Hugh Staunton

Microdysgenesis in resected temporal neocortex Incidence and clinical significance in focal epilepsy

Fifty patients underwent superficial temporal lobectomy for intractable temporal lobe epilepsy. Total cure rate was 52%, and significant improvement was achieved in 88%. Cytoarchitectural changes in gray and white tissue were analyzed under light microscopy. Neuronal dysgenesis was correlated with the duration of seizure disorder, age of onset, and other etiologic factors, and with clinical outcome. Temporal lobes from 33 neurologically normal autopsy brains which were age- and sex-matched with patients were examined as controls. Severe neuronal ectopia (> 8 neurons/2 mm2 white matter) was present in 42% of patients with epilepsy and in none of controls. There was neuronal clustering in 28% of those with epilepsy, and Chaslins (subpial) gliosis in 38%. Controls did not have these changes. The presence of severe neuronal ectopia and clustering was predictive of a favorable clinical outcome following surgery (p < 0.05). No correlation was found between microdysgenesis and other factors. These findings suggest that the presence of neuronal dysgenesis may be of significance in the clinical outcome following surgery, and that the abnormal tissue may be important as a morphologic substrate for seizures in some patients.

Learning and retention of words and designs following excision from medial or lateral temporal-lobe structures

We sought to elucidate the contributions of the amygdala, hippocampus and temporal neocortex to learning and memory for verbal and visuospatial material. Two matched learning tasks, using abstract words versus abstract designs, were administered to patients with unilateral neocorticectomy (NCE; Dublin), selective amygdalohippocampectomy (AHE; Zurich) or anterior temporal-lobe resection invading the amygdala and hippocampus (ATL; Montreal). Data were analysed according to side and type of resection. Learning and recall for words was impaired in groups with resection from the left temporal lobe, irrespective of whether mediobasal structures were spared or temporal neocortex was spared. All right-resection groups were unimpaired. Learning for abstract designs was impaired across all trials in the right AHE and NCE groups, and on the last two trials in the right ATL group. Restricted deficits of lower magnitude were observed on some trials in left-resection groups. These results show a partial dissociation between side of excision and type of material, but the finding of similar deficits in all resection types was unexpected. We propose that excision from either the hippocampal region or temporal neocortex may result in a disconnection, giving a similar functional outcome, as both types of resection interrupt a circuit likely to be essential for normal storage and retrieval of information.

Topographical disorientation following unilateral temporal lobe lesions in humans.

Studies of the non-human temporal lobe, particularly the hippocampus, confirm its significant role in learning and memory, particularly allocentric spatial mapping of the environment. The role of the human temporal lobes in topographical orientation was investigated by examining the formation of representations of a large-scale real-world environment after unilateral left and right temporal lobe surgery. Patients and normal control subjects viewed videotape presentations of overlapping routes through a novel urban area. Topographical orientation was then assessed across a range of parameters. Right temporal lobe lesions alone gave rise to deficits in making proximity judgements. However, on all other topographical orientation tasks both right and left temporal lobe lesion groups were impaired relative to the normal control group, but the two patient groups did not differ significantly from each other. These findings suggest that such is the nature of remembering and way-finding in the environment that the integrity of both human temporal lobes is required.

Patients' Aims for Epilepsy Surgery: Desires Beyond Seizure Freedom

Summary:  Purpose: To evaluate prospectively patients aims for epilepsy surgery as previously outlined theoretically by Taylor et al. (Epilepsia 1997;3:625–30).

Temporal neocorticectomy in management of intractable epilepsy : long-term outcome and predictive factors

Summary: We report the results of a long‐term follow‐up study of 50 patients who underwent removal of temporal neocortex with preservation of deeper limbic structures as surgical therapy for intractable temporal lobe epilepsy. The follow‐up period ranged from 3 to 15 years. Preoperative EEG investigations were based on interictal discharges alone. Three factors were predictive of a good outcome: (a) A clear unilateral anterior‐midtemporal focus (p < 0.01), (b) stereotypical onset of temporal lobe seizure (p < 0.005), and (c) greater volume of tissue removed at operation (p < 0.05). Overall results showed that 62% of patients experienced an outcome of “cure” or “almost cure,” as classified according to a modified version of Crandalls criteria (Crandalls I and II). Those who experienced a significant reduction in seizures but who continued to have intractable epilepsy (Crandalls III) were not considered to have had a good result. Overall outcome compares favorably with other that of centers using different surgical approaches and indicates that neocorticectomy is a suitable procedure in a highly selected population even when limited resources are available.

Gender and the integration of acoustic dimensions of prosody: implications for clinical studies.

This study was conducted to detect the existence of a relationship between spectral and temporal prosodic cues and to examine gender differences in any such relationship. The rationale for the investigation was to gain a greater understanding of normal prosody and the requirements for control groups in clinical studies of prosody. Ten male and 10 female speakers with no known speech or neurological deficits participated in the study. They performed a reading task which involved delivering 10 sentences first with a declarative and then repeated with an interrogative intonation (20 sentences per speaker). Intrasubject and intersubject analyses of the speech data revealed a dependence of pitch on duration that differed between male and female speakers. Significant differences between the genders were also found in speech rate, pitch range, and pitch slope. The findings suggest that an integrated treatment of acoustic cues may provide a more invariant feature of normal prosody against which clinical groups may be compared. The data also imply that in clinical studies of the production of prosody gender should be carefully controlled.

Peripheral nerve amyloidosis

Peripheral nerve amyloidosis is the cardinal feature of familial amyloid polyneuropathy (FAP) but can also be seen in primary light chain (AL) amyloidosis and dialysis (β2‐microglobulin) related amyloidosis. The generalized neuropathy seen in all forms of peripheral nerve amyloidosis is similar, characterized by a severe progressive mixed neuropathy with autonomic dysfunction. Pathologically, amyloid is found in the peripheral nervous system as amorphous, eosinophilic, extracellular deposits. FAP is most commonly associated with variant plasma transthyretin (TTR), although it has also been described in association with mutant apolipoprotein A‐1 and gelsolin. There are now at least 36 point mutations in the TTR gene associated with FAP and these continue to be described. Recent studies on the possible role individual point mutations in the TTR gene may play in amyloidosis have helped give us an insight into the mechanisms behind peripheral nerve amyloidosis. This article reviews the clinical and pathological features of the peripheral nerve amyloidosis and discusses theories of amyloidogenesis based on studies of FAP.

The Irish epilepsy surgery experience: Long-term follow-up

AIM To assess the long-term seizure outcome of Irish patients who underwent resective surgery for refractory epilepsy since 1975. We also wished to determine the impact of pathology and surgical technique (with particular reference to neocorticectomy) on seizure outcome. METHODS A retrospective review of medical notes, radiological and histopathological records, was undertaken between 1975 and 2005. Missing data was supplemented by telephone calls to patients. One hundred and ninety-nine patients suited the criteria for inclusion and had at least 1-year follow-up (1-24 years, mean 7.0 years). Engels criteria were used to classify seizure outcome at 1, 2, 5, 10, 15 and >15 years follow-up. RESULTS The percentage of patients seizure free at 2, 5, 10, 15 and >15 years were, 56.6%, 41.4%, 44%, 25% and 31.3%, respectively. Of patients with a pathologically confirmed diagnosis of mesial temporal sclerosis, 55.6% were seizure free at 10 years. Equivalent figures for tumour were 62.5%, for cortical dysplasia, 34.8%, for those without any demonstrable pathologic abnormality, 50%, for dual pathology, 50% and for all others, 33.3%. Of those with 10 years or greater follow-up only 20% of neocorticectomy patients were in Engel class 1, compared with an average of 58.5% for the other surgical techniques. CONCLUSION Seizure freedom rates for Irish Patients were comparable to other large retrospective studies. Patients who underwent selective procedures tended to do better than those undergoing lobar resections, in keeping with international trends. The surgical technique unique to the Irish cohort, temporal necocorticectomy, had the worst long-term outcome.

An international survey of long-term video/EEG services.

To determine current practices in the provision of video-EEG services, the authors conducted an international survey by post. The aim of the survey was to evaluate, by reference to other centres, how and why certain things are done, be assured that their own center is providing a quality service, identify weaknesses in their service, and from this, set improvement goals and objectives. A purposive sampling method was used by sending questionnaires to 78 hospitals where it was believed a long-term video-EEG monitoring service existed. Completed survey questionnaires were returned from 42 centers. Although the survey mechanism may have resulted in self-selection bias, evaluation of the responses provides information on patient management, staffing levels, equipment, and equipment management. Ultimately, these data may aid in identifying a minimum set of requirements for the provision of a video-EEG telemetry service.

Interictal Spike Localisation with Methohexitone: Preoperative Activation and Surgical Follow-Up

Summary: Thirty‐four patients with intractable temporal lobe epilepsy underwent preoperative and perioperative EEG activation with methohexitone sodium. Subse‐ quently, all patients underwent anterior temporal lobec‐ tomy with deep structure preservation. Preoperative spike localisation with methohexitone was concordant with peroperative recording in most cases. Large doses of methohexitone were administered to two patients, rendering the EEG almost isoelectric. Areas of abnormal spiking activity were refractory to the effects of metho‐ hexitone, and recovery was marked by an increase in spike frequency. Postoperative clinical evaluation con‐ firmed the specificity of methohexitone for abnormally epileptogenic tissue.