Diabetic neuropathy

The most common inherited peripheral neuropathy, comprising more than 70 genetic subtypes that cause slowly progressive distal weakness, sensory loss, areflexia, and foot deformity; diagnosis rests on nerve conduction studies and confirmatory genetic testing, and management is supportive since there is no disease-modifying drug therapy.

Guillain-Barre syndrome is an acute, post-infectious autoimmune polyradiculoneuropathy causing rapidly progressive ascending flaccid weakness and areflexia. Diagnosis is clinical, supported by albuminocytologic dissociation on CSF and demyelinating changes on electrodiagnostic studies; first-line treatment is IVIG or plasma exchange with close monitoring for respiratory failure.

Radiculopathy is dysfunction of a spinal nerve root, most often from disk herniation or degenerative spinal disease, producing radicular pain, dermatomal sensory loss, myotomal weakness, and reduced reflexes in a nerve-root distribution. Diagnosis is clinical; most cases resolve with conservative therapy within 6 to 12 weeks, and imaging is reserved for red flags or persistent symptoms.

Meralgia paresthetica is a mononeuropathy from entrapment of the lateral femoral cutaneous nerve near the inguinal ligament, causing anterolateral thigh numbness, tingling, and burning pain without motor weakness. Diagnosis is clinical, and first-line treatment is weight loss and avoiding tight clothing, with gabapentin or injection reserved for persistent symptoms.

Wilson disease is an autosomal recessive disorder of the ATP7B copper-transporting ATPase causing toxic copper accumulation in the liver, brain, and cornea, presenting with hepatic and/or neuropsychiatric disease usually before age 40; diagnosis rests on ceruloplasmin, urinary copper, and Kayser-Fleischer rings, and lifelong treatment is chelation with penicillamine or trientine, or zinc, unless liver transplant is required.

Friedreich ataxia is an autosomal recessive trinucleotide (GAA) repeat disorder that silences the frataxin gene, causing mitochondrial iron accumulation and degeneration of the spinocerebellar and dorsal column tracts. It presents in childhood or adolescence with progressive gait ataxia, dysarthria, and loss of deep tendon reflexes, and its leading cause of death is hypertrophic cardiomyopathy. Diagnosis is by genetic testing; management is multidisciplinary and supportive.

Hypothyroidism is thyroid hormone deficiency, most commonly caused by autoimmune (Hashimoto) thyroid failure in iodine-sufficient countries, diagnosed by an elevated thyroid-stimulating hormone with a low or normal free thyroxine. First-line treatment is levothyroxine dosed at 1.6 mcg/kg lean body weight orally once daily, titrated using thyroid-stimulating hormone rechecked no sooner than 6 weeks after any dose change.

The false sensation of self or environmental movement, classified as peripheral (inner ear or vestibular nerve) or central (brainstem or cerebellum) based on history, nystagmus pattern, and the bedside HINTS exam. Peripheral vertigo is managed with repositioning maneuvers or vestibular suppressants; central vertigo requires urgent stroke evaluation, since it can be the sole presenting symptom of a posterior circulation stroke.