From the Guidelines
The initial differential diagnosis for a patient presenting with a left hand tremor of 5 months duration should include Parkinson's disease, essential tremor, physiologic tremor, drug-induced tremor, cerebellar tremor, psychogenic tremor, and dystonic tremor, with a comprehensive neurological examination and laboratory tests such as complete blood count, comprehensive metabolic panel, thyroid function tests, liver function tests, and serum ceruloplasmin. The recommended initial workup should focus on characterizing the tremor, including its type (rest vs. action), frequency, amplitude, and associated neurological signs, as well as a thorough medication history 1. Key laboratory tests to consider include:
- Complete blood count
- Comprehensive metabolic panel
- Thyroid function tests (TSH, free T4)
- Liver function tests
- Serum ceruloplasmin to rule out Wilson's disease Additional tests may be necessary, such as:
- Brain MRI to evaluate for structural lesions
- DaTscan (dopamine transporter scan) if Parkinson's disease is suspected
- Electromyography (EMG) in selected cases to characterize the tremor Medication review is crucial, as certain medications like beta-agonists, antipsychotics, antidepressants, and stimulants can cause tremor 1. The pattern of tremor can help narrow the diagnosis, with rest tremor suggesting Parkinson's disease and postural and action tremors pointing toward essential tremor. Given the unilateral presentation, neuroimaging is particularly important to rule out structural lesions or early Parkinson's disease. It is essential to document tremor severity, impact on daily activities, and progression rate to establish a baseline for monitoring treatment response. The most recent and highest quality study, 1, published in 2022, provides guidance on the evaluation of motor features in dementia with Lewy bodies, which can inform the assessment of tremor in other conditions as well.
From the Research
Initial Differential Diagnosis
The initial differential diagnosis for a patient presenting with a left hand tremor of 5 months duration includes:
- Essential tremor
- Parkinson's disease (PD)
- Enhanced physiologic tremor
- Drug-induced tremor
- Dystonic tremor
- Orthostatic tremor
- Cerebellar tremor
- Psychogenic tremor
Recommended Labs/Tests
The recommended labs/tests for a patient presenting with a left hand tremor include:
- A thorough history and physical examination to determine the type of tremor (action or resting) and its characteristics
- Neurological examination to assess for other signs of parkinsonism, such as bradykinesia, rigidity, and cognitive slowing
- Single-photon emission computed tomography (SPECT) to visualize the integrity of the dopaminergic pathways in the brain, which may be useful in diagnosing Parkinson's disease 2
- Electromyogram (EMG) to assess the frequency and characteristics of the tremor
- Imaging studies, such as computed tomography (CT) or magnetic resonance imaging (MRI), to rule out other causes of tremor, such as brain tumors 3
- Laboratory tests to rule out metabolic or drug-induced causes of tremor
Diagnostic Approach
The diagnostic approach to tremor involves a history and a neurologic examination that is focused on the nuances of tremor phenomenology 4. The evaluation should begin with a tremor history and a focused neurologic examination to establish whether the main type of tremor is an action tremor or a resting tremor. The clinician should then 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 4. A diagnosis of PD is likely if the patient has two of three major clinical features: resting tremor, bradykinesia, and rigidity 5.