Neuropathies

Neuropathies are disorders of the peripheral nervous system, encompassing damage to sensory, motor, and autonomic fibers. They can be focal, affecting a single nerve, or diffuse, involving many nerves (polyneuropathy). Pathology may be axonal, demyelinating, or mixed, influencing presentation and prognosis.

Causes are varied and several categories are recognized. Common etiologies include diabetes mellitus–related neuropathy, other metabolic disorders, nutritional deficiencies (notably vitamin B12 and thiamine), chronic alcohol use, autoimmune and inflammatory conditions (such as CIDP), infectious diseases, toxins, and hereditary disorders (for example Charcot–Marie–Tooth disease). Focal entrapment neuropathies, such as carpal tunnel, are also frequent. Some neuropathies occur after trauma, surgery, or exposure to certain therapies.

Symptoms depend on the fibers affected and their distribution. Sensory symptoms include numbness, tingling, burning pain, and hypersensitivity. Motor involvement can cause weakness and muscle wasting. Autonomic symptoms may include blood pressure fluctuations, digestive or bladder problems, and abnormal sweating. Examination may reveal sensory loss in a stocking-glove pattern, reduced reflexes, and focal weakness. Diagnosis relies on history and neurologic examination, supported by nerve conduction studies and electromyography to distinguish axonal from demyelinating processes. Laboratory testing screens for diabetes, thyroid disease, nutritional deficiencies, kidney or liver disease, HIV, autoimmune markers, and other infectious or toxic causes. Imaging and, rarely, nerve biopsy may be used in selected cases.

Treatment targets the underlying cause when possible and provides symptomatic relief. This may include metabolic control, nutritional supplementation, immunotherapy for immune-mediated forms, and avoidance of toxins. Pain management commonly employs anticonvulsants, serotonin-norepinephrine reuptake inhibitors, and topical therapies. Physical and occupational therapy and assistive devices support function. Prognosis varies by cause and severity, with some neuropathies improving and others remaining chronic.