0521779407-14 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 21:17
Myasthenic (Lambert-Eaton) Syndrome 1027MYASTHENIC (LAMBERT-EATON) SYNDROME
MICHAEL J. AMINOFF, MD, DSchistory & physical
■Variable weakness, esp. proximally in limbs, typically improving w/
activity
■Diplopia or dysphagia may occur
■Xerostoma, postural dizziness, constipation, impotence common
■May be history of malignancy
■Exam reveals weakness in variable distribution; improves after
exercise
■Depressed tendon reflexes, augmented after exercise
tests
■May be mild response to IV edrophonium
■Electrodiagnostic findings are characteristic
■Chest x-ray may reveal underlying lung cancer
differential diagnosis
■Dysautonomic symptoms, response to activity & association with
malignancy distinguish it from myasthenia gravis
■Pattern & variability of weakness distinguishes myopathies, motor
neuropathies, motor neuronopathies
management
■Underlying malignancy (usually small cell lung cancer) should be
sought & treated
■Ensure ventilation is adequate & prevent aspiration
specific therapy
■Cholinesterase inhibitors (pyridostigmine) may have mild benefit
■Guanidine sometimes helpful in escalating dose
■Diaminopyridine (not available in U.S.)
■Occasional pts require steroids, azathioprine, plasmapheresis or IV
immunoglobulins, as for myasthenia gravis
follow-up
■Close follow-up required to monitor neurologic disorder & underly-
ing malignancy
complications and prognosis
■50% of pts have underlying malignancy
■Aspiration pneumonia & ventilatory inadequacy may have fatal
outcome