Supratentorial cavernous haemangiomas and epilepsy: a review of the literature and case series

OBJECTIVES

To characterise the clinical features and response to treatment of supratentorial cavernomas associated with epilepsy.

METHODS

A systematic review of the literature was carried out and a retrospective case series of patients with cavernoma diagnosed by MRI and/or histology was compiled. Patient selection biases in the literature review were reduced as far as possible by selection of unbiased publications.

RESULTS

In the literature, cavernomas were relatively less common in the frontal lobes. There were multiple cavernomas in 23% of cases. The main clinical manifestations were seizures (79%) and haemorrhage (16%). The annual haemorrhage rate was 0.7%. The outcome after excision was good with improvement in seizures in 92% of patients. In the case series the surgical outcome was less favourable, reflecting inclusion of a higher proportion of patients with intractable epilepsy. In both the literature review and the case series, outcome was poorer in cases with a longer duration of seizures at the time of surgery.

CONCLUSIONS

The good surgical results, particularly in cases treated earlier, and the significant cumulative haemorrhage rate, suggest that excision is the optimum treatment. However, these factors have not been examined prospectively and, despite the availability of several retrospective studies, the optimum treatment, particularly for non-intractable cases, will only be determined by a prospective study.

Surgical outcome in patients with epilepsy and dual pathology

High-resolution MRI can detect dual pathology (an extrahippocampal lesion plus hippocampal atrophy) in about 5-20% of patients with refractory partial epilepsy referred for surgical evaluation. We report the results of 41 surgical interventions in 38 adults (mean age 31 years, range 14-63 years) with dual pathology. Three patients had two operations. The mean postoperative follow-up was 37 months (range 12-180 months). The extrahippocampal lesions were cortical dysgenesis in 15, tumour in 10, contusion/infarct in eight and vascular malformation in five patients. The surgical approach aimed to remove what was considered to be the most epileptogenic lesion, and the 41 operations were classified into lesionectomy (removal of an extrahippocampal lesion); mesial temporal resection (removal of an atrophic hippocampus); and lesionectomy plus mesial temporal resection (removal of both the lesion and the atrophic hippocampus). Lesionectomy plus mesial temporal resection resulted in complete freedom from seizures in 11/15 (73%) patients, while only 2/10 (20%) patients who had mesial temporal resection alone and 2/16 (12.5%) who had a lesionectomy alone were seizure-free (P < 0.001). When classes I and II were considered together results improved to 86, 30 and 31%, respectively. Our findings indicate that in patients with dual pathology removal of both the lesion and the atrophic hippocampus is the best surgical approach and should be considered whenever possible.

Evidence for nodular epileptogenicity and gender differences in periventricular nodular heterotopia

OBJECTIVE

To determine whether clinical differences between the sexes seen in periventricular nodular heterotopia (PNH) have structural correlates on imaging.

BACKGROUND

PNH is the most common dysgenesis associated with hippocampal sclerosis (HS). Women with PNH have normal intellect; men may have mental retardation and other changes. Familial PNH, seen in women, is linked to Xq28-a region also abnormal in a sporadic male infant with PNH and retardation-suggesting sexual differences in gene expression. Epilepsy associated with PNH may be refractory to drugs, and surgery for associated HS does not stop seizures, suggesting intrinsic epileptogenicity of PNH.

METHODS

Quantitative MRI analysis was performed using established techniques for detecting subtle structural changes in 13 female patients (11 sporadic and two familial) and four male patients (sporadic).

RESULTS

There is structural heterogeneity in PNH, even in patients with bilateral PNH. On MRI, men have more cerebral abnormalities beyond PNH than control subjects or female patients (p < 0.005).

CONCLUSIONS

The findings support the concept of intrinsic epileptogenicity of PNH. There may be additional structural abnormalities relevant to seizure generation, especially in men. Structural heterogeneity, and widespread abnormalities, may need consideration when patients are referred for surgical treatment or when additional studies of patients with PNH are conducted.

Disproportion in the distribution of gray and white matter: neuropsychological correlates

OBJECTIVE

To examine the relationship between measures of disproportion in the regional distribution of gray and white matter and preoperative neuropsychological function in temporal lobe epilepsy patients with proved hippocampal sclerosis (HS).

BACKGROUND

Subtle cerebral structural disruption, not evident on routine inspection of high-resolution MRI, is associated with poor surgical outcome in patients with histologically proved HS. Preoperative global memory dysfunction is also associated with poor postoperative seizure control. The authors hypothesize that patients with HS and abnormal regional distributions of gray and white matter would show more diffuse neuropsychological deficits preoperatively than patients with isolated HS alone.

METHODS

A total of 28 adults with lateralized temporal lobe epilepsy and hippocampal volume loss measured on MRI were assessed preoperatively on neuropsychological tests of general intellect and the learning and recall of both verbal and nonverbal material. Quantitative MRI analysis of the regional distribution of gray and white matter was performed. Chi-square analyses were used to examine the relation between the presence or absence of cerebral abnormalities and preoperative performance on the neuropsychological tests.

RESULTS

A total of 15 of 28 patients had extrahippocampal abnormalities on quantitative MRI analysis. Thirteen patients had global memory impairment. Bilateral memory deficits were significantly associated with both the presence of cerebral abnormalities (p < 0.02) and poor postoperative seizure control (p < 0.05).

CONCLUSIONS

Disproportion in the regional distribution of gray and white matter in patients with HS may form the structural basis of global memory disturbance in a distinct group of patients with temporal lobe epilepsy.

Presurgical evaluation of patients with epilepsy and normal MRI: role of scalp video-EEG telemetry

When considering surgery for intractable partial seizures, even with high resolution MRI, some patients do not show structural abnormalities. The aim was to consider whether these patients were likely to proceed to surgical treatment after scalp video-EEG telemetry. All patients undergoing presurgical evaluation at the National Hospital for Neurology and Neurosurgery between 1995 and 1997 were reviewed and 40 were identified without definite MRI abnormalities. None of 40 disclosed a well localised epileptogenic zone concordant with other tests that would have allowed the patient to proceed directly to surgery. In five of the 40, evaluation led to a hypothesis that could be tested by intracranial studies; three proceeded to surgery. It is suggested that high quality MRI is performed first when surgical evaluation is undertaken and if negative the patient carefully counselled before proceeding with any investigations, as successful resective surgery is an unlikely outcome in such MRI negative cases.

Identifying homologous anatomical landmarks on reconstructed magnetic resonance images of the human cerebral cortical surface

Guided by a review of the anatomical literature, 36 sulci on the human cerebral cortical surface were designated as homologous. These sulci were assessed for visibility on 3-dimensional images reconstructed from magnetic resonance imaging scans of the brains of 20 normal volunteers by 2 independent observers. Those sulci that were found to be reproducibly identifiable were used to define 24 landmarks around the cortical surface. The interobserver and intraobserver variabilities of measurement of the 24 landmarks were calculated. These reliably reproducible landmarks can be used for detailed morphometric analysis, and may prove helpful in the analysis of suspected cerebral cortical structured abnormalities in patients with such conditions as epilepsy.

Autosomal dominant nocturnal frontal-lobe epilepsy: genetic heterogeneity and evidence for a second locus at 15q24

Autosomal dominant nocturnal frontal-lobe epilepsy (ADNFLE) is a recently identified partial epilepsy in which two different mutations have been described in the alpha4 subunit of the neuronal nicotinic acetylcholine receptor (CHRNA4). An additional seven families are presented in which ADNFLE is unlinked to the CHRNA4 region on chromosome 20q13.2. Seven additional sporadic cases showed no evidence of defective CHRNA4. One of the families showed evidence of linkage to 15q24, close to the CHRNA3/CHRNA5/CHRNB4 cluster (maximum LOD score of 3.01 with D15S152). Recombination between ADNFLE and CHRNA4, linkage to 15q24 in one family, and exclusion from 15q24 and 20q13.2 in others demonstrate genetic heterogeneity with at least three different genes for ADNFLE. The CHRNA4 gene and the two known CHRNA4 mutations are responsible for only a minority of ADNFLE. Although the ADNFLE phenotype is clinically homogeneous, there appear to be a variety of molecular defects responsible for this disorder, which will provide a challenge to the understanding of the basic mechanism of epileptogenesis.

Identification of EEG events in the MR scanner: the problem of pulse artifact and a method for its subtraction

Triggering functional MRI (fMRI) image acquisition immediately after an EEG event can provide information on the location of the event generator. However, EEG artifact associated with pulsatile blood flow in a subject inside the scanner may obscure EEG events. This pulse artifact (PA) has been widely recognized as a significant problem, although its characteristics are unpredictable. We have investigated the amplitude, distribution on the scalp, and frequency of occurrence of this artifact. This showed large interindividual variations in amplitude, although PA is normally largest in the frontal region. In five of six subjects, PA was greater than 50 microV in at least one of the temporal, parasagittal, and central channels analyzed. Therefore, we developed and validated a method for removing PA. This subtracts an averaged PA waveform calculated for each electrode during the previous 10 s. Particular attention has been given to reliable ECG peak detection and ensuring that the average PA waveform is free of other EEG artifacts. Comparison of frequency spectra for EEG recorded outside and inside the scanner, with and without PA subtraction, showed a clear reduction in artifact after PA subtraction for all four frequency ranges analyzed. As further validation, lateralized epileptiform spikes were added to recordings from inside and outside the scanner: PA subtraction significantly increased the proportion of these spikes that were correctly identified and decreased the number of false spike detections. We conclude that in some subjects, EEG/fMRI studies will be feasible only using PA subtraction.

The detection and significance of subtle changes in mixed-signal brain lesions by serial MRI scan matching and spatial normalization

The purpose of this work is to detect and assess the significance of subtle signal changes in mixed-signal lesions based on serial MRI scan matching. Pairs of serially acquired T1-weighted volume MR images from 20 normal controls and seven patients with epilepsy were matched and difference images obtained. The precision and consistency of the registration were evaluated. The Gaussian noise level in the difference images was determined automatically. A structured difference filter was then used to segment structured (changed) voxels from the Gaussian noise. In the controls, the structured difference images were normalized into Talairach space, resulting in a structured noise map. The significance of changes in patients was assessed by spatial normalization and comparison with the structured noise map. The precision and consistency of the co-registration were < or = 0.06 mm with a registration success rate of 100%. The Gaussian noise level in the difference images was in the range 3.0-6.9. In the controls, an average of 1.6% of the brain voxels were classified as structured. Sine-based registration resulted in a reduction of < 1% in the amount of structure compared to linear interpolation. The structured noise map in controls showed high noise density in areas affected by image artefacts. We show examples of significant changes found in lesions which had been reported as unchanged on visual inspection. A novel quantitative approach has been presented for the detection and quantification of subtle signal changes in lesions. This method is of potential clinical value in the non-invasive characterization of signal change and biological behaviour of neoplastic lesions.

Cerebral activation in malformations of cortical development

Malformations of cortical development (MCD) are an important aetiology of localization-related epilepsy. Previous MRI and [11C]flumazenil PET studies have demonstrated widespread structural and neuroreceptor abnormalities beyond the region of MCD that is visually apparent on MRI. We investigated the ability of brain regions affected by MCD to participate in normal cognitive and motor tasks and compared the responses seen in such patients with those in normal subjects. We studied five patients known to have MCD affecting the occipital region and seven normal subjects using H2 (15)O PET whilst they were performing a visual attention task. We also studied five right-handed patients known to have MCD affecting the left frontal lobe and seven right-handed normal subjects, using H2 (15)O PET whilst they were performing a motor learning task with the right hand. The patient and normal control data were examined using statistical parametric mapping to determine the ability of the brain region affected by MCD to participate in the task and also to detect evidence for atypical organization of cortical function in association with the MCD. Eight of the ten patients with MCD showed significant alteration of relative regional cerebral blood flow during the task compared with 'rest' in the affected brain region. These regions included focally dysgenetic cortex, the cortex lining schizencephalic clefts, heterotopic bands, subependymal grey matter heterotopia, and the cortex overlying band and subependymal heterotopia. In addition there was a significant alteration in the overall activation pattern in five patients compared with the normal control groups; in all five patients this atypical organization involved regions of cortex that appeared entirely normal on MRI. We conclude that regions of MCD may participate in normal cognitive functions but widespread cortical atypical organization may be seen. These findings have implications for surgical planning in any such patients.

Effects of electrical stimulation on edema formation in different strains of rats

BACKGROUND AND PURPOSE

Although electrical stimulation (ES) is commonly used to curb edema formation, efficacy has been demonstrated in only one species of frog and one strain of rat. The purpose of this study was to determine whether different strains of rats respond differently to ES.

SUBJECTS AND METHODS

Feet of Sprague-Dawley, Zucker-Lean, and Brown Norway rats were injured in a uniform manner. One foot served as a control, and the other foot received four 30-minute exposures to cathodal high-voltage pulsed current at amplitudes 10% less than those required to induce visible muscle activity. Each treatment period was followed by a 30-minute rest period. Limb volumes were measured before and after trauma and after each treatment and rest period. Changes from pretrauma volumes were analyzed by repeated-measures analysis of variance.

RESULTS

Edema formation was curbed in Zucker-Lean and Brown Norway rats but not in Sprague-Dawley rats.

CONCLUSION AND DISCUSSION

The finding that two of the three strains of rats responded to ES suggests that some strains of rats may be suitable models for the study of edema. That frogs and rats respond to high-voltage pulsed current suggests that humans might respond similarly.

Musculoskeletal disorders in dentists

Occupational injuries involving musculoskeletal tissues are often related to repetitive movements of upper limbs and prolonged postures such as sitting and standing--activities common in dentistry. Surveys of the incidence of musculoskeletal disorders among dentists are few, but in Nebraska, 29 percent of more than 1,000 dentists reported symptoms of peripheral neuropathy in the upper limbs or neck. The Nebraskan dentists reported that crown and bridge work was most likely to evoke altered sensations in their upper limbs. Furthermore, since 47 percent of carpal tunnel syndrome cases in the general population are work-related and are often associated with repetitive motions, it is reasonable to suspect that dentists may be at risk for this musculoskeletal disorder. And, since it is estimated that 60 percent to 80 percent of adults will experience low back pain at one time or another, resulting in it being the second leading cause of absences from work in the general population, dental practitioners are most likely to be among those susceptible to this problem. This article focuses on two ailments afflicting dentists: carpal tunnel syndrome and low back pain.

Photosensitivity--better informing patients with epilepsy of their individual risk

Photosensitive epilepsy is relatively rare. However, a large proportion of individuals with epilepsy perceive that they are at an increased risk of a seizure whilst exposed to specific photic material. The difference between perceived and real risk may be due to inadequate education and misinformation. One half of the participants in the present survey could not recall being informed of the result of the 'gold standard' test for photosensitivity--intermittent photic stimulation during an electroencephalogram. Furthermore, approximately one-third of our sample were apparently given inaccurate and overcautious advice about their everyday exposure to photic material. Better information and advice is crucial to improve this situation in the future. The majority of people with epilepsy (>95%) who are not photosensitive can pursue activities that involve flickering or patterned light, encompassing educational, employment and leisure opportunities, without undue concern.

Circumstances of death in sudden death in epilepsy: interviews of bereaved relatives

OBJECTIVES

To study the circumstances of death in sudden death in epilepsy.

METHODS

Self referred bereaved relatives of patients with epilepsy who had died suddenly were interviewed with information obtained substantiated through other sources-namely, coroners' officers' reports, postmortem reports, previous medical records, and EEG reports.

RESULTS

Of 34 cases, 26 were classified as sudden unexpected deaths in epilepsy (SUDEP). Twenty four of 26 cases of SUDEP were unwitnessed. Evidence indicative or suggestive of a seizure was found in most. In 11 of 26 the position of the head was such that breathing could have been compromised. Cases included both localisation related and idiopathic primary generalised epilepsy. Only three were in remission at the time of death. Most relatives expressed the view that they would have preferred to have known that epilepsy could be fatal.

CONCLUSIONS

Although the deaths in question were largely unwitnessed, the available evidence suggested that most cases of SUDEP represented ictal or postictal seizure deaths, occurring in people with a history of generalised tonic clonic seizures, and in both primary generalised and localisation related epilepsy. These interviews highlight the needs of bereaved relatives and their sense of isolation in the face of an entirely unexpected and apparently unexplained loss.

A survey of epilepsy-patient perceptions of video-game material/electronic screens and other factors as seizure precipitants

The risk of seizures while playing video games in photosensitive (PS) individuals with epilepsy is well established. However, media reporting, game packaging and anecdotal advice of medical practitioners may have implicated a broader proportion of the epilepsy population, i.e. not just those with PS, to be at risk. By using a hospital outpatient survey this paper investigates the perceived risk of using video games and electronic screens among those individuals with epilepsy. More than a quarter of those surveyed indicated that they thought that a substantially greater proportion of people with epilepsy were at risk from this stimulus than the estimated real risk suggests. One in 13 perceived that every individual with epilepsy is at risk of a seizure as a result of playing video games. Our results also indicate that the proportion of individuals with epilepsy surveyed who saw themselves to be at risk from video games, is two to three times the estimated real risk. For many individuals seizures during video-game play will represent a chance occurrence without a causal link. It is essential that accurate information is passed on to every individual with epilepsy regarding their personal susceptibility to photic-induced seizures so that those who are not at increased risk may participate in relevant activities without undue concern.

Effect of high-voltage pulsed current and alternating current on macromolecular leakage in hamster cheek pouch microcirculation

BACKGROUND AND PURPOSE

Electrical stimulation (ES) is supposed to affect edema formation by inhibiting macromolecular leakage from microvessels. The purpose of the study was to determine the effects of various forms of ES on macromolecular leakage from microvessels.

SUBJECTS

Fifty-three hamsters were randomly assigned to one of seven groups: a control group (histamine only); groups that received histamine with cathodal high-voltage pulsed current (HVPC) at intensities of 90%, 50%, and 10% of visible motor threshold (VMT); groups that received anodal HVPC at intensities of 90% and 50% of VMT; and a group that received alternating current (AC) at 90% of VMT.

METHODS

Anesthetized animals were injected with fluorescein-labeled dextran. Macromolecular leakage was determined by computer analysis of fluorescence microscopy images for 5 minutes after treatment.

RESULTS

When compared with controls, leakage was less in groups treated with cathodal HVPC at 90% and 50% of VMT and anodal HVPC at 90% of VMT.

CONCLUSION AND DISCUSSION

Cathodal and anodal HVPC, but not AC, curb macromolecular leakage from the microvessels of histamine-treated hamsters. [Taylor K, Mendel FC, Fish DR, et al. Effect of high-voltage pulsed current and alternating current on macromolecular leakage in hamster cheek pouch microcirculation.

Recording of EEG during fMRI experiments: patient safety

The acquisition of electroencephalograms (EEG) during functional magnetic resonance imaging (fMRI) experiments raises important practical issues of patient safety. The presence of electrical wires connected to the patient in rapidly changing magnetic fields results in currents flowing through the patient due to induced electromotive forces (EMF), by three possible mechanisms: fixed loop in rapidly changing gradient fields; fixed loop in a RF electromagnetic field; moving loop in the static magnetic field. RF-induced EMFs were identified as the most important potential hazard. We calculated the minimum value of current-limiting resistance to be fitted in each EEG electrode lead for a representative worst case loop, and measured RF magnetic field intensity and heating in a specific type of current-limiting resistors. The results show that electrode resistance should be > or = 13 k(omega) for our setup. The methodology presented is general and can be useful for other centers.

Widespread cerebral structural changes in two patients with gelastic seizures and hypothalamic hamartomata

PURPOSE

We tested the hypothesis that widespread extralesional abnormalities of cerebral structure exist in association with apparently isolated hypothalamic hamartomata, providing a structural basis for the poor response of seizures to removal of the hamartoma or other apparently focal epileptogenic zones present.

METHODS

High-resolution magnetic resonance imaging (MRI) brain scans of 2 patients with hypothalamic hamartomata were quantified by determination of regional distribution and symmetry of distribution of cortical gray matter and subcortical matter volumes. The results were compared with normal ranges for the distribution of such tissues in 33 controls.

RESULTS

Both patients had abnormalities of distribution of gray and subcortical matter, whereas control subjects did not. These abnormalities were beyond the hamartoma itself, in areas of cerebrum that on visual inspection alone appeared completely normal.

CONCLUSIONS

Extralesional abnormalities of cerebral structure are present in the cerebrum of patients with hypothalamic hamartoma, as in most patients with other dysgeneses. These abnormalities may explain the poor outcome of epilepsy surgery in patients with this form of dysgenesis. These preliminary findings require further investigation.

Effects of cold water immersion on edema formation after blunt injury to the hind limbs of rats

OBJECTIVE

Despite the long history of using cryotherapy to control edema, we found no randomized, controlled studies providing evidence to substantiate this common clinical practice. The purpose of this study was to determine whether cold water immersion affects edema formation following blunt injuries in rats.

DESIGN AND SETTING

The feet of 16 rats were traumatized after hind limb volumes were determined. Four 30-minute treatments of cold water immersion (12.8 degrees C to 15.6 degrees C, 55 degrees F to 60 degrees F), interspersed with four 30-minute rest periods, began immediately after trauma to one randomly selected hind limb of each rat. The limb remained in a dependent position during all treatments, rest periods, and volumetric measurements.

SUBJECTS

Sixteen anesthetized Zucker Lean rats were used in the study.

MEASUREMENTS

Limb volumes were measured after each treatment and rest period for a total of 4 hours.

RESULTS

The volume of treated limbs was significantly smaller (p < .05) than the volume of untreated limbs after the first treatment and remained smaller throughout the experiment.

CONCLUSIONS

Immersing rat limbs in 12.8 degrees C to 15.6 degrees C (55 degrees F to60 degrees F) water immediately after blunt injury was effective in curbing edema formation.

Periventricular nodular heterotopia and intractable temporal lobe epilepsy: poor outcome after temporal lobe resection

We describe 5 women and 5 men with periventricular nodular heterotopia and electroclinical features suggestive of temporal lobe epilepsy, who were surgically treated for control of medically refractory seizures. Magnetic resonance imaging revealed bilateral periventricular nodular heterotopia in 7 of the 10 patients. Because of the lack of clear localization, 6 patients were studied with intracranial depth electrode recordings. Seizures were of hippocampal onset (3 patients), regional temporal lobe onset (2 patients), or occipital-temporal onset (1 patient). Anterior temporal lobectomy was performed in 6 patients; selective amygdalohippocampectomy, in 1; and anterior temporal lobectomy plus resection of the heterotopic tissue, in 3. None of the 9 patients followed for more than 12 months postoperatively were seizure free. Two patients were initially seizure free for approximately 18 months, but then seizures recurred. One patient had a major reduction in seizure frequency at a 39-month follow-up after most of the unilateral heterotopic tissue was included in the temporal resection. Temporal resection did not lead to a long-term favorable outcome in this group of patients with periventricular nodular heterotopia and epileptogenic discharges involving the temporal lobe. This suggests a more widespread disorder with epileptogenic activity possibly originating in or near the heterotopic tissue. The clinical and electrographic features of periventricular nodular heterotopia pointing to temporal lobe origin are misleading and temporal resection does not result in long-term cessation of seizures.

Correlation of widespread preoperative magnetic resonance imaging changes with unsuccessful surgery for hippocampal sclerosis

Despite meticulous preoperative assessment, about 30% of patients with refractory partial epilepsy due to hippocampal sclerosis fail to become seizure free after appropriate temporal lobe surgery. Perioperative complications, hippocampal remnants, and bitemporal disease do not account for all failures; extrahippocampal epileptogenic tissue must persist in some patients. Such dual pathology is detected on routine visual inspection of magnetic resonance images in about 15% of patients with hippocampal sclerosis, but most such patients are excluded from surgery. We postulated that some patients have occult extrahippocampal cerebral structural abnormalities (i.e., subtle dual pathology) and that the presence of these abnormalities would be associated with a poor surgical outcome. Quantitative postprocessing of preoperative magnetic resonance images from 27 patients subsequently proved to have hippocampal sclerosis demonstrated extrahippocampal structural abnormalities in 14, 10 of whom did not become seizure free, while 11 of 13 patients without such changes did become seizure free (chi2, p < 0.005). Such structural information may supplement clinical decision making in some patients being evaluated for epilepsy surgery and help to explain the biological basis of poor outcome from such surgery.

Somatosensory evoked potentials in adults with cortical dysgenesis and epilepsy

Cortical dysgenesis (CD) is a well-recognised cause of epilepsy, but its functional anatomy is not fully understood. We recorded cortical somatosensory evoked potentials (SEPs) in 13 adult patients with epilepsy and various CDs excluding diffuse gyral malformations as diagnosed by MRI. The CD involved the perirolandic/perisylvian region in 7 patients. Six patients had neurological signs but only 3 had sensory dysfunction (astereognosis). As compared with 12 control subjects, SEPs were considered definitely abnormal in 7 patients (including the 6 with neurological signs) and equivocally abnormal in 2. The abnormalities ranged from defects affecting single components to absence of all potentials of cortical origin in one patient with hemiparesis and astereognosis. In this case it appears that gross sensory function must have been mediated by subcortical structures or through diffuse cortical projections. The initial cortical potentials (N20/P20) were absent in 6 patients, 5 of whom had CD in zones involving or bordering on the primary sensory cortex. Parietal potentials following N20 were absent or attenuated in 4 patients and of abnormally wide distribution, spreading to frontal, midline and ipsilateral electrodes, in 3 frontal components following P20 were absent, attenuated, delayed or distorted by abnormal spread of the parietal activity in 5 patients. Five patients with unilateral CD showed definite or equivocal SEP abnormalities to stimulation of both arms, suggesting there may be more widespread disturbance of cortical organisation and/or synaptogenesis, beyond the resolution of present day neuroimaging.

Surgical treatment of patients with single and dual pathology: relevance of lesion and of hippocampal atrophy to seizure outcome

Modern neuroimaging can disclose epileptogenic lesions in many patients with partial epilepsy and, at times, display the coexistence of hippocampal atrophy in addition to an extrahippocampal lesion (dual pathology). We studied the postoperative seizure outcome of 64 patients with lesional epilepsy (median follow-up, 30 months) and considered separately the surgical results in the 51 patients with a single lesion and in the 13 who had dual pathology. In patients with a single lesion, 85% were seizure free or significantly improved (Engel's class I-II) when the lesion was totally removed compared with only 40% when there was incomplete resection (p < 0.007). All three patients with dual pathology who had both the lesion and the atrophic hippocampus removed became seizure free. In contrast, only 2 of the 10 patients with dual pathology undergoing surgery aimed at the lesion or at the hippocampus alone became seizure free (p < 0.05), although 4 of them showed significant improvement (Engel's class II). We conclude that the outcome in patients with single epileptogenic lesions is usually dependent upon the completeness of lesion resection. In patients with dual pathology, surgery should, if possible, include resection of both the lesion and the atrophic hippocampus.

Chronic encephalitis and epilepsy in adults and adolescents: a variant of Rasmussen's syndrome?

Chronic encephalitis and epilepsy (Rasmussen's encephalitis) is a rare progressive disorder of uncertain etiology that usually occurs in children, producing focal epilepsy, hemiparesis, and intellectual deterioration. We identified 13 patients in whom seizures developed in adolescence or adulthood with a pathologic picture of chronic encephalitis. The clinical characteristics were more variable than those occurring in children, with the patients falling into three groups: five patients developed seizures in adulthood, but otherwise showed many resemblances to the childhood form; five developed seizures in adolescence, with similar presentation but rather more benign course than in the younger patients; and three presented with clinical features initially suggestive of a tumor. Occipital onset to the seizures appeared to be more common than in the childhood form, and bilateral disease also occurred.