal lobe receives vestibular and acoustic nerve fibres, one does not get more than tinnitus and vertigo, as evidence of their involvement, to be of any specific clinical value.
The chief localising features of temporal lobe tumours are (1) homonymous hemianopsia which is not strictly congruous. (2) hallucinations, (3) convulsions and (4) aphasia.
Homonymous hemianopsia: occurs contralateral to the lesion and theoretically there should be sparing of the macula which is not always the case. A look at [Figure - 44] will tell us why the hemianopsia is not strictly congruous, because in their sweep towards the tip of the temporal lobe, the anterior group of visual fibres separate widely and the fibres do not get picked out as a bundle as in the case of the posterior group of fibres where fibres from the corresponding areas of the retina get closely associated before they enter the internal capsule to reach this occipital lobe. The field defects will therefore tend to get more congnious as the posterior end of the lobe is approached when we get congruous upper quadrantic hemianopsias depending upon the site of the tumour. In the early stages, especially if the tumour is anteriorly placed, there may not be any field defect at all.
One other characteristic field in temporal lobe pathology as pointed out by Traquair, is the selective involvement of the unpaired extreme temporal parts of the field (monocular field.) It may be affected selectively or spared in an otherwise homonymous defect.
Convulsions and hallucinations: These are neighbourhood symptoms caused by involvement of the hippocampus and the uncinate gyrus. The convulsions are characterised by an aura of hallucinations of unpleasant smell and taste and sometimes by visual hallucinations of coloured spectra or of actual persons and scenes. [Figure - 45]
Aphasia: Is not an early sign and found in left-sided lesions in right handed persons as a result of extension of the tumour to Broca's area. As visualised by Prof. Woollard there is a cortical lake with two receptors-sensory vision and hearing-and on the emissary side there are two outlets-writing and speech. If the receptor side is affected one gets word blindness or word deafness as the case may be. If the emissary paths are affected we get motor aphasia or agraphia. It is very rare for a single path to be picked out. It is mostly a mixture of one or other of these receptor and emissary paths that get involved so that we may get what is called a jargon of sensory and motor disturbances of speech.
Other signs of pressure on neighbouring structures are:
- hemiparesis---pressure on the peduncle.
- Disturbances of gait-pressure on the cerebellum.
- Ocular palsies involving the VI, IV and III cranial nerves.
- Facial palsy.
| Occipital Tumours|| |
These tumours are rather uncommon to find. Hematoma from a head injury can give rise to the features of a space-occupying cerebral lesion in this part, as in one of our cases. Often an injury may cause a hemorrhage within a tumour in this situation and may precipitate the symptoms and signs of increased intracranial tension and thus indirectly lead to the discovery of the tumour.
Tumours in this situation resemble temporal lobe tumours in many respects and clinical differentiation may be difficult. One has to resort to comparative differences between the two sometimes for this purpose. Thus:
Seizures or fits are more of the epileptic petit or grand mal type in occipital tumours, which are preceded less often by gustatory and olfactory hallucinations than by visual hallucinations.
There are more mental symptoms, like memory defects, lack of attention, drowsiness and lethargy, when the tumour is occipital.
Anomalies of conjugate movements are more often come across, because experimental stimulation of the occipital cortex turns the eyes to the side opposie to the one irritated.
Occipital visual field defects are more congruous than in the case of temporal lobe tumours, and central field defects are more common. [Figure - 47],[Figure - 48],[Figure - 49]
Hemiparesis is less frequent because the peduncles become a more distant relation.
Other features like aphasia, muscle paralysis (indirect), headache, papilloedema do not seem to offer any difference between the two locations.
| Tumours of the Brain Stem|| |
These are found at three locations (i) the midbrain (ii) the pons and (iii) the medulla, but there is never a strict localisation to any one of them. Mostly they are seen in children and are usually gliomas of a malignant order (a) glioblastoma multiforme, (b) astroblastoma (c) spongioblastoma.
A. Midbrain Tumours
Signs of raised intracranial tension are early and severe due to obstruction of the aqueduct of Sylvius.
Since the midbrain contains the nuclei of the III, IV, VI and V (motor nuclei) cranial nerves, the colliculi, the red nucleus and ascending and descending tracts, the symptomatology will reflect the affections of one or more of these structures. Several syndromes have been described according to the location of such lesions. [Figure - 50],[Figure - 51]
1. Parinaud's syndrome: Paralysis of upward or downward conjugate movement through involvement of the upper or lower part of corpora quadrigemina respectively. These are accompanied by pupillary and accommodation disturbances since the pupillary fibres pass through the brachium of the superior quadrigeminal bodies.
2. Benedikt's syndrome: A rhythmic tumor of the arm opposite to the side of the lesion and a third nerve paralysis on the side of the lesion reflect involvement of the red nucleus and the III nerve.
3. Weber's Syndrome: Homolateral III nerve paralysis with hemiplegia of the opposite side signifies involvement of the more ventral part of the midbrain when the cerebral peduncles are involved.
Since the midbrain contains the nuclei of the III and IV cranial nerves, palsies of these nuclei in various forms of admixture, complete or incomplete have to be expected.
B. Pontine Tumours
With the presence of the nuclei of the V, VI, VII and VIII cranial nerves and of the several tracts to which the pons affords passage, the manifestations of pontine lesions will be several. We are mostly concerned with lesions causing paralysis of the V and VI nerves as they come to us first for paralytic squint and facial palsy when the VII is affected. The important thing is to recognise them as nuclear palsies and view such with suspicion since papilloedema is a late manifestation as compared to midbrain tumours.
A typical syndrome here is Foville's syndrome, which is characterized by (a) contralateral hemiplegia, (b) homolateral VI and VII nerve palsies-internal squint with paralysis of facial expression, (c) paralysis of conjugate movement of the eyes to the side of the lesion. Importance lies in the fact that a lesion of the pons causing this sydrome is inoperable.
Other signs of a pontine lesion are (a) cerebellar ataxia, through involvement of the ponto-cerebellar fibres, (b) retention or incontinence of urine, (c) deafness and vertigo.
C. Tumours of the Medulla
Since the symptoms and signs do not involve the eyes, except perhaps papilloedema very rarely, I do not propose to deal with them.
| Cerebellopontine Angle Tumours|| |
They are mostly neuromas, neurofibromas or gliomas in connection with the acoustic and vestibular nerves. Naturally the emphasis of such tumours will be on deafness and vestibular dysfunction.
Ophthalmic symptomatology is of secondary interest since ocular symptoms are late and infrequent. The nerve that suffers most commonly is the fifth, with loss of corneal sensation which along with an incomplete involvement of the facial and unilateral deafness strongly suggests an "angle" tumour.
Pressure on the neighbouring pons gradually evokes symptoms of bulbar paralysis involving ocular movements described under pontine tumours. On the other side involvement of the IX, X causes loss of sensation of taste and dysphagia.
| Cerebellar Tumours|| |
These tumours generally occur in early ages. The tumour often is a medulloblastoma and grows rapidly. The tumours have a tendency to infiltrate along the spinal cord. Haemangioblastoma occurs between 30 and 40 years of age. The cardinal signs are (1) unsteadiness of gait and ataxia. (2) hypotonicity and (3) nystagmus.
The patient is unable to stand, the body oscillates and gets twisted. Cerebellar ataxia is not modified by the aid of vision. The finger to nose test is very positive and very coarse. Fingers cannot perform such simple daily operations as fastening the buttons of a coat.
The muscles feel soft and slack and their weakness and inability to do prolonged work is exhibited by asking the patient to pronate and supinate his hand repeatedly (dysdiadokokinesia).
The nystagmus is coarse and horizontal and slows down as the eyes approach the position of rest. A skew deviation may occur.
The symptoms are those of increased intracranial pressure with ocular and cerebellar signs and pressure on adjacent structures. A slow pulse, severe headache and vomiting even though present have little localising value. Ocular signs met with in these cases are bilateral papilloedema. diplopia due to paralysis mostly of the abducens nerve (indirect type) and nystagmus. Field defects are difficult to obtain in younger individuals and children.
In one year we encountered five cases of cerebellar tumours. Papilloedema was present bilaterally in two cases, it was present in two cases only on the right side and in one case there was optic atrophy. Bilateral paralysis of the external rectus (indirect) was observed in two cases and paralysis of the internal rectus in one. Nystagmus was present in all cases and one patient had a divergent squint.
Of interest was one case of plexiform neuroma in the cerebellar region in a case of von Recklinghausen's disease. The tumour, through the thinned cut occipital bone felt like a bag of worms. Although there were definite signs of cerebellar disease, there were no ocular signs, no headache and no papilloedema.
This brings to an end the presentation of a subject, a huge subject with all the limitations required for presenting it in as condensed a form as possible.
In my introduction I had mentioned about the happy collaboration between ophthalmologist and neurologists. In my concluding remarks I take great pleasure in naming the collaborators, without whose help it would not have been possible to prepare for today's task. I thank them most heartily. You will see that the list is not a small one and they are not all neurologists.
The neurologists are Dr. R. G. Ginde, and Dr. V. G. Daftary. Dr. B. M. Dadhich has helped with X-Ray studies.
Dr. B. S. Syngal, an expert on EEG has provided relevant material from his stock.
Dr. Amin, the senior pathologist has supplied the pathological specimens and literature from records and Dr. Ilona Bulbelis, the neuropathologist of the King Edward Memorial Hospital has done neurophotography work.
Dr. Jadhav, the Superintendent of the Bombay Hospital has made all the relevant case histories available from the hospital records and Dr. D. Sah, registrar of the neurological department has checked them.
Dr. Ursekar (Bombay), Dr. Venkataswamy (Madurai), and Drs. Sengupta and I. S. Roy of Calcutta have provided material and help in various little ways.
Finally there is the silent help from standard text-books by world renowned authors without reference to which no study would be complete and in this connection I offer my thanks to Elder, Dr. Huber.
I have also to thank Dr. S. N. Cooper for his help in rearranging this oration for purposes of publication.
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[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7], [Figure - 8], [Figure - 9], [Figure - 10], [Figure - 11], [Figure - 12], [Figure - 13], [Figure - 14], [Figure - 15], [Figure - 16], [Figure - 17], [Figure - 18], [Figure - 19], [Figure - 20], [Figure - 21], [Figure - 22], [Figure - 23], [Figure - 24], [Figure - 25], [Figure - 26], [Figure - 27], [Figure - 28], [Figure - 29], [Figure - 30], [Figure - 31], [Figure - 32], [Figure - 33], [Figure - 34], [Figure - 35], [Figure - 36], [Figure - 37], [Figure - 38], [Figure - 39], [Figure - 40], [Figure - 41], [Figure - 42], [Figure - 43], [Figure - 44], [Figure - 45], [Figure - 46], [Figure - 47], [Figure - 48], [Figure - 49], [Figure - 50], [Figure - 51], [Figure - 52]