Diagnostic Approach to Unilateral Hand Tremor

Initial Clinical Assessment

The American Academy of Neurology suggests that determining whether the tremor occurs at rest or with action/posture is crucial in narrowing the differential diagnosis and directing the workup 1
Resting tremor, present when the hand is fully supported against gravity and disappears with voluntary movement, strongly suggests Parkinson's disease, which typically begins asymmetrically and unilaterally 1
Action/postural tremor, which occurs during tasks like holding objects or maintaining posture, indicates essential tremor or enhanced physiologic tremor 1, 2
Variable frequency, amplitude, and direction with sudden onset in the context of stress suggest functional/conversion tremor 1, 3
The timing of tremor onset is important, with gradual onset favoring Parkinson's disease or essential tremor, and sudden onset suggesting functional tremor 1
A positive family history points toward essential tremor rather than Parkinson's disease 1
Medication review is essential to identify potentially causative drugs that must be discontinued before further workup 1

For unilateral resting tremor, the primary diagnosis to evaluate is Parkinson's disease 1
No routine imaging is required for typical unilateral resting tremor consistent with Parkinson's disease, unless atypical features are present 1
A trial of levodopa/carbidopa serves as both diagnostic and therapeutic, with significant improvement confirming parkinsonian tremor 1
For unilateral action/postural tremor, essential tremor should be considered if there is a bilateral family history and gradual progression 1, 2
Enhanced physiologic tremor should be considered if associated with caffeine, stress, or thyroid dysfunction 3

The American Academy of Neurology recommends avoiding the diagnosis of essential tremor based solely on unilateral resting tremor, as essential tremor is primarily postural/action tremor and typically bilateral 1
Potentially causative drugs like stimulants or antipsychotics should be discontinued before starting tremor medications 1
Beta-blockers like propranolol are only effective for essential tremor and enhanced physiologic tremor, and should not be used for parkinsonian resting tremor 1, 2
Functional tremor should not be dismissed as "psychogenic", as symptoms are involuntary and require specific therapeutic approaches including rhythm modification techniques 1, 2
Extensive imaging should not be ordered for typical presentations, as clinical diagnosis based on tremor characteristics is usually sufficient 1