Myasthenia Gravis |
Autoimmune disorder where antibodies target acetylcholine receptors at the neuromuscular junction, impairing synaptic transmission.
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- Fluctuating weakness, worsens with activity
- Ptosis, diplopia
- Difficulty swallowing, breathing in severe cases
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- Anti-AChR antibodies
- Electromyography (EMG)
- CT/MRI for thymoma
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Guillain-Barré Syndrome (GBS) |
Acute, immune-mediated demyelination of peripheral nerves, often triggered by an infection (e.g., Campylobacter).
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- Ascending weakness starting in the legs
- Reduced reflexes
- Can progress to respiratory muscle weakness
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- Nerve conduction studies (NCS)
- Cerebrospinal fluid (CSF) analysis: Elevated protein with normal cell count (albuminocytologic dissociation)
- Clinical history
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Amyotrophic Lateral Sclerosis (ALS) |
Degeneration of upper and lower motor neurons in the brain and spinal cord, leading to progressive weakness and muscle atrophy.
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- Progressive muscle weakness, atrophy
- Fasciculations
- Spasticity and hyperreflexia (upper motor neuron signs)
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- Electromyography (EMG)
- Nerve conduction studies (NCS)
- MRI to rule out structural lesions
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Muscular Dystrophies (e.g., Duchenne, Becker) |
Genetic disorders characterized by progressive muscle fiber degeneration, often due to mutations in the dystrophin gene.
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- Progressive muscle weakness (proximal > distal)
- Pseudohypertrophy of calves (Duchenne)
- Respiratory failure in advanced stages
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- Genetic testing (dystrophin gene mutations)
- Muscle biopsy
- Creatine kinase (CK) levels: Elevated
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Botulism |
Neurotoxin produced by *Clostridium botulinum* blocks acetylcholine release at neuromuscular junctions.
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- Acute descending paralysis
- Ptosis, blurred vision, difficulty swallowing
- Respiratory muscle weakness
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- Toxin assay (serum or stool)
- Clinical history (foodborne, wound exposure)
- Nerve conduction studies (NCS)
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Polymyositis/Dermatomyositis |
Inflammatory myopathies causing immune-mediated muscle inflammation and degeneration.
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- Proximal muscle weakness (shoulders, hips)
- Dermatomyositis: Rash (heliotrope, Gottron's papules)
- Dysphagia in advanced cases
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- Creatine kinase (CK): Elevated
- Muscle biopsy
- Autoantibody panel (e.g., anti-Jo-1, ANA)
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Lambert-Eaton Myasthenic Syndrome (LEMS) |
Autoimmune disorder where antibodies attack voltage-gated calcium channels at presynaptic nerve terminals, impairing acetylcholine release.
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- Proximal muscle weakness, especially in legs
- Autonomic symptoms (dry mouth, erectile dysfunction)
- Improvement with repeated muscle use
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- Anti-VGCC antibody test
- Electromyography (EMG)
- Screen for small cell lung cancer (often associated)
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Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) |
Autoimmune condition causing chronic demyelination of peripheral nerves, similar to Guillain-Barré Syndrome but with a more chronic course.
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- Progressive, symmetrical limb weakness
- Loss of reflexes
- Sensory deficits
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- Nerve conduction studies (NCS)
- Electromyography (EMG)
- Cerebrospinal fluid (CSF): Elevated protein
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