What causes numbness
Numbness and tingling (paraesthesia) arise from disruption of sensory nerve pathways at any level — peripheral nerve, nerve root, spinal cord or brain. Peripheral neuropathy is the most common cause, typically presenting as symmetrical numbness starting in the feet (diabetic, nutritional, autoimmune or medication-related). Entrapment neuropathies — carpal tunnel syndrome (hand numbness at night), ulnar neuropathy (ring and little finger numbness) — produce focal sensory disturbance in a nerve distribution. Central causes (stroke, multiple sclerosis, spinal cord compression) produce asymmetric or level-specific sensory loss.
The pattern of numbness provides diagnostic clues: length-dependent (stocking-glove) distribution suggests peripheral neuropathy; dermatomal distribution suggests radiculopathy; sudden onset with weakness or speech change suggests stroke. History maps distribution, onset (acute vs gradual), duration, associated features (weakness, pain, bowel/bladder change) and metabolic or medication contributors.
- Peripheral neuropathy — symmetrical, feet first, stocking-glove
- Carpal tunnel syndrome — hand numbness, worse at night
- Radiculopathy — dermatomal distribution
- Stroke or central cause — sudden onset, asymmetric, with focal signs
Related: Neuropathy Treatment → · Dr. Jitendra Knowledge Hub → · ICHD-3 Topic →
Evaluation approach
Evaluation begins with detailed history of numbness distribution, onset, duration, triggers and associated features. Neurological examination includes sensory mapping (light touch, pinprick, vibration, proprioception), motor testing, and reflex assessment to localise the lesion level. Red flags — sudden onset, progressive deficit, bowel/bladder involvement, bilateral leg weakness — prompt urgent escalation.
Nerve conduction studies (NCS/EMG) are discussed when they would clarify cause or severity — for example, distinguishing axonal from demyelinating neuropathy, confirming entrapment, or quantifying severity for follow-up. Blood tests may include glucose (HbA1c), B12, thyroid function and renal function. Imaging is reserved for focal neurological signs or suspected structural causes. The clinic focuses on reversible contributors and avoids reflexive investigation.
- Sensory mapping — light touch, pinprick, vibration, proprioception
- NCS/EMG when findings would clarify cause or severity
- Blood tests: glucose, B12, thyroid, renal function
- Imaging reserved for focal signs or suspected structural causes