Lambert-Eaton Syndrome

Question 1

What is Lambert-Eaton Myasthenic Syndrome?

Answer 1

a rare autoimmune disorder involving the neuromuscular junction

Question 2

What is the primary clinical manifestation of lambert-eaton syndrome?

Answer 2

muscle weakness

dif. climbing stairs or arising from chair is common early sxs due to weakness of pelvic girdle muscles

Question 3

50% of cases are associated with…

Answer 3

malignancy > paraneoplastic syndrome

MC: small cell lung CA

Question 4

Risk factors for Lambert-eaton syndrome?

Answer 4

malignancy

personal or fam hx of autoimmune disorder

Question 5

Pathophys of lambert-eaton syndrome?

Answer 5

Abs bind to the voltage gated calcium channel > interfere with calcium influx > reduced Ach release from presynaptic membrane > impaired muscle func

Question 6

paraneoplastic v. non-neoplastic LEMS?

Answer 6

paraneoplastic tend to experience more rapid progression and higher level of impairment

Question 7

Sxs of LEMS?

Answer 7

• slow progressive symmetric proximal limp/muscle weakness
• alteration in gait
• muscle fatiguability or cramping after prolonged exercise
• autonomic dysfunction i.e dry mouth, ptosis, diplopia

Question 8

PE findings for LEMS?

Answer 8

• alteration in gait
• depressed or absent DTRs but post-exercise facilitation:: recovery of DTRs or improvement in muscle strength with brief muscle vigorous activation
• dry mouth, ptosis, sluggish pupillary light reflex

Question 9

How can you tell the difference btwn MG and LEMS?

Answer 9

Muscle strength/DTRS improve with muscle activation in LEMS

in MG, the more they use their muscles the weaker they will be

Question 10

Presentation of Lambert eaton syndrome v. Guillan Barre syndrome?

Answer 10

LEMS: progressive symmetrical proximal muscle weakness + autonomic dysfunction

GBS: weakness starts at feet/LE and ascends, NO autonomic dysfunction

Question 11

Diagnostic tests for LEMS?

Answer 11

nerve conduction studies (NCS) and needle electromyography (EMG)

VGCC abs

Malignancy work up: CXR CT, biopsy

Question 12

How does presentation of LEMS differ from that at ALS?

Answer 12

LEMS- symmetrical muscle weakness

ALS: unilateral

Question 13

Tx for LEMS?

Answer 13

if paraneoplastic > tumor resection may reverse sxs

if mild weakness > monitor

if mod/severe >

• Pyridostigmine: Acetylcholinesterase-I
• 3,4 diaminopyridine: enhances Ca entry at presynaptic terminal

Prednisone and Azathioprine

IV immune globulin