Botulinum Toxin Type B in Parkinson's Disease- related Drooling
Abstract & commentary
By Panida Piboolnurak, MD, Assistant Professor, Department of Neurology and Neuroscience, Weill Medical College, Cornell University. Dr. Piboolnurak reports no financial relationship relevant to this field of study.
Synopsis: Botulinum toxin type B injection into the parotid glands is safe and effective for PD-related drooling, with duration of action of 3–6 months.
Source: Lagalla G, Millevolte M, Capecci M, et al. Long-lasting benefits of botulinum toxin type B in Parkinson's disease-related drooling. J Neurol 2009; April 23 DOI 10.1007/s00415-009-0085-1 [Epub ahead of print].
Drooling is common in Parkinson's disease (PD), and it can affect the patient's quality of life. Current treatment options, including anticholinergics, parotid gland irradiation, and salivary gland ligation or excision, are limited because of their potential side effects and invasiveness. Because botulinum toxin (BTX) can inhibit acetylcholine release at the autonomic nerve terminals, it may be able to reduce saliva secretion. Given a higher incidence of autonomic effects of BTX-B compared to BTX-A, BTX-B can provide some advantages in the treatment of drooling. A previous randomized, controlled trial already showed benefit of BTX-B injections into parotid and submandibular glands in 16 PD patients. This study was designed to ascertain the effectiveness of BTX-B on PD-related drooling and to determine duration of its effect.
PD patients with moderate to severe drooling were recruited and were randomly assigned to receive either BTX-B 4000 U (0.8 ml) or placebo (0.8 ml of 0.9% saline) into each pre-auricular portion of the parotid gland, guided by anatomic landmark. Clinical assessment was performed at baseline and one month after the injections using both subjective measures (Drooling Severity and Frequency Scale, patient embarrassment within the familial and social context, drooling and dysphagia subscores of UPDRS, and Global Impression Score) and objective measures (weight of five dental rolls retained in the mouth for five minutes and evaluation of masseter strength and resistance). Duration of action was determined by patients' subjective report and objective measures of saliva production.
Thirty-six subjects (26 men and 10 women; age 71.9 ± 5.9 years) with disease duration of 12.0 + 6.8 years and Hoehn and Yahr (H&Y) stage II to IV were randomly assigned to receive BTX-B or placebo (18 subjects each group). One month after the injections, subjects in BTX-B group had less drooling, whereas most controls did not have significant change in drooling severity. All subjects given BTX-B were satisfied with the result, but only seven controls were satisfied. The odds ratio of achieving a moderate to dramatic improvement after BTX-B treatment compared to placebo was 59.5 (95% confidence limits: 5.9–595). Three BTX-B patients had mild, transient dysphagia which started 10 days after the injections and recovered within two weeks. One BTX-B patient had a transient mild jaw weakness. No patient had hematoma, facial palsy or any other adverse events. The duration of effect on drooling from the injections was 19.2 ± 6.3 weeks in BTX-B group and 6.7 ± 1.4 weeks in seven controls who reported an improvement.
Commentary
Drooling in PD is caused by a reduction in swallowing frequency and stooped posture. Since BTX can block secretion of saliva and has minimal systemic side effects, it can be helpful in PD-related drooling. Although it has been shown that BTX-B has higher incidence of autonomic effects, there is not enough evidence to suggest that BTX-B is better than BTX-A in reducing saliva drooling. A study on treatment of drooling in children with cerebral palsy or neurodegenerative diseases with BTX showed no significant difference between BTX-A and BTX-B.1
BTX can be injected into either parotid gland or submandibular gland, or both. However, since the parotid gland is more superficial and is not very close to the muscles involving in swallowing, it is a safer target. BTX injection can be given using anatomical, ultrasound, or EMG-guided techniques. A future study comparing different injection techniques will be able to determine which technique is the most appropriate.
Reference
1. Wilken B, Aslami B, Backes H. Successful treatment of drooling in children with neurological disorders with botulinum toxin A or B. Neuropediatrics 2008;39: 200-204.
Botulinum toxin type B injection into the parotid glands is safe and effective for PD-related drooling, with duration of action of 3–6 months.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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