From the Guidelines
The diagnostic approach to tremor involves a systematic evaluation to determine its cause and guide treatment, starting with a detailed history and physical examination to characterize the tremor and identify associated neurological signs 1. The history should note the tremor's onset, progression, exacerbating factors, and associated symptoms, as well as family history, medication use, alcohol consumption, and caffeine intake.
- The physical examination should characterize the tremor by its frequency, amplitude, distribution, and whether it occurs at rest, with posture maintenance, or during action.
- Observe for associated neurological signs like bradykinesia, rigidity, or postural instability. Laboratory tests should include thyroid function, liver function, electrolytes, glucose, and drug levels when appropriate, as suggested by recent studies 1. Neuroimaging with MRI may be indicated if structural lesions are suspected, and electrophysiological studies can help differentiate tremor types by measuring frequency and pattern. In unclear cases, a therapeutic trial may aid diagnosis - for example, propranolol (20-40mg twice daily) for essential tremor or levodopa for parkinsonian tremor, as these have been shown to be effective in recent studies 1. The response to alcohol can provide diagnostic clues, as essential tremor typically improves temporarily. Specialized tests like DaTscan may help distinguish essential tremor from parkinsonian tremors by evaluating dopaminergic function, as recommended by recent guidelines 1. This systematic approach allows accurate classification of tremor as physiologic, essential, parkinsonian, cerebellar, or other types, which is crucial for appropriate management, and is supported by recent studies on functional neurological disorder 1.
From the Research
Diagnostic Approach to Tremor
The diagnosis of tremor is based on clinical information obtained from the history and physical examination 2. The first step in evaluating a patient with tremor is to categorize the tremor based on its activation condition, topographic distribution, and frequency.
- Resting tremors occur in a body part that is relaxed and completely supported against gravity.
- Action tremors occur with voluntary contraction of a muscle and can be further subdivided into postural, isometric, and kinetic tremors.
Classification of Tremor
Tremors may be classified as:
- Postural tremors
- Resting tremors
- Action tremors This classification is crucial in determining the underlying cause of the tremor and guiding the diagnostic process 3, 4, 5.
Diagnostic Techniques
The diagnostic process of patients with tremor can be laborious and challenging, and a clear, systematic overview of available diagnostic techniques is lacking 6.
- In most patients, history and clinical examination by an experienced movement disorders neurologist are sufficient to establish a correct diagnosis, and further ancillary examinations will not be needed.
- Ancillary investigation should always be guided by tremor type(s) present and other associated signs and symptoms.
- The main ancillary examination techniques currently are electromyography and SPECT imaging.
Common Types of Tremor
The most common tremors in patients presenting to primary care physicians are: