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IMPORTANCEThere is an unmet need for safe and efficacious treatments for upper-extremity dystonic tremor (DT). To date, only uncontrolled retrospective case series have reported the effect of botulinum neurotoxin (BoNT) injections on upper-extremity DT.OBJECTIVE To assess the effect of BoNT injections on tremor in patients with upper-extremity DT. DESIGN, SETTING, AND PARTICIPANTSIn this placebo-controlled, parallel-group randomized clinical trial, 30 adult patients with upper-extremity DT treated at a movement disorder clinic in a tertiary care university hospital were randomized in a 1:1 ratio to BoNT or saline injection, 0.9%, using a computer-generated randomization sequence. Randomization was masked using opaque envelopes. The participant, injector, outcome assessor, and statistician were blinded to the randomization. Participants were recruited between November 20, 2018, and December 12, 2019, and the last follow-up was completed in March 2020.INTERVENTIONS Participants received electromyographically guided intramuscular injections of BoNT or placebo into the tremulous muscles of the upper extremity. Injection patterns and doses were individualized according to tremor phenomenologic findings. MAIN OUTCOMES AND MEASURESThe primary outcome was the total score on the Fahn-Tolosa-Marin Tremor Rating Scale 6 weeks after the intervention. Outcomes were assessed at baseline, 6 weeks, and 12 weeks. All patients were offered open-label BoNT injections after 12 weeks and reassessed 6 weeks later.RESULTS A total of 48 adult patients with a diagnosis of brachial dystonia with DT were screened. Fifteen were ineligible and 3 refused consent; therefore, 30 patients (mean [SD] age, 46.0 [18.6] years; 26 [86.7%] male) were recruited, with 15 randomized to receive BoNT and 15 to receive placebo. In the intention-to-treat group, the Fahn-Tolosa-Marin Tremor Rating Scale total score was significantly lower in the BoNT group at 6 weeks (adjusted mean difference, -10.9; 95% CI, -15.4 to -6.5; P < .001) and 12 weeks (adjusted mean difference, -5.7; 95% CI, -11.0 to -0.5; P = .03). More participants in the BoNT group reported global improvement on the Global Impression of Change (PGIC) assessment (PGIC 1,2, and 3: BoNT: 4 [26.7%], 6 [40.0%], and 5 [33.3%]; placebo: 5 [33.3%], 10 [66.7%], and 0, respectively; P = .047). Subjective hand weakness (BoNT: 6 [40.0%]; placebo: 4 [28.6%], P = .52) and dynamometer-assessed grip strength (mean difference, -0.2 log 10 [kgf/m 2 ] 2 / Hz-Hz; 95% CI, -0.9 to 0.4 log 10 [kgf/m 2 ] 2 /Hz-Hz; P = .45) were similar in both groups. CONCLUSIONS AND RELEVANCEIn this randomized clinical trial, botulinum neurotoxin injections were superior to placebo in reducing tremor severity in upper-extremity DT. An individualized approach to muscle selection and dosing was beneficial without unacceptable adverse effects.

BackgroundNeuropathic Tremor (NT) is a postural/kinetic tremor of the upper extremity, often encountered in patients with chronic neuropathies such as paraprotein‐associated and hereditary neuropathies.ObjectivesTo describe the clinical and electrophysiological features of NT in a previously underrecognized setting‐ during recovery from Guillain‐Barré Syndrome (GBS).MethodsPatients with a documented diagnosis of GBS in the past, presenting with tremor were identified from review of clinical records. Participants underwent structured, videotaped neurological examination, and electrophysiological analysis using tri‐axial accelerometry‐surface electromyography. Tremor severity was assessed using the Fahn‐Tolosa‐Marin Tremor Rating Scale.ResultsWe describe the clinical and electrophysiological features of 5 patients with GBS associated NT. Our cohort had a fine, fast, and slightly jerky postural tremor of frequency ranging from 8 to 10 Hz. Dystonic posturing and overflow movements were noted in 4/5 patients. Tremor appeared 3 months–5 years after the onset of GBS, when patients had regained near normal muscle strength and deep tendon jerks were well elicitable. Electrophysiological analysis of tremor strongly suggested the presence of a central oscillator in all patients.ConclusionNT is not limited to chronic inflammatory or hereditary neuropathies and may occur in the recovery phase of GBS. The tremor is characterized by a high frequency, jerky postural tremor with dystonic posturing. Electrophysiological evaluation suggests the presence of a central oscillator, hypothetically the cerebellum driven by impaired sensorimotor feedback.

Background Social cognition is the study of how people make sense of themselves and others. Impairment in several domains of social cognition is increasingly being recognized in Parkinson's disease (PD). Objectives We aimed to study multiple domains of social cognition in Indian PD patients using a culturally appropriate, validated instrument. Methods We recruited 52 individuals with PD and 31 healthy volunteers (HV) and used the Social Cognition Rating Tools in Indian Setting (SOCRATIS) tool to assess theory of mind (ToM), attributional biases and social cue perception. Quality of life (QoL) was assessed using the PDQOL scale. Results Baseline characteristics were comparable between PD and HV. The mean (SD) FOT index (first order ToM index) was 0.86(0.18) in PD and 0.99(0.07) in HV [P < 0.001]. The PD group showed higher Externalizing Bias [EB, 4.42(3.91)], compared to HV [1.58(3.22), P = 0.001]. The mean (SD) Faux Pas Composite Index (FPCI ALT) was 0.69(0.09) in PD and 0.78(0.13) in HV [P < 0.001]. Social cognition indices were not associated with QoL in PD. Clinical parameters—age, gender, HAM‐D, MOCA, education, levodopa equivalent daily dose of medication, number of PD drugs and trihexyphenidyl use did not predict social cognition. Conclusion PD patients were less successful than age, gender matched controls in understanding social situations and other's thought processes and had higher tendency to attribute undesirable events to external causes. Deficits in social cognition did not impair the quality of life.

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