Individual Response to Botulinum Toxin Therapy in Movement Disorders: A Time Series Analysis Approach.

On a group level, satisfaction with botulinum neurotoxin (BoNT) treatment in neurological indications is high. However, it is well known that a relevant amount of patients may not respond as expected. The aim of this study is to evaluate the BoNT treatment outcome on an individual level using a statistical single-case analysis as an adjunct to traditional group statistics. The course of the daily perceived severity of symptoms across a BoNT cycle was analyzed in 20 cervical dystonia (CD) and 15 hemifacial spasm (HFS) patients. A parametric single-case autoregressive integrated moving average (ARIMA) time series analysis was used to detect individual responsiveness to BoNT treatment. Overall, both CD and HFS patients significantly responded to BoNT treatment with a gradual worsening of symptom intensities towards BoNT reinjection. However, only 8/20 CD patients (40%) and 5/15 HFS patients (33.3%) displayed the expected U-shaped curve of BoNT efficacy across a single treatment cycle. CD (but not HFS) patients who followed the expected outcome course had longer BoNT injection intervals, showed a better match to objective symptom assessments, and were characterized by a stronger certainty to control their somatic symptoms (i.e., internal medical locus of control). In addition to standard evaluation procedures, patients should be identified who do not follow the mean course-of-treatment effect. Thus, the ARIMA single-case time series analysis seems to be an appropriate addition to clinical treatment studies in order to detect individual courses of subjective symptom intensities.

Subjective versus objective symptom intensities ratings in cervical dystonia and hemifacial spasm across a botulinum neurotoxin cycle.

BACKGROUND: Subjective symptom complaints often do not match the expert's ratings in focal dystonia. Nonetheless, perceived symptom intensities drive compliance and outcome of botulinum neurotoxin (BoNT) treatment. METHODS: Perception of symptom development across a BoNT cycle was obtained in 21 cervical dystonia (CD) and 15 hemifacial spasm (HFS) patients at four time points during a BoNT cycle. Subjective assessments were recorded by means of a quality-of-life questionnaire and a patient diary containing items related to subjective severity of disease, mood, pain, social impairment, and quality of life. Medical investigation used the Tsui score and TWSTRS, and a HFS rating score, respectively. RESULTS: In both patient groups, subjective intensities were strongly associated with psychological variables. Only in CD did objective assessment moderately correlate with subjective ratings solely at the beginning and the end of the BoNT cycle. Overall, the beneficial effects of BoNT treatment were only loosely associated with subjective experiences in both groups. CONCLUSION: The emotional situation should be assessed regularly in patients undergoing BoNT therapy.