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- When dealing with weakness and sensory complaints in the ED, the time course of symptoms and physical exam findings help identify emergent conditions.
- We often talk about upper motor neuron vs. lower motor neuron signs that distinguish whether a lesion is in the central or peripheral nervous system.
- Characteristics that differentiate between central vs. peripheral nervous system pathology include:
| Central Nervous System | Peripheral Nervous System | |
| Pattern of Symptoms | • Hemibody involvement • Weakness of UE extensors • Weakness of LE flexors | • Distal involvement in polyneuropathy • Distal and proximal involvement in polyradiculoneuropathy • Proximal involvement in polyradiculopathy • Sensory often precedes motor symptoms • Pure proximal>distal weakness may be due to myopathy or NMJ disorder |
| Sensory Symptoms | • Central poststroke pain (hyperalgesia, allodynia) • Sensory level in spinal cord pathology • Proprioception involved early in dorsal column disorders | • Neuropathic pain (burning, tingling, shock-like) • Ascending sensory loss involving distal BLE>BUE in polyneuropathy • Proprioception involved late in polyneuropathy |
| Reflexes | • Hyperreflexia in affected limb(s) after acute period • Positive Babinski’s sign | • Hyporeflexia in affected limb(s) |
| Tone | • Increased after acute period | • Decreased |
UE = upper extremity
LE = lower extremity
NMJ = neuromuscular junction
Bottom Line: A systematic approach to the evaluation of weakness and sensory complaints in the ED help differentiate between central vs. peripheral nervous system pathology.
References
London ZN. A structured approach to the diagnosis of peripheral nervous system disorders. Continuum Minneap Minn) 2020;26(5, Peripheral Nerve and Motor Neuron Disorders):1130-60.
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