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Objectives: It is not known whether current use of the medication primidone affects brain γ-aminobutyric acid (GABA) concentrations. This is an important potential confound in studies of the pathophysiology of essential tremor (ET), one of the most common neurological diseases. We compared GABA concentrations in the dentate nucleus in 6 ET patients taking primidone versus 26 ET patients not taking primidone., Methods: (1)H magnetic resonance spectroscopy was performed using a 3.0-T Siemens Tim Trio scanner. The MEGA-PRESS J-editing sequence was used for GABA detection in 2 cerebellar volumes of interest (left and right) that included the dentate nucleus., Results: The right dentate GABA concentration was similar in the 2 groups (2.21 ± 0.46 [on primidone] vs 1.93 ± 0.39 [not on primidone], P = 0.15), as was the left dentate GABA concentration (1.61 ± 0.35 [on primidone] vs 1.67 ± 0.34 [not on primidone], P = 0.72). The daily primidone dose was not associated with either right or left dentate GABA concentrations (P = 0.89 and 0.76, respectively)., Conclusions: We did not find a difference in dentate GABA concentrations between 6 ET patients taking daily primidone and 26 ET patients not taking primidone. Furthermore, there was no association between daily primidone dose and dentate GABA concentration. These data suggest that it is not necessary to exclude ET patients on primidone from magnetic resonance spectroscopy studies of dentate GABA concentration, and if assessment of these concentrations was to be developed as a biomarker for ET, primidone usage would not confound interpretation of the results.

Objectives: Cerebellar tremor is a disabling sign of multiple sclerosis (MS), and various kinds of treatments have been proposed with different results. Primidone is one of the medications, mostly advised for essential tremor. The aim of our study was to determine the tolerability and efficacy of primidone in reducing severe cerebellar tremor in patients with MS., Methods: Ten patients with severe cerebellar tremor were enrolled in this study. Primidone started with dose of 31.5 mg and gradually increased up to maximum of 750 mg/d. The severity of tremor was assessed with Activity of Daily Living (ADL), Nine-Hole Peg Test (NHPT), and Fahn Tremor Rating Scale (FTRS) at baseline and 2 follow-up studies after 6 and 12 weeks., Results: All outcome measures including ADL, FTRS, and NHPT of dominant and nondominant hands improved. The mean ADL changed from 51.8 at baseline to 36.8 after 12 weeks. FTRS was 14.8 at baseline, which reduced to 9.5 during this period. These changes were statistically significant. Although the time of the NHPT showed some improvement, it did not reach a statistically significant point after 6 weeks.The drug was well tolerated in all patients, and mild drowsiness reported by the patients disappeared at the end of the study., Conclusions: Our study showed that primidone is tolerable in MS patients and effectively reduces severe cerebellar tremor in such patients.

We here report on 3 patients with essential tremor, otherwise unresponsive to pharmacological treatment, who greatly benefited from low doses of topiramate (50 mg/d). No side effects were observed and improvement was sustained during a mean of 7 months (range 3-12 months) follow up. Our results suggest that topiramate titration should be performed gradually, so as not to neglect cases responsive to low doses.

The long-term efficacy of primidone (375-750 mg/day) in essential tremor was evaluated prospectively in 11 patients who had shown a favorable response to 4-week treatment with the drug under placebo-controlled conditions. On accelerometric evaluation, the magnitude of tremor after 3, 6, and 12 months on primidone was still significantly reduced compared with the initial placebo period. After discontinuation of primidone, tremor amplitude reverted to the placebo levels. Some loss of efficacy during long-term administration, however, was suggested by the results of self-assessment, physician's assessment, and performance tests. Three patients discontinued prematurely the drug because the sedative effects outweighed the potential therapeutic benefit. Side effects (especially drowsiness and sedation) were common at 4 weeks and 3 months but tended to subside thereafter. It is concluded that primidone retains at least part of its tremorolytic effect for up to 1 year, although the overall clinical benefit is limited in most patients.

Essential tremor may not represent a single condition. Subclassifications include kinetic predominant tremor; combined resting-postural tremor; primary writing tremor; isolated voice, chin, or tongue tremor; and orthostatic truncal tremor. We report patients with these disorders. An association of these conditions with essential tremor is suggested by a high occurrence of a family history of essential tremor, frequent presence of a mild postural tremor, and tremor reduction with alcohol ingestion. Pharmacologic responsiveness is different for these disorders. Propranolol and primidone often have beneficial effects but clonazepam was the only drug effective in some cases of kinetic predominant tremor and in orthostatic truncal tremor. Combined resting-postural tremor and voice tremor were often unresponsive to treatment.