Lambert-Eaton myasthenic syndrome: Difference between revisions
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==Background== | |||
*Disease of the neuromuscular junction leading to primary presentation of weakness | |||
*Caused by auto-antibodies against the voltage-gated calcium channels at the NMJ | |||
==Clinical Features== | |||
*Often presents with alteration in gait or difficulty rising from a chair | |||
*Symmetrical muscle weakness and fatiguability often beginning in lower extremities | |||
*Autonomic dysfunction (dry mouth, erectile dysfunction) | |||
*Compared with myastenia gravis, ELS begins with lower extremities weakness and rarely begins with extraocular muscle weakness | |||
*Respiratory failure can occur in late stages of the disease | |||
*Paraneoplastic and autoimmune form of LEMS have similar signs and symptoms | |||
==Differential Diagnosis== | |||
*Myasthenia Gravis | |||
*Myositis | |||
*Dermatomyositis | |||
*Amyotrophic Lateral Sclerosis | |||
*Limb-Girdle Muscle Dystrophy | |||
*Inclusion Body Myositis | |||
==Diagnosis== | |||
*Diagnosis is generally a clinical diagnosis | |||
*Confirmation testing for VGCC antibodies | |||
*Neurophysiologic testing | |||
==Management== | |||
*Guanidine | |||
*Aminopyridines | |||
*Acetylcholinesterase inhibitors | |||
*IVIG | |||
*Glucocorticoids | |||
*Plasma exchange | |||
==Disposition== | |||
*Referral to rheumatology | |||
*Any patients with risk factors for small cell lung cancer will need to be referred for evaluation of underlying malignancy | |||
==See Also== | |||
==External Links== | |||
==References== | |||
<UpToDate> |
Revision as of 12:50, 7 February 2016
Background
- Autoantibodies against Ca channels of axon nerve terminals responsible for ACh release
- Epidemiology
- Predominantly a disease a/w older men w/ history of cigarette smoking and lung cancer
- 50% of pts have concurrent small-cell lung cancer
- Syndrome can precede detection of malignancy by several years
- Predominantly a disease a/w older men w/ history of cigarette smoking and lung cancer
Clinical Features
- Fluctuating symmetric weakness and fatigue, esp of proximal leg muscles
- Improvement in strength with sustained or repeated exercise (in contrast to MG)
- Lambert sign: handshake strength increases over several seconds
- Myalgias
- Muscle stiffness (especially in hip and shoulders)
- Paresthesias
- Metallic taste
- Autonomic symptoms (dry mouth, impotence)
- Eye movements are unaffected
- Sensory examination normal
Differential Diagnosis
Weakness
- Neuromuscular weakness
- Upper motor neuron:
- CVA
- Hemorrhagic stroke
- Multiple sclerosis
- Amyotrophic Lateral Sclerosis (ALS) (upper and lower motor neuron)
- Lower motor neuron:
- Spinal and bulbar muscular atrophy (Kennedy's syndrome)
- Spinal cord disease:
- Infection (Epidural abscess)
- Infarction/ischemia
- Trauma (Spinal Cord Syndromes)
- Inflammation (Transverse Myelitis)
- Degenerative (Spinal muscular atrophy)
- Tumor
- Peripheral nerve disease:
- Neuromuscular junction disease:
- Muscle disease:
- Rhabdomyolysis
- Dermatomyositis
- Polymyositis
- Alcoholic myopathy
- Upper motor neuron:
- Non-neuromuscular weakness
- Can't miss diagnoses:
- ACS
- Arrhythmia/Syncope
- Severe infection/Sepsis
- Hypoglycemia
- Periodic paralysis (electrolyte disturbance, K, Mg, Ca)
- Respiratory failure
- Emergent Diagnoses:
- Symptomatic Anemia
- Severe dehydration
- Hypothyroidism
- Polypharmacy
- Malignancy
- Aortic disease - occlusion, stenosis, dissection
- Other causes of weakness and paralysis
- Acute intermittent porphyria (ascending weakness)
- Can't miss diagnoses:
Diagnosis
Treatment
- Supportive (progression to respiratory or bulbar failure is rare)
- Acetylcholinesterase inhibitors (e.g. pyridostigmine) can improve symptoms
Disposition
- Admission required when infectious complications occur or when severe disability requires inpatient immunotherapy
See Also
References
Background
- Disease of the neuromuscular junction leading to primary presentation of weakness
- Caused by auto-antibodies against the voltage-gated calcium channels at the NMJ
Clinical Features
- Often presents with alteration in gait or difficulty rising from a chair
- Symmetrical muscle weakness and fatiguability often beginning in lower extremities
- Autonomic dysfunction (dry mouth, erectile dysfunction)
- Compared with myastenia gravis, ELS begins with lower extremities weakness and rarely begins with extraocular muscle weakness
- Respiratory failure can occur in late stages of the disease
- Paraneoplastic and autoimmune form of LEMS have similar signs and symptoms
Differential Diagnosis
- Myasthenia Gravis
- Myositis
- Dermatomyositis
- Amyotrophic Lateral Sclerosis
- Limb-Girdle Muscle Dystrophy
- Inclusion Body Myositis
Diagnosis
- Diagnosis is generally a clinical diagnosis
- Confirmation testing for VGCC antibodies
- Neurophysiologic testing
Management
- Guanidine
- Aminopyridines
- Acetylcholinesterase inhibitors
- IVIG
- Glucocorticoids
- Plasma exchange
Disposition
- Referral to rheumatology
- Any patients with risk factors for small cell lung cancer will need to be referred for evaluation of underlying malignancy
See Also
External Links
References
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