A 47-year-old dentist consults you because of tremor, which is interfering with his work. The tremor has come on gradually over the past several years and seems more prominent after the ingestion of caffeine; he notices that, in the evening after work, an alcoholic beverage will decrease the tremor. No one in his family has a similar tremor. He is otherwise healthy and takes no medications. On examination his vital signs are normal. Except for the tremor, his neurological examination is normal; in particular there is no focal weakness, rigidity, or bradykinesia. When he holds out his arms and extends his fingers, you detect a rapid fine tremor of both hands; the tremor goes away when he rests his arms at his side.
What is the best next step in the management of this patient?A) MRI scan to visualize the basal ganglia
This patient’s action tremor (ie, brought out by sustained motor activity) and otherwise normal neurological examination are diagnostic of essential tremor. Fifty percent of patients will have a positive family history (benign familial tremor). The tremor is termed “benign” to separate it from Parkinson disease and other progressive neurological diseases and because it does not affect other areas of function; however, about 15% of patients (especially those in professions that require fine motor control) will be functionally impaired. An identical rapid fine action tremor can be seen in normal persons after strenuous motor activity or with anxiety. Hyperthyroidism, caffeine overuse, alcohol withdrawal, and use of sympathomimetic drugs (such as cocaine and amphetamines) can cause an identical tremor and can exacerbate the tremor in familial cases.
Neurological imaging is normal in patients with essential tremor. The EMG is nonspecific. This patient has no features (eg, weakness, fasciculations) to suggest motor neuron disease. Patients with essential tremor are managed with medications, especially beta-blockers, to decrease the severity of the tremor. Most neurologists feel that nonselective beta-blockers (blocking both beta-1 and beta-2 receptors) are most effective. They can be used on an “as needed” basis (ie, before performance of fine tasks) if the patient is not troubled by the tremor at other times. Primidone is also effective but is associated with more side effects, especially at higher doses.