ANN OPHTHALMOL. 2000;32(2):146–148146

Reprints:Kaan Gündüz, MD, G.M.K. Bulvari, 116/3, Maltepe 06570, Ankara, Turkey.

The authors are from the Department of Ophthalmology, Faculty of Medicine, AnkaraUniversity, Ankara, Turkey.

C A S E R E P O R T

The most common ocular findings in myastheniagravis are ptosis and ophthalmoplegia. Retraction

of the upper eyelids in myasthenia gravis without evi-dence of thyroid dysfunction is uncommon.1 Kansuand Subutay2 previously reported on 4 myasthenicpatients who presented with lid retraction on 1 sideand normal or ptotic eyelids on the other. Three of the4 patients developed this sign during medical treat-ment and after thymectomy. All 4 cases had normalthyroid function studies, and other signs of thyroiddisease were absent.

Because of the rarity of this condition, we reportanother case of myasthenia gravis developing bilater-al lid retraction during medical treatment afterthymectomy.

Case ReportA 45-year-old man was seen because of intermittentdiplopia on right and left gaze. Ophthalmologic exam-ination showed right-sided ptosis and no apparent pto-sis or lid retraction on the left. Eye movements wereslightly restricted in right and left gaze. Limitation ofupgaze and convergence insufficiency were the otherfindings noted. Light responses of both pupils to lightwere brisk and equal. The ophthalmologic examina-tion was otherwise normal. Neurologic findings weredysarthria, dysphagia, and generalized muscle weak-ness. His complaints worsened on exercise. The edro-phonium chloride test was positive.

Kaan Gündüz, MD, & Teksin Eryilmaz, MD

Bilateral Upper EyelidRetraction in Myasthenia GravisFollowing Thymectomy Surgery

This article reports the case of a 45-year-old man with systemic

myasthenia gravis who developed right upper eyelid ptosis. One

month after thymectomy surgery, he developed bilateral upper eye-

lid retraction. Lid retraction in the absence of thyroid eye disease is

uncommon in myasthenia gravis, although it can develop during

periods of medical treatment and after thymectomy surgery. Exclu-

sion of thyroid disease is essential before ascribing lid retraction to

myasthenia gravis.

A B S T R A C T

ANN OPHTHALMOL. 2000;32(2) 147

A tentative diagnosis of myasthenia gravis wasmade and the patient was placed on pyridostigmine 60mg 5 times daily. His complaints did not improve andhe underwent plasmapheresis 3 times. He subse-quently experienced difficulty in breathing and washospitalized for thymectomy. Histopathologic exami-nation disclosed thymoma. One month after the oper-ation, his symptoms resolved markedly but hedeveloped bilateral upper eyelid retraction 4 mmabove the limbus (Fig 1). Thyroid function studies (T3,T4, TSH, LATS [long-acting thyroid stimulator], anti-thyroglobulin antibodies) and thyroid-releasing hor-mone suppression tests were unremarkable. All 4rectus muscles were normal in magnetic resonanceimaging (Fig 2).

The patient was placed on a tapering dose of 80 mgoral prednisolone and 60 mg pyridostigmine. Theupper eyelid retraction resolved slowly over the next 2months (Fig 3). He has been followed for 4 monthswithout evidence of eyelid retraction and maintainsthe normal eyelid posture depicted in Figure 3. He hasapproximately 2 mm of scleral show below the limbusin both eyes; however, judging by his earlier pho-tographs, he has always had this appearance.

DiscussionIn the evaluation of a myasthenic patient with lidretraction, it should be borne in mind that myastheniagravis may be associated with thyroid eye disease.1

Thyroid disease is still the most common cause of lidretraction in a myasthenic patient. In our patient, thy-roid function tests and thyrotropin-releasing hormonesuppression test were within normal limits. Extraocu-lar muscles were normal in magnetic resonance imag-ing studies. Consequently, the presence ofconcomitant thyroid ophthalmopathy was excluded.

Lid retraction in myasthenia gravis can take sever-al types. Cases that demonstrate lid retraction afterprolonged upgaze are explained by post-tetanic facili-tation.3 Some other cases may demonstrate Cogan’s lidtwitch sing, which means lid retraction following a

saccade from downward gaze to primary position.4

Finally, patients with unilateral ptosis may develop lidretraction on the other side in the attempt to elevatethe ptotic lid.5 Our patient developed bilateral lidretraction after thymectomy surgery while he hadright upper eyelid ptosis before.

The cause of lid retraction in myasthenia gravis isnot well understood. Hering’s law of equal innervationof yoke muscles has been used to explain this phe-nomenon. The levator palpebra superior muscle onthe ptotic side receives increased innervation by Her-ing’s law of equal innervation and the contralaterallevator muscle also receives increased stimulation,which results in lid retraction.5,6

Another explanation may be that because theretraction is frequently seen after institution of treat-ment, facilitation of activation in myasthenicallyinvolved muscles may be responsible. In other words,cholinergic overstimulation of the neuromusculartransmission may be the explanation.2,7

Yet another surmise may be that the myasthenicpatient prefers fixation by the least affected eye, in amanner similar to that in acquired nerve palsies. Thismay be the eye that has the ptotic lid. Therefore, theptotic lid assumes a normal position as it is elevatedabove the visual axis, but this effort produces retrac-tion on the opposite side.2,7

Because lid retraction was observed bilaterally inour patient, we believe the second mechanism, ie,facilitation of activation or cholinergic overstimula-tion, might have been responsible. Although the lidretraction resolved after oral corticosteroid and pyri-dostigmine treatment, we cannot be certain about therelative benefit of each medication on the resolutionof the lid retraction.

We think this case presentation is interestingbecause it touches on a rarely noted occasion of lidretraction in myasthenia gravis. It must be empha-sized that exclusion of thyroid eye disease is essentialbefore ascribing this clinical presentation to myasthe-nia gravis.

Fig 1.—Facial photograph shows bilateral upper lid retraction after thymectomyoperation.

Fig 2.—Axial T2 weighted magnetic resonance image of the brain and orbit demon-strates normal medial and lateral rectus muscles.

ANN OPHTHALMOL. 2000;32(2)148

References1. Burde RM, Savino PJ, Trobe JD. Clinical Decision-making in

Neuro-ophthalmology. St. Louis: Mosby; 1985:175–254.2. Kansu T, Subutay N. Lid retraction in myasthenia gravis. J Clin

Neuro-ophthalmol. 1987;7:145–148.3. Puklin JE, Sacks JG, Boshes B. Transient eyelid retraction in

myasthenia gravis. J Neurol Neurosurg Psychiatry. 1976;39:44–47.4. Cogan DG. Myasthenia gravis: a review of the disease and a

description of lid twitch as a characteristic sign. Arch Ophthalmol.1965;74:217–221.

5. Schechter RJ. Ptosis with contralateral lid retraction due to exces-sive innervation of the levator palpebrae superioris. Ann Ophthal-mol. 1978;10:1324–1328.

6. Walsh TJ. Neuro-ophthalmology: Clinical Signs and Symptoms.3rd ed. Philadelphia: Lea Febiger; 1992:156–161.

7. Walsh FB, Hoyt WF. Clinical Neuro-ophthalmology. Vol. 2. 3rd ed.Baltimore: Williams and Wilkins; 1969:1284–1285.

Fig 3.—Facial photograph demonstrates resolution of upper eyelid retraction after 2months of medical treatment with oral steroids and pyridostigmine.