How best to address these common movement disorders

Physiologic tremor: Pharmacologic Tx is usually not needed
Physiologic tremor is benign, high frequency (8-12 Hz), low amplitude, and postural. An exaggerated form of this tremor may result from anxiety, hyperthyroidism, pheochromocytoma, hypoglycemia, excessive caffeine consumption, fever, withdrawal from opioids and sedatives, and some medications. No drug treatment is necessary unless symptoms become bothersome. Correct the underlying cause or have the patient avoid the triggering factor, and offer reassurance that the condition is not pathological or progressive.^2,12 For anxiety, consider cognitive-behavioral/relaxation therapy or benzodiazepines (if tremor did not result from withdrawal of benzodiazepines) or beta-adrenergic antagonists (eg, propranolol).^12,13

Essential tremor: Try propranolol or primidone first
Essential tremor (ET) is the most common movement disorder. It often results in functional disability and leads to many physical and emotional difficulties. ET is bilateral, usually symmetric (although mild asymmetry is possible), and postural or kinetic, typically affecting hands and forearms. The frequency of ET is 4 to 12 Hz. Cranial musculature may be involved in 30% of cases, affecting the head and voice.³ Prevalence ranges from 4 to 40 cases per 1000 people. The age-adjusted incidence is 17.5/100,000 per year; it peaks during the teen years and the fifth decade.^2,3

Autosomal dominant type of inheritance is common, and a family history of ET is often present, particularly with younger patients. The differential diagnosis includes Parkinson’s disease tremor; dystonic, cerebellar, rubral, and psychogenic tremors; and asterixis.³ Unlike ET, many of these disorders have associated neurologic, psychiatric, or systemic signs.

Treatment with propranolol or primidone is indicated if ET causes functional impairment or social or emotional problems for the patient.^2,3,10,13 Both propranolol and primidone reduce limb tremor^2,10,13 (SOR: B), but only propranolol is approved by the US Food and Drug Administration (FDA) for treatment of ET. Propranolol is more effective for hand and forearm tremor than for head and voice tremor. Start propranolol at 20 to 40 mg twice a day and increase the dose as needed to achieve symptom relief.¹⁴

A maintenance dose of 240 to 320 mg/d may be needed. Major adverse effects are fatigue, sedation, depression, and erectile dysfunction. Contraindications to propranolol include asthma, second-degree atrioventricular block, and insulin-dependent diabetes.

If starting with primidone alone, prescribe at a dose <25 mg at bedtime and increase the dose slowly over several weeks to prevent onset of nausea, vomiting, sedation, confusion, or ataxia. The maximum allowable dose is 750 mg/d in 3 divided doses.¹⁰ Primidone and propranolol may be used in combination to treat limb tremor when monotherapy is insufficient (SOR: B).¹³

Thirty percent of patients with ET will not respond to propranolol or primidone. An alternative choice is the anticonvulsant gabapentin^10,12-14 (SOR: C). However, clinical experience with it is limited. Lethargy, fatigue, decreased libido, dizziness, nervousness, and shortness of breath are adverse effects of gabapentin; they are usually mild and tolerable.¹³ Topiramate is another option that seems to be as effective as gabapentin^10,13 (SOR: C), but studies of long-term outcomes are lacking. Topiramate’s side effects include weight loss and paresthesias. Additionally, alprazolam, clonazepam, clozapine, olanzapine, atenolol, sotalol, nadolol, and nimodipine may reduce limb tremor² (SOR: C). Alcohol reduces tremor amplitude in 50% to 90% of patients, but tremor may worsen after the effect of alcohol has worn off.¹⁵

For patients with essential hand tremor that fails to respond to oral agents, consider botulinum toxin A¹⁶ (SOR: B). However, it is also associated with dose-dependent hand weakness¹⁶ (SOR: C). Botulinum toxin may reduce head and voice tremor¹⁶ (SOR: C), but hoarseness and swallowing difficulties may occur after use for voice tremor.¹⁶

Invasive therapies may benefit patients with refractory tremor. Deep brain stimulation and thalamotomy are highly effective in reducing limb tremor¹³ (SOR: C). Each carries a small risk of major complications. Some deep brain stimulation adverse events may resolve with time. Other adverse events may resolve with adjustment of stimulator settings. No evidence exists for surgical treatment for voice and head tremor or for gamma-knife thalamotomy.¹³

Drug-induced tremor
Drugs with the potential to cause postural tremor, intention tremor, or rest tremor include the following: ¹⁵

• alcohol (chronic)
• amiodarone
• amphetamines
• beta-adrenergic agonists
• caffeine
• calcitonin
• carbamazepine
• cocaine
• cyclosporine
• dopamine
• lithium
• metoclopramide
• neuroleptics
• procainamide
• steroids
• theophylline
• thyroid hormones
• tricyclic antidepressants
• trifluoperazine
• valproic acid

With drug-induced tremor, carefully evaluate a patient’s need for the drug. Discontinue the offending agent if possible, or try lowering the dose.

Psychogenic tremor: A history of somatization is a clue
Psychogenic tremor can occur at rest or during postural or kinetic movement. Clinical features include an abrupt onset, a static course, spontaneous remission, and unclassifiable tremors.¹⁷ Psychogenic tremor increases under direct observation and decreases with distraction. Patients with psychogenic tremor often have a history of somatization.¹⁸ Electrophysiologic testing can help confirm the diagnosis. If remission does not occur spontaneously, patients may find relief with psychotherapy or placebo.¹⁹