Clinical characteristics and long-term outcome of cerebral cavernous malformations-related epilepsy.

OBJECTIVE: Cerebral cavernous malformations (CCMs) present variably, and epileptic seizures are the most common symptom. The factors contributing to cavernoma-related epilepsy (CRE) and drug resistance remain inconclusive. The outcomes of CRE after different treatment modalities have not yet been fully addressed. This study aimed to characterize the clinical features of patients with CRE and the long-term seizure outcomes of medical and surgical treatment strategies. METHODS: This was a retrospective cohort of 135 patients with CCM who were diagnosed in 2007-2011 and followed up for 93.6 months on average. The patients were divided into drug-resistant epilepsy (DRE; n = 29), non-DRE (n = 45), and no epilepsy (NE; n = 61). RESULTS: Temporal CCM was the factor most strongly associated with the development of both CRE and DRE. The majority of patients with single temporal CCMs had CRE (86.8%, n = 33), and 50% had DRE, whereas only 14.7% (n = 5) with a nontemporal supratentorial CCM had DRE (p < .05). The most common lesion site in the DRE group was the mesiotemporal lobe (50%). Multiple CCMs were more frequently observed in the CRE (29.2%) than the NE (11.5%) group (p < .05). In patients with CRE, multiple lesions were associated with a higher rebleeding rate (odds ratio = 11.1), particularly in those with DRE (odds ratio = 15.4). The majority of patients who underwent resective surgery for DRE (76.5%, n = 13) achieved International League Against Epilepsy Class I and II seizure outcomes even after a long disease course. SIGNIFICANCE: Temporal CCM not only predisposes to CRE but also is a major risk factor for drug resistance. The mesiotemporal lobe is the most epileptogenic zone. Multiple CCMs are another risk factor for CRE and increase the rebleeding risk in these patients. Surgical resection could provide beneficial long-term seizure outcomes in patients with DRE.

Utilization of Amplitude-Integrated Electroencephalography to Predict Neurologic Function after Resuscitation in Adults with Cardiogenic Cardiac Arrest.

BACKGROUND: Amplitude-integrated electroencephalography (aEEG) has been used as a tool to recognize brain activity in children with hypoxic encephalopathy. OBJECTIVES: To assess the prognostic value of aEEG during the post-resuscitation period of adult cardiogenic cardiac arrest, comatose survivors were monitored within 24 h of a return of spontaneous circulation using aEEG. METHODS: Forty-two consecutive patients experiencing cardiac arrest were retrospectively enrolled, and a return of spontaneous circulation was achieved in all cases. These patients were admitted to the Coronary Intensive Care Unit due to cardiogenic cardiac arrest. The primary outcome was the best neurologic outcome within 6 months after resuscitation, and the registered patients were divided into two groups based on the Cerebral Performance Category (CPC) scale (CPC 1-2, good neurologic function group; CPC 3-5, poor neurologic function group). All patients received an aEEG examination within 24 h after a return of spontaneous circulation, and the parameters and patterns of aEEG recordings were compared. RESULTS: Nineteen patients were in the good neurologic function group, and 23 were in the poor group. The four voltage parameters (minimum, maximum, span, average) of the aEEG recordings in the good neurologic function groups were significantly higher than in the poor group. Moreover, the continuous pattern, but not the status epilepticus or burst suppression patterns, could predict mid-term good neurologic function. CONCLUSIONS: aEEG can be used to predict neurologic outcomes based on the recordings' parameters and patterns in unconscious adults who have experienced a cardiac collapse, resuscitation, and return of spontaneous circulation.

Acute withdrawal of new-generation antiepileptic drugs in epilepsy monitoring units: Safety and efficacy.

INTRODUCTION: Acute withdrawal of antiepileptic drugs (AEDs) is a safe and effective approach to provoking seizures in order to complete video-electroencephalogram (V-EEG) studies in a timely manner. Previous studies have focused only on withdrawal from conventional AEDs, and the effects of withdrawal from new-generation AEDs have not been extensively studied. MATERIALS AND METHODS: This study examined adult patients with drug-resistant epilepsy admitted to an epilepsy monitoring unit between 2015 and 2018. Patients were classified according to whether they received conventional AEDs (Con; n = 13) or new-generation AEDs (N-Gen; n = 26). We then compared the effects of withdrawing these two types of AEDs over a period of one week in terms of efficacy (time to complete V-EEG monitoring) and safety, including the incidence of cluster seizures (CS), focal to bilateral tonic-clonic seizures (FBTCS) and status epilepticus (SE). RESULTS: In both groups, approximately one week was required to complete V-EEG analysis: N-Gen group (5.6 days) and Con group (6.3 days). No differences were observed between the two groups in terms of the median number of seizures, the onset of the 1st seizure, the distribution of CS, FBTCS, or SE. Following acute withdrawal of medication, a high percentage of patients with a history of CS or FBTCS, respectively, presented CS or FBTCS. CONCLUSIONS: We did not observe significant differences between patients taking new-generation AEDs and those taking conventional AEDs following withdrawal during V-EEG recording. In the current study, we employed a standard protocol for the rapid withdrawal of AEDs (daily dose reduction of 50%), which was sufficient for 80% of patients to complete V-EEG monitoring within one week.

Ictal networks of temporal lobe epilepsy: views from high-frequency oscillations in stereoelectroencephalography.

OBJECTIVEIn this study, the authors investigated high-frequency oscillation (HFO) networks during seizures in order to determine how HFOs spread from the focal cerebral cortex and become synchronized across various areas of the brain.METHODSAll data were obtained from stereoelectroencephalography (SEEG) signals in patients with drug-resistant temporal lobe epilepsy (TLE). The authors calculated intercontact cross-coefficients between all pairs of contacts to construct HFO networks in 20 seizures that occurred in 5 patients. They then calculated HFO network topology metrics (i.e., network density and component size) after normalizing seizure duration data by dividing each seizure into 10 intervals of equal length (labeled I1-I10).RESULTSFrom the perspective of the dynamic topologies of cortical and subcortical HFO networks, the authors observed a significant increase in network density during intervals I5-I10. A significant increase was also observed in overall energy during intervals I3-I8. The results of subnetwork analysis revealed that the number of components continuously decreased following the onset of seizures, and those results were statistically significant during intervals I3-I10. Furthermore, the majority of nodes were connected to a single dominant component during the propagation of seizures, and the percentage of nodes within the largest component grew significantly until seizure termination.CONCLUSIONSThe consistent topological changes that the authors observed suggest that TLE is affected by common epileptogenic patterns. Indeed, the findings help to elucidate the epileptogenic network that characterizes TLE, which may be of interest to researchers and physicians working to improve treatment modalities for epilepsy, including resection, cortical stimulation, and neuromodulation treatments that are responsive to network topologies.

Aberrant Sensory Gating of the Primary Somatosensory Cortex Contributes to the Motor Circuit Dysfunction in Paroxysmal Kinesigenic Dyskinesia.

Paroxysmal kinesigenic dyskinesia (PKD) is conventionally regarded as a movement disorder (MD) and characterized by episodic hyperkinesia by sudden movements. However, patients of PKD often have sensory aura and respond excellently to antiepileptic agents. PRRT2 mutations, the most common genetic etiology of PKD, could cause epilepsy syndromes as well. Standing in the twilight zone between MDs and epilepsy, the pathogenesis of PKD is unclear. Gamma oscillations arise from the inhibitory interneurons which are crucial in the thalamocortical circuits. The role of synchronized gamma oscillations in sensory gating is an important mechanism of automatic cortical inhibition. The patterns of gamma oscillations have been used to characterize neurophysiological features of many neurological diseases, including epilepsy and MDs. This study was aimed to investigate the features of gamma synchronizations in PKD. In the paired-pulse electrical-stimulation task, we recorded the magnetoencephalographic data with distributed source modeling and time-frequency analysis in 19 patients of newly-diagnosed PKD without receiving pharmacotherapy and 18 healthy controls. In combination with the magnetic resonance imaging, the source of gamma oscillations was localized in the primary somatosensory cortex. Somatosensory evoked fields of PKD patients had a reduced peak frequency (p < 0.001 for the first and the second response) and a prolonged peak latency (the first response p = 0.02, the second response p = 0.002), indicating the synchronization of gamma oscillation is significantly attenuated. The power ratio between two responses was much higher in the PKD group (p = 0.013), indicating the incompetence of activity suppression. Aberrant gamma synchronizations revealed the defective sensory gating of the somatosensory area contributes the pathogenesis of PKD. Our findings documented disinhibited cortical function is a pathomechanism common to PKD and epilepsy, thus rationalized the clinical overlaps of these two diseases and the therapeutic effect of antiepileptic agents for PKD. There is a greater reduction of the peak gamma frequency in PRRT2-related PKD than the non-PRRT PKD group (p = 0.028 for the first response, p = 0.004 for the second response). Loss-of-function PRRT2 mutations could lead to synaptic dysfunction. The disinhibiton change on neurophysiology reflected the impacts of PRRT2 mutations on human neurophysiology.

Sample Entropy of High Frequency Oscillations for Epileptogenic Zone Localization.

For epileptic patients whose seizures are poorly controlled with medication, removing the brain region responsible for seizure onset is a treatment option. This requires the epileptogenic zone (EZ) to be accurately delineated. In this paper, a two-stage approach for EZ delineation is proposed. The algorithm starts by detecting events of high-frequency oscillations (HFOs) directly from the multi-channel intracranial electroencephalograms (iEEGs). The sample entropy is then computed for each of their channels that will be used for determining the channels correlated with the EZ. The performance of our proposed method is evaluated using the receiver operating characteristic curve analysis, and the results indicate that our proposed approach can provide an accurate estimation of the EZ.

Identification of genes associated with cortical malformation using a transposon-mediated somatic mutagenesis screen in mice.

Mutations in genes involved in the production, migration, or differentiation of cortical neurons often lead to malformations of cortical development (MCDs). However, many genetic mutations involved in MCD pathogenesis remain unidentified. Here we developed a genetic screening paradigm based on transposon-mediated somatic mutagenesis by in utero electroporation and the inability of mutant neuronal precursors to migrate to the cortex and identified 33 candidate MCD genes. Consistent with the screen, several genes have already been implicated in neural development and disorders. Functional disruption of the candidate genes by RNAi or CRISPR/Cas9 causes altered neuronal distributions that resemble human cortical dysplasia. To verify potential clinical relevance of these candidate genes, we analyzed somatic mutations in brain tissue from patients with focal cortical dysplasia and found that mutations are enriched in these candidate genes. These results demonstrate that this approach is able to identify potential mouse genes involved in cortical development and MCD pathogenesis.

Prognostic significance of postoperative spikes varied in different surgical procedures for mesial temporal sclerosis.

PURPOSE: We conducted this study to compare the occurrence and prognostic significance of early postoperative interictal epileptiform discharges (IEDs) on seizure outcomes between corticoamygdalohippocampectomy (CAH) and selective amygdalohippocampectomy (SAH). METHODS: We reviewed our database of patients who had epilepsy surgery with hippocampus atrophy or signal changes on brain MRIs and pathology of mesial temporal sclerosis. One hundred and seventy-seven CAH and 39 SAH patients were enrolled. Postoperative EEG within 30days, other preoperative variables and seizure outcome 2years after surgery were obtained for analysis. Engel's IA and IB were defined as seizure-free. RESULTS: There was no significant difference in the seizure-free rate between the two procedures (127 (71.8%) of CAH vs 30 (76.9%) of SAH, p=0.51). Postoperative IEDs were more frequently seen in the SAH group (64.1%) than in the CAH group (29.9%), p<0.001. The IEDs in the SAH group did not show correlation with the seizure outcome 2 years after surgery. In the CAH group, patients who had no postoperative IEDs showed a higher seizure-free rate compared to those with IEDs (78.2% vs 56.6%, p=0.003; OR 2.267, 95% CI 1.09-4.73, p=0.029 in multivariate logistic regression). CONCLUSIONS: Early postoperative IEDs are more frequently seen in SAH than in CAH. Unlike in patients with CAH, the presence of IEDs after SAH was not a predictor of seizure recurrence. The type of surgery should be considered while utilizing postoperative IEDs for evaluating the prognosis.

Ictus emeticus presenting as an unusual seizure type in chromosome 22q11.2 deletion syndrome.

We present a case study of a patient with chromosome 22q11.2 deletion syndrome presenting with ictus emeticus, together with a review of the relevant literature. The patient developed generalized tonic-clonic seizures at 3 months old, and seizures eventually remitted after calcium therapy. He then experienced vigorous vomiting that occurred during sleep, with glassy eyes and legs flexion. Video-EEG recordings exhibited a switch in background activity from organized reactivity during normal sleep to left lateralized temporal delta activity, which was bilaterally synchronized during an emetic attack. The ictal vomiting ceased following management with oxcarbazepine, high-dose phenobarbital, and a ketogenic diet. The unique seizure type and rare ictal EEG findings are the first reported in a child with chromosome 22q11.2 deletion syndrome. This case highlights that ictus emeticus without detectable epileptic discharge on EEG is one potential epileptic presentation in this genetic syndrome. [Published with video sequence on www.epilepticdisorders.com].

Review of clinical studies of perampanel in adolescent patients.

AIM: To assess the clinical trial and real-world data for adjunctive perampanel in adolescents and develop consensus recommendations to guide the use of perampanel in this population in clinical practice. METHODS: In May 2015, 15 epilepsy experts attended a Consensus Development Meeting to assess the clinical trial data for perampanel, specific to the adolescent age group (12-17 years) and develop consensus treatment recommendations. RESULTS AND DISCUSSION: Analysis of the adolescent subgroup data of three pivotal placebo-controlled, double-blind, phase 3 trials investigating perampanel in patients with ongoing focal epileptic seizures despite receiving one to three antiepileptic drugs found that perampanel 4-12 mg was superior to placebo. The tolerability profile of perampanel was generally acceptable. Adolescent patients receiving long-term treatment with perampanel in an open-label extension study maintained improvements in seizure control compared with baseline, with a favorable risk-benefit profile. A phase 2 study showed that perampanel had no clinically important effects on cognitive function, growth, and development. CONCLUSION: Perampanel is a welcome addition to the armamentarium of existing antiepileptic drugs as it represents a new approach in the management of epilepsy, with a novel mechanism of action, and the potential to have a considerable impact on the treatment of adolescents with epilepsy.

PRRT2 mutations lead to neuronal dysfunction and neurodevelopmental defects.

Mutations in the proline-rich transmembrane protein 2 (PRRT2) gene cause a wide spectrum of neurological diseases, ranging from paroxysmal kinesigenic dyskinesia (PKD) to mental retardation and epilepsy. Previously, seven PKD-related PRRT2 heterozygous mutations were identified in the Taiwanese population: P91QfsX, E199X, S202HfsX, R217PfsX, R217EfsX, R240X and R308C. This study aimed to investigate the disease-causing mechanisms of these PRRT2 mutations. We first documented that Prrt2 was localized at the pre- and post-synaptic membranes with a close spatial association with SNAP25 by synaptic membrane fractionation and immunostaining of the rat neurons. Our results then revealed that the six truncating Prrt2 mutants were accumulated in the cytoplasm and thus failed to target to the cell membrane; the R308C missense mutant had significantly reduced protein expression, suggesting loss-of function effects generated by these mutations. Using in utero electroporation of shRNA into cortical neurons, we further found that knocking down Prrt2 expression in vivo resulted in a delay in neuronal migration during embryonic development and a marked decrease in synaptic density after birth. These pathologic effects and novel disease-causing mechanisms may contribute to the severe clinical symptoms in PRRT2-related diseases.

Zonisamide: Review of Recent Clinical Evidence for Treatment of Epilepsy.

Zonisamide is an orally administered antiepileptic drug that was first approved for clinical use in Japan in 1989. Since then, it has been licensed in Korea for a broad spectrum of epilepsies in adults and children, and in the USA for adjunctive therapy of adults with partial seizures, and in Europe for monotherapy of adults with newly diagnosed partial seizures and adjunctive therapy of adults and adolescents and children aged ≥6 years with partial seizures with or without secondary generalization. Zonisamide is a benzisoxazole derivative with a unique chemical structure, predictable dose-dependent pharmacokinetics, and multiple complementary mechanisms of action. Treatment with zonisamide is well tolerated and is not known to be associated with clinically significant drug-drug interactions, including with oral contraceptives or other antiepileptic drugs. There have been >2 million patient-years of experience with zonisamide for treatment of epilepsy, and this drug has International League Against Epilepsy level A evidence for efficacy/effectiveness as initial monotherapy for adults with partial-onset seizures. This review presents the evidence for zonisamide across the spectrum of epilepsy, with emphasis on real-world clinical practice and special populations of patients (children, elderly patients, and women of childbearing age) who are likely to be treated in daily clinical practice.

Increased Intrinsic Connectivity of the Default Mode Network in Temporal Lobe Epilepsy: Evidence from Resting-State MEG Recordings.

The electrophysiological signature of resting state oscillatory functional connectivity within the default mode network (DMN) during spike-free periods in temporal lobe epilepsy (TLE) remains unclear. Using magnetoencephalographic (MEG) recordings, this study investigated how the connectivity within the DMN was altered in TLE, and we examined the effect of lateralized TLE on functional connectivity. Sixteen medically intractable TLE patients and 22 controls participated in this study. Whole-scalp 306-channel MEG epochs without interictal spikes generated from both MEG and EEG data were analyzed using a minimum norm estimate (MNE) and source-based imaginary coherence analysis. With this processing, we obtained the cortical activation and functional connectivity within the DMN. The functional connectivity was increased between DMN and the right medial temporal (MT) region at the delta band and between DMN and the bilateral anterior cingulate cortex (ACC) regions at the theta band. The functional change was associated with the lateralization of TLE. The right TLE showed enhanced DMN connectivity with the right MT while the left TLE demonstrated increased DMN connectivity with the bilateral MT. There was no lateralization effect of TLE upon the DMN connectivity with ACC. These findings suggest that the resting-state functional connectivity within the DMN is reinforced in temporal lobe epilepsy during spike-free periods. Future studies are needed to examine if the altered functional connectivity can be used as a biomarker for treatment responses, cognitive dysfunction and prognosis in patients with TLE.

Theory of mind and social functioning in patients with temporal lobe epilepsy.

OBJECTIVE: This study aimed to explore the effects of theory of mind (ToM) and related potential risk factors, including cognitive functions, psychiatric status, and seizure-related clinical variables, on social functioning in patients with temporal lobe epilepsy (TLE). METHODS: Sixty-seven patients with intractable TLE who were potential candidates for epilepsy surgery and 30 matched controls were included. All participants completed four tasks measuring different levels of ToM (False Belief, Faux Pas Recognition, Implication Stories, and Visual Cartoon), the Symptom Checklist-90-Revised (SCL-90-R), the Social and Occupational Functioning Scale for Epilepsy (SOFSE), and neuropsychological tests. RESULTS: The patients exhibited impairments in both basic and advanced ToM. Multiple regression analyses revealed the following: (1) the SOFSE total score was significantly predicted by the Faux Pas Recognition (FPR), Global Severity Index (GSI) score of the SCL-90-R, and Full-Scale intelligence quotient (IQ) of the Wechsler Adult Intelligence Scale (WAIS), which accounted for 38%, 11%, and 8% of the variance, respectively; and (2) the FPR was a significant predictor of all SOFSE subscales, whereas the GSI score contributed substantially to the Interpersonal Relationships, Communication, and Occupation subscales of the SOFSE. SIGNIFICANCE: Advanced ToM, measured by impaired faux pas recognition, is a relatively strong predictor of poor social functioning in surgical candidates for intractable TLE. Identifying ToM impairment may help plan nonpharmacologic treatment for improving social functions in patients with intractable TLE.

Long-term health-related quality of life in drug-resistant temporal lobe epilepsy after anterior temporal lobectomy.

Epilepsy surgery is beneficial to patients suffering from drug-resistant temporal lobe epilepsy in the short term, but fewer reports of long-term outcomes have been published. To clarify the long-term outcomes of seizure control and health-related quality of life after epilepsy surgery, we enrolled 48 patients suffering from drug-resistant temporal lobe epilepsy. All of the patients received comprehensive presurgical evaluations, including the Quality of Life in Epilepsy Inventory-89 (QOLIE-89) questionnaire to measure their health-related quality of life. Among the patients, 28 patients received surgery (surgical group) and 20 patients remained under medication (medical group). Eight years later, the seizure frequency and QOLIE-89 were evaluated. The seizure-free rate was much higher in the surgical group (53.6%) than in the medical group (5%), eight years after the initial evaluation. The follow-up QOLIE-89 score was significantly higher in the surgical group than in the medical group. Moreover, the seizure frequency inversely correlated to the QOLIE-89 score, regardless of the treatment group. Our results provide evidence that epilepsy surgery confers benefits with respect to seizure control and health-related quality of life for drug-resistant temporal lobe epilepsy patients based on long-term follow-up.

Cognitive and epilepsy outcomes after epilepsy surgery caused by focal cortical dysplasia in children: early intervention maybe better.

BACKGROUND: Focal cortical dysplasia (FCD) is a specific malformation of cortical development harboring intrinsic epileptogenicity, and most of the patients develop drug-resistant epilepsy in early childhood. The detrimental effects of early and frequent seizures on cognitive function in children are significant clinical issues. In this study, we evaluate the effects of early surgical intervention of FCD on epilepsy outcome and cognitive development. METHODS: From 2006 to 2013, 30 children younger than 18 years old underwent resective surgery for FCDs at Taipei Veterans General Hospital. The mean age at surgery was 10.0 years (range 1.7 to 17.6 years). There were 21 boys and 9 girls. In this retrospective clinical study, seizure outcome, cognitive function, and quality of life were evaluated. To evaluate the effects to outcomes on early interventions, the patients were categorized into four groups according to age of seizure onset, duration of seizure before surgery, and severity of cognitive deficits. RESULTS: Eleven of 22 (50 %) patients demonstrated developmental delay preoperatively. The Engel seizure outcome achievements were class I in 21 (70 %), class II in 2 (7 %), class III in 6 (20 %), and class IV in 1 (3 %) patients. The locations of FCDs resected were in the frontal lobe in 18 cases, temporal lobe in 7, parietal lobe in 2, and in bilobes including frontoparietal lobe in 2 and parieto-occipital lobes in 1. Eight cases that had FCDs involved in the rolandic cortex presented hemiparesis before surgical resection. Motor function in four of them improved after operation. The histopathological types of FCDs were type Ia in 1, type Ib in 7, type IIa in 7, type IIb in 12, and type III in 3 patients. FCDs were completely resected in 20 patients. Eighteen (90 %) of them were seizure free (p < 0.001) with three patients that received more than one surgery to accomplish complete resection. The patients who had early seizure onset, no significant cognitive function deficit, and early surgical intervention with complete resection in less than 2 years of seizure duration showed best outcomes on seizure control, cognitive function, and quality of life. CONCLUSION: Delay in cognitive development and poor quality of life is common in children treated for FCDs. Early surgical intervention and complete resection of the lesion help for a better seizure control, cognitive function development, and quality of life. FCDs involved eloquent cortex may not prohibit complete resection for better outcomes.

Altered inhibitory modulation of somatosensory cortices in paroxysmal kinesigenic dyskinesia.

BACKGROUND: The objective of this study was to clarify the excitability profiles of the somatosensory cortices in patients with paroxysmal kinesigenic dyskinesia. METHODS: Whole-head magnetoencephalography was used to record the somatosensory evoked fields elicited by paired-pulse electric stimulation of the median nerve in 15 patients with paroxysmal kinesigenic dyskinesia and in a control group of 18 age-matched, healthy volunteers. Twelve of the patients were studied in both the drug-off and drug-on state. RESULTS: The paired-pulse inhibition ratios of the primary somatosensory cortical P35m responses and the secondary somatosensory cortical responses were significantly greater in drug-off patients with paroxysmal kinesigenic dyskinesia compared with either the drug-on patients or the control group. No significant difference in paired-pulse inhibition ratio was observed between the drug-on patients with paroxysmal kinesigenic dyskinesia and the control group. CONCLUSIONS: In patients with paroxysmal kinesigenic dyskinesia, intracortical inhibition of the primary and secondary somatosensory cortical areas is impaired, and the associated hyperexcitable phenomenon is modulatable by antiepileptic drugs.

Reduced postmovement cortical inhibition in patients with paroxysmal kinesigenic dyskinesia.

OBJECTIVE: To characterize movement-related neural oscillatory activity and to clarify its neurophysiologic role in paroxysmal kinesigenic dyskinesia (PKD). METHODS: We recorded neuromagnetic event-related desynchronization (ERD) and event-related synchronization (ERS) activities in response to a self-paced finger-lifting task in 16 patients with PKD and 17 healthy controls. RESULTS: The amplitude of α-ERD was comparable between the healthy controls and patients with PKD, whereas either the contralateral or ipsilateral ß-ERS was decreased. The peak latency of contralateral ß-ERS was delayed in patients with PKD. Patients with less frequent dyskinetic attacks demonstrated a larger ipsilateral ß-ERS. Moreover, some patients with PKD revealed a lesser degree of contralateral preponderance of ß-ERS generation. CONCLUSIONS: The present data imply a decreased postmovement inhibition of motor cortex in patients with PKD, and the inhibitory function in the contralateral hemisphere is more affected than that in the ipsilateral hemisphere.