Repetitive transcranial magnetic stimulation to SMA worsens complex movements in Parkinson's disease.

OBJECTIVES: To evaluate the therapeutic potential of repetitive transcranial magnetic stimulation (rTMS) for Parkinson's disease (PD) by delivering stimulation at higher intensity and frequency over longer time than in previous research. Promising beneficial effects on movement during or after rTMS have been reported. METHODS: Ten patients with idiopathic PD were enrolled in a randomized crossover study comparing active versus sham rTMS to the supplementary motor area (SMA). Assessments included reaction and movement times (RT/MT), quantitative spiral analysis, timed motor performance tests, United Parkinson's Disease Rating Scale (UPDRS), patient self-report and guess as to stimulation condition. RESULTS: Two of 10 patients could not tolerate the protocol. Thirty to 45 min following stimulation, active rTMS as compared with sham stimulation worsened spiral drawing (P=0.001) and prolonged RT in the most affected limb (P=0.030). No other significant differences were detected. CONCLUSIONS: We sought clinically promising improvement in PD but found subclinical worsening of complex and preparatory movement following rTMS to SMA. These results raise safety concerns regarding the persistence of dysfunction induced by rTMS while supporting the value of rTMS as a research tool. Studies aimed at understanding basic mechanisms and timing of rTMS effects are needed.

Determinants of seizure threshold in ECT: benzodiazepine use, anesthetic dosage, and other factors.

The electrical dosage of the ECT stimulus impacts on efficacy and cognitive side effects, yet seizure threshold (ST) may vary as much as 50-fold across patients. It would be desirable to predict ST on the basis of patient and treatment characteristics. In particular, concerns have been raised that benzodiazepine use and higher dosage of barbiturate anesthetics elevate ST. In a three-site study, ST was quantified at the first ECT session using an identical empirical titration procedure in 294 patients who met RDC and DSM-IIIR criteria for a major depressive episode. ST varied over a 35-fold range across patients treated with right unilateral (RUL) (n = 267) and bilateral (BL) (n = 27) ECT. Higher ST was associated with BL electrode placement (p = 0.001). Among patients treated with RUL ECT, univariate analyses indicated that higher ST was associated with advanced age (p < 0.001), male gender (p < 0.001), greater burden of medical illness (p < 0.001), weight (p < 0.01), duration of mood disorder (p < 0.01), and history of previous ECT (p < 0.05). Average lorazepam dose in the 48 hours prior to ECT was not associated with ST, but was associated with decreased seizure duration (p < 0.01). Absolute, but not weight-adjusted, methohexital dose was associated with ST (p < 0.01). Multivariate analyses in patients treated with unilateral ECT showed that only 27.6% of the variance in ST (p < 0.0001) could be predicted. In the multivariate analyses, only age (p = 0.0001), gender (p = 0.01), and methohexital dose (p = 0.0001) were independently related to ST. Low dosage of lorazepam and methohexital dosage below 1 mg/kg are unlikely to impact on ST. Given the limited capacity to predict ST, empirical titration remains the only accurate method to determine electrical dosage in RUL ECT.