Between electromyography (EMG)-guided and non-EMG-guided “point-touch” techniques, which is better in the laryngeal botulinum toxin (BTX) injection treatment of adductor spasmodic dysphonia (AdSD)?
Background: AdSD is the most common form of spasmodic dysphonia. The preferred treatment modality is the injection of BTX type A into the intrinsic adductor muscle compartment of the larynx. No particular injection technique has been shown to be superior to another, however.
Study design: Retrospective chart review.
Setting: Division of Laryngology and Professional Voice, Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, Milwaukee; Department of Otolaryngology-Head and Neck Surgery, University of Washington, Seattle.
Synopsis: A percutaneous EMG-guided technique was compared with a permucosal endoscopy-guided technique using two different preparations of BTX for 64 patients who received 417 injections between June 2001 and June 2009. The outcome measures analyzed were patient report of beneficial effect (presence and duration of fluent speech), negative effects (presence of breathiness for greater than one week and presence of dysphagia) and an alteration or modification of dose compared to the prior injection. There were no statistically significant differences in the rate of effective injections, the need to alter dose, breathiness or dysphagia between the two groups. A subgroup analysis was performed on the 21 subjects who underwent injection using both techniques. Again, no statistically significant difference was found. The authors noted that benefits of EMG guidance of BTX include the ability to target dystonic motor units and localize injection near the motor endplates. In addition, a more accurately placed dose in a particular muscle should reduce any side effect of inappropriate dosing of an adjacent muscle. Disadvantages include the possibility that EMG signal may be misleading and the fact that the technique is time consuming, redundant to anatomic localization and more uncomfortable due to additional needle positioning and maneuvering.
Bottom line: Both point-touch and EMG-guided delivery of BTX are effective techniques for treatment of AdSD, and treating physicians should choose the injection technique that is most familiar and that suits their practice.
Citation: Fulmer SL, Merati AL, Blumin JH. Efficacy of laryngeal botulinum toxin injection: Comparison of two techniques. Laryngoscope. 2011;121(9):1924-1928.
—Reviewed by Sue Pondrom