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Show Journal of Clinical Neuro-ophthalmology 7(3):145-148,1987. Lid Retraction in Myasthenia Gravis Tulay Kansu, M.D., and Nese Subutay, M.D. rg 1987 Raven Press, Ltd., New York Four of 150 patients with myasthenia gravis had upper lid retraction. Only two had apparent ptosis in the contralateral eye. Three patients developed this paradoxical sign during medical treatment and after thymectomy. Hering's law of equal innervation does not adequately explain this phenomenon, and the possibility of cholinergic overstimulation in neuromuscular transmission is raised. Key Words: Lid retraction-Myasthenia gravis-Ptosis -Ophthalmoplegia. From the Department of Neurology, Neuro-ophthalmology Unit, Hacettepe University Hospitals, Ankara, Turkey. Address correspondence and reprint requests to Tulay Kansu, M.D., Department of Neurology, Neuro-ophthal· mology Unit, Ankara, Turkey. /45 The ocular findings of myasthenia gravis are the result of dysfunction at the myoneural junction. The most common ocular findings are asymmetric ptosis and ophthalmoplegia. Long-standing retraction of the upper lids in myasthenia gravis without evidence of thyroid dysfunction is uncommon (1). From the literature, it is impossible to derive the frequency of occurrence of this seemingly paradoxical finding. In the presence of lid retraction, a mild contralateral ptosis can be overlooked. If other signs of myasthenia gravis are absent, the diagnostic evaluation of what appears to be unilateral lid retraction will turn in an appropriate direction. Since we have observed unilateral lid retraction in 4 of our 150 myasthenic patients, we would like to call attention to this unusual presentation. CASE REPORTS Case 1 A 26-year-old woman was seen with transient diplopia in January 1982. The examination was within normal limits. Two months later she developed dysarthria, dysphagia, and ptosis of the left eyelid. The diagnosis of myasthenia gravis was made, and pyridostigmine was started. A thymectomy was performed in January 1982. A month later, right upper lid retraction was noted. The right upper lid was 1 mm above the limbus, and the left appeared to be in the appropriate position (Fig. 1). There was no weakness of lid closure. Thyroid function studies were within normal limits. The patient was maintained on pyridostigmine, and methylprednisolone was added to the treatment because of ocular and generalized findings. The retraction of the right eyelid remained during the period of observation of the next 4 months. /46 T. KANSU AND N. SUBUTAY FIG. 2. Case 2: ptosis on the right and retraction on Case 4 A 22-year-old man was first seen in July, 1980, with a history of diplopia and left ptosis. Eye movements were restricted on lateral gaze bilaterally, and upward gaze was limited in the left eye. There was a marked ptosis on the left (Fig. 4A). The remainder of the neurological examination was normal. The edrophonium chloride test was positive, and treatment was started with pyridostigmine, 60 mg four times daily. The patient subsequently developed generalized weakness and difficulty with breathing. He was hospitalized in January, 1982, for steroid treatment and thymectomy. On admission, his eye movements were restricted in all directions. He had bilateral ptosis (Fig. 4B) and proximal weakness in all four limbs. After thymectomy, while he was receiving pyridostigmine (60 mg seven times daily) and deltacortryl (60 mg per day), a marked lid retraction was FIG. 3. Case 3: right ptosis and left retraction. tient's bulbar symptoms improved, but mild generalized weakness and ocular findings persisted 1 month after her discharge while she was receiving anticholinesterase and steroid treatment. Case 3 A 24-year-old man was first seen in January, 1986, with a 2-month history of right ptosis and intermittent diplopia on right gaze. On examination, a mild ptosis on the right and retraction of the left upper lid (1 mm above the limbus) were noted (Fig. 3). Eye movements were mildly restricted on adduction and abduction. The remainder of the neurological examination was normal. The edrophonium chloride test was positive, and thyroid function studies were normal. Pyridostigmine, 60 mg three times a day, was started, and 1 month later there was marked improvement in the right ptosis and left lid retraction. FIG. 1. Case 1: upper lid retraction on the right and no apparent ptosis on the left. Case 2 A 17-year-old woman presented in August, 1982, with an acute onset of diplopia and a 10month history of left-sided ptosis. Bulbar symptoms developed while she was on anticholinesterase medication, and she was hospitalized for thymectomy. Prior to admission, a left-sided ptosis and right upper lid retraction were noted; however, on admission, the lid retraction was no longer present. Eye movements were restricted in all directions of gaze in the left eye and on upgaze in the right eye. The patient had bilateral facial, palatal, and limb weakness that was more prominent proximally. On the eighth postoperative day, right-sided ptosis and a marked left-sided lid retraction were noted (Fig. 2). The retracted lid remained slightly behind the globe on downgaze. Thyroid function studies were normal. The pa- J Clill Nellro-opllthalmol, Vol. 7, No.3, 1987 FIG. 4. Case 4: ocular findings at different stages of the disease. A: Ptosis and limited upgaze on the left. B: Bilateral ptosis. C: Left lid retraction with no apparent ptosis on the right. c MYASTHENIA GRAVIS 147 noted in the left eye (3 mm above the limbus). There was no apparent ptosis in the right eye (Fig. 4C). On the last follow-up examination in January, 1986, while the patient was on pyridostigmine, 60 mg four times daily, and deltacortryl, 20 mg per day, he was asymptomatic; neurological examination was within normal limits. DISCUSSION There appear to be three types of eyelid retraction that may be observed in myasthenia gravis (2). First, patients with ptosis may develop brief eyelid retraction lasting only a few seconds follOWing a saccade from downward gaze to primary position (Cogan's lid twitch sign) (3). Second, patients may develop transient eyelid retraction lasting several seconds or minutes after looking upward for several minutes. This finding is explained by posttetanic facilitation of the levator palpebrae superioris (4). Finally, patients with unilateral ptosis may develop contralateral eyelid retraction as they attempt to elevate the ptotic lid. Sustained or long-duration lid retraction in myasthenia gravis with ptosis of the contralateral eyelid, as represented by our patients, is a fairly well-known but not often cited feature of the disease, although the finding has been reported as far back as the early 1900s (5-7). The usual explanation for lid retraction in myasthenia gravis is Hering's law of equal innervation of yoke muscles (8). If a patient has myasthenic ptosis in the right eye, his or her nervous system attempts to keep the eye open by increasing the level of innervation to the right levator palpebrae superioris. According to Hering's law, the nonptotic left levator also receives increased innervation, and, since it is less involved by the myasthenic process, it rises above the normal position and appears retracted while the other lid may appear to be positioned normally or to be slightly ptotic. If the ptotic lid is covered or the lid manually elevated, the retraction in the other eye may disappear. Although Hering's law is offered as an explanation for lid retraction, the fact that lid retraction is rarely seen (and in three of our cases only developed after institution of therapy) makes us question the validity of this hypothesis. We feel a possible explanation for eyelid retraction in patients with myasthenia gravis is the facilitation of activation of JClill NelirO-Ol'hthalmol. Vol. 7, No.3, ]987 148 T. KANSU AND N. SUBUTAY myasthenically involved muscles by various treatment regimes (9).1 In the evaluation of a myasthenic patient with lid retraction, it should be remembered that myasthenia gravis is often associated with thyroid disease. Thyroid disease, of course, is the most common cause of lid retraction. In thyroid disease, the lid retraction, at least initially, is due to sympathetic stimulation of Mueller's muscle. Later, fibrosis of the levator palpebrae superioris occurs, and the result is a stiff, fibrotic lid (10). The fact that the patients presented here had normal thyroid function studies and absence of other signs of thyroid disease is additional evidence that these patients did not have a subclinical thyroid ophthalmopathy. 2 The lid retraction in our four patients indicates that this finding is one to look for in patients with myasthenia gravis and should be included among the ocular signs of myasthenia gravis. The underlying mechanisms may need further explanation. REFERENCES 1. Burde RM, Savino PJ, Trobe JD. Clinical decisions in neuroophthalmology. St. Louis: Mosby, 1985:175, 254. 2. Miller NR. Walsh and Hoyt's clinical neuro-ophthalmology (vol. 2). 4th ed. Baltimore: Williams & Wilkins, 1985:844-5. 3. Cogan DG. Myasthenia gravis: a review of the disease and a description of lid twitch as a characteristic sign. Arch Ophthaimol 1965;74:217-21. 4. Puklin JE, Sacks JG, Boshes B. Transient eyelid retraction in myasthenia gravis. J Neural Neurosurg Psychiatry 1976; 39:44-7. 5. Buzzard T. Clinical lecture on cases of myasthenia gravis pseudo-paralytica. Br Med J1900;1:493-6. 6. Walsh FB. Myasthenia gravis and its ocular signs: a review. Trans Am Ophthalmol Soc 1943;41:556-624. 7. Chavanne H, Girard PF, Rougier J. Retraction paipebrale et myasthenie oculaire. Rev OtoneuroophthaI1955;27:18-21. 8. Gay A], Salmon ML, Windsor CEo Hering's law, the levators and their relationship in disease states. Arch OphthalmoI1967; 77:157-60. 9. Walsh FB, Hoyt WF. Clinical neuro-ophthalmology (vol. 2). 3rd ed. Baltimore: Williams & Wilkins, 1969:1284-5. 10. Dresner Sc, Kennerdell JS. Dysthyroid orbitopathy. Neurology 1985;35:1628-34. 1 Editor's (R.M.B.) /late: The authors feel that a Significant problem with invoking Hering's law to explain lid retraction in myasthenia gravis is that lid retraction is an infrequent finding in patients with myasthenia ptosis. From the editorial viewpoint, a more plausible explanation for the infrequent finding of lid retraction in patients with myasthenic ptosis is that patients prefer to fix with the least involved eye, a pattern similar to that adopted by most patients with acquired ocular motor palsies. The onset of lid retraction following the institution of therapy in three of the patients presented here is best explained by making fixation with a dominant eye easier by allowing a ptotic lid to assume a position where it can be elevated above the visual axis. This effort will produce lid retraction on the opposite side. 2 Editor's (R.M.B.) /late: In patients with lid retraction associated with thyroid disease, the lid remains retracted in downward gaze, whereas in patients with myasthenia gravis, with prolonged downgaze the lid will slowly relax to an appropriate position. I Clin Nellro-ophthalmol, Vol. 7, No.3, 1987 |
