Approach to Weakness Localization
Ask about functional issues (getting out of chair, tripping over curbs/stairs)
UMN signs: spasticity, increased tone, hyperreflexia, + Babinski | LMN signs: fasciculations, atrophy, decreased tone, hyporeflexia
Pattern: UMN (extensors in UEs, flexors in LEs), proximal (many myopathies), bulbar (dysphagia, dysarthria, diplopia)
Associated Sensory Sx: reduced sensation, tingling, burning, allodynia, hyperalgesia, decreased temperature sense, imbalance
Autonomic Sx: orthostasis, constipation, urinary retention, erectile dysfunction, changes in sweating, hair loss, post-prandial nausea
EMG/NCS: Can be helpful with localization, determining fiber type involved, determining if disease is axonal vs demyelinating (which guides tx), and determining injury extent (which guides prognosis). Often higher yield at least 2-3 weeks into illness and as outpt.
Brain - Cortical signs (language/visual field/neglect), cerebellar sx, UMN signs
Spinal Cord - Sensory level, bowel/bladder dysfxn, UMN signs.
Anterior horn cell - LMN signs. If motor neuron dz: both UMN and LMN signs.
Radiculopathy - Motor/sensory sx corresponding to nerve root. +Radiating pain.
Peripheral Neuropathy - Sensory symptoms; autonomic dysfxn if small fibers affected. Often symmetric and length dependent. GBS is ascending.
NMJ - Weakness is fatigable and improves with rest. A/w ptosis, diplopia. No sensory sx.
Myopathy - Proximal weakness most common. Pain uncommon.
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