September 14, 2010

Age Influences Botox Response in Patients with Spasmodic Dysphonia

Dr. Chang recently published a book chapter discussing how age influences response to botox injections in patients suffering from spasmodic dysphonia.

Introduction
Spasmodic dysphonia is a dystonia (muscle spasms) involving the muscles of the voicebox resulting in involuntary attacks of a strangled sounding voice. Treatment is botox injection to the involved muscles resulting in a decrease of such spasms thereby resulting in a more smooth-sounding voice.

Unfortunately, there are side effects with botox injections to the voicebox including aspiration, dysphagia, breathy voice, etc for a short period of time prior to the good voice. Typically, one week of side effects results in about 3 months of a good voice.

Research into this area typically has been to try and maximize the duration of a good voice while decreasing the duration of side effects.

A prior paper published by Dr. Chang tried to establish what the correct dose is to maximize a good voice and minimize side effects.

This book chapter tries to determine if age influences botox response.

Age and Botox Responses
What was found is a positive correlation between age and duration of normal voice and duration of side effects after botox injection. Age did not appear to play a role in the severity of side effects experienced by patients. However, the number of BTX-A injections received by a given patient was negatively correlated with duration of normal voice and side effects to a degree greater than age.

What does this mean?

Age must be taken into consideration when deciding on what dose of botox to inject since as a patient becomes older, one may see a slow increase in not only duration of normal voice, but also duration of side effects reported. Stated another way, for a given dose, the duration of side effects is larger for an older patient compared with a younger one. However, as the cumulative number of injections a patient receives increases over time, the duration of normal voice and side effects would be expected to decrease slowly.

Reference:
Age as a Factor in Responses to Botulinum Toxin Injection in Adductor Spasmodic Dysphonia Patients pp. 101-112
Fauquier blog
Fauquier ENT

Dr. Christopher Chang is a private practice otolaryngology, head & neck surgeon specializing in the treatment of problems related to the ear, nose, and throat. Located in Warrenton, VA about 45 minutes west of Washington DC, he also provides inhalant allergy testing/treatment, hearing tests, and dispenses hearing aids.


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