What is the initial differential diagnosis of tremor, and what parts of the history are important?

Tremor has a wide differential diagnosis. Medications can cause tremor, especially psychotropic medications. Metabolic tremors can be from hepatic or renal disease, including Wilson’s disease, and tremor can be a complication of rheumatic fever. A common cause of tremor is benign essential tremor, which may be familial, but Parkinson’s disease and related disorders are of course on the list. Therefore, it is important to obtain the past medical, psychiatric, and family history for these patients.

When narrowing down the diagnosis in the history, it is helpful to define the extent of the tremor: is it in the hands only, or does it extend to the head, voice, or even legs? Is it symmetric, or does it favor one side? Does it seem to occur at rest or when the patient is moving or trying to accomplish tasks? Does alcohol seem to relieve the tremor (as is the case with benign essential tremor)? Associated symptoms to ask about include any problems with balance or gait, sense of smell, small handwriting, hypophonia (as in Parkinson’s disease), or behavioral problems (as in Huntington’s disease).

What are the cardinal features of Parkinson’s disease?

Parkinson’s disease is a hypokinetic movement disorder characterized by bradykinesia, rigidity, resting tremor, postural instability, and a masked face.

What is the expected tremor for Parkinson’s disease?

Tremor is generally asymmetric and in early disease unilateral, although patients may not seek treatment until symptoms are more severe and bilateral. The tremor is low frequency, 4 to 6 Hz, and is “pill rolling” (supination-pronation movement). It usually involves the distal extremities and affects the upper limbs more than the lower limbs. Tremor is worse with distraction and can commonly be seen when patients are walking or when given a distracting task (such as counting down from 100 by 7 [serial 7’s task]).