Effects of subthalamic deep brain stimulation on dysarthrophonia in Parkinson’s disease.
Klostermann F, Ehlen F, Vesper J, Nubel K, Gross M, Marzinzik F, Curio G, Sappok T. (2007) Effects of subthalamic deep brain stimulation on dysarthrophonia in Parkinson’s disease. , J Neurol Neurosurg Psychiatry. 2007 Aug 31; [Epub ahead of print]
This study began by discussing the mixed findings in the literature regarding speech and DBS-STN. It was noted that it is likely that the different findings are due to the different measures used to evaluate speech (machine, speech therapist, patient, physician, etc.) as well as what is classified as “speech” (broad or specific). Therefore it was the goal of their paper to look at speech from multiple perspectives (patient, physician, speech therapist, and “technical measures”). It is notable that this study was conducted in Germany on long-term patients with DBS-STN. They found that motor symptoms improved after DBS-STN. The authors also found that speech was notably worse during stimulation than without as rated by the patients, physicians, and speech therapists. In regard to the technical measures of speech, the authors found that specific measures of speech improved during stimulation (voice tremor, duration of phonation for a vowel, number of syllables in a set reading time, and lower pause time while reading) . The authors concluded that DBS-STN improved specific motoric “speech subfunctions” that are due to Parkinson’s disease itself, but that these subfunction improvements do not equate to noticeable overall improved speech for the patient. The authors then discussed possible etiology of worsened speech due to DBS-STN (spread of the stimulation to surrounding areas, and direct stimulation of the STN). Limitations of this study included that drug-stimulation effects were not evaluated, the patients were long term, and the etiology of the difficulties were speculative. Limitations in this area of study as concluded by the authors include that some aspects of speech are difficult to measure with technical measures and the true measure of someone’s speech being intelligible after DBS-STN is if someone else can truly understand what that PWP is saying. Future research must incorporate the perception of the PWP and family in regard to quality of speech after DBS-STN for a true measure of this adverse side effect of this overall beneficial surgery.