Botulinum Toxin Therapy in Writer’s Cramp and Musician’s Dystonia

Task-specific focal dystonia is characterized by muscle contraction(s) during a specific task, resulting in abnormal postures or movements. Specifically, writer’s cramp involves the upper extremity during the act of writing. Musician’s dystonia has a highly variable presentation, and thus makes therapeutic options more limited. Treatments include oral pharmacologic agents, neuromodulation, surgery and, most often, botulinum toxin (BoNT) injection. Selection of target muscles for toxin injection continues to be an area of active research for these task-specific movements. We present a review of the literature selected from a predefined search of the MEDLINE and ClinicalTrials.gov databases. We include six controlled studies of botulinum toxin for the management of writer’s cramp and focal task-specific dystonia (FTSD), including musician’s dystonia. Overall, 139 patients were included across all studies, with 99 individuals injected for writer’s cramp and the remaining 40 individuals with FTSD. The age range of all patients was 18–80 years old. We included studies that utilized only the BoNT-A serotype. These studies utilized various severity scales to quantify response to toxin injection, with ratings of instrument or pen control included as subjective ratings. Of the included 139 patients in this review, pooled data for toxin response show that 73% of patients who received the drug demonstrated improvement. Specific techniques for muscle localization and targeting were difficult to study as variable methods were employed. This remains an area of ongoing exploration.

The effect of background speech on attentive sound processing: A pupil dilation study

Everyday cognitive tasks are rarely performed in a quiet environment. Quite on the contrary, very diverse surrounding acoustic signals such as speech can involuntarily deviate our attention from the task at hand. Despite its tight relation to attentional processes, pupillometry remained a rather unexploited method to measure attention allocation towards irrelevant speech. In the present study, we registered changes in pupil diameter size to quantify the effect of meaningfulness of background speech upon performance in an attentional task. We recruited 41 native German speakers who had neither received formal instruction in French nor had extensive informal contact with this language. The focal task consisted of an auditory oddball task. Participants performed an animal sound duration discrimination task containing frequently repeated standard sounds and rarely presented deviant sounds while a story was read in German or (non-meaningful) French in the background. Our results revealed that, whereas effects of language meaningfulness on attention were not detectable at the behavioural level, participants’ pupil dilated more in response to the sounds of the auditory task when background speech was played in non-meaningful French compared to German, independent of sound type. This could suggest that semantic processing of the native language required attentional resources, which lead to fewer resources devoted to the processing of the sounds of the focal task. Our results highlight the potential of the pupil dilation response for the investigation of subtle cognitive processes that might not surface when only behaviour is measured.

Subspace based Multiple Constrained Minimum Variance (SMCMV) Beamformers

In MEG and EEG brain imaging research two popular approaches are often used for spatial localization of focal task- or stimuli-related brain activations. One is a so called MUSIC approach applied in the form of RAP or TRAP MUSIC algorithms. Another one is the beamformer approach, specifically multiple constrained minimum variance (MCMV) beamformer when dealing with significantly correlated activations. Either method is using its own source localizer functions. Considering simplicity, accuracy and computational efficiency both approaches have their advantages and disadvantages. In this study we introduce a novel set of so called Subspace MCMV (or SMCMV) beamformers whose localizer functions combine MUSIC and MCMV localizers. We show that in ideal situations where forward modeling, data recording and noise measurements are error-free, SMCMV localizers allow precise identification of n arbitrarily correlated sources irrespective to their strength in just n scans of the brain volume using RAP MUSIC type algorithm. We also demonstrate by extensive computer simulations that with respect to source localization errors and the total number of identified sources SMCMV outperforms both the TRAP MUSIC and MIA MCMV (which is the most accurate MCMV algorithm to our knowledge) in non-ideal practical situations, specifically when the noise covariance cannot be estimated precisely, signal to noise ratios are small, source correlations are significant and larger numbers of sources are involved.

Metacognition in Human Factors: The Rewards and Consequences of Repeated Assessment

Recent publications have encouraged researchers to consider how metacognition affects users’ judgments of usability and workload by integrating metacognitive assessments with traditional testing paradigms. However, the repercussions of collecting these measures concurrently are unknown. We used a visual search task to determine how the frequency of metacognitive assessments affected metacognitive accuracy and performance. Frequent assessments did not impact performance on the focal task; however, they did reduce the accuracy of participants’ metacognitive judgments by about 7%. This finding suggests that researchers should consider context when selecting a metacognitive assessment strategy.

Botulinum Toxin for the Treatment of Focal Task-Specific Hand Dystonias: Systematic Review and Meta-Analysis

Objective:Botulinum Toxin (BTX) has become a widely used treatment in several dystonic conditions, but the evidence for its efficacy has largely come from open trials and expert opinion. This systematic review examined the efficacy and safety of BTX in the treatment of Focal Hand Dystonia (FHD) in Randomized Controlled Trials (RCTs).Methods:We searched Ovid MEDLINE, EMBASE, Cochrane Database of Systematic Reviews (CDSR), Database of Abstracts of Reviews of Effects (DARE), Cochrane Central Register of Controlled Trials (CENTRAL), CINAHL, SPORT Discus, SCOPUS, Web of Science, PEDro, ClinicalTrials.gov, and the International Clinical Trials Registry Platform (ICTRP) for randomized, placebo-controlled trials on the use of BTX for FHD.Results:Of 1,116 publications retrieved from the databases searched, three publications were included. The evidence identified pertains to focal task-specific hand dystonias. Sixty-nine participants were involved in the three RCTs with a mean duration of symptoms of 7.5 years. Participants were assessed using a combination of self-reported and functional performance outcome measures following injections of BTX subtype A (BTX-A) or placebo. The Oxford Quality Scale was used to assess the included studies, and the three studies each scored 3/5 or above. The included studies reported no adverse events with BTX-A use, other than muscle weakness and pain at the injection sites.Conclusion:The number of participants included in these three trials is too small to draw dependable conclusions about the efficacy and safety of BTX-A for FHD. There is currently not enough evidence to recommend the routine use of BTX-A for FHD.

Tongue Position Variability During Sustained Notes in Healthy vs Dystonic Horn Players Using Real-Time MRI

OBJECTIVE: Embouchure dystonia (EmD) is a variant of focal task-specific dystonia in musicians characterized by the loss of control in facial and oral muscles while controlling airflow into the mouthpiece of a wind or brass instrument. We compared tongue position variability (TPV) during sustained notes between healthy, elite horn players and horn players affected by EmD. METHODS: Real-time MRI films at 33.3 ms resolution were obtained from 8 healthy elite and 5 EmD horn players as they performed on a non-ferromagnetic horn at each of three different dynamic levels: pianissimo, mezzo forte, and fortissimo. Nine profile lines (3 from anterior, 3 from middle, and 3 from posterior oral cavity regions) were overlaid on each image using a customized MATLAB toolkit, and the variability of the dorsal tongue edge position was examined at each dynamic from temporal intensity profiles produced by MATLAB. RESULTS: Despite trends for more pronounced TPV (larger standard deviations) in the elite musicians (p=0.062), 2-way repeated measures ANOVA revealed no significant differences between groups. However, dynamic level significantly influenced TPV for all subjects, combined (p=0.048) and different regions of the oral cavity showed differing TPV (p<0.001). When only the most active region (anterior oral cavity) was included in the model, differences between groups reached statistical significance (elite > EmD, p<0.048), particularly at the fortissimo dynamic. We postulate that these differences may be due, in part, to a greater degree of generalized orofacial muscle tension in the EmD subjects that includes the tongue.