Patients with myasthenia gravis or the Lambert-Eaton myasthenic syndrome may present limb weakness. These conditions can often be distinguished based on clinical and laboratory findings.
Parameters:
(1) ocular involvement
(2) bulbar involvement
(3) deep tendon reflexes
(4) sensory symptoms
(5) autonomic involvement
(6) tensilon test findings
(7) serum antibodies
(8) findings on electrodiagnostic tests
|
Parameter |
Myasthenia Gravis |
Lambert-Eaton |
|
ocular involvement |
common, prominent |
uncommon, subtle |
|
bulbar involvement |
common, prominent |
uncommon, subtle |
|
deep tendon reflexes |
normal |
absent or depressed |
|
sensory symptoms |
none |
paresthesias common |
|
autonomic involvement |
none |
dry mouth, impotence, gastroparesis |
|
tensilon test |
often positive |
occasionally positive |
|
serum antibodies |
postsynaptic acetylcholine receptor |
presynaptic voltage-gated receptors; directed against calcium channels |
|
Electrodiagnostic Test Findings |
Myasthenia Gravis |
Lambert-Eaton |
|
motor nerve conduction |
normal |
low amplitudes |
|
post-exercise motor |
no change |
significant amplitudes (more than 50%) |
|
slow repetitive nerve stimulation |
decrement |
decrement |
|
rapid repetitive nerve stimulation |
no change or decrement |
increment |
Purpose: To distinguish between myasthenia gravis and the Lambert-Eaton myasthenic syndrome by clinical and laboratory findings.
Specialty: Immunology/Rheumatology
Objective: clinical diagnosis, including family history for genetics, laboratory tests, differential diagnosis and mimics, red flags
ICD-10: G70, G70.8,
