From the Guidelines
The workup of chin tremor should begin with a thorough clinical evaluation to determine the underlying cause, focusing on essential tremor and Parkinson's disease as common causes, and utilizing strategies such as superimposing alternative rhythms and relaxation techniques to manage functional tremor, as recommended by the occupational therapy consensus recommendations for functional neurological disorder 1.
Clinical Evaluation
The clinical evaluation should start with a detailed history focusing on onset, progression, exacerbating factors, family history of movement disorders, and medication use. Physical examination should assess tremor characteristics including frequency, amplitude, rhythmicity, and whether it's present at rest, with posture maintenance, or during voluntary movement.
Diagnostic Considerations
Essential tremor and Parkinson's disease are common causes of chin tremor, with essential tremor typically being postural or action-related while Parkinsonian tremor occurs at rest. Laboratory tests should include thyroid function tests, liver function tests, and serum electrolytes to rule out metabolic causes. Consider testing for Wilson's disease with serum ceruloplasmin and 24-hour urinary copper excretion in younger patients. Neuroimaging with MRI brain may be indicated to exclude structural lesions.
Management Strategies
For functional tremor, strategies such as superimposing alternative rhythms, using the unaffected limb to dictate a new rhythm, and assisting the person to relax the muscles in the limb can be helpful, as outlined in the occupational therapy consensus recommendations for functional neurological disorder 1. Additionally, employing anxiety management and distraction techniques when undertaking a task can be beneficial. Electromyography can help characterize the tremor pattern, and treatment depends on the underlying cause, with propranolol or primidone often effective for essential tremor, while Parkinson's disease may require levodopa therapy, as discussed in the context of Parkinsonian syndromes 1.
Treatment Options
Botulinum toxin injections into the mentalis muscle can provide symptomatic relief in refractory cases. It is essential to consider the potential benefits and harms of interventions, including the use of splinting, which may prevent restoration of normal movement and function, and to prioritize strategies that encourage normal movement patterns and resting postures, as recommended by the occupational therapy consensus recommendations for functional neurological disorder 1. The diagnostic validity of laryngeal electromyography (LEMG) for upper motor neuron disorders, laryngeal dystonia, and vocal tremor is unknown, and its use should be approached with caution, as noted in the recommendations of the neurolaryngology study group on laryngeal electromyography 1.
From the Research
Workup of Chin Tremor
The workup of chin tremor involves a detailed history and a focused neurologic examination to establish the type of tremor and its underlying cause.
- The evaluation should start with a tremor history, including the onset, duration, and characteristics of the tremor, as well as any associated symptoms or conditions 2, 3.
- A focused neurologic examination should attend to the subtleties of tremor phenomenology, including whether the tremor is an action tremor (postural, kinetic, or intention tremor) or a resting tremor 2, 3.
- The clinician should then formulate differential diagnoses based on the type of tremor, including disorders in which action tremor is the predominant tremor (e.g. essential tremor, enhanced physiologic tremor, drug-induced tremor) versus those in which resting tremor is the predominant tremor (e.g. Parkinson's disease) 2, 3.
Differential Diagnoses
The differential diagnoses for chin tremor include:
- Essential tremor: a common movement disorder characterized by action tremor, which may affect the chin, hands, or other body parts 2, 4, 3.
- Parkinson's disease: a neurodegenerative disorder characterized by resting tremor, bradykinesia, rigidity, and postural instability, which may also cause chin tremor 2, 4, 3.
- Dystonic tremor: a type of tremor associated with dystonia, a movement disorder characterized by involuntary muscle contractions 2, 3.
- Drug-induced tremor: a type of tremor caused by certain medications, such as antidepressants, antipsychotics, or lithium 2, 3.
Diagnostic Tests
Diagnostic tests may be used to support the diagnosis and rule out other conditions, including:
- Dopamine transporter (DAT) scans: may be used to diagnose Parkinson's disease and distinguish it from other parkinsonian disorders 5.
- Levodopa trials: may be used to diagnose Parkinson's disease and assess the response to treatment 5.
- Neuroimaging studies: such as MRI or CT scans, may be used to rule out other conditions that may cause tremor, such as stroke or tumor 3.