Propranolol and Botulinum Toxin for Essential Vocal Tremor

Essential tremor is the most common adult-onset movement disorder, and essential voice tremor is the vocal manifestation of essential tremor. While nearly all essential tremor patients experience hand tremor, many also manifest head tremor and voice tremor. Essential voice tremor can lead to increased vocal effort, decreased intelligibility, and misconstrued emotional state. Only one medication, propranolol, is FDA-approved to treat essential tremor. Propranolol is not felt to be nearly as effective for axial tremors (head, trunk, neck) as it is for extremity tremors. However, this has not been studied with any objective assessment in a prospective way for EVT. For patients with essential voice tremor, the limited published data suggests that botulinum toxin has been shown to lead to functional voice improvement. Botulinum toxin, though also not well-studied with objective voice outcomes, is a commonly used clinical therapy for treatment of essential voice tremor. While it is used more often for essential voice tremor than propranolol therapy, botulinum toxin also has not been prospectively studied with validated, objective voice outcome measures. The investigators would like to determine if propranolol has any significant effect on vocal tremor. The investigators would also like to determine, in an objective way, the effect of botulinum toxin on vocal tremor. If effective, propranolol would provide an affordable and non-invasive alternative or addition to botulinum toxin injections for patients with essential voice tremor.

Specific Aims

• Determine the effect of propranolol on vocal tremor in the treatment-seeking population.

To date, the nonselective beta-blocker propranolol remains the only agent approved for the treatment of essential tremor (ET). For ET, immediate and sustained release formations of propranolol are equally effective, while other beta-blockers like nadolol and timolol are not as effective. While propranolol improves tremor in greater than half of patients with essential tremor, its effects on tremor are not evenly distributed. Improvement in tremor symptoms is greater for limb tremor than axial tremor, and therefore propranolol is not commonly used for the treatment of essential voice tremor (EVT). However, its effect on essential voice tremor has never been objectively, prospectively studied. Our aim is to objectively determine the effect of propranolol on essential voice tremor in the treatment-seeking population by evaluating patients with EVT before and after propranolol therapy.

• Determine the effect of botulinum toxin injections on vocal tremor in the treatment-seeking population.

More recently, botulinum toxin A has been used for the treatment of EVT. Chemical denervation with botulinum toxin is only modestly effective in reducing limb tremor in ET and complicated by side effects of weakness. However, botulinum toxin seems to be more effective in treating EVT than other manifestations of ET. While prior studies have not enlisted validated assessments of voice quality to measure the effect of botulinum toxin injections on EVT, they have shown subjective improvement in acoustic measures of tremor and ratings of videotaped speech after therapy with botulinum toxin. Our aim is to objectively determine the effect of botulinum toxin on vocal tremor in the treatment-seeking population by evaluating patients with EVT before and after botulinum therapy.

Voice Evaluations and Medications

For the first evaluation, a research coordinator will collect demographics and patient reported data. This data will result from providing patient questionnaires and recording the patient's voice. VRQOL data will be collected by having the patient answer ten statements on a 1-5 scale, such as "I have trouble speaking loudly or being heard in noisy situations" or "I run out of air and need to take frequent breaths." QUEST data will be also recorded to a 30-item essential tremor-specific questionnaire. Patient will also complete a global voice rating of a 0-7 scoring of "How would you rate your voice today?" After these subjective questionnaires, patient will participate in a vocal recording using prompts and passages from the validated CAPE-V voice assessment tool.

After a discussion of the risks and benefits of propranolol therapy, the patient will then be given a prescription by the principal investigator for propranolol.

The second evaluation will occur at an office visit two weeks after initiating propranolol therapy. Again, this will consist of patient-reported V-RQOL, QUEST, and global voice rating data. Patient will participate in a second vocal recording using prompts and passages from the validated CAPE-V voice assessment tool.

At this second evaluation, patient will receive botulinum toxin injections. The risks and benefits of botulinum toxin therapy will be explained to the patient, and bilateral injections will take place.

Four weeks after botulinum toxin injection, the patient will undergo the third voice assessment. Again, this will consist of patient-reported V-RQOL, QUEST, and global voice rating data. Patient will participate in a third vocal recording using prompts and passages from the validated CAPE-V voice assessment tool.

Eligibility Criteria:
Inclusion Criteria:

* Diagnosis of essential voice tremor
* Patients who have received or are planning to receive botulinum toxin injections for essential voice tremor
* Patients who give informed consent to be contacted for research

Exclusion Criteria:

* Patients who are already on a beta blocker
* Patients who suffer from hypotension, bradycardia, or otherwise have a medical contraindication to beta blocker therapy (eg. moderate to severe bronchial asthma)

If the patient has received botulinum toxin injections for EVT previously, a three-month washout period is necessary before participation.