Differential and better response to deep brain stimulation of chorea compared to dystonia in Huntington's disease.

Huntington's disease (HD) is an autosomal dominant and progressive neurodegenerative syndrome characterized by motor, cognitive and psychiatric manifestations. Chorea and dystonia are features that may be troublesome to some patients and may potentially prove unresponsive to pharmacological treatments. There are several reports on the results of globus pallidus internus deep brain stimulation (DBS) surgery for HD. In these published cases, DBS was utilized mainly to treat disabling chorea. We report our experience with 2 HD cases treated with DBS. The cases illustrate a differential response with a better outcome in the choreic presentation compared to the dystonic presentation. Additionally, DBS worsened gait features in both cases.

Are selective serotonin reuptake inhibitors associated with greater apathy in Parkinson's disease?

Apathy is a common neuropsychiatric feature of Parkinson's disease (PD), but little is known of relationships between apathy and specific medications in PD. Following a retrospective database and chart review of 181 Parkinson's patients, relationships between Apathy Scale scores and use of psychotropic and antiparkinsonian medications were examined with multiple regression. Controlling for age, sex, education, and depression, the use of selective serotonin reuptake inhibitors (SSRIs), but not other antidepressants, was associated with greater apathy. Use of monoamine oxidase B inhibitors was associated with less apathy. Longitudinal studies are needed to evaluate a potential SSRI-induced apathy syndrome in PD.

GPi and STN deep brain stimulation can suppress dyskinesia in Parkinson's disease.

OBJECTIVES: To compare subthalamic nucleus (STN) to globus pallidus internus (GPi) deep brain stimulation (DBS) for control of motor fluctuations and for potential dyskinesia-suppressing qualities. METHODS: We conducted a retrospective database review of all patients who underwent GPi or STN DBS for idiopathic Parkinson's disease. Direct dyskinesia suppression (dDS) was defined as improvement in dyskinesia subscore of the unified Parkinson's disease rating scale (UPDRS) part IV (items 32-34), despite lack of reduction in dopaminergic medication dosage. We analyzed the data using methods appropriate for a case-control study. RESULTS: A total of 133 patients were evaluated. At the last evaluation Dyskinesia scores and motor fluctuations significantly improved in both the GPi (p < 0.0001) and STN groups (p < 0.0001). The GPi group was more likely than the STN group to experience dDS (odds ratio = 1.95, 95% CI = 0.556, 3.21). However, the association between DBS target and dDS was not statistically significant (Pearson chi-square = 2.286, p = 0.131). CONCLUSIONS: The overall clinical outcome of STN and GPi DBS for control of dyskinesia and motor fluctuations was similar. STN and GPi DBS both had some direct dyskinesia suppression effects.

Low-Frequency Deep Brain Stimulation for Dystonia: Lower is Not Always Better.

BACKGROUND: It has been observed that low-frequency stimulation (LFS) may be effective for dystonia, and the use of LFS may alleviate the need for frequent battery changes in a subset of patients. The aim of this study was to analyze LFS as a strategy to treat deep brain stimulation (DBS) patients with various dystonias. METHODS: Subjects had to receive a minimum of 6 months of clinical follow-up at the University of Florida, and were required to have a minimum of 3 months on a LFS trial. Twenty-seven dystonia DBS patients were retrospectively analyzed from the UF-INFORM database. RESULTS: Thirteen subjects met inclusion criteria. Of the 13 subjects, all had bilateral internal pallidum (GPi) DBS, and five (38.5%) remained with at least one side on LFS settings at their last follow up (average follow up 24 months, range 6-46 months). Within the first 6 months, six (46%) subjects remained on LFS and seven (54%) were changed to high-frequency stimulation (HFS). Those who remained on LFS settings at 6 months were characterized by shorter disease durations than those on HFS settings. There were no significant differences in dystonia severity (Unified Dystonia Rating Scale and Burke-Fahn-Marsden Dystonia Rating Scale) at baseline between the two settings. The estimated battery life for LFS (79.9±30.5) was significantly longer than for HFS settings (32.2±13.1, p<0.001). DISCUSSION: LFS was ultimately chosen for 38.5% of all subjects. Although this study failed to yield solid predictive features, subjects on LFS tended to have shorter disease durations.

Steady or not following thalamic deep brain stimulation for essential tremor.

Deep brain stimulation (DBS) has become an important option for medication-refractory essential tremor (ET), but may contribute to worsened gait and falling. This study evaluates impaired gait in a cohort of patients treated with DBS with a retrospective review of ET patients before and after DBS implantation. Factors examined included: age, duration of symptoms, pre-morbid gait difficulties/falls, Fahn-Tolosa-Marin tremorrating scale (TRS) scores at baseline, 6 months post-unilateral DBS implantation, and 6 or 12 months post-bilateral implantation. All implantations targeted the nucleus ventralis intermediate (Vim). Thirty-eight patients (25 males, 13 females) were included. Twenty-five patients (65.8%) underwent unilateral DBS implantation and 13 (34.2%) bilateral. The mean age at surgery was 67.1 years ± 11.4 (range 34-81). The mean disease duration was 31 years ± 18.3 (range 6-67). Fifty-eight percent of patients had worsened gait post-operatively. Seventy percent of patients with unilateral Vim DBS experienced gait worsening while 55% of bilateral DBS patients experienced gait worsening. Patients with worsened gait post-DBS had higher baseline pre-operative TRS scores than those without worsened gait (43.1 points ± 8.4 vs. 33.1 points ± 10.1, p = 0.002) (odds ratio 2.5, p = 0.02). Gait/balance may worsen following DBS for medication refractory ET. Higher baseline TRS score may factor into these issues, although a larger prospective study will be required with a control population. The larger percentage of difficulties observed in unilateral versus bilateral cases likely reflected the bias not to proceed to second-sided surgery if gait/balance problems were encountered.