MIAM BEACH – Botulinum toxin injections provided good, long-term symptom control for many patients with oromandibular dystonia in a retrospective analysis of a series of patients treated at a single center.
Oromandibular dystonia (OMD) is involuntary, repetitive, or twisting spasms of the muscles around the mouth and lower face. Affected people experience jaw opening, jaw closing, lateral jaw deviation, or a combination of these forms.
"Long-term management of OMD with botulinum toxin has minimal morbidity and is useful for all clinical forms," Dr. Catherine F. Sinclair said at the Triological Society’s Combined Sections meeting. With no cure for the condition and oral medication that only improves symptoms for about one-third of patients, botulinum toxin is considered a treatment option, she added.
Along with colleagues Dr. Lowell E. Gurey and Dr. Andrew Blitzer, Dr. Sinclair reported on a series of 59 patients treated with onabotulinumtoxinA (Botox) for OMD since 1995. They assessed the long-term management of the patients and also sought to develop a treatment algorithm for OMD and compare the current series with an original cohort of 20 OMD patients treated by Dr. Blitzer in the 1980s (Ann. Otol. Rhinol. Laryngol. 1989;98:93-7).
In the current series, 10 patients required only one treatment session, another 10 had two sessions, and 39 returned more than twice for subsequent injections of onabotulinumtoxinA. Functional response determined the need and timing of subsequent injections. For example, patients with less than a 50% improvement on a 1 to 100 function rating scale were re-injected less than a month following their initial treatment. The overall median time between treatments was 3 months.
An advantage of onabotulinumtoxinA injections, compared with oral medications, is a greater ability to tailor the treatment. "Injections can be titrated by dose and site to address the predominant muscle systems involved," Dr. Sinclair said at the meeting, which was jointly sponsored by The Triological Society and the American College of Surgeons.
Initial injection dosage ranged from 2.4 U to 5.0 U onabotulinumtoxinA. "Regardless of clinical type, if a patient experiences no response or less than 50% functional improvement, they should be re-injected with either the same dose as the initial injection or with a dose increase of 5 U to 10 U botulinum toxin," said Dr. Sinclair, an otolaryngology fellow at St. Luke’s–Roosevelt Hospital in New York. Also consider treatment of additional muscles, she added.
OMD subtype dictated the specific muscles injected. The masseter and/or temporalis muscles were most often injected for the jaw closing subtype, for example. The internal pterygoid was most often injected for the jaw opening and lateral deviation types of OMD. All injections were percutaneous except for external pterygoid injections, where were done intra-orally, Dr. Sinclair said.
One major caveat is to avoid significant post-injection dysphagia. For this reason, Dr. Sinclair said, anterior digastric muscle injections are performed superficially to avoid diffusion into the underlying floor of the mouth and tongue base musculature. In the study patients, automated machine guidance coupled with visual inspection of areas of maximum muscular hypertrophy determined initial needle placement. Optimal placement was confirmed with voluntary movement.
Not surprisingly, large muscles such at the masseter and temporalis typically receive higher toxin dose and a higher median number of injections. For example, these two muscles are typically injected at five sites, compared with three each for the pterygoid or digastric muscles, Dr. Sinclair said.
The injections appear to be relatively safe in this population. There were no complications reported post-injection by any patient in the current series, Dr. Sinclair said.
The mean age among the 59 patients was 57 years, and 72% were women. The mean follow-up time was 4.3 years.
"Of note, significantly more patients with jaw opening form of OMD were treated in the more recent data set," Dr. Sinclair said. "In line with this, there was an increase in lateral pterygoid and anterior digastric injections," compared with the older series. Despite the increase in jaw opening dystonia in more recent years, the majority of patients (65%) still presented with the jaw closing form.
Dr. Sinclair reported having no relevant financial disclosures.