From the Guidelines
The workup for tremors should begin with a thorough history and physical examination to characterize the tremor type and identify potential causes, as correctly diagnosing a Parkinsonian syndrome on clinical features alone can be quite challenging 1. When evaluating a patient presenting with tremors, it is essential to consider the various types of tremors, including resting tremor, bradykinesia, and rigidity, which are characteristic of Parkinsonian syndromes, such as Parkinson's disease (PD), progressive supranuclear palsy (PSP), multiple system atrophy (MSA), and corticobasal degeneration (CBD) 1. Key elements to consider in the history and physical examination include:
- Timing (rest, postural, action, or intention tremor)
- Frequency
- Amplitude
- Distribution
- Exacerbating factors
- Associated symptoms, such as autonomic dysfunction, behavioral changes, and dementia, which are common in PD and other Parkinsonian syndromes 1 Laboratory tests should include:
- Thyroid function tests
- Liver function tests
- Complete blood count
- Comprehensive metabolic panel
- Serum ceruloplasmin (to rule out Wilson's disease) Additional tests may include:
- Blood glucose
- Calcium levels
- Toxicology screening if substance use is suspected
- Medication review is essential as many drugs can cause tremors, including beta-agonists, valproic acid, lithium, and stimulants Neuroimaging with MRI brain may be indicated if structural lesions are suspected, and electromyography can help characterize the tremor's neurophysiological characteristics 1. For essential tremor, a therapeutic trial with propranolol or primidone can be both diagnostic and therapeutic, while for parkinsonian tremor, a levodopa trial may be appropriate 1. Referral to a neurologist is recommended for tremors that are disabling, rapidly progressive, asymmetric, or accompanied by other neurological symptoms, to ensure accurate diagnosis and management of the underlying condition 1.
From the Research
Tremor Workup
- The diagnosis of tremor is based on clinical information obtained from the history and physical examination 2
- The evaluation should start with a detailed tremor history followed by a focused neurologic examination, which should attend to the many subtleties of tremor phenomenology 3, 4
- The examination should establish whether the main type of tremor is an action tremor (ie, postural, kinetic, or intention tremor) or a resting tremor 3, 4
Types of Tremors
- Action tremors occur with voluntary contraction of a muscle and can be further subdivided into postural, isometric, and kinetic tremors 2
- Resting tremors occur in a body part that is relaxed and completely supported against gravity 2
- The most common pathologic tremor is essential tremor, which affects 0.4% to 6% of the population 2
- Other types of tremor include enhanced physiologic tremor, parkinsonian tremor, cerebellar tremor, dystonic tremor, and drug- or metabolic-induced tremor 2, 3, 4
Diagnostic Approach
- The clinician should formulate two sets of differential diagnoses: disorders in which action tremor is the predominant tremor versus those in which resting tremor is the main tremor 3, 4
- If there is diagnostic uncertainty, single-photon emission computed tomography can be used to visualize the integrity of the dopaminergic pathways in the brain, and transcranial ultrasonography may be useful to diagnose Parkinson disease 2
Treatment Options
- The first line of treatment for limb tremor is pharmacotherapy with propranolol or primidone 5
- Surgical interventions include deep brain stimulation, magnetic resonance-guided focused ultrasound, and thalamotomy for unilateral and deep brain stimulation for bilateral procedures 5
- Botulinum toxin injections are likely efficacious for limb, voice, and head tremor but are associated with side effects 5