Effect of constant-current pallidal deep brain stimulation for primary dystonia on cognition, mood and quality of life: Results from a prospective pilot trial.

OBJECTIVE: Knowledge on the effects of DBS on cognitive functions is limited and no data exists on the effects of constant-current DBS (CC-GPi-DBS), which appears to prevail over constant-voltage stimulation. Our aim was to prospectively assess the effect of Constant-Current-GPi-DBS, using an 8-contact lead, on cognition, mood and quality of life. PATIENTS AND METHODS: Ten patients aged 27-49 underwent prospective neuropsychological assessment using dedicated tests. Various cognitive domains (intelligence, executive functions, memory, attention, visuo-spatial perception, verbal intelligence) as well as emotional state and quality of life were examined preoperatively and 1, 6 and 12 months after continuous constant-current DBS. RESULTS: Patients performed preoperatively below average on information processing speed, phonemic verbal fluency and working memory. At 6-months there was an improvement in phonemic verbal fluency (p < .05), which was retained at 12-months postoperatively (p = .05). Results also showed marginal improvement in the Trail Making-A test (p = .051) and the Stroop colour-word test (p < .05). Despite improvement in Quality of Life (Physical and Mental Component improved by 32.42% and 29.46% respectively), patients showed no discernible change in anxiety and depression status. CONCLUSIONS: CC-GPi-DBS for primary dystonia has no discernible negative impact on cognition and mood. If anything, we noted an improvement of certain cognitive functions.

Constant-Current Deep Brain Stimulation of the Globus Pallidus Internus in the Treatment of Primary Dystonia by a Novel 8-Contact (Octrode) Lead.

OBJECTIVE: To evaluate bilateral constant-current globus pallidus internus (GPi) deep brain stimulation using an 8-contact lead. METHODS: This prospective, open-label, single-center pilot study of 10 patients assessed the feasibility of delivering bilaterally constant-current GPi deep brain stimulation with a novel 8-channel lead to treat primary dystonia using standard scales as outcome measures. RESULTS: Patients included 4 men and 6 women with a mean age of 35.8 years ± 9.2 (range, 27-49 years). Mean age of onset was 18.5 years ± 9.1 (range, 8-35 years), and mean disease duration was 17.3 years (range, 7-27 years). All had primary dystonia (8 generalized dystonia, 1 segmental dystonia, 1 focal dystonia). The primary variable was determined as 50% reduction in dystonia symptoms from baseline to the 6-month follow-up, as defined by the Burke-Fahn-Marsden Dystonia Rating Scale. Six patients (60.0%) achieved >50% reduction in Burke-Fahn-Marsden Dystonia Rating Scale score and were classified as responders at the 6-month follow-up. Five of these 6 responders (83.3%) sustained that response through the assessment at the end of the first year. Constant-current stimulation was associated with significant improvement in pain and quality of life in all patients. Nearly 84% of the overall improvement occurred by the end of first month after stimulation onset, documenting an early response to treatment. Axial symptoms responded the best. CONCLUSIONS: Constant-current GPi deep brain stimulation proved safe and efficacious for treatment of primary dystonia. Motor scores improved by 54%, mostly within the first month. No phenotype-specific stimulation could be achieved, despite the capability of the new lead to stimulate specific loci within the GPi.

Neuromyotonia in idiopathic hypoparathyroidism.

Alpha 62-year-old man was presented with bilateral cataract, proximal muscle weakness and difficulty in relaxing the hands after voluntary contraction. Idiopathic hypoparathyroidism was diagnosed. Electrophysiological study showed spontaneous motor unit action potentials, occurring and disappearing abruptly, as duplets, triplets and multiplets, with an intra-burst frequency of up to 100 Hz and some of them waning in amplitude, findings consistent with neuromyotonia.