MR-guided laser interstitial thermal therapy for drug-resistant lesional epilepsy: a single-center experience.

BACKGROUND: To describe and report the efficacy and safety of MR-guided laser interstitial thermal therapy (MRgLITT) in the treatment of drug-resistant epilepsy. METHODS: A retrospective review of all MRgLITT procedures in our hospital was performed. All procedures were performed using a surgical laser ablation system. Demographic and outcome data were compiled and analyzed. RESULTS: A total of 19 patients underwent MRgLITT procedures from June 2021 to November 2021. The average age at surgery was 18.1 years (3-61.4 years). The average length of hospitalization post-surgery was 4.95 days (4-7 days). Surgical substrates included 8 patients with hypothalamic hamartomas, 5 with medial temporal lobe epilepsy, 3 with deep focal cortical dysplasia, 1 with tuberous sclerosis, 1 with a cavernous malformation, and 1 with Lennox-Gastaut syndrome who underwent anterior corpus callosotomy. Complications occurred in three patients. After an average follow-up of 1 year, 6 patients were seizure-free (Engel I, 31.6%), 1 had significant seizure control (Engel II, 5.3%), 7 had seizure control (Engel III, 36.8%), and 5 had no improvement in their seizures (Engel IV, 26.3%). Fisher's exact tests did not reveal statistical significance for the association between Engel class outcome and epileptic disease. CONCLUSION: This study confirmed that MRgLITT, as a method for treating drug-resistant epilepsy, is minimally invasive, safe, and efficient and that it can reduce the incidence of surgery-related complications.

Automatic Epileptic Tissue Localization through Spatial Pattern Clustering of High Frequency Activity.

High-frequency activity (HFA) in intracranial electroencephalography recordings are diagnostic biomarkers for refractory epilepsy. Clinical utilities based on HFA have been extensively examined. HFA often exhibits different spatial patterns corresponding to specific states of neural activation, which will potentially improve epileptic tissue localization. However, research on quantitative measurement and separation of such patterns is still lacking. In this paper, spatial pattern clustering of HFA (SPC-HFA) is developed. The process is composed of three steps: (1) feature extraction: skewness which quantifies the intensity of HFA is extracted; (2) clustering: k-means clustering is applied to separate column vectors within the feature matrix into intrinsic spatial patterns; (3) localization: the determination of epileptic tissue is performed based on the cluster centroid with HFA expanding to the largest spatial extent. Experiments were conducted on a public iEEG dataset with 20 patients. Compared with existing localization methods, SPC-HFA demonstrates improvement (Cohen's d > 0.2) and ranks top in 10 out of 20 patients in terms of the area under the curve. In addition, after extending SPC-HFA to high-frequency oscillation detection algorithms, corresponding localization results also improve with effect size Cohen's d ≥ 0.48. Therefore, SPC-HFA can be utilized to guide clinical and surgical treatment of refractory epilepsy.

Epileptic Tissue Localization through Skewness-Based Functional Connectivity in the High-Frequency Band of Intracranial EEG.

Functional connectivity analysis of intracranial electroencephalography (iEEG) plays an important role in understanding the mechanism of epilepsy and seizure dynamics. However, existing connectivity analysis is only suitable for low-frequency bands below 80 Hz. High-frequency oscillations (HFOs) and high-frequency activity (HFA) in the high-frequency band (80-500 Hz) are thought to be specific biomarkers in epileptic tissue localization. However, the transience in duration and variability of occurrence time and amplitudes of these events pose a challenge for conducting effective connectivity analysis. To deal with this problem, we proposed skewness-based functional connectivity (SFC) in the high-frequency band and explored its utility in epileptic tissue localization and surgical outcome evaluation. SFC comprises three main steps. The first step is the quantitative measurement of amplitude distribution asymmetry between HFOs/HFA and baseline activity. The second step is functional network construction on the basis of rank correlation of asymmetry across time. The third step is connectivity strength extraction from the functional network. Experiments were conducted in two separate datasets which consist of iEEG recordings from 59 patients with drug-resistant epilepsy. Significant difference (p<0.001) in connectivity strength was found between epileptic and non-epileptic tissue. Results were quantified via the receiver operating characteristic curve and the area under the curve (AUC). Compared with low-frequency bands, SFC demonstrated superior performance. With respect to pooled and individual epileptic tissue localization for seizure-free patients, AUCs were 0.66 (95% confidence interval (CI): 0.63-0.69) and (0.63 95% CI 0.56-0.71), respectively. For surgical outcome classification, the AUC was 0.75 (95% CI 0.59-0.85). Therefore, SFC can act as a promising assessment tool in characterizing the epileptic network and potentially provide better treatment options for patients with drug-resistant epilepsy.

Prognostic values of optic nerve sheath diameter for comatose patients with acute stroke: An observational study.

BACKGROUND: Optic nerve sheath diameter (ONSD) measurement is one of the non-invasive methods recommended for increased intracranial pressure (ICP) monitoring. AIM: This study aimed to evaluate the roles of optic nerve sheath diameter (ONSD) and ONSD/eyeball transverse diameter (ETD) ratio in predicting prognosis of death in comatose patients with acute stroke during their hospitalization. METHODS: A total of 67 comatose patients with acute stroke were retrospectively recruited. The ONSD and ETD were measured by cranial computed tomography (CT) scan. All patients underwent cranial CT scan within 24 h after coma onset. Patients were divided into death group and survival group according to their survival status at discharge. The differences of the ONSD and ONSD/ETD ratio between the two groups and their prognostic values were compared. RESULTS: The ONSD and ONSD/ETD ratio were 6.07 ± 0.72 mm and 0.27 ± 0.03 in the comatose patients, respectively. The ONSD was significantly greater in the death group than that in the survival group (6.32 ± 0.67 mm vs 5.65 ± 0.62 mm, t = 4.078, P < 0.0001). The ONSD/ETD ratio was significantly higher in the death group than that in the survival group (0.28 ± 0.03 vs 0.25 ± 0.02, t = 4.625, P < 0.0001). The area under the receiver operating characteristic curve was 0.760 (95%CI: 0.637-0.882, P < 0.0001) for the ONSD and 0.808 (95%CI: 0.696-0.920, P < 0.0001) for the ONSD/ETD ratio. CONCLUSION: The mortality increased in comatose patients with acute stroke when the ONSD was > 5.7 mm or the ONSD/ETD ratio was > 0.25. Both indexes could be used as prognostic tools for comatose patients with acute stroke. The ONSD/ETD ratio was more stable than the ONSD alone, which would be preferred in clinical practice.

Neuronal intranuclear inclusion disease presented with recurrent vestibular migraine-like attack: a case presentation.

BACKGROUND: Neuronal intranuclear inclusion disease (NIID) is a neurodegenerative disorder characterized by dementia, tremor, episodic encephalopathy and autonomic nervous dysfunction. To date, vestibular migraine (VM)-like attack has never been reported in cases with NIID. Here, we describe an 86-year-old patient with NIID who presented with recurrent vertigo associated with headache for more than 30 years. CASE PRESENTATION: An 86-year-old Chinese woman with vertigo, headache, weakness of limbs, fever, and disturbance of consciousness was admitted to our hospital. She had suffered from recurrent vertigo associated with headache since her 50 s,followed by essential tremor and dementia. On this admission, brain magnetic resonance imaging revealed high intensity signals along the corticomedullary junction on diffusion weighted imaging (DWI). Peripheral neuropathy of the extremities was detected through electrophysiological studies. We diagnosed NIID after detecting eosinophilic intranuclear inclusions in the ductal epithelial cells of sweat glands and identifying an abnormal expansion of 81 GGC repeats in the 5'UTR of NOTCH2NLC gene. CONCLUSIONS: VM-like attack may be associated with NIID.

The clinical and prognostic values of optic nerve sheath diameter and optic nerve sheath diameter/eyeball transverse diameter ratio in comatose patients with supratentorial lesions.

BACKGROUND: The optic nerve sheath diameter (ONSD) and ONSD/eyeball transverse diameter (ETD) ratio have been proven to be correlated with intracranial pressure. This study aimed to evaluate the prognostic roles of ONSD and the ONSD/ETD ratio in comatose patients with supratentorial lesions and to determine the relationship of these two indices with the prognosis of such patients. METHODS: A total of 54 comatose patients with supratentorial lesions and 50 healthy controls were retrospectively included in this study. ONSD and ETD were measured by unenhanced computed tomography (CT). The differences in ONSD and the ONSD/ETD ratio between the two groups were compared. The prognosis of comatose patients was scored using the Glasgow Outcome Scale (GOS) at the 3-month follow-up, and these patients were classified into good (GOS score ≥ 3) and poor (GOS score < 3) prognosis groups. The differences in ONSD and the ONSD/ETD ratio were compared between comatose patients with good prognoses and those with poor prognoses. RESULTS: The ONSD and ONSD/ETD ratios in the comatose patients were 6.30 ± 0.60 mm and 0.27 ± 0.03, respectively, and both were significantly greater than those in the healthy controls (5.10 ± 0.47 mm, t = 11.426, P < 0.0001; 0.22 ± 0.02, t = 11.468, P < 0.0001; respectively). ONSD in patients with poor prognosis was significantly greater than that in patients with good prognosis (6.40 ± 0.56 vs. 6.03 ± 0.61 mm, t = 2.197, P = 0.032). The ONSD/ETD ratio in patients with poor prognosis was significantly greater than that in patients with good prognosis (0.28 ± 0.02 vs. 0.26 ± 0.03, t = 2.622, P = 0.011). The area under the receiver operating characteristic (ROC) curve, used to predict the prognosis of comatose patients, was 0.650 (95% confidence interval (CI): 0.486-0.815, P = 0.078) for ONSD and 0.711 (95% CI: 0.548-0.874, P = 0.014) for the ONSD/ETD ratio. CONCLUSIONS: The ONSD and ONSD/ETD ratios were elevated in comatose patients. The ONSD/ETD ratio might be more valuable than ONSD in predicting the prognoses of comatose patients with supratentorial lesions.

Postoperative incidence of seizure and cerebral infarction in pediatric patients with epileptic type moyamoya disease: a meta-analysis of single rate.

BACKGROUND: Surgery is a conventional mature treatment for moyamoya disease (MMD). However, whether surgery is also an effective therapy for epileptic type MMD has seldom been investigated systematically. The study aims to summarize the pooled postoperative incidence of seizure and cerebral infarction in pediatric patients with epileptic type moyamoya disease. METHOD: The study was a systematic review and critical appraisal with a meta-analysis of cohort studies, both prospective and retrospective. Studies were identified by a computerized search of PubMed, Embase, Web of Science, Wanfang, and CNKI databases. In a literature search, a total of 7 cohort studies were identified. The I2statistic was used to quantify heterogeneity. A fixed-effect model was used to synthesize the results. The linear regression test of funnel plot asymmetry was used to estimate the potential publication bias. RESULTS: The pooled estimated postoperative incidence of seizure in pediatric patients with epileptic type moyamoya disease was 23.44%. The pooled estimated postoperative incidence of cerebral infarction in pediatric patients with epileptic type moyamoya disease was 9.12%. Low substantial heterogeneity and potential publication bias were present. CONCLUSIONS: Evidence from this study suggests that the postoperative incidence of seizure and cerebral infarction is relatively low. Surgery is an effective and secure therapy for pediatric patients with epileptic type moyamoya disease.

Electroencephalographic features in pediatric patients with moyamoya disease in China.

BACKGROUND: Moyamoya disease (MMD) is a relatively important and common disease, especially in East Asian children. There are few reports about EEG in children with MMD in China till now. This study is aimed to analyze the electroencephalographic features of MMD in pediatric patients in China preliminarily. METHODS: Pediatric patients with MMD who were hospitalized in Peking University International Hospital and Beijing Tiantan Hospital from January 2016 to December 2018 were collected. Clinical and electroencephalography (EEG) findings were analyzed retrospectively. RESULTS: A total of 110 pediatric patients with MMD were involved, and 17 (15.5%) cases had a history of seizure or epilepsy. Ischemic stroke was associated with a 1.62-fold relative risk of seizure. A subset of 15 patients with complete EEG data was identified. Indications for EEG in patients with MMD included limb shaking, unilateral weakness, or generalized convulsion. Abnormal EEG was seen in 14 (93.3%) cases, with the most common findings being focal slowing 12 (80.0%), followed by epileptiform discharge 10 (66.7%), and diffuse slowing 9 (60.0%). "Re-build up" phenomenon on EEG was observed in one patient. CONCLUSIONS: Seizure and abnormal background activity or epileptiform discharge on EEG were common in pediatric patients with MMD. EEG may play a role in differential diagnosis among the transient neurological events in MMD such as transient ischemic attack and seizure.

Hypothalamic sydrome as an initial presentation of Wernicke encephalopathy: A case report.

RATIONALE: Wernicke encephalopathy (WE) is a syndrome characterized by an acute or subacute onset of ataxia, ophthalmoplegia, and mental status changes. To our knowledge, hypothalamic syndrome is rare in WE. PATIENT CONCERNS: A 73-year-old female patient with acute cerebral infarct, who showed initial symptoms of vomiting, nausea, ataxia, and subsequent anorexia, was treated with parenteral nutritional supplement for 20 days. Nevertheless, the patient still developed refractory hyponatremia despite the appropriate sodium supplement given for a week following parenteral nutritional supplement. In fact, after 14 days of parenteral nutritional supplement, the patient gradually showed hypotension and apathy. Hyponatremia, hypotension, anorexia and apathy were signs of hypothalamic syndrome. DIAGNOSES: Finally, the patient was diagnosed as WE by head magnetic resonance imaging, which showed symmetrical lesions in T2-weighted imaging images and FLAIR high signal intensity in the periaqueduct, hypothalamus, thalamus, mammiliary bodies, medulla oblongata, and vermis cerebelli. INTERVENTIONS: The patient was given thiamine supplementation. OUTCOMES: The patient regained consciousness within 3 days. The sings of hyponatremia, hypotension, and apathy were relieved subsequently. LESSONS: When patients develop unexplained hypothalamic syndrome, we should think of the possibility of WE. The concomitant presence of hyponatremia, hypotension, anorexia, and apathy in WE is rare. Therefore, this case is reported here for discussion.

Clinical practice guidelines for the diagnosis and treatment of adult diffuse glioma-related epilepsy.

BACKGROUND: Glioma-related epilepsy (GRE) is defined as symptomatic epileptic seizures secondary to gliomas, it brings both heavy financial and psychosocial burdens to patients with diffuse glioma and significantly decreases their quality of life. To date, there have been no clinical guidelines that provide recommendations for the optimal diagnostic and therapeutic procedures for GRE patients. METHODS: In March 2017, the Joint Task Force for GRE of China Association Against Epilepsy and Society for Neuro-Oncology of China launched the guideline committee for the diagnosis and treatment of GRE. The guideline committee conducted a comprehensive review of relevant domestic and international literatures that were evaluated and graded based on the Oxford Centre for Evidence-Based Medicine Levels of Evidence, and then held three consensus meetings to discuss relevant recommendations. The recommendations were eventually given according to those relevant literatures, together with the experiences in the diagnosis and treatment of over 3000 GRE cases from 24 tertiary level hospitals that specialize in clinical research of epilepsy, glioma, and GRE in China. RESULTS: The manuscript presented the current standard recommendations for the diagnostic and therapeutic procedures of GRE. CONCLUSIONS: The current work will provide a framework and assurance for the diagnosis and treatment strategy of GRE to reduce complications and costs caused by unnecessary treatment. Additionally, it can serve as a reference for all professionals involved in the management of patients with GRE.

Current status and potential application of navigated transcranial magnetic stimulation in neurosurgery: a literature review.

Transcranial magnetic stimulation (TMS) is a noninvasive neurophysiologic technique that can stimulate the human brain. Positioning of the coil was often performed based merely on external landmarks on the head, meaning that the anatomical target in the cortex remains inaccurate. Navigated transcranial magnetic stimulation (nTMS) combines a frameless stereotactic navigational system and TMS coil and can provide a highly accurate delivery of TMS pulses with the guidance of imaging. Therefore, many novel utilities for TMS could be explored due to the ability of precise localization. Many studies have been published, which indicate nTMS enables presurgical functional mapping. This review aimed to provide a comprehensive literature review on nTMS, especially the principles and clinical applications of nTMS. All articles in PubMed with keywords of "motor mapping," "presurgical mapping," "navigated transcranial magnetic stimulation," and "language mapping" published from 2000 to 2018 were included in the study. Frequently cited publications before 2000 were also included. The most valuable published original and review articles related to our objective were selected. Motor mapping of nTMS is validated to be a trustful tool to recognize functional areas belonging to both normal and lesioned primary motor cortex. It can offer reliable mapping of speech and motor regions at cortex prior to operation and has comparable accuracy as direct electrical cortical stimulation. nTMS is a powerful tool for mapping of motor and linguistic function prior to operation, has high application value in neurosurgery and the treatment of neurological and psychiatric diseases, and has gained increasing acceptance in neurosurgical centers across the world.

Topography of Synchronization of Somatosensory Evoked Potentials Elicited by Stimulation of the Sciatic Nerve in Rat.

PURPOSE: Traditionally, the topography of somatosensory evoked potentials (SEPs) is generated based on amplitude and latency. However, this operation focuses on the physical morphology and field potential-power, so it suffers from difficulties in performing identification in an objective manner. In this study, measurement of the synchronization of SEPs is proposed as a method to explore brain functional networks as well as the plasticity after peripheral nerve injury. METHOD: SEPs elicited by unilateral sciatic nerve stimulation in twelve adult male Sprague-Dawley (SD) rats in the normal group were compared with SEPs evoked after unilateral sciatic nerve hemisection in four peripheral nerve injured SD rats. The characterization of synchronized networks from SEPs was conducted using equal-time correlation, correlation matrix analysis, and comparison to randomized surrogate data. Eigenvalues of the correlation matrix were used to identify the clusters of functionally synchronized neuronal activity, and the participation index (PI) was calculated to indicate the involvement of each channel in the cluster. The PI value at the knee point of the PI histogram was used as a threshold to demarcate the cortical boundary. RESULTS: Ten out of the twelve normal rats showed only one synchronized brain network. The remaining two normal rats showed one strong and one weak network. In the peripheral nerve injured group, only one synchronized brain network was found in each rat. In the normal group, all network shapes appear regular and the network is largely contained in the posterior cortex. In the injured group, the network shapes appear irregular, the network extends anteriorly and posteriorly, and the network area is significantly larger. There are considerable individual variations in the shape and location of the network after peripheral nerve injury. CONCLUSION: The proposed method can detect functional brain networks. Compared to the results of the traditional SEP-morphology-based analysis method, the synchronized functional network area is much larger. Furthermore, the proposed method can also characterize the rapid cortical plasticity after a peripheral nerve is acutely injured.

An EEMD-ICA Approach to Enhancing Artifact Rejection for Noisy Multivariate Neural Data.

As neural data are generally noisy, artifact rejection is crucial for data preprocessing. It has long been a grand research challenge for an approach which is able: 1) to remove the artifacts and 2) to avoid loss or disruption of the structural information at the same time, thus the risk of introducing bias to data interpretation may be minimized. In this study, an approach (namely EEMD-ICA) was proposed to first decompose multivariate neural data that are possibly noisy into intrinsic mode functions (IMFs) using ensemble empirical mode decomposition (EEMD). Independent component analysis (ICA) was then applied to the IMFs to separate the artifactual components. The approach was tested against the classical ICA and the automatic wavelet ICA (AWICA) methods, which were dominant methods for artifact rejection. In order to evaluate the effectiveness of the proposed approach in handling neural data possibly with intensive noises, experiments on artifact removal were performed using semi-simulated data mixed with a variety of noises. Experimental results indicate that the proposed approach continuously outperforms the counterparts in terms of both normalized mean square error (NMSE) and Structure SIMilarity (SSIM). The superiority becomes even greater with the decrease of SNR in all cases, e.g., SSIM of the EEMD-ICA can almost double that of AWICA and triple that of ICA. To further examine the potentials of the approach in sophisticated applications, the approach together with the counterparts were used to preprocess a real-life epileptic EEG with absence seizure. Experiments were carried out with the focus on characterizing the dynamics of the data after artifact rejection, i.e., distinguishing seizure-free, pre-seizure and seizure states. Using multi-scale permutation entropy to extract feature and linear discriminant analysis for classification, the EEMD-ICA performed the best for classifying the states (87.4%, about 4.1% and 8.7% higher than that of AWICA and ICA respectively), which was closest to the results of the manually selected dataset (89.7%).

Using Relevance Feedback to Distinguish the Changes in EEG During Different Absence Seizure Phases.

We carried out a series of statistical experiments to explore the utility of using relevance feedback on electroencephalogram (EEG) data to distinguish between different activity states in human absence epilepsy. EEG recordings from 10 patients with absence epilepsy are sampled, filtered, selected, and dissected from seizure-free, preseizure, and seizure phases. A total of 112 two-second 19-channel EEG epochs from 10 patients were selected from each phase. For each epoch, multiscale permutation entropy of the EEG data was calculated. The feature dimensionality was reduced by linear discriminant analysis to obtain a more discriminative and compact representation. Finally, a relevance feedback technique, that is, direct biased discriminant analysis, was applied to 68 randomly selected queries over nine iterations. This study is a first attempt to apply the statistical analysis of relevance feedback to the distinction of different EEG activity states in absence epilepsy. The average precision in the top 10 returned results was 97.5%, and the standard deviation suggested that embedding relevance feedback can effectively distinguish different seizure phases in absence epilepsy. The experimental results indicate that relevance feedback may be an effective tool for the prediction of different activity states in human absence epilepsy. The simultaneous analysis of multichannel EEG signals provides a powerful tool for the exploration of abnormal electrical brain activity in patients with epilepsy.

[Application of continuous video-electroencephalographic monitoring in patients with consciousness disorders in intensive care unit].

OBJECTIVE: To evaluate the application value of continuous video-electroencephalographic (cVEEG) monitoring in patients with consciousness disorders in intensive care unit (ICU). METHODS: Retrospective analyses were conducted for applying cVEEG in the clinical diagnosis and outcome evaluation of 54 patients with consciousness disorders in intensive care unit (ICU) at our hospital from January 2008 to April 2014. RESULTS: The most common cause was cerebrovascular disease (46.3%) followed by ischemic-hypoxic encephalopathy after cadio-pulmonary resuscitation (18.5%). And 49 cases (90.7%) showed an abnormal background on initial cVEEG, 19 cases (35.2%) had epileptic discharge and 8 cases (14.8%) were diagnosed with nonconvulsive status epilepticus (NCSE). Among 6 cases of convulsive patients, only 1 had epileptic discharge patterns of isoelectric, invariable low amplitude. Burst-suppression, persistent θ rhythm-like background activity, persistent diffuse epileptic discharge and periodic waves had high mortality rate. CONCLUSION: Stroke is a major cause of consciousness disorders. And continuous VEEG monitoring is beneficial for clinical diagnosis, differential diagnosis and outcome evaluation.

[Paroxysmal kinesigenic dyskinesia: 2 case reports].

Paroxysmal kinesigenic dyskinesia (PKD) is a rare neurological condition in which brief and frequent dyskinetic attacks are provoked by sudden movement. PKD is more common in men and can be idiopathic (commonly familial) or due to a variety of causes. The pathophysiology of PKD is uncertain but it could be an ion-channel disorder. Genetic linkage studies have isolated several loci on chromosome 16, and proline-rich transmembrane protein 2 (PRRT2) has been identified as a causative gene of PKD by using a combination of exome sequencing and linkage analysis. Antiepileptic drugs, particularly, carbamazepine are very helpful in a large proportion of cases. Sometimes it can be difficult to distinguish this syndrome from epilepsy. We reported 2 patients who presented abnormal involuntary attack. Evaluations included general physical examinations, endocrinologic and metabolic studies, video electroencephalograms and brain MRI imaging. All of these studies were normal. All of symptoms showed excellent response to carbamazepine.

Classifying normal and abnormal status based on video recordings of epileptic patients.

Based on video recordings of the movement of the patients with epilepsy, this paper proposed a human action recognition scheme to detect distinct motion patterns and to distinguish the normal status from the abnormal status of epileptic patients. The scheme first extracts local features and holistic features, which are complementary to each other. Afterwards, a support vector machine is applied to classification. Based on the experimental results, this scheme obtains a satisfactory classification result and provides a fundamental analysis towards the human-robot interaction with socially assistive robots in caring the patients with epilepsy (or other patients with brain disorders) in order to protect them from injury.

Dynamic characteristics of absence EEG recordings with multiscale permutation entropy analysis.

Understanding the transition of brain activities towards an absence seizure, called pre-epileptic seizure, is a challenge. In this study, multiscale permutation entropy (MPE) is proposed to describe dynamical characteristics of electroencephalograph (EEG) recordings on different absence seizure states. The classification ability of the MPE measures using linear discriminant analysis is evaluated by a series of experiments. Compared to a traditional multiscale entropy method with 86.1% as its classification accuracy, the classification rate of MPE is 90.6%. Experimental results demonstrate there is a reduction of permutation entropy of EEG from the seizure-free state to the seizure state. Moreover, it is indicated that the dynamical characteristics of EEG data with MPE can identify the differences among seizure-free, pre-seizure and seizure states. This also supports the view that EEG has a detectable change prior to an absence seizure.