The syndrome of chronic encephalitis with epilepsy (Rasmussen's syndrome) typically occurs in children and is characterized by the development of intractable focal seizures, progressive hemiparesis and intellectual deterioration. The etiology is unknown, and the pathological abnormalities vary from those of active disease, with numerous microglial nodules, with or without neuronophagia, perivascular round cells and glial scarring, to those of remote disease, demonstrated by neuronal loss, gliosis and perivascular round cells but few microglial nodules. We describe five patients presenting with clinical features typical of Rasmussen's syndrome, in whom pathological examination showed a second, previously unsuspected pathology in addition to the changes of chronic encephalitis. Two of the patients had vascular abnormalities bearing some resemblance to cavernous angiomata, one had a tumor, one had tuberous sclerosis, and one the forme fruste of tuberous sclerosis. The coexistence of a second pathology in these patients may provide information about the underlying mechanism of this rare condition.

Background: Seizures in patients with tuberous sclerosis complex (TSC) are often intractable to antiepileptic medications and searching investigation may provide evidence that surgical treatment can be considered. Objective: To review the results of investigation and surgical therapy, a treatment modality not generally considered in patients with medically refractory seizures and TSC. Methods: We report 18 patients (9 male) with TSC who underwent surgical treatment of medically refractory epilepsy. Twelve patients had a well-localized epileptogenic lesion and were treated by lesionectomy or focal resection. Resections were: 7 frontal, 4 temporal, 1 frontotemporal, 1 occipital, and I frontoparietal. Four patients underwent more than one operation. Six patients had corpus callosotomy (CC). Results: Follow-up ranged from 1 month to 47 years. Outcome of the patients treated by resection was excellent in 7 (5 were seizure-free and 2 had auras only), good in 1, fair in 3, and 1 was lost to follow-up. Best outcome was obtained in patients who had focal seizures and good imaging and EEG correlation, although they might have multiple seizure types, other imaging abnormalities, and multifocal or generalized EEG findings. When there was no such correlation, CC was found to be an option as five patients had at least some improvement and only one showed no change. Conclusion: Surgical treatment of patients with TSC and intractable epilepsy is most effective when a single tuber or epileptogenic area can be identified as the source of seizures and resected. This may be possible even when other tubers or diffuse EEG abnormalities are present. In patients with unlocalizable epileptic abnormalities, palliation may be obtained by CC.

The prognostic significance of epileptiform activity (EA) recorded at electrocorticography (ECOG) was examined in a group of 60 consecutive non-tumoral patients with intractable frontal lobe epilepsy (FLE). Pre-excision EA was documented as absent, focal (one gyrus), regional (two gyri), lobar (3 gyri) or multilobar (frontal+temporal gyri). Post-excision EA was documented as absent, restricted to the resection border, or recorded distant to the resection border, and was quantitated by spike frequency. Pre-excision EA from ≤2 gyri and absence of post-resection EA correlated with Class I or II (Engel classification) outcome while pre-excision EA from ≥3 gyri and persistent post-resection EA, especially distant to the resection border, correlated with Class III or IV outcome (P<0.001). A significant correlation between poorer outcomes and increased abundance of distant post-resection EA was observed (P<0.001). EA restricted to the resection border was not significantly correlated with outcome. Presence of a circumscribed lesion correlated with Class I outcome (P<0.01) and absence of pathological abnormality correlated with Class IV outcome (P<0.05). Neither side nor extent of surgical excision correlated with outcome. EA recorded at ECOG is of prognostic significance in FLE. A lobar or multilobar distribution of pre-excision EA and persistent post-excision EA distant to the resection border, especially when abundant, are highly unfavorable prognostic indicators. In contrast, a restricted distribution of pre-excision EA and absence of post-resection EA both herald a favorable outcome.

Seizures in patients with tuberous sclerosis complex (TSC) are often intractable to antiepileptic medications and searching investigation may provide evidence that surgical treatment can be considered.To review the results of investigation and surgical therapy, a treatment modality not generally considered in patients with medically refractory seizures and TSC.We report 18 patients (9 male) with TSC who underwent surgical treatment of medically refractory epilepsy. Twelve patients had a well-localized epileptogenic lesion and were treated by lesionectomy or focal resection. Resections were: 7 frontal, 4 temporal, 1 frontotemporal, 1 occipital, and 1 frontoparietal. Four patients underwent more than one operation. Six patients had corpus callosotomy (CC).Follow-up ranged from 1 month to 47 years. Outcome of the patients treated by resection was excellent in 7 (5 were seizure-free and 2 had auras only), good in 1, fair in 3, and 1 was lost to follow-up. Best outcome was obtained in patients who had focal seizures and good imaging and EEG correlation, although they might have multiple seizure types, other imaging abnormalities, and multifocal or generalized EEG findings. When there was no such correlation, CC was found to be an option as five patients had at least some improvement and only one showed no change.Surgical treatment of patients with TSC and intractable epilepsy is most effective when a single tuber or epileptogenic area can be identified as the source of seizures and resected. This may be possible even when other tubers or diffuse EEG abnormalities are present. In patients with unlocalizable epileptic abnormalities, palliation may be obtained by CC.

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.

We compared 100 patients with temporal lobe epilepsy, who exhibited the running down phenomenon following temporal resections, with two groups of patients: 100 patients who became seizure-free, and 100 patients who continued to have frequent seizures following temporal resection. We found a significant correlation between prognosis and the size of the epileptogenic area as defined; patients with smaller epileptogenic areas had the best prognosis (seizure-free group). Patients exhibiting the running down phenomenon had intermediate size epileptogenic areas, while those patients who continued to have seizures had the largest epileptogenic areas often involving the lateral temporal and posterior temporal cortex. Other factors predictive of good outcome were: a history of febrile seizures, predominantly unilateral interictal spiking, anterior temporal localization, extent of resection of the mesial temporal structures, surgery under the age of 30 years, and the absence of habitual seizures in the immediate postoperative period. Patients with history of head trauma, encephalitis, posterior temporal localization and bitemporal spiking had a worse outcome. The frequency and types of aurae, and laterality of resection did not correlate with outcome.

Between 1934 and 1988, 34 patients with tumoural parietal lobe epilepsy were treated surgically at the Montreal Neurological Institute (MNI). Fifteen had right-sided and 16 left-sided resections. The remaining three patients had biopsies only. Follow-up ranging from 1 to 40 years (mean 12.3 years) was available for 28 patients. Seventy-five percent (21 out of 28) became seizure free or had rare seizures. Permanent post-operative sensory deficits were described in 12% of patients. An aura was described by 79%. 62% had somatosensory symptoms, contralateral to the epileptogenic region in all but one. Visual illusions (12%), aphasia (9%) and disturbances of body image (6%), were much less common at the beginning of the attacks. Intra-operative cortical stimulation reproduced the habitual aurae in 10 out of 25 (40%) of the patients. The clinical manifestations suggested different spread patterns: 21% had tonic posturing of the extremities, 82% focal clonic activity, 15% head deviation, 9% automatisms and 6% difficulty speaking. Eleven (32%) had Todd's paralysis and 18% postictal dysphasia. Almost half the patients had impaired two-point discrimination in contralateral fingers; two of these also had impaired stereognosis, but only one had astereognosis without coexisting primary cortical sensory deficit. Review of this, now historical, series shows that parietal lobe tumours can be resected with good control of previously intractable seizures. Such an approach is preferable to postponing resection until the lesion is shown to increase in volume.

We report the clinical manifestations and outcome of 82 patients with nontumoural parietal lobe epilepsy treated surgically at the Montreal Neurological Institute between 1929 and 1988. Patients with extensive resections extending outside the parietal lobe were excluded. Ninety-four percent exhibited aurae: the most common were somatosensory, described by 52 patients; 13 of these also described pain. Other aurae included disturbances of body image, visual illusions, vertiginous sensations and aphasia or dysphasia. A few patients exhibited complex visual or auditory hallucinations and elementary visual hallucinations. Intraoperative cortical stimulation reproduced the habitual aurae in 44 patients. Often the clinical manifestations indicated ictal spread to the frontal, supplementary motor area, or temporo-limbic areas: 28% of patients exhibited tonic posturing of the extremities, 57% unilateral clonic activity, 17% oral or gestural automatisms and 4% complex automatisms. Sixty-one percent of patients with tonic posturing had epileptogenic zones which included the superior parietal lobe, and in 79% of patients with automatisms the epileptogenic zones extended to the inferior parietal lobe, suggesting different spread patterns. Forty-three patients underwent right, and 39 left parietal corticectomies. Postoperative sensory deficits were seen only when the corticectomy extended into the post-central gyrus. Early in the series extensive nondominant inferior parietal resections led to disturbances of body image in a few patients. Follow-up ranging from 2 to 50 years was available for 79 patients. Sixty-five percent had a complete or nearly complete cessation of seizures. Those patients with no post-resection electrocorticographic epileptiform discharges had a more favourable outcome.

Between 1929 and 1980, 284 patients with refractory nontumoral frontal lobe epilepsy (FLE) underwent operation at the Montreal Neurological Institute (MNI). We studied 39 patients (14%) who required reoperation. Mean age at the time of first operation was 18 years and at reoperation was 22 years. Clinical manifestations were similar to those of patients with "a pure culture of frontal lobe epilepsy" as reported by Rasmussen in 1983. At the time of first operation, large epileptogenic zones were noted in most patients. Resection was confined to the frontal lobe. Continuing seizure activity was due to residual areas of epileptogenesis, and reoperation with more extensive resection of cortex increased the number of seizure-free patients. Twenty-six patients underwent further frontal resection, and in 13 surgical removal was extended to the temporal lobe. Residual electrocorticographic (ECoG) spiking was documented in 15 of 23 (65%) of the reoperated patients. Thirty-five patients were followed for periods ranging from 4 to 46 years. One fifth became seizure-free, and 31% had significant seizure reduction. Thus, half of these patients had a good result. Patients with residual postexcision ECoG spiking had poor outcomes and evidence of large epileptogenic zones. None of the patients who underwent frontotemporal resections became seizure-free. Reoperation should be considered if initial resection does not lead to a satisfactory result and may convert an initial failure into a good surgical result.

Poor localization of the interictal epileptic abnormality and the rather unreliable EEG localization of ictal onsets in patients with frontal lobe epilepsy may be due to some of the following factors: (1) high risk of EEG sampling error, (2) early seizure spread within and outside the frontal lobe, (3) widespread distribution of the epileptogenic brain tissue responsible for the patient's habitual seizures, and (4) secondary bilateral synchrony and secondary epileptogenesis. The relevance of these factors in the preoperative investigation of patients with frontal lobe epilepsy was studied in: (a) 34 adult patients (mean age: 25 years) who became and persisted seizure free after restrictive surgical removal of the anterofrontal region, the parasagittal region convexity or the fronto-opercular area; (b) 12 patients in whom the pre-operative EEG investigation with extracranial electrodes failed to localize the site of seizure onset, leading to further investigation with depth electrodes.

Our study documents the clinical and electrographic findings in 42 patients with medically refractory occipital lobe epilepsy, who underwent surgery at the Montreal Neurological Institute between 1930 and 1991, and the evolving manner in which those patients were studied by successive generations of investigators. In more than two-thirds of the patients the clinical manifestations indicated the occipital onset of the seizures. Seventy-three percent experienced visual aurae, of which elementary hallucinations were the most common and 12 also had ictal blindness. Other occipital manifestations included: contralateral eye deviation, blinking, a sensation of eye movement and nystagmoid eye movements. Intra-operative cortical stimulation elicited a habitual aura in 37% of 29 patients. Lateralizing clinical features were seen in almost two-thirds of patients: contralateral head deviation occurred in half, 59% had visual field defects contralateral to the epileptogenic area and 64% had abnormal imaging studies ipsilateral to the side of surgery. More than one-third of patients exhibited more than one seizure type, suggesting ictal spread to temporal or frontal lobe: 50% had typical temporal lobe automatisms, and 38% exhibited focal motor seizure activity. Surface electroencephalogram (EEG) recordings showed posterior temporal-occipital epileptiform discharges in 46% of patients. Only 18% had electronegative spiking limited to 01 or 02. Large epileptogenic areas were often found on intracranial recording with depth electrodes and on electrocorticography. Pre-excision electrocorticography spiking was restricted to the occipital lobe in only 13 out of 34 patients. More often spiking also involved the posterior temporal and posterior parietal regions. Twenty-three patients underwent only occipital resections; five had only temporal resections, so as to preserve the visual fields, and the remaining 14 patients had extensive resections, which included the posterior temporal or posterior parietal regions. A follow-up period of 1 to 46 yrs (mean 17 yrs) was available for 37 patients. Forty-six percent became seizure free and 21% had a significant reduction in seizure frequency. A better outcome was observed in those patients in whom there was no post-resection electrocorticographic or surface EEG epileptiform discharge, or who exhibited an occipital lobe lesion.

The ictal clinical manifestations of 40 patients with frontal lobe epilepsy who became and remained seizure free after selective removal of the parasagittal or anterolaterodorsal convexities were studied. Seizures arising from the parasagittal region were characterized by a high incidence of somatosensory auras (60%) and by tonic and/or clonic motor behavior (100%) and never exhibited automatisms. Conversely, the anterolaterodorsal convexity group never showed somatosensory auras but often had warnings more typical of temporal lobe seizures, only displayed partial motor seizure activity in half the cases, and included a relatively high incidence of automatisms (30%). These clinical differences may be useful in the localization of frontal lobe epileptogenic foci. The manifestations of anterolaterodorsal convexity seizures may reflect frequent spread to the temporal lobe, whereas parasagittal convexity seizures often show initial ictal behavior, in keeping with seizure activity in that region. Early ictal unilateral head turning without other motor manifestations was seen in 3 of 10 patients in the parasagittal convexity group and in 9 of 30 patients in the anterolaterodorsal convexity group. In 11 of these 12 cases, the head turning was contralateral to the surgical removal.

.Surgical treatment for frontal lobe epilepsy provides both a challenge in localization and an opportunity to better understand the pathophysiology of this condition. EEG localization is difficult because anatomic and pathophysiologic characteristics of the frontal lobe result in widespread and generalized epileptiform activity at the scalp, generated from more focal epileptogenic zones. Preoperative EEG investigation of 34 adults and 45 children, who had surgical removal of frontal lobe epileptogenic zones, reveals a continuum of interictal disturbances, ranging from focal abnormalities to lobar and multilobar epileptogene sis. The degree and direction of spread of epileptogenic activity varies widely with the location of the source and with the age of the patient. Correlation of EEG data with ancillary diagnostic procedures is crucial for proper interpretation.