Myasthenia Gravis:

32-year-old female with progressive LUL ptosis for several years

Myasthenia Gravis:

32-year-old female with progressive LUL ptosis for several years

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Chief Complaint: 32-year-old female examined in oculoplastics for evaluation and repair of LUL ptosis.

History of Present Illness: Patient noted progressive ptosis of the LUL for 5 years, which now blocks her vision. She has no other complaints or problems.

POH/PMH: Healthy, no history of eye problems.

EXAM:

• Vision 20/20 OU without correction.
• Extraocular motility with -2 elevation defect OU.
• VF full OD, VF with ~20% superior VF cut OS.
• Pupils: 5 mm in the dark, 3 mm in the light, no RAPD, equally reactive
• IOP 18 mmHg OU
• Anterior segment normal.
• DFE normal.

Patient maintains chin up position. There's RUL retraction and marked ptosis OS. Palpebral fissures are 10 mm OD and 5 mm OS with palpebral function of 15 mm OD and 10 mm OS. There is a twitching of the LUL when the patient looks up after looking down.

Discussion

This young female presented with progressive LUL ptosis, Cogan's lid twitch, and bilateral ophthalmoplegia on upgaze. The diagnosis of myasthenia gravis was made. After careful history taking, she states that her RUL retraction is better and her LUL ptosis is less in the morning. Because of equal innervation of the levator (Hering's law), asymmetric ptosis may cause lid retraction on the opposite side as the patient is attempting to maintain lid opening. With lid retraction, you should think of thyroid disease, but usually we do not see ptosis with Grave's ophthalmopathy (however 5% of myasthenia gravis patients could have underlying Grave's).

Myasthenia gravis, although a systemic disease, may present with only ocular symptoms 50% of the time. Patients often present complaining of binocular diplopia, and the ocular motility deficits may mimic other neurologic disorders, e.g. 6th nerve palsy, 4th nerve palsy, internuclear ophthalmoplegia, etc... The hallmark signs of myasthenia gravis include: fluctuation & fatigability, diplopia, ophthalmoplegia, ptosis, weakness of jaw, weak neck/trunk/limbs, dysphagia, hoarseness, dysarthria, and dyspnea. Clearly, some of these manifestations may be life threatening.

Because some patients with myasthenia may have an underlying thymoma, a CT scan of the chest should be performed. In this case it was negative.

We performed the Tensilon test (edrophonium chloride) IV. This is a short acting acetylcholinesterase inhibitor.

Photo of lids before Tensilon. Note the RUL retraction and LUL ptosis.

Click here for video demonstrations of manifestations of Myasthenia Gravis and the response to testing. Special thanks to Drs. Kardon and Olson for sharing this video.

Photo of lids after Tensilon. Note the RUL retraction is less and the LUL ptosis improved.

Photo of lids after treatment with Mestinon (pyridostigmine bromide).

Diagnosis of myasthenia gravis can be confirmed by the presence of anti-Ach receptor antibodies, but a NEGATIVE result does not rule-out myasthenia gravis because the panel of antibodies screened may not be complete. Also, a NEGATIVE Tensilon test does not rule-out the disease either. If myasthenia gravis is still suspected, then a Prostigmin test (longer acting acetylcholinesterase inhibitor) should be given with atropine (prevent life threatening bradycardia and respiratory depression). The ice or sleep test may also be useful.

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Diagnosis: Myasthenia gravis

EPIDEMIOLOGY Prevalence : 1-14 per 100,000 Male:Female ratio 2:3 Ages: neonates from maternal antibodies, bimodal distribution of 20-30-year-olds and 50+-year-olds. Autoimmune disease of postsynaptic ACh receptors of unknown etiology.	SIGNS Cogan's lid twitch Unilateral ptosis with contralateral lid retraction. Improvement of symptoms with rest. Improvement of symptoms with ice test. Positive anti-ACh receptor AB test (50% of cases may be false negatives, so a negative test does not rule-out disease). Improvement of symptoms with edrophonium or neostigmine test.
SYMPTOMS Ptosis. Ophthalmoplegia. May present as only ocular myasthenia gravis ~50% of the time. Systemic manifestations include: shortness of breath, dysphagia, hoarseness, and fatigue. May be associated with Grave's in ~5% of cases. May mimic other cranial nerve palsies, e.g., 6th nerve palsy, 4th nerve palsy, internuclear ophthalmoplegia, etc... May be associated with thymoma.	TREATMENT Treat patient with neurology consultation. May follow patient closely if patient has mild symptoms. For symptomatic patients, pyridostigmine bromide 60 mg PO 4X/day with dosage adjustment according to response. Dosing of over 120 mg PO Q3H is rarely helpful.Systemic steroids may be needed for severe cases. Other immunosuppressive therapy may be indicated. Removal of thymoma.

Differential Diagnoses

• Myasthenia-like syndrome due to medications
• Chronic progressive external ophthalmoplegia (CPEO) & Kearns-Sayre syndrome
• Eaton-Lambert Syndrome
• Third-Nerve Palsy (must rule-out in young person b/c pupil involved third-nerve palsy in a young person WITHOUT vasculopathic risk factors is a PCOM aneurysm until proven otherwise)
• Horner's syndrome (look for anisocoria).
• Levator dehiscence or disinsertion.
• Thyroid disease
• Myotonic dystrophy
• Congenital fibrosis (b/c of the restriction of eye movements)