|Year : 2002 | Volume
| Issue : 2 | Page : 142-144
Inverse marcus gunn phenomenon
MV Prakash, M Radhakrishnan, A Yogeshwari, W Nazir, K Maragatham, K Natarajan
Department of Orbit and Oculoplasty, Regional Institute of Ophthalmology, Government Ophthalmic Hospital, Egmore, Chennai, India
M V Prakash
Department of Orbit and Oculoplasty, Regional Institute of Ophthalmology, Government Ophthalmic Hospital, Egmore, Chennai
Inverse Marcus-Gunn phenomenon is very rare. It is usually acquired. We report a young male patient presenting with congenital ptosis and inverse Marcus-Gunn phenomenon
Keywords: Inverse Marcus-Gunn phenomenon, ptosis, synkinesis
|How to cite this article:|
Prakash M V, Radhakrishnan M, Yogeshwari A, Nazir W, Maragatham K, Natarajan K. Inverse marcus gunn phenomenon. Indian J Ophthalmol 2002;50:142-4
|How to cite this URL:|
Prakash M V, Radhakrishnan M, Yogeshwari A, Nazir W, Maragatham K, Natarajan K. Inverse marcus gunn phenomenon. Indian J Ophthalmol [serial online] 2002 [cited 2014 Aug 27];50:142-4. Available from: http://www.ijo.in/text.asp?2002/50/2/142/14802
Paradoxical (synkinetic) movements of the upper lids constitute a rare type of congenital anomaly, noted in association with movements of either extra-ocular muscles or the muscles of mastication (external pterygoids). These movements are outside the volition of the patient and termed 'associated reflexes of misdirection'. Marcus-Gunn (M-G) jaw-winking phenomenon is the most common congenital synkinetic movement. When the mouth is opened or the jaw is moved laterally, the ptotic eyelid elevates. This results from a congenital, aberrant connection between the trigeminal nerve controlling mastication and the oculomotor nerve supplying the levator. In inverse M-G phenomenon the upper lid falls to cover the eye with movements of mastication. This is more commonly seen as an acquired rather than congenital anomaly in central nervous system (CNS) disease. This has to be differentiated from facial synkinesis following seventh nerve paresis.
| Case report|| |
A 20-year old male patient presented with drooping of left upper lid since birth and defective vision in left eye since 6 years. He was moderately built and well nourished. On refraction, his best-corrected visual acuity was 6/6, N6 in each eye. Both eyes showed horizontal widening of palpebral fissure (35 mm) as in euryblepharon. He had a mild chin elevation.
Extraocular movements were full in right eye but the left eye showed restriction of elevation and abduction by 15° (Hess screen). There was 4 mm ptosis in the left eye along with 15° hypotropia. On fixing with left eye, there was no change in the amount of ptosis. The left eye was found suppressed in Worth's four dot test. The lid crease level was 5 mm in both eyes. The levator function was 15 mm in the right eye and 6 mm in left eye. The ptotic left eye revealed inverse M-G phenomenon - on opening the mouth, the ptosis increased instead of decreasing. Bell's phenomenon was absent.
Slitlamp examination showed normal anterior segment in both eyes. Intraocular pressure (IOP) was 17.3 mm Hg by (Schiotz tonometry). Ophthalmoscopy showed normal fundi in both eyes. No abnormality was noticed on the central nervous system (CNS) examination.
The patient was not willing to have ptosis surgery. As Bell's phenomenon was absent, surgical correction was not considered. Crutch glasses were advised as a palliative measure.
| Discussion|| |
Synkinesis is a simultaneous movement or a coordinated sequence of movements of muscles supplied by different nerves or by separate peripheral branches of the same nerve. Marcus-Gunn jaw winking is a well-recognized synkinesis in congenital ptosis. It was first reported by Marcus-Gunn in 1883. In its fully developed form, the upper lid covers the upper half of cornea at rest (a condition of partial ptosis), but when the jaw is opened, the apparently paretic upper lid shoots upward to a level higher than that of the normal eye. In attempt to look upwards, the mouth is usually opened, thus allowing the lids to be raised. The upshoot of the lid occurs on the act of opening the jaw but is not maintained if the mouth is kept open. If the jaw is deviated to the affected side, the ptosis increases, but if it is deviated towards the opposite side, a maximal retraction occurs.
In inverse M-G phenomenon, the ipsilateral eyelid closes when the external pterygoid muscle moves the jaw to the opposite side. When eyes are in primary position and mouth closed, there is a mild degree of ptosis in the affected eye. This movement is governed by the orbicularis oculi and initiated not by movements of the mandible, but by the lower facial muscles. This syndrome was seen only in the presence of facial hemiparesis or spasm. Thus it seemed to be an interfacial association rather than trigemino-facial synkinesis..
The exact mechanism of all these associated movements is not fully understood. The most commonly accepted hypothesis is that an abnormal nervous connection exists in the CNS between the nerve supply of the levator and the associated muscle. The levator palpebrae superioris (LPS) is perhaps innervationally connected not only with the third nucleus but also with the external pterygoid portion of the fifth nucleus. The exact level of this anomalous connection is disputed. No anatomical basis for this hypothesis has been demonstrated.
In acquired cases, there seems to be a functional interference, either by irritation or the release of inhibition, with the unknown paths of communication between the cortical and sub-cortical centers or a spread of impulses by irradiation. Harman (1903) suggested an atavistic reversion to the relationship between the mouth and gills found in fishes, where there is a close association between the superficial and deep muscles around the mouth. These muscles are represented in man by the external pterygoid and orbicularis respectively. In man, the actions of the levator and orbicularis are normally well balanced. In M-G ptosis, since the balance is upset, the weak levator can lift the lid only when its antagonist, the orbicularis is reflexly relaxed.
The inverse M-G phenomenon suggests an awakening of an ancient phylogenetic reflex. It can be argued that the old intimate association of the orbicularis and the external pterygoid muscles, although separated in the course of development, may be re-united as a release-phenomenon in presence of supra-nuclear lesion affecting the cortical connections of the trigeminal system. In normal subjects, Sano has demonstrated by electromyography (EMG), distinct co-firing of the extraocular muscles innervated by the third nerve and the muscles of mastication innervated by the fifth nerve. This supports Wartenberg's hypothesis of 'release-phenomena'. Therefore, release-phenomena represent failure of inhibition of primitive reflexes.
Facial synkinesis in a patient recovering from seventh nerve paresis is a different entity. Here, ipsilateral involuntary narrowing of the palpebral fissure is noticed on volitional contraction of the orbicularis oris and other facial muscles. In addition, the lower facial muscles may contract during volitional eye closure. This phenomenon is caused by aberrant regeneration of the seventh nerve with sprouts of axons supplying more than one muscle group. EMG showed that the narrowing of the palpebral fissure was secondary to contraction of the ipsilateral orbicularis oculi muscle and not due to inhibition of levator.
In the inverse M-G phenomenon, Lubkin demonstrated by EMG, inhibition of the affected LPS muscle concurrent with external pterygoid contraction, but no associated activity of the orbicularis oculi. Therefore, trigeminal innervation to the pterygoids is associated with inhibition of the oculomotor branch to the levator. In the true M-G phenomenon, it is associated with excitation of the oculomotor branch to the levator.
Treatment may not be necessary for patients with a slight degree of deformity. For acute cases, bilateral frontalis sling with disinsertion of the levator has been suggested. Medline search revealed only 2 reports of acquired inverse M-G phenomenon., Both these cases were following facial nerve palsy. The patient reported had moderate ptosis of left eye since birth. He has not suffered from facial paresis or any other CNS disease earlier. Restriction of elevation and abduction was most probably due to the associated congenital abnormality of the superior rectus and lateral rectus muscles. The congenital origin of the inverse M-G phenomenon reported here is rare.
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[Figure - 1], [Figure - 2]
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