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Pathology

Antibody mediated disorder causing muscle weakness, loss of reflexes and autonomic dysfunction. 
Antibodies interfere with calcium dependent acetylcholine release in presynaptic junction 
Both muscle strength and reflexes improve post exercise

Aetiology

Commonly a paraneoplastic phenomenon associated with small cell lung cancer

Signs

Reflexes are reduced but improve post exercise, proximal muscle weakness

Symptoms

Ataxia, orthostatic hypotension, impaired sweating, dry mouth, incontinence.

Investigations

Bloods: Voltage gated calcium channel antibodies
Imaging: Chest X-Ray and CT chest to look for lung cancer
Special tests: Nerve conduction studies and repetitive nerve stimulation show 
an increase in compound muscle action potentials after voluntary 
exercise..

Treatment

Medical: Acetylcholine esterase inhibitors, corticosteroids, intravenous 
immunoglobulin and plasma exchange
Surgical: Tumour removal

Prognosis

Dependent on prognosis of underlying cancer  
Certain medications can cause deterioration in symptoms

Key Facts

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Key Images

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Key References

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