Numbness

Numbness is loss or alteration of sensation, and the distribution matters more than the severity. Symmetric numbness starting in the toes and creeping upward — the glove-and-stocking pattern — indicates a length-dependent polyneuropathy, most commonly from diabetes or prediabetes, with vitamin B12 deficiency, alcohol, chemotherapy, hypothyroidism and chronic kidney disease making up much of the remainder. Numbness in a single nerve territory suggests entrapment: thumb, index and middle finger with night waking points to carpal tunnel syndrome; little and ring finger points to ulnar compression at the elbow. Numbness in a dermatomal band suggests nerve root compression from a disc. Sudden numbness affecting one side of the body, especially with weakness or speech change, is a stroke or TIA and is a time-critical emergency. Patchy numbness with visual or bladder symptoms in a younger adult raises multiple sclerosis. The nutritional angle is genuinely important here but cuts both ways. B12 deficiency causes a treatable neuropathy that becomes irreversible if left long enough, and it is under-diagnosed in metformin users, people on long-term proton pump inhibitors, vegans and older adults. Conversely, vitamin B6 taken in excess — above roughly 50mg daily long term — causes a sensory neuropathy that itself presents as numbness, and this is a common and entirely avoidable supplement-induced harm.

• •Pins and needles or loss of feeling in the feet
• •Symmetric numbness that creeps upward over months
• •Night waking with numb hands
• •Numbness in a band across the trunk or down one limb
• •Burning pain accompanying the numbness
• •Unsteadiness in the dark from loss of position sense

• •Diabetic and prediabetic peripheral neuropathy
• •Vitamin B12 deficiency
• •Excess vitamin B6 intake
• •Carpal tunnel and other entrapment neuropathies
• •Cervical or lumbar nerve root compression
• •Alcohol-related neuropathy
• •Chemotherapy-induced peripheral neuropathy
• •Hypothyroidism
• •Multiple sclerosis
• •Stroke or transient ischaemic attack

Length-dependent axonal degeneration from metabolic injury (hyperglycaemia, uraemia, alcohol) affects the longest nerves first, producing the stocking pattern. Demyelination from B12 deficiency damages the dorsal columns as well as peripheral nerves. Mechanical compression produces focal conduction block. Central lesions in the brain or spinal cord produce distributions that follow tracts rather than nerves.