Day #340 - Occular Myasthenia

Today we discussed a patient who presented with bilateral ptosis. EMG revealed evidence of myasthenia gravis and the patient responded to treatment with an acetylcholine esterase inhibitor.




The JAMA rational clinical exam series addresses the physical diagnosis of MG here.



History:

"speech becoming unintelligible during prolonged speaking" LR 4.5

presence of the peek sign increase the likelihood of myasthenia gravis LR 30 (eyes "peek" open within 30 seconds of closure)

Bedside Tests:

• Ice test LR + 24 LR - 0.16
  (apply ice to the eyelids x 2 mins then evaluate response which should be immediate and short-lived)


• Response to an anticholinesterase medication LR+ 15 LR - 0.11
  (give tensilon, look for response within 30 seconds lasting less than 5 mins)


• Sleep test LR+ 53.0; LR - 0.16
  (have patient lie in a dark room resting the eyes for 30 mins, look for improvement of ptosis)

A review of autoimmune NMJ diseases is available here.

A discussion of myasthenia mimics is available here.