Tremors

Tremor is an involuntary rhythmic oscillation, and the single most useful question is when it happens. Rest tremor, present when the limb is fully supported and reduced by voluntary movement, points to Parkinson's disease and is often asymmetric with a pill-rolling quality. Action tremor, appearing when reaching for a glass or writing, points to essential tremor — the most common movement disorder, frequently bilateral, often with a family history, and classically improved by a small amount of alcohol. Postural tremor when holding the arms outstretched can be either, or simply an exaggerated physiological tremor. Enhanced physiological tremor is a genuinely common and reversible category: caffeine, nicotine, anxiety, sleep deprivation, hyperthyroidism, hypoglycaemia, alcohol withdrawal and a long list of drugs including salbutamol, lithium, valproate, SSRIs, amiodarone and corticosteroids all produce it. Cerebellar tremor, which worsens as the hand approaches a target, points to structural disease or alcohol-related cerebellar degeneration. Dystonic tremor and functional tremor complete the picture and are frequently misdiagnosed. Nutritional contributions are narrow. Vitamin B12 deficiency and severe thiamine deficiency can produce tremor along with wider neurological signs, and correcting them helps. Magnesium deficiency can cause tremulousness. Beyond correcting a documented deficiency, no supplement has trial evidence for reducing tremor, and self-treatment delays the diagnostic work that determines prognosis.

• •Shaking of the hands when reaching or writing
• •Shaking of a hand at rest that stops on movement
• •Head or voice tremor
• •Worsening with stress, caffeine or fatigue
• •Difficulty with fine tasks such as buttons or soup spoons
• •Asymmetry between the two hands

• •Essential tremor
• •Parkinson's disease
• •Enhanced physiological tremor from caffeine, anxiety or sleep loss
• •Hyperthyroidism
• •Medication including salbutamol, lithium, valproate, SSRIs and steroids
• •Alcohol withdrawal or chronic alcohol use
• •Vitamin B12 deficiency
• •Cerebellar disease
• •Functional (dissociative) tremor

Oscillatory activity in cerebello-thalamo-cortical circuits underlies essential tremor, while nigrostriatal dopaminergic loss drives Parkinsonian rest tremor. Enhanced physiological tremor reflects beta-adrenergic activation of muscle spindles, which is why beta-blockers and caffeine reduction help it. Cerebellar tremor arises from disrupted feedback control of limb trajectory.