From the Guidelines
To assess tremors, using the Unified Parkinson's Disease Rating Scale (UPDRS) or the Movement Disorder Society-sponsored revision of the UPDRS (MDS-UPDRS) is recommended, as these scales have been validated for measuring parkinsonism and can help evaluate the severity of tremors 1. When assessing tremors, it is essential to observe the tremor's characteristics during rest, posture maintenance, and action, noting the location, amplitude, frequency, and triggers. The following steps can be taken:
- Observe the patient's tremor during rest, posture maintenance, and action
- Note the tremor's location, amplitude, frequency, and whether it occurs at rest, with sustained posture, or during movement
- Ask the patient about tremor triggers, alleviating factors, and impact on daily activities
- Perform specific tests like having the patient extend their arms, touch their nose with alternating index fingers, draw a spiral, or write a sentence
- Assess for associated neurological signs like rigidity or bradykinesia
- Document tremor severity using standardized scales such as the UPDRS or MDS-UPDRS The MDS-UPDRS is a newer version that differs from the UPDRS, especially in the evaluation of non-motor aspects of Parkinson's disease, and adds further motor aspects, including freezing of gait, separating postural and kinetic tremor, and separating the amplitude and constancy of rest tremor 1. Additionally, considering the patient's medication history and family history can help identify potential causes of the tremor, such as certain drugs or genetic components 1. It is also important to note that the use of technology, such as wearable sensors or kinematic analysis tools, may hold promise for improving the sensitivity, accuracy, reproducibility, and feasibility of objectively capturing changes in motor function, especially when assessed at home in unsupervised conditions 1.
From the Research
Assessing Tremors
To assess tremors, the following steps can be taken:
- Categorize the tremor based on its activation condition, topographic distribution, and frequency 2
- Determine if the tremor is a resting tremor or an action tremor, and further subdivide action tremors into postural, isometric, and kinetic tremors 2, 3
- Evaluate the patient's history and perform a focused neurologic examination to establish the type of tremor and its characteristics 2, 3
- Formulate differential diagnoses based on the type of tremor, including essential tremor, enhanced physiologic tremor, drug-induced tremor, dystonic tremor, orthostatic tremor, and cerebellar tremor for action tremors, and Parkinson disease and drug-induced resting tremor for resting tremors 2, 3
Diagnostic Tools
The following diagnostic tools can be used to assess tremors:
- Single-photon emission computed tomography to visualize the integrity of the dopaminergic pathways in the brain 2
- Transcranial ultrasonography to diagnose Parkinson disease 2
- Neuroimaging approaches, such as MRI-guided focused ultrasound thalamotomy, to evaluate the brain and guide treatment 4
Types of Tremors
The following types of tremors can be assessed:
- Essential tremor: a common movement disorder that affects 0.4% to 6% of the population, often transmitted in an autosomal-dominant fashion 2, 5, 4, 6
- Enhanced physiologic tremor: a type of tremor that can be enhanced by anxiety, medication use, caffeine intake, or fatigue 2
- Parkinsonian tremor: a type of tremor that is typically unilateral, occurs at rest, and becomes less prominent with voluntary movement 2
- Cerebellar tremor: a type of tremor that is associated with cerebellar damage or disease 3
- Dystonic tremor: a type of tremor that is associated with dystonic movements or posturing 3