Panida Piboolnurak

Long-term outcome of bilateral pallidal deep brain stimulation for primary cervical dystonia.

Ten patients with severe cervical dystonia (CD) unresponsive to medical treatment underwent bilateral globus pallidus internus (GPi) deep brain stimulation (DBS) and were followed for 31.9 ± 20.9 months. At last follow-up, the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) severity score improved by 54.8%, the TWSTRS disability score improved by 59.1%, and the TWSTRS pain score improved by 50.4%. Bilateral GPi DBS is an effective long-term therapy in patients with CD.

Levodopa response in long-term bilateral subthalamic stimulation for Parkinson's disease

Subthalamic nucleus deep brain stimulation (STN‐DBS) is effective in advanced Parkinsons disease (PD), but its effects on the levodopa response are unclear. We studied the levodopa response after long‐term STN‐DBS, STN‐DBS efficacy and predictive value of preoperative levodopa response to long‐term DBS benefit in 33 PD patients with bilateral STN‐DBS. Patients were assessed using the Unified Parkinsons Disease Rating Scale preoperatively (with and without medications) and postoperatively (without medications or stimulation, with only medications or stimulation, and with both medications and stimulation). Levodopa response significantly decreased postoperatively by 31.1% at 3 years and 32.3% at 5 years, possibly related to the reduction in medication requirement, direct STN stimulation effect or PD progression. STN‐DBS alone significantly improved motor scores (37.2% at 3 years and 35.1% at 5 years) and activities of daily living scores (27.1% at 3 years and 19.2% at 5 years). Anti‐PD drugs were significantly reduced by 47.9% at 3 years and 39.8% at 5 years. However, the magnitude of the preoperative response to levodopa did not predict DBS benefit at 3 and 5 years.

Evaluation of the pull test technique in assessing postural instability in Parkinson’s disease

Variability in pull test (PT) performance can lead to inadequate evaluation of postural instability in patients with Parkinson’s disease (PD). Assessing 66 PTs by 25 examiners, at least two of four raters agreed that specific items were performed incorrectly for stance in 27.3%, for strength and briskness of the pull in 84.9%, for examiner’s response in 36.4%, and for technique issues in 9.1%. Examiners were consistent in their errors, and only 9% of examinations were error-free.

Unilateral subdural motor cortex stimulation improves essential tremor but not Parkinson’s disease

Epidural motor cortex stimulation has been reported to be effective in treating some movement disorders. Nevertheless, clinical results have been variable and no double-blinded evaluations have been reported. The aim of this study was to investigate efficacy and safety of unilateral subdural motor cortex stimulation in patients with essential tremor and Parkinsons disease. Six patients with essential tremor and five parkinsonian patients were selected. Craniotomy was performed under local anaesthesia with conscious sedation. A four contact electrode (Resume II model 3587, Medtronic, Inc) was positioned on the motor cortex, after identification of the area with direct monopolar cortical stimulation. Soon after surgery, a variety of different settings of stimulation were assessed using standard rating scales to select the optimal stimulation parameters. The effects of chronic stimulation were evaluated in both groups of patients after 3 months (double-blinded fashion) and 1 year (open fashion). In essential tremor, contralateral hand tremor scores significantly improved (P = 0.04) with stimulation during the double-blinded study, whereas in Parkinsons disease, there were no changes in the OFF medication/on stimulation motor scores compared with off stimulation. At 1 year, tremor was improved by stimulation in two out of three patients with essential tremor available at follow-up, whereas no improvement was observed in the five parkinsonian patients. One parkinsonian patient had a cortical venous infarct. Three other patients had self-limiting seizures with aggressive trials of stimulation in the period of dosage selection. These findings suggest that unilateral subdural motor cortex stimulation may be useful for contralateral hand tremor in selected patients with essential tremor but was not effective in improving parkinsonian signs in our series.

Pallidal stimulation in cervical dystonia: clinical implications of acute changes in stimulation parameters

Background and purpose:  Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is successful in dystonia, but the role of each electrical parameters of stimulation is unclear. We studied the clinical effects of acute changes of different parameters of GPi–DBS in cervical dystonia (CD).

Transcranial magnetic stimulation in ALS: Utility of central motor conduction tests

Objective: To investigate transcranial magnetic stimulation (TMS) measures as clinical correlates and longitudinal markers of amyotrophic lateral sclerosis (ALS). Methods: We prospectively studied 60 patients with ALS subtypes (sporadic ALS, familial ALS, progressive muscular atrophy, and primary lateral sclerosis) using single pulse TMS, recording from abductor digiti minimi (ADM) and tibialis anterior (TA) muscles. We evaluated three measures: 1) TMS motor response threshold to the ADM, 2) central motor conduction time (CMCT), and 3) motor evoked potential amplitude (correcting for peripheral changes). Patients were evaluated at baseline, compared with controls, and followed every 3 months for up to six visits. Changes were analyzed using generalized estimation equations to test linear trends with time. Results: TMS threshold, CMCT, and TMS amplitude correlated (p < 0.05) with clinical upper motor neuron (UMN) signs at baseline and were different (p < 0.05) from normal controls in at least one response. Seventy-eight percent of patients with UMN (41/52) and 50% (4/8) of patients without clinical UMN signs had prolonged CMCT. All three measures revealed significant deterioration over time: TMS amplitude showed the greatest change, decreasing 8% per month; threshold increased 1.8% per month; and CMCT increased by 0.9% per month. Conclusions: Transcranial magnetic stimulation (TMS) findings, particularly TMS amplitude, can objectively discriminate corticospinal tract involvement in amyotrophic lateral sclerosis (ALS) from controls and assess the progression of ALS. While central motor conduction time and response threshold worsen by less than 2% per month, TMS amplitude decrease averages 8% per month, and may be a useful objective marker of disease progression.

Neuroimaging Markers of Motor and Nonmotor Features of Parkinson's Disease: An [18F]Fluorodeoxyglucose Positron Emission Computed Tomography Study

Aim: We sought to identify markers of motor and nonmotor function in Parkinsons disease (PD) using advanced neuroimaging techniques in subjects with PD. Methods: We enrolled 26 nondemented PD subjects and 12 control subjects. All subjects underwent [18F]fluorodeoxyglucose positron emission computed tomography (FDG-PET) and magnetic resonance imaging, and a complete neuropsychological battery. Results: FDG-PET of subjects with PD revealed significant metabolic elevations in the bilateral posterior lentiform nucleus, posterior cingulate, and parahippocampus, and metabolic reductions in the bilateral temporoparietal association cortex and occipital lobe versus controls. PD subjects had significant reductions in executive/attention function, memory/verbal learning, and speed of thinking, and significantly increased depression, anxiety and apathy scores compared with controls. Motor dysfunction correlated with increased metabolism in the posterior lentiform nucleus, pons, and cerebellum, and decreased metabolism in the temporoparietal lobe. Cognitive dysfunction correlated with increased posterior cingulate metabolism and decreased temporoparietal lobe metabolism. Depressive symptoms correlated with increased amygdala metabolism; anxiety scores correlated with decreased caudate metabolism, and apathy scores correlated with increased metabolism in the anterior cingulate and orbitofrontal lobe and decreased metabolism in the temporoparietal association cortex. Conclusions: Our findings showed that motor, cognitive, and emotional dysfunction in PD are associated with distinct patterns of cerebral metabolic changes.

Spiral analysis in Niemann-Pick disease type C

Spiral analysis is a computerized method of analyzing upper limb motor physiology through the quantification of spiral drawing. The objective of this study was to determine whether spirals drawn by patients with Niemann‐Pick disease type C (NPC) could be distinguished from those of controls, and to physiologically characterize movement abnormalities in NPC. Spiral data consisting of position, pressure, and time were collected from 14 NPC patients and 14 age‐matched controls, and were analyzed by the Mann‐Whitney U test. NPC spirals were characterized by: lower speed (2.67 vs. 9.56 cm/s, P < 0.001) and acceleration (0.10 vs. 2.04 cm/s2, P < 0.001), higher loop width variability (0.88 vs. 0.28, P < 0.001), tremor (5/10 vs. 0/10 trials in the dominant hand, P < 0.001), and poor overall spiral rating (2.53 vs. 0.70, P < 0.005). NPC spirals also exhibited sustained drawing pressure profiles that were abnormally invariant with time. Other features, such as the tightness of loop widths, were normal. Our findings reveal that differing aspects of tremor, Parkinsonism, ataxia, and dystonia are quantifiable in NPC patients.

Clinical Characteristics of Exacerbations in Parkinson Disease

Background: Episodes of subacute worsening of motor function occur commonly in Parkinson disease (PD), but there has been surprisingly little research about the clinical characteristics of these exacerbations in the outpatient setting. Methods: Retrospective study of an established cohort of 120 outpatients with PD. Primary outcome measures were the frequency, causes, and outcomes of motor exacerbations. Statistical analysis was performed to compare baseline characteristics of subjects with subsequent exacerbations versus without subsequent exacerbations. Results: Over an 18-month period, 43 exacerbations occurred, affecting 30 of 120 subjects (25.0%). Infection was the single most frequent underlying cause, accounting for 11 of 43 (25.6%) exacerbations. Other common etiologies were anxiety (n=8), medication errors (n=6), poor adherence (n=6), medication side effects (n=3), and postoperative decline (n=3). Overall, 35 episodes (81.4%) were attributable to reversible or treatable causes. Most subjects recovered fully, but 10 (33.3%) experienced recurrent episodes, 5 (16.7%) suffered permanent decline, and 1 died. At baseline, subjects with exacerbations had a significantly longer median disease duration (7.8 vs. 5.7 y, P=0.003), lower Mini-Mental State Examination scores (27.0±3.3 vs. 28.6±1.6, P=0.02), higher modified Hoehn and Yahr scores (2.2±0.5 vs. 1.9±0.5, P=0.006), greater dopaminergic medication use (median, 750.0 vs. 395.0 levodopa equivalents; P=0.009), and a greater prevalence of motor complications (55.2% vs. 29.4%, P=0.01) than subjects without exacerbations. Conclusions: Exacerbations are common in PD, associated with more advanced disease, and usually attributable to treatable secondary causes such as intercurrent infection. Increased recognition of these underlying causes may help to decrease morbidity, reduce health care costs, and optimize quality of care in PD.

Psychogenic tremor disorders identified using tree‐based statistical algorithms and quantitative tremor analysis

Detecting psychogenic tremors (PsychT) is often challenging. As there are no laboratory investigations or imaging techniques that can confirm the diagnosis, PsychT is identified on a clinical basis. We present a tree‐based statistical algorithm derived from quantitative computerized tremor recordings as a novel method to help in the recognition of PsychT. The goal of this study was to show that objective data from computerized tremor recordings, when processed through a tree‐based statistical algorithm, can be used to determine whether a patient can be classified as having PsychT.