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| + | ====== Ocular Myasthenia Gravis ====== | ||
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| + | ===== Clinical Features ===== | ||
| + | * Triad: Ptosis, Oculomotor paresis and Obicularis oculi weakness | ||
| + | * **Ptosis** may be unilateral or bilateral | ||
| + | * Alternating ptosis is specific for this condition | ||
| + | * **Eyelid fatigue** | ||
| + | * Ptosis worsens with prolonged upgaze or upon return to primary gaze | ||
| + | * **Cogan' | ||
| + | * After brief but sustained downgaze, a saccade to primary gaze results in the eyelid quickly rising and falling (1 mm or more typically) | ||
| + | * **Eyelid Curtaining** | ||
| + | * When lifting the more ptotic eyelid, the contralateral eyelid will droop more because of Hering' | ||
| + | * Resting for 5 minutes with the eyes closed will cause improvement in ptosis | ||
| + | * Strabismus that fluctuates or appears fatiguable | ||
| + | * Any type of strabismus possible | ||
| + | * prolonged or sustained gaze in the field of action of the affected muscle may show increasing paresis | ||
| + | * Lagophthalmos is rare | ||
| + | * attempt to open the eyelid against forced closue- if the eyelid can be opened it suggest obicularis weakness | ||
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| + | ===== Diagnostic Tests ===== | ||
| + | ==== Antibody Tests ==== | ||
| + | * **Acetylcholine Receptor Antibody** | ||
| + | * sensitivity 50% in Ocular myasthenia vs 90% in Generalized myasthenia | ||
| + | * The most specific test, no false positives have been reported | ||
| + | * Muscle specific tyrosine kinase antibodies (MuSK) | ||
| + | * Rare cares of this antibody present in the setting of ocular myathenia without acetylcholine receptor antibodies | ||
| + | * LRP4 antibodies | ||
| + | * 3 cases reported these present in setting of ocular myasthenia | ||
| + | ==== Other tests ==== | ||
| + | * **Ice Pack Test** | ||
| + | * Place a bag of ice on the ptotic lid for 1 minute | ||
| + | * Immediately asses ptosis when ice removed | ||
| + | * improvement is transient (<1 min) | ||
| + | * sensitivity 80% if prominent ptosis present | ||
| + | * **Tensilon test** | ||
| + | * Edrophonium- inhibits acetylcholinesterase | ||
| + | * transiently reverses muscle weakness | ||
| + | * Sensitivity 85-95% | ||
| + | * Electrophysiology | ||
| + | * Repetitive nerve stimlation- reduction in amplitudes with repetitive stimulation | ||
| + | * Single-fiber EMG- temoral variability of adjacent motor nerve fibers known as " | ||
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