tremors

Tremor refers to an involuntary rhythmic movement of a body part. Tremors vary in frequency and amplitude and most commonly affect the hands, arms, head, voice, or legs. They can be transient, occurring with anxiety or fatigue, or persistent, reflecting an underlying medical condition.

Medical tremors are classified by pattern and context: rest tremor occurs when muscles are not voluntarily moved and is typical of Parkinson's disease; action tremors occur with movement and include postural tremor (holding a position), kinetic tremor (during a task), and intention tremor (increasing toward a target). Physiological tremor is a normal, usually small, oscillation seen in everyone.

Common causes include neurodegenerative diseases (Parkinson's disease, multiple sclerosis), cerebellar disorders, stroke, thyroid disorders, metabolic disturbances, medications (such as certain bronchodilators, antidepressants, and antiemetics), fatigue, caffeine, and alcohol withdrawal. Age is a known risk factor for many tremor types.

Diagnosis involves a neurological examination and review of medical history; additional tests may include thyroid function tests, blood chemistry, and brain imaging. Treatment targets the underlying cause and may include medications (beta-blockers or anticonvulsants for essential tremor), botulinum toxin injections for focal tremors, physical therapy, lifestyle changes, or deep brain stimulation in severe cases.

In popular culture, Tremors refers to a 1990 American monster comedy film that spawned a long-running film series and a television adaptation, featuring subterranean creatures called Graboids and their encounters with humans.