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10 marksDrNB 2025NeurologyNeuromuscular
Describe the approach to a patient with hand weakness.
Hand weakness refers to reduced muscle strength in the hand, impairing fine motor skills and grip. It indicates underlying neuromuscular dysfunction affecting motor pathways, peripheral nerves, or muscles (Harrison's 21e, Ch. 365).
Hand weakness results from lesions at various levels of motor control — cortical, spinal cord, peripheral nerve, neuromuscular junction, or muscle.
| Level | Common Pathologies | Mechanism |
|---|---|---|
| Upper Motor Neuron (UMN) | Stroke, Multiple Sclerosis, Brain tumors | Corticospinal tract damage causing spastic weakness and exaggerated reflexes |
| Anterior Horn Cell | Amyotrophic lateral sclerosis (ALS) | Lower motor neuron death causing flaccid weakness and muscle wasting |
| Peripheral Nerve | Carpal tunnel syndrome, Radiculopathy, Trauma | Demyelination/axonal loss causing distal weakness and sensory deficit |
| Neuromuscular Junction | Myasthenia gravis, Lambert-Eaton syndrome | Impaired synaptic transmission causing fatigable weakness |
| Muscle | Muscular dystrophies, Inflammatory myopathies | Primary muscle fiber dysfunction causing symmetric weakness |
Mnemonics: "UMN CAP" - UMN, Anterior horn cell, Peripheral nerve, NMJ, and Muscle (Bradley's Neurology, 8e).
References
Bradley's Neurology, 8eFirestein's Rheumatology, 11eHarrison's 21eHarrison's 21e, Ch. 365Harrison's 21e, Ch. 365; Bradley's Neurology, 8e