Blood pressure and sympathetic nerve tone relation during hemodialysis may reflect cardiovascular dysfunction.

BACKGROUND: The blood pressure response to the rapid removal of fluid during hemodialysis is complex and the pathophysiological mechanisms underlying intradialytic hypotension are not clear and sometimes these mechanisms render dialysis difficult to continue. PURPOSE: We analyzed the changes in blood pressure and sympathetic nerve tone and attempted to clarify whether the dynamic pattern of this relationship reflects cardiovascular dysfunction. METHODS: The dynamic pattern of sympathetic nerve activity throughout dialysis was analyzed by frequency analysis of RR intervals recorded by 24 hours Holter electrocardiography in 64 patients and 3 minutes ECG every 15 minutes during dialysis in 121 stable end-stage renal failure patients who underwent maintenance hemodialysis. Blood pressure and fluid volume removed was measured every 15-30 minutes during dialysis and the average value of the ratio of low to high frequency components (LF/HF) was calculated as an index of sympathetic nerve tone. The relationship between removed fluid volume, systolic blood pressure (Bp) and LF/HF was analyzed. RESULTS: The patients were classified into 3 groups based on the correlation between the LF/HF and Bp as follows: positive (52 cases), inverse (54 cases), and not significant (NS; 61 cases). Eighteen patients who showed multiple arrhythmias, atrial fibrillation and other artifacts or noises were eliminated as they were inadequate for frequency analysis of RR intervals. The positive group was characterized by a hypotension-resistant response with a low LF/HF, whereas the inverse group was characterized by a hypotension-prone response with high LF/HF. These results suggest that cardiovascular dysfunction is responsible for the inverse correlation. CONCLUSION: Analysis of the relationship between sympathetic nerve tone and Bp is effective in predicting the existing of cardiovascular dysfunction.

Attempt of quantitative analysis of visual evaluation for (123)I-BMIPP myocardial scintigraphy images.

We developed a new technique to quantitatively analyze visual evaluation single photon emission computed tomography (SPECT). Short axis tomograms and color scales were computer scanned. The scales were divided into 25 parts; numbers of each hue pixel were scored 0-100%. Short-axis images were divided into eight equal partitions, numbers of hue pixels distributed in each partition were scored, and total scores were obtained. Each partition's radio-isotope (RI) accumulation index was calculated as partition score/highest score. For method validation, scintigrams from each left ventricular phantom part were divided into eight partitions and filled with (123)I-BMPP (10-100%). The error between theoretical and calculated concentrations was within 20% in the concentration range of ≥50%, suggesting a good correlation and indicating the method's validity.

Evaluation of carotid atherosclerosis from the perspective of blood flow reflection.

Detection and prevention of atherosclerosis at an early stage is important for its prevention. The aim of this study was to propose a valid and highly reliable index for the evaluation of carotid atherosclerosis or carotid function. Images of carotid Doppler wave profiles were processed using an image processing software, and the relative fluctuation in blood flow was calculated from the luminance in one cardiac cycle. Frequency analysis was performed and up to 10 time components of basic frequency (f1) were indicated. The evaluation function alpha was estimated by calculating the ratio of the sum of components f3-f10 against the f1 + f2 components. Blood pressure of the finger was continuously measured using Finapress during passive postural change from the supine to the standing position, the baroreceptor function was evaluated by the frequency method, and the plaque score was measured by ultrasound tomography. The influence of factors such as arterial compliance, blood vessel resistance, and heart rate on this index was studied using electric circuit model simulation. The subjects were 33 patients (18 men, 15 women) who had various types of atherosclerotic disease and hypertension. The average age was 67.3 + 12.2 years. The results showed that index alpha had a strong negative correlation with age and plaque score, and a weak positive correlation with baroreceptor function. Simulation results supported the clinical result. We proposed a new index to evaluate carotid atherosclerosis without blood pressure measurement using the carotid Doppler method. It is a potential index for detecting atherosclerosis of local arteries such as the carotid.

Effects of daily physical activity level on the degree of sympathetic tone.

BACKGROUND: Exercise is recommended for the treatment and prevention of cardiac disorders. Relaxation of the sympathetic nervous system has been considered to be one of the therapeutic mechanisms. However, the means by which the level of daily physical activity affects sympathetic activity remains unclear. OBJECTIVE: To evaluate the effects of daily physical activity on autonomic nervous tone. METHODS: Daily physical activity was measured for 5 or more days in 26 patients with various cardiac disorders of NYHA class 1 or 2 and in 6 healthy individuals using an intelligent calorie counter. Recumbent resting ECG was recorded for 3 minutes immediately before waking up and after going to bed using a digital ECG. Low- (Lf, 0.03-0.15 Hz) and high- (Hf, 0.15-0.45 Hz) frequency components were calculated by frequency analysis of the R-R interval, and Lf/Hf ratio was calculated as an index of sympathetic tone. RESULTS: The average values of energy expenditure and time were 145+/-93.6 kcal/day and 47.8+/-24.3 min/day, respectively. The morning Lf/Hf ratio decreased following an increased physical activity level the day before, but increased with subsequent increase in the activity level in 65.6% of subjects. A negative correlation was observed in 34.4% of subjects, which suggested that an appropriate level of physical activity led to relaxation of sympathetic tone. CONCLUSION: The daily level of physical activity affects sympathetic tone, and an appropriate level results in sympathetic relaxation. The results of this study provide a useful index to enable patients with cardiac disorder to perform exercise without overloading.

Involvement of carotid baroreceptor function in blood pressure control in the chronic phase: effect on 24-hour ambulatory blood pressure.

BACKGROUND: It is generally thought that the sole function of baroreceptors is for the regulation of rapid blood pressure fluctuations caused by postural changes and other motion. However, recent studies have suggested that baroreceptors may also be involved in blood pressure control in the chronic phase. PURPOSE: The study was performed to examine the involvement of carotid baroreceptors in blood pressure control in the chronic phase, through determination of the relationship between 24-hour blood pressure data and carotid baroreceptor function. METHODS: Ambulatory blood pressure, ECG, and the number of steps during exercise were measured every 15 minutes with an ambulatory blood pressure monitor and a 24-hour Holter ECG fitted with an accelerometer (Cardy-II-p, Suzuken KK, Japan). In addition, the dependence of blood pressure on autonomic nerve activity and exercise was analyzed based on the frequency of the RR interval. Patients were divided into three groups based on different blood-pressure types: autonomic nerve-dependent, exercise-dependent, and independent types. Carotid baroreceptor function was evaluated using the sequence method; subjects adopted a supine position on a tilt table and their arterial pressure was monitored continuously using a Finapress finger cuff (Finapress, Ohmeda, Louisville, Colorado, USA). The study was performed in 90 patients, including 42 with essential hypertension whose blood pressure was well controlled. RESULTS AND CONCLUSIONS: A significant negative correlation was found between the mean 24-hour blood pressure and baroreceptor function for both systolic and diastolic pressure. Systolic pressure in patients of the independent type was significantly higher than that in patients of the exercise-dependent type. Furthermore, non-dipper hypertension was noted more frequently and baroreceptor function was significantly lower in independent-type patients, compared with autonomic nerve-dependent and exercise-dependent types, suggesting that independent-type blood pressure may be due to baroreceptor dysfunction. In conclusion, our results suggest that baroreceptor function might be involved in blood pressure control in the chronic phase, and baroreceptor dysfunction may contribute to the development of essential hypertension.

Circadian variation of the myocardial ischemic threshold in patients with ischemic heart disease.

PURPOSE: Circadian variation of the heart rate (HR) at the myocardial ischemic threshold was compared with that of the HR at the sympathetic tone threshold in 16 cases of effort angina pectoris. METHODS: The high (0.15-0.40 Hz, Hf) and low (0.03-0.15 Hz, Lf) frequency spectral components were extracted every twenty seconds, using frequency domain analysis of the RR interval recorded by a 24-hour Holter ECG with an accelerometer. HR-Hf data collected every five minutes were plotted as the X-Y coordinates, and a two-compartment analysis was performed. The HR at the autonomic tone threshold was then determined at the intersection point of the lines. A loop of the HR-ST segment was drawn during walking to determine the ischemic threshold at which heart rate ischemic ST segment depression began and circadian variation was observed. RESULTS: The circadian rhythm at the sympathetic tone threshold and the HR at the ischemic threshold were high during the day and low at night. The HR at the ischemic threshold was 15-20% higher than that at the sympathetic tone threshold at night but only 9-13% higher during the day. Also, there was a period during which there was no significant difference between the HR at the two thresholds. CONCLUSION: In comparing circadian variation between HR at the sympathetic tone threshold and HR at the ischemic threshold, there was a period during which there was no significant difference between the HRs. This might suggest a period in which a high incidence of cardiac ischemic attack is likely. This information could provide a feasible indicator for appropriate exercise training for patients with ischemic heart disease.

A population-based survey of childhood epilepsy in Okayama Prefecture, Japan: reclassification by a newly proposed diagnostic scheme of epilepsies in 2001.

The purpose of this study is to clarify the usefulness and problems of the newly proposed classification of epilepsies (International League Against Epilepsy: ILAE, 2001) in the epidemiological studies of epilepsy. We previously conducted an epidemiological study in Okayama Prefecture, Japan, in 1999, using the ILAE 1989 classification. Among 250,997 children under 13 years of age, 2220 epileptic patients were ascertained. In this study, we reclassified them according to the ILAE 2001 classification, focusing on axes 2 (seizure types) and 3 (syndromes). We were able to classify 1803 (95.0%) seizure types out of 1899 with detailed clinical information. In focal seizures, the most common were secondarily generalized seizures (88.6%), which generally do not represent a unique anatomic substrate. In generalized seizures, topic-clonic seizures (40.7%) and spasms (21.0%) were the most common. We identified only 269 (12.1%) patients with specific epilepsy syndromes out of the 2220. We classified 1761 patients without specific syndromic diagnoses only by axis 2, but the new concept of epileptic seizure types, representing a unique pathophysiologic mechanism and anatomic substrate, was not very meaningful in most cases, even in those with focal seizures.

Prevalence of childhood epilepsy and distribution of epileptic syndromes: a population-based survey in Okayama, Japan.

PURPOSE: A population-based survey childhood epilepsy was undertaken in Okayama Prefecture, Japan, to determine the prevalence rate and the distribution of epilepsies and epileptic syndromes according to the International Classification (ILAE, 1989). METHODS: Information on patients younger than 13 years with active epilepsy was collected from medical records. Patients diagnosed with epilepsy according to clinical and EEG findings were put on the list even if those patients had had a single seizure or seizures occurring during febrile episodes. RESULTS: In total, 2,220 cases were identified from a background population of 250,997. The prevalence rate was 8.8 per 1,000. If we exclude patients who had experienced a single seizure or seizures occurring during febrile episodes to compare our results with previous reports, the prevalence rate was 5.3 per 1,000. Of the 2,220 cases, 2,030 (91.4%) were classified into three major categories by ILAE classification. They consisted of 1,556 (76.7%) with localization-related epilepsy, 453 (22.3%) with generalized epilepsy, and 21 (1.0%) with undetermined epilepsy. Of the 2,030 cases, 309 (15.2%) were classified into epileptic syndrome categories, and 84.8% of the total were nonspecific types of epilepsy. CONCLUSIONS: The prevalence rate of childhood epilepsy was distributed from 5.3 to 8.8 per 1,000. The appearance rate of various types of epileptic syndromes was low. Most cases could not be classified into the detailed categories of the International Classification (ILAE, 1989).

Symptoms related to ADHD observed in patients with pervasive developmental disorder.

To elucidate attention-deficit/hyperactivity disorder (ADHD)-related factors observed in high-function pervasive developmental disorder (PDD) and their impact on daily life, we classified high-function PDD patients according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria for ADHD with the exception of the exclusion criteria (coexistence with PDD), and studied the relationship between ADHD-related aspects and daily behavior problems using the Child Behavior Checklist (CBCL). The subjects were divided into two groups: Group 1, eight patients less than 6 years of age; and Group II, eight patients 6 years of age and older. Six patients in Group II met the criteria for ADHD. Five of them were classified as having the predominantly inattentive type of ADHD, and the remaining patient exhibited the combined type. However, no patient in Group I met the criteria for ADHD, suggesting the low sensitivity of the DSM-IV criteria for assessing the inattentiveness of preschoolers. The analyses of the correlation between corresponding items in the DSM-IV criteria and CBCL scores suggested that ADHD-related symptoms in high-function PDD patients have an impact on their daily lives.

Evaluation of the severity of dementia using expectation control function.

The results of an animal experiment without anesthesia suggested the presence of expectation control in which sympathetic nerve tone increases at rest immediately before behaviors to prepare for the subsequent behavior. We investigated whether such function is present in humans in their daily living and whether patients with dementia could be differentiated from healthy adults based on this finding. Using a Holter electrocardiograph with an acceleration sensor, electrocardiograms (ECG) and behavioral states were recorded. The total recorded ECG was divided by 20 sec, and high (HF, 0. 15-0.4 Hz) and low (LF, 0.03-0.15 Hz) frequency components were extracted by frequency analysis of the RR interval. We used the HF component, L/H ratio, and RR interval as the index grade of parasympathetic/sympathetic nerve tone. The mean value of each parameter was calculated and compared between the time zone during which resting persisted for 1 min or more (3 intervals) and that during which behaviors occurred immediately after a 1-min rest., In 32 patients with dementia, Holter ECG and behaviors were serially recorded, and the time zone during which intentional behaviors occurred was detected. RR interval and HF component decreased and L/H increased. Increasing in sympathetic nerve tone was observed at rest condition immediately before intentional behaviors, suggesting a presence of expectation control function. The expectation control mechanism will present in humans and involved in this function by severity of dementia. This parameter may be useful for objectively evaluating the severity of dementia.

Relationship between severity of epilepsy and developmental outcome in Angelman syndrome.

To clarify the relationship between the degree of developmental disturbance and the severity of epilepsy in Angelman syndrome, we investigated 11 patients and measured both clinical outcomes and EEG parameters. Seven patients were followed up until after 8 years of age. Eight patients were found to have 15q11-q13 deletions. All patients experienced epileptic seizures and all but one displayed non-convulsive status epilepticus (NCSE) during the period of observation. Epileptic seizures, including NCSE, disappeared by around 8 years of age. In addition, specific epileptic discharges, as measured by EEG, tended to subside with age. Although development seemed almost normal or only slightly delayed during the first 6 months of life, all patients eventually developed severe retardation. Two patients displayed very severe retardation and were unable to comprehend language or walk independently at the last follow-up. Only one patient was able to speak a few meaningful words. In one of the most severely affected patients, who showed the earliest onset of seizures and NCSE, it is possible that the repetitive bouts of NCSE might be responsible for the severe developmental outcome. However, the other patient with particularly severe retardation did not experience NCSE, while the patient with the most favorable outcome had repetitive episodes of NCSE. Therefore, we conclude that the severity of developmental disturbance in Angelman syndrome is not necessarily related to the degree of epilepsy. However, intensive therapy for NCSE might still be justified because there are some patients in whom NCSE results in a transient and sometimes permanent decline in mental and motor functioning.

Dipole analysis in panayiotopoulos syndrome.

Panayiotopoulos syndrome (PS) is a type of benign childhood partial epilepsy, which has a good prognosis despite the fact that it is frequently associated with abundant multifocal spikes on the electroencephalography (EEG). We investigated whether stable dipoles, as seen in rolandic epilepsy, were also present in PS. We performed dipole analysis of the interictal spike discharges seen in the interictal EEGs of eight children with PS. We chose more than 10 spikes for each kind of spike, and investigated whether or not more than three of these spikes showed consistently stable dipole locations. (1) We observed 15 different kinds of spikes in various regions in the EEGs of the eight children. (2) Twelve of the 15 kinds of spikes had dipoles with a high goodness of fit. Furthermore, 14 of the 15 spikes had stable dipoles with similar locations for more than three individual spikes. (3) Fourteen of the 15 spikes, including frontal spikes, showed dense dipole locations in the mesial occipital area. Thirteen of these 14 spikes also showed other dipole locations in the rolandic area and/or the vertex (Cz). Our study revealed that the various types of spikes observed in PS have similar and stable dipole locations. The dipoles showing high stability, were located in the mesial occipital area, and were accompanied by dipoles located in the rolandic area. The stability and location of these dipoles indicate that there may be a pathogenetic link between PS and rolandic epilepsy.

Initiation of treatment and selection of antiepileptic drugs in childhood epilepsy.

PURPOSE: A retrospective study was carried out on 53 cases with childhood epilepsy to evaluate the validity of the initial selection of antiepileptic drug (AED). METHODS: We investigated the AEDs selected at the beginning of the treatment from the medical records of 53 untreated cases. A follow-up study was undertaken to evaluate the effects of the AEDs. In the second study, we investigated the AEDs of 10 cases with atypical benign partial epilepsy (ABPE), to clarify whether the initial AEDs selected for rolandic epilepsy were related to the appearance of ABPE. RESULTS: The AEDs used at the initial stage consisted of carbamazepine (CBZ), valproic acid (VPA), phenobarbital (PB), and vitamin B6. The main AEDs were CBZ and VPA for localization-related epilepsy, and VPA for generalized epilepsy. The initial selection of AEDs in 41 (85.4%) of 48 cases treated with AEDs were considered to be correct from the results of follow-up. We could not specify any AEDs that related to the appearance of ABPE. CONCLUSIONS: The selection of AED in this series was considered to be most appropriate. We proposed a criterion to determine whether to begin the AED treatment immediately at the initial seizure.

Kinesigenic attacks with ictal electroencephalographic abnormalities.

We report on a 14-year 5-month-old male who had attacks similar to those of paroxysmal kinesigenic choreoathetosis. The attacks were elicited exclusively by sudden movements. On several occasions, these attacks were immediately followed by loss of consciousness or a seizure. Ictal electroencephalograms of his attacks without loss of consciousness or a seizure indicated 1.5-3.0 Hz activity in the left hemisphere. A small dosage of carbamazepine was remarkably effective in stopping the attacks. This case demonstrates that a thorough ictal electroencephalographic examination is indispensable for clarifying the pathophysiology of kinesigenic attacks. The relationship between paroxysmal kinesigenic choreoathetosis and supplementary motor area seizures is also discussed.

Ictal MEG in two children with partial seizures.

UNLABELLED: We report on the successful identification of epileptic foci in two children with partial epilepsy using ictal magnetoencephalography (MEG). Case 1 is a 12-year-old male suffering with simple partial seizures with leftwards nystagmus. Ictal SPECT revealed a hyperperfusion area in the right lateral occipital area, and MRI revealed cortical dysplasia in the same area. Interictal EEG dipoles were concentrated in the right mesial occipital lobe. Both interictal and ictal MEG dipoles were concentrated in the right mesial occipital lobe, which corresponded well with neuroimaging data and his clinical features. Case 2 is a 5-year-old female suffering with simple partial seizures with left-side facial twitching. Interictal EEG dipoles were located in her left motor area, the pre-sylvian fissure, close to the location of the interictal MEG-estimated dipoles. Ictal EEGs showed no remarkable changes associated with her clinical manifestations. However, ictal MEG showed high-voltage slow waves over her left hemisphere, and ictal MEG iso-contour maps revealed a clear dipolar pattern, which suggested that the MEG dipole was located in the area of the sylvian fissure. Ictal SPECT revealed hyperperfusion areas around the left sylvian fissure. CONCLUSION: Ictal MEG is useful for determining the precise location of epileptic focus in patients with motionless seizures, including children.

Memory function decline over 18 months after selective amygdalohippocampectomy.

We report on a 22 year-old woman with left temporal lobe epilepsy who had suffered complex partial seizures since childhood. At 19 years 10 months of age she underwent selective amygdalohippocampectomy, which resulted in a complete cessation of seizures. Preoperatively, the Logical Memory II section of the WMS-R revealed poor logical memory function. Postoperatively, the patient's scores on several neuropsychological tests had deteriorated, namely, the Miyake Paired-Associate Word Learning Test (related and unrelated pairs), several sections of the WMS-R (Figural Memory, Logical memory I, Visual Reproduction II, Visual Paired Associates I, and Verbal Paired Associates I and II), and the BVRT-R. In particular, her scores on the Visual Paired Associates I, Verbal Paired Associates I and II sections of the WMS-R, and the BVRT-R not only declined at one and three months post-surgery, but also showed progressive deterioration at 16 and 18 months post-surgery. It should be kept in mind that selective amygdalohippocampectomy can result in progressive postoperative, deterioration in some aspects of memory function.

Utility of scalp-recorded ictal electroencephalograms in childhood epilepsy with complex partial seizures.

BACKGROUND: The authors evaluated the usefulness of scalp-recorded ictal electroencephalograms (EEG) in diagnosing the epileptogenic area in epilepsy with complex partial seizures. METHODS: The authors analyzed the ictal EEG of 395 seizures in 43 patients with complex partial seizures. Based on EEG findings the patients were classified according to the degree of localization of their onset areas. The results were then compared with neuroimaging findings. RESULTS: Only 10 patients fell into the category 'discrete', meaning that all the onset areas (as measured by ictal EEG) were localized in the same lobe of the same hemisphere. Seven patients were categorized as 'lateralized', meaning that all the onset areas were clearly lateralized in the same hemisphere but without consistent localization. Eleven patients were classified as 'localized', meaning that the onset area were localized simultaneously in bilateral same lobes, or changed consistently from one lobe in one hemisphere to the same lobe in the opposite hemisphere. The onset area could not be defined in 15 patients and these were categorized as 'not defined'. No patient who underwent seven or more ictal recordings was categorized as discrete. However, when confined only to those patients in whom over 75% of the ictal recordings showed the same onset area, there was a high correlation between the epileptogenic lesions detected by ictal EEG and those detected by neuroimaging techniques. CONCLUSIONS: The findings of the present study indicate that ictal EEG recordings are useful for determining the epileptogenic area in epilepsy with complex partial seizures, provided that more than 75% of the ictal recordings show the same ictal onset area.

Clinical and electroencephalographic characteristics of children with febrile seizures plus.

OBJECTIVES: Febrile seizures plus (FS+) are attracting attention for their corresponding genetic abnormalities, and are defined as febrile seizures (FS) continuing beyond 6 years of age (late FS) or those associated with afebrile seizures. We tried to elucidate their clinical and EEG characteristics as compared with those of children having only FS. SUBJECTS AND METHODS: We reviewed clinical records in a pediatric neurology clinic to identify 31 patients with FS+ (group FS+) and 51 with only FS (group FS). Their family history of seizures, clinical features and EEG findings were compared. RESULTS: A family history of seizures was noted in 14 patients (45.2%) of group FS+ and in 24 (47.1%) of group FS. In group FS+, 19 patients had late FS, 11 had afebrile seizures, and the remaining one had both types of seizures. Two patients had seizures induced by TV/video-game as well, and another suffered from absences. Epileptic EEG abnormalities, which included diffuse spike-waves and focal spikes, were noted in 13 patients (41.9%) of group FS+ and 12 (23.5%) of group FS. CONCLUSIONS: The clinical and EEG characteristics of the children having FS+ were diverse, without significant differences from those with FS except for the seizures types.

EEG in childhood absence epilepsy.

UNLABELLED: We performed a longitudinal clinico-electroencephalographic study of 23 children who were diagnosed as having absence epilepsy on their initial visits to our facility and we analysed those factors which lead to an unfavourable prognosis. SUBJECTS AND METHODS: We divided the 23 patients into three groups according to their clinical courses: Group A: eight patients who responded well to the therapy and became seizure free without relapse of epileptic discharges on EEGs; Group B: thirteen patients who suffered from relapse of epileptic discharges on EEGs despite clinical seizure cessation; Group C: two patients who continued to suffer from seizures. RESULTS: (1) Fifty-six percent of all patients had focal epileptic discharges, including a surprising 63% of patients in Group A. (2) "Lead in" in the ictal EEGs and automatisms during seizures were most commonly observed in patients in Group B, although there were no significant differences between the three groups. (3) The epilepsy of one patient in Group C evolved into complex partial seizures or absence status during her clinical course. She seemed to suffer from so-called "frontal absence", despite the fact that her initial EEG did not show any focal abnormalities. (4) Patients in Group B were treated with lower AED dosages than those in Group A. In addition, one patient in Group C was treated irregularly. CONCLUSION: We conclude that it is not uncommon for patients with absence epilepsy to show focal abnormalities on EEGs and clinical ictal automatisms. Thus, the existence of clinical ictal automatisms and focal signs in electroencephalographic features are not sufficient indicators of the final outcome. Furthermore, it appears that regular and adequate drug therapy is important for a favourable prognosis.

Very fast rhythmic activity on scalp EEG associated with epileptic spasms.

PURPOSE: Very fast activity was investigated on the ictal EEGs of epileptic spasms to elucidate the pathophysiology of West syndrome (WS) and related disorders from a novel point of view. METHODS: The traces of scalp ictal EEG of spasms temporally were expanded in 11 patients whose clinical diagnosis was symptomatic WS in six, cryptogenic WS in two, Aicardi syndrome in one, and symptomatic generalized epilepsy after WS in the remaining two. Time evolution of averaged power spectra of the ictal fast activity also was analyzed in each patient. RESULTS: Rhythmic gamma activity with frequency ranging from 50 to 100 Hz was detected in a total of 345 of 537 spasms. Fast activity was seen bilaterally in nine patients, was lateralized to one hemisphere in another, and appeared independently on each hemisphere in the remaining infant with Aicardi syndrome. Power spectra showed a clear peak corresponding to spasm-associated gamma rhythm, with frequency centering approximately 65 Hz and ranging from 51 to 98 Hz. The morphology and spectral characteristics of ictal gamma rhythm were completely different from those of muscle activity or alternating current (AC) artifacts. CONCLUSIONS: Spasm-associated gamma activity was clearly detected on the scalp. This observation may provide a clue to the pathophysiology of spasms.