Young-Ho Sohn

Neuroanatomic basis of amnestic MCI differs in patients with and without Parkinson disease

Objective: To explore the neuroanatomic basis of amnestic mild cognitive impairment (aMCI) in patients with Parkinson disease (PD; aMCI-PD+) and without PD (aMCI-PD−). Methods: A total of 119 patients with aMCI (aMCI-PD−, n = 78, and aMCI-PD+, n = 41) underwent T1-weighted MRI, and the image data were analyzed using voxel-based morphometry. Results: No significant differences in demographic characteristics or general cognition were found between patients with aMCI-PD− and aMCI-PD+. Comparisons of neuropsychological tests between groups revealed that patients with aMCI-PD− had lower scores in delayed verbal and visual recognition memory, whereas visuospatial dysfunction was more severe in patients with aMCI-PD+. Gray matter (GM) density in the right temporal and posterior cingular cortices was significantly lower in the aMCI-PD− group compared with controls. In contrast, GM density in the aMCI-PD+ group was significantly lower in the precuneus and left prefrontal and primary motor areas relative to controls. A direct comparison between groups showed that decreased GM density in aMCI-PD− relative to aMCI-PD+ was localized in the right temporal and anterior prefrontal areas, whereas decreased GM density in aMCI-PD+ relative to aMCI-PD− was involved in the bilateral precuneus, left primary motor, and right parietal areas. Memory decline was correlated with temporal area atrophy in aMCI-PD− and with posterior cingulate cortex atrophy in aMCI-PD+. Conclusions: Our data suggest that different neuroanatomic systems underlie memory dysfunction in patients with aMCI-PD− and aMCI-PD+.

The burden of white matter hyperintensities is a predictor of progressive mild cognitive impairment in patients with Parkinson's disease

To evaluate whether white matter hyperintensities (WMHs) may act as an independent predictor for progression of cognitive status, the authors analyzed the longitudinal effects of WMHs on cognitive dysfunction in non‐demented patients with Parkinsons disease (PD).

Corticospinal disinhibition in paroxysmal kinesigenic dyskinesia

OBJECTIVE To investigate the underlying mechanism responsible for paroxysmal kinesigenic dyskinesia (PKD). METHODS We performed a transcranial magnetic stimulation (TMS) study in 12 drug-naïve patients with PKD and 10 healthy volunteers. TMS parameters included resting motor threshold, recruitment curve of motor evoked potential amplitudes, short intracortical inhibition and facilitation, long intracortical inhibition (LICI), and silent period. We also measured compound muscle action potential. RESULTS LICI, representing GABA-mediated inhibition, was significantly reduced in the patients (P = 0.033), while results for all other TMS parameters tested were comparable between the two groups. CONCLUSIONS AND SIGNIFICANCE These results suggest that a specific type of corticospinal inhibitory mechanism is impaired in patients with PKD.

Does serum uric acid act as a modulator of cerebrospinal fluid Alzheimer's disease biomarker related cognitive decline?

The association of serum uric acid, cerebrospinal fluid (CSF) biomarkers of Alzheimers disease (AD) and longitudinal cognitive decline was evaluated using the AD Neuroimaging Initiative database.

Highly task‐specific oromandibular dystonia in a telephone operator

S. Y. Kang, H. Kim, H.-I. Ma, Y. J. Kim, S.-B. Kwon, S. H. Hwang and Y. H. Sohn Department of Neurology, Hallym University College of Medicine, Seoul; Graduate Program in Speech and Language Pathology, Department of Rehabilitation Medicine, & Research Institute of Rehabilitation Medicine; and Department of Neurology and Brain Research Institute, Yonsei University College of Medicine, Seoul, Korea

Dental implants-induced task-specific oromandibular dystonia

Task-specificity is a unique characteristic of focal dystonia; that is, abnormal movements or postures are predominantly or even exclusively present under specific circumstances [1]. Task-specific oromandibular dystonia (OMD) is a rare condition, and reported exclusively as a result of excessive speech and playing a wind instrument [2–5]. Here we present a case of task-specific OMD following dental implant surgery. A 56-year-old housewife presented with a 1-year history of involuntary retraction of her lips while speaking. She underwent dental implant surgery 6 months earlier, but had neither a relevant medical history nor exposure to relevant medications. She did not have an occupation, hobby or religion requiring an excessive use of perioral muscles. She reported that her symptoms had not progressed after onset. The involuntary movements occurred when she vocalized, regardless of ordinary conservational speech, reading out loud or singing. The lips returned to the normal position immediately after vocalization stopped, and the symptom did not occur while eating or drinking (Video S1). She denied any discomfort in the implant insertion site. This involuntary movement was improved when she put her finger or a depressor on her tongue while speaking, but was not alleviated by chewing gum or sucking on a candy (Video S2). Neurological examination revealed no other neurological deficit. Over a 6-month follow-up, she received medications including procyclidine, metoclopropamide and dantrolene sodium, resulting in mild-to-moderate improvement without progression. Patterned and repeated involvement of the same perioral muscles along with aggravation by voluntary movements are compatible with the clinical characteristics of primary dystonia [1]. The presence of a sensory trick, namely the symptomatic alleviation by touching the tongue, provides additional evidence to diagnose as primary dystonia in this patient [1]. Because her symptom was present exclusively while speaking, it was diagnosed as task-specific OMD. Previously reported cases of speech-induced task-specific OMD were exclusively associated with long-term experiences of excessive speech due to occupation or religious rituals [2– 5], but our patient lacks this association. Peripheral injury, including dental procedures, is a potential predisposing factor to induce OMD [6], but none of the previous cases was task-specific. The causal relationship between dental implants and the development of OMD is unclear. However, OMD in this patient fits the criteria defining peripherally induced OMD suggested by Sankhla et al. [6] well, which include temporal relationship within a year, well documentation of the trauma, and anatomical relationship between the injured site and location of dystonia. The underlying mechanism for task-specific dystonia is still unclear, although deficient central nervous system inhibition, abnormal sensorimotor integration and maladaptive plasticity are suggested [7]. In addition to the longterm overuse of affected muscles, the present case may illustrate another potential relationship between peripheral injury and task-specific OMD.

F149. Low-frequency repetitive transcranial cerebellar magnetic stimulation as an ‘Add-On’ therapy in patients with essential tremor

Introduction ET is a common movement disorder. It is not life threatening, but it can significantly impair patients’ activities of daily living. Beta-blockers and primidone have been used as the treatment of choice for patients with ET. However, up to 50% of ET patients report that they are not satisfied with the improvement of tremor symptoms by these medications. We investigated effect of cerebellar low-frequency repetitive transcranial magnetic stimulation (rTMS) as an ‘add-on’ treatment on patients with Essential tremor (ET). Methods This was a single-center, prospective, sham-controlled and single-blinded study. Fourteen ET patients participated. ET was diagnosed when the patient had bilateral postural or kinetic tremor of the arms, no dystonia and no possibility of drug-induced secondary tremor. In addition, we included subjects in this study only if they had residual significant tremor despite beta-blockers and other drugs as symptomatic management. Subjects were randomized into a group receiving real-rTMS and another group receiving sham-rTMS. rTMS was applied over each side of the cerebellum in turn. The order of the stimulation to each side was randomly assigned. For 5 days, 600 stimulations a day were applied with an intensity of 90% of the resting motor threshold (RMT) with 1-Hz frequency. Clinical tremor rating scale (CTRS) was measured before, a week and 5 weeks after starting day of the rTMS procedure. Results Eight and 6 patients were randomized to the groups of real and sham-rTMS, respectively. The mean age, symptoms duration and baseline CTRS scores were comparable. ANOVA analysis showed that all three parts (A, B and C) of CTRS were not different before, a week and 5 weeks after starting rTMS procedure both in real and sham-rTMS groups. There were no adverse events including headache, dizziness, syncope and seizure. Conclusion Cerebellar low-frequency rTMS is safe but not effective as an ‘add-on’ therapy in patients with ET.

Sleepiness and Depression in Parkinson’s Disease Patients Treated with Ropinirole and Levodopa

Objective We aimed to investigate the effect of ropinirole on excessive daytime sleepiness (EDS) and depression in Parkinson’s disease (PD) with a large population. Methods We conducted a cross-sectional observational study at nine hospitals in Korea between April 24, 2013, and April 22, 2015. We analyzed the demographic and clinical features, other medical history, history of antiparkinsonian medication within 6 months, Hoehn and Yahr stage (HY stage), Unified Parkinson’s Disease Rating Scale (UPDRS) part II and III, Epworth Sleepiness Scale (ESS), and 30-item Geriatric Depression Scale (GDS-30). Results Four-hundred-thirteen patients with PD (mean age: 65.2 ± 9.0 years; men: 227 patients) were analyzed. Multivariate logistic regression analysis showed that age at examination, UPDRS II, and GDS-30 were independent risk factors for EDS and that sex, UPDRS II, and ESS were independent risk factors for depression. Conclusion Our large group study did not find any significant associations of ropinirole with EDS and depression in Korean PD patients.

Volumetric analysis of the cerebellum in patients with progressive supranuclear palsy

Although early cerebellar symptoms are one of the exclusive criteria in the diagnosis of progressive supranuclear palsy (PSP), cerebellar involvement in PSP is evident both clinically and pathologically. However, structural analysis focusing on the cerebellum has not been previously studied in patients with PSP. We aimed to evaluate cerebellar involvement in PSP using a magnetic resonance imaging‐based segmental volumetric analysis.

P23-17 The differential effects of concurrent repetitive movements on surround inhibition in the motor system between non-musician and professional pianists

Objectives: Surround inhibition (SI) is a neural mechanism by which desired neural processes can be adjusted by suppression of unwanted, neighboring neural activity for the selection of the proper neuronal response. Dystonia is clinically pertinent to impaired SI. Disturbed SI has been demonstrated in patients with focal hand dystonia (FHD). FHD usually develops following a period of highly repetitive movements that typically require extreme motor precision. To explore the effect of muscle overuse on SI, we measured changes in SI after short-term exercise with repetition of two different types of finger movements. Methods: Right-handed healthy non-musicians and professional pianists participated. We studied changes of SI in the motor system with transcranial magnetic stimulation technique after a short-term exercise with simultaneous repetition of unrelated finger movements or repetition of single finger movements. Results: As reported previously, motor evoked potentials (MEPs) were suppressed in the little finger muscle (abductor digiti mini; ADM) during flexion of the index finger muscle (flexor digitorum superficialis; FDS). After short-term exercise, MEPs of the ADM were no longer suppressed but instead were enhanced during the flexion of the FDS in nonmusician healthy volunteers. Exercise comprising simultaneous ADM and FDS movements produced significantly larger and longer-lasting enhancements than those of the ADM movement alone. In professional pianists, on the contrary, alterations in SI after both types of exercise were similar. Conclusions: This result provides neurophysiological evidence that repetitive practice of unrelated finger movements can disturb SI. The exercise types differently affect SI between non-musicians and professional musicians. Significance: This altered SI supports the idea that muscle overuse may contribute to the development of task-specific dystonia. The different behavior of the SI between non-musicians and professional musicians supports the hypothesis that neurophysiological mechanisms regulating SI in professional musicians may be different, probably due to previous long-term practice finger movements.