tremor_hands

Alcohol Withdrawal Tremor
Alcohol withdrawal tremor is similar to essential tremor on examination but with subtle differences. Alcohol withdrawal tremor has a frequency between 6 and 10.5 Hz. In one study,¹⁰ 74 percent of the patients with alcohol withdrawal tremors had tremors at a frequency above 8 Hz. In this same series, tremors in all of the patients who had essential tremor were at a frequency below 8 Hz. Thus, the tremor of alcohol withdrawal tends to be more rapid than essential tremor.

A family history of tremor was found in only 1 percent of the patients with alcohol withdrawal tremor, as compared with almost one half of the patients with essential tremor.¹⁰ In addition, severity and degree of functional disability were less with alcohol withdrawal tremor.

Only the hands are affected in patients with alcohol withdrawal tremor, but multiple sites of involvement are possible in patients with essential tremor. Overactivity of the sympathetic nervous system is thought to be responsible for alcohol withdrawal tremor, and prolonged alcohol abuse can result in a chronic tremor disorder.¹⁰

Psychogenic Tremor
Psychogenic tremor is a complex tremor that can occur at rest, during postural movement and during kinetic movement. The etiology and pathophysiology of psychogenic tremor are likely to differ from patient to patient, and the main focus of treatment should be psychotherapy, not medication.

Clinical features of psychogenic tremor include an abrupt onset, a static course, spontaneous remission and unclassifiable tremors.¹¹ Unresponsiveness to antitremor drugs, an increase in frequency and amplitude with attention and a decrease in frequency and amplitude with distraction, responsiveness to placebo, absence of other neurologic signs and remission with psychotherapy are also signs of psychogenic tremor.¹¹ Clinical inconsistencies, such as being able to write words yet not being able to draw a spiral, and changing characteristics, such as direction and affected body part, are also representative of psychogenic tremor.¹¹

Other Tremors
Other types of tremor occur much less commonly than the previously described tremors. Orthostatic tremor is defined as a postural tremor of the legs, occurring at a frequency of 13 to 18 Hz, initiated on standing and alleviated by walking or sitting.¹² It is more readily noticeable during palpation than by sight and is not influenced by peripheral feedback.¹³ Unsteadiness, feelings of imbalance or weakness, and trembling and shaking in the lower limbs are associated features of orthostatic tremor.¹⁴ The etiology of orthostatic tremor is unknown, but it is currently regarded as an entity separate from essential tremor.^12-14

Tremor associated with peripheral neuropathy is clinically similar to essential tremor. Its etiology is diverse. Not only can it be idiopathic, it can also be caused by demyelination from immunoglobulin M paraproteinemic neuropathies.² Tremor in association with peripheral neuropathy can also result from Charcot-Marie-Tooth disease, diabetes mellitus, uremia and porphyria.²

Drug Treatment of Tremor

Parkinsonian Tremor
Treatment of Parkinson's disease includes both medical and surgical intervention. Dopamine replacement therapy by means of levodopa clearly revolutionized the treatment of Parkinson's disease. Levodopa is almost exclusively given in combination with the peripheral decarboxylase inhibitor carbidopa (Sinemet). Carbidopa blocks the peripheral metabolism of levodopa to dopamine, decreasing the peripheral adverse effects of levodopa, such as nausea and vomiting, while increasing levodopa's availability in the brain.^15,16 In addition to modulating the tremor associated with Parkinson's disease, levodopa improves bradykinesia, rigidity and other commonly associated symptoms. Carbidopalevodopa is available in formulations of 10/100 mg, 25/100 mg and 25/250 mg. It is advantageous to begin treatment of mild disease with the 25/100-mg dosage, one tablet three times a day, and then increase the dosage as symptoms become less manageable.

When tremor is the predominant presenting symptom of Parkinson's disease or when tremor persists despite adequate control of other parkinsonian symptoms with low dosages of levodopa, an anticholinergic agent such as trihexyphenidyl (Artane) or benztropine (Cogentin) may be the treatment of choice. In most patients, however, anticholinergics do not significantly improve bradykinesia and rigidity. Trihexyphenidyl dosages necessary to improve tremor are between 4 and 10 mg per day (maximum: 32 mg), and useful benztropine dosages range from 1 to 4 mg per day. The side effects of these agents are their limiting factor, particularly in the elderly. Side effects include memory impairment, hallucinations, dry mouth, urinary difficulties and blurred vision.¹⁵

Other antiparkinsonian drugs--for example, amantadine (Symmetrel), tolcapone (Tasmar) and dopamine agonists such as pergolide (Permax), bromocriptine (Parlodel), ropinirole (Requip) and pramipexole (Mirapex)--are most helpful in patients whose tremor responds poorly to levodopa alone.

Classification of Tremor and Update on TreatmentP. DAVID CHARLES, M.D., GREGORY J. ESPER, B.S., THOMAS L. DAVIS, M.D., ROBERT J. MACIUNAS, M.D., and DAVID ROBERTSON, M.D.