Parahippocampal epilepsy with subtle dysplasia: A cause of “imaging negative” partial epilepsy

Purpose: Lesion‐negative refractory partial epilepsy is a major challenge in the assessment of patients for potential surgery. Finding a potential epileptogenic lesion simplifies assessment and is associated with good outcome. Here we describe imaging features of subtle parahippocampal dysplasia in five cases that were initially assessed as having imaging‐negative frontal or temporal lobe epilepsy. Methods: We analyzed the clinical and imaging features of five patients with seizures from the parahippocampal region. Results: Five patients had subtle but distinctive magnetic resonance imaging (MRI) abnormalities in the parahippocampal gyrus. This was a unilateral signal abnormality in the parahippocampal white matter extending into gray matter on heavily T₁‐ and T₂‐weighted images with relative preservation of the gray–white matter boundary on T₁‐weighted volume sequences. Only one of these patients had typical electroclinical unilateral temporal lobe epilepsy (TLE); one mimicked frontal lobe epilepsy, two showed bitemporal seizures, and one had unlocalized partial seizures. All have had surgery; four are seizure‐free (one has occasional auras only, follow‐up 6 months to 10 years), and one has a >50% seizure reduction. Histopathologic evaluation suggested dysplastic features in the surgical specimens in all. Discussion: In patients with lesion‐negative partial epilepsy with frontal or temporal semiology, or in cases with apparent bitemporal seizures, subtle parahippocampal abnormalities should be carefully excluded. Recognizing the MRI findings of an abnormal parahippocampal gyrus can lead to successful surgery without invasive monitoring, despite apparently incongruent electroclinical features.     

Clinical manifestations of insular lobe seizures: a stereo-electroencephalographic study

PURPOSE: In this study, we report the clinical features of insular lobe seizures based on data from video and stereo-electroencephalographic (SEEG) ictal recordings and direct electric insular stimulation of the insular cortex performed in patients referred for presurgical evaluation of temporal lobe epilepsy (TLE). METHODS: Since our first recordings of insular seizures, the insular cortex has been included as one of the targets of stereo-electroencephalographic (SEEG) electrode implantation in 50 consecutive patients with TLE whose seizures were suspected to originate from, or rapidly to propagate to, the perisylvian cortex. In six, a stereotyped sequence of ictal symptoms associated with intrainsular discharges could be identified. RESULTS: This ictal sequence occurred in full consciousness, beginning with a sensation of laryngeal constriction and paresthesiae, often unpleasant, affecting large cutaneous territories, most often at the onset of a complex partial seizure (five of the six patients). It was eventually followed by dysarthric speech and focal motor convulsive symptoms. The insular origin of these symptoms was supported by the data from functional cortical mapping of the insula by using direct cortical stimulations. CONCLUSIONS: This sequence of ictal symptoms looks reliable enough to characterize insular lobe epileptic seizures (ILESs). Observation of this clinical sequence at the onset of seizures on video-EEG recordings in TLE patients strongly suggests that the seizure-onset zone is located not in the temporal but in the insular lobe; recording directly from the insular cortex should occur before making any decision regarding epilepsy surgery.     

Interictal depression, anxiety, personality traits, and psychological dissociation in patients with temporal lobe epilepsy (TLE) and extra-TLE

PURPOSE: This study was performed to investigate the relation between symptoms of interictal depression, anxiety, personality traits, and psychological dissociation with the localization and lateralization of the epileptogenic zone in patients with partial epilepsy. METHODS: All patients were diagnosed according to the localization-related concept of the 1989 International League Against Epilepsy (ILAE) Classification of Epilepsies and Epileptic Syndromes, and the localization and lateralization of the epileptogenic zone was established by using the clinical criteria for noninvasive presurgical evaluation. This resulted in 67 patients with temporal lobe epilepsy (TLE) and 64 patients with extra-TLE. All patients were assessed on the various aspects of psychopathology by using a comprehensive battery of standardized diagnostic instruments. RESULTS: We did not find the hypothesized excess of psychiatric symptoms in patients with (mesial) TLE in comparison with patients with extra-TLE. We also found no differences between patients with the lateralization of epilepsy in the left versus the right hemisphere. CONCLUSIONS: TLE per se cannot be considered a risk factor in developing more or more severe symptoms of psychopathology in patients with partial epilepsy. Concomitant factors, such as the duration of epilepsy, seizure frequency, and frontal lobe dysfunction may play an additional role. Our findings support the hypothesis of a multifactorial explanation for the psychiatric symptoms in patients with epilepsy.     

Ictal spitting in left temporal lobe epilepsy: report of three cases.

PURPOSE: Ictal spitting is rarely reported in patients with epilepsy. More often it is observed in patients with temporal lobe epilepsy (TLE) and is presumed to be a lateralizing sign to language nondominant hemisphere. We report three patients with left TLE who had ictal spitting registered during prolonged video-EEG monitoring. METHODS: Medical charts of all patients with medically refractory partial epilepsy submitted to prolonged video-EEG monitoring in the Epilepsy Unit at UNIFESP during a 3-year period were reviewed, in search of reports of ictal spitting. The clinical, neurophysiological and neuroimaging data of the identified patients were reviewed. RESULTS: Among 136 patients evaluated with prolonged video-EEG monitoring, three (2.2%) presented spitting automatisms during complex partial seizures. All of them were right-handed, and had clear signs of left hippocampal sclerosis on MRI. In two patients, in all seizures in which ictal spitting was observed, EEG seizure onset was seen in the left temporal lobe. In the third patient, ictal onset with scalp electrodes was observed in the right temporal lobe, but semi-invasive monitoring with foramen ovale electrodes revealed ictal onset in the left temporal lobe, confirming false lateralization in surface records. The three patients became seizure-free following left anterior temporal lobectomy. CONCLUSIONS: Ictal spitting is a rare finding in patients with epilepsy, and may be considered a localizing sign of seizure onset in the temporal lobe. It may be observed in seizures originating from the left temporal lobe, and thus should not be considered a lateralizing sign of nondominant TLE.     

Hypersalivation in temporal lobe epilepsy

PURPOSE: We sought to determine whether hypersalivation helps lateralize seizure onset during complex partial seizures of temporal lobe origin. Several clinical signs, which help lateralize seizure onset, have been reported in temporal lobe epilepsy (TLE). Increased salivation only occasionally has been reported as a manifestation of partial epilepsy. METHODS: Of 590 consecutive patients admitted for video-EEG monitoring, either as a part of a presurgical evaluation of medically intractable epilepsy or for diagnosis and clarification of their paroxysmal symptoms, we identified 10 patients with ictal hypersalivation as a prominent manifestation of complex partial seizures. We reviewed the clinical features, scalp-sphenoidal video-EEG monitoring, intracarotid amytal (Wada) testing, hippocampal volumetric magnetic resonance imaging (MRI), and fluorodeoxyglucose-positron emission tomography (FDG-PET) scans of these patients. RESULTS: Of the 10 patients with ictal hypersalivation, seven patients had nondominant/right TLE, and three patients had dominant/left TLE. All patients had hippocampal atrophy on volumetric MRI. Eight of the 10 patients underwent standard temporal lobectomy with amygdalohippocampectomy (six right, two left). All of the operated-on patients had a seizure-free (Engel class I) outcome, and their increased salivation resolved. Two patients, who did not undergo surgical treatment, continue to have complex partial seizures with increased salivation. CONCLUSIONS: We conclude that increased salivation as a prominent ictal finding in complex partial seizures of temporal lobe origin is more likely to be of nondominant temporal lobe origin. Further studies with larger numbers of patients are needed to replicate this finding.     

Clinical study on temporal lobe epilepsy in childhood caused by temporal lobe space-occupying lesions

We studied the clinicoelectrical and neuroimaging features of 11 patients with symptomatic temporal lobe epilepsy (TLE) caused by temporal lobe space occupying lesions (SOLs), and compared its characteristics with those of 19 mesial TLE (MTLE) patients. Brain MRI demonstrated SOLs in the mesiotemporal lobe in 9, and laterotemporal lobe in the remaining 2 patients. Ten of the 11 patients successfully underwent surgery, which revealed tumors in 7 and focal cortical dysplasia in 3 patients. Comparisons of the clinical features between those with SOTLE and MTLE showed that both conditions shared the same clinical seizure manifestations such as gastric uprising sensation or ictal fear and a favorable response to surgery. However, the patients with SOTLE had fewer febrile convulsion, and more frequent seizure recurrences as well as TLE EEG discharges and associations of the monophasic clinical course than those with MTLE. In addition, the MRI findings were characterized by unilateral hippocampal atrophy in MTLE and expanding or SOLs in the SOTLE group. Children with complex partial seizures of suspected temporal lobe origin should undergo extensive neuroimaging evaluation.     

Seizure semiology and electroencephalography in young children with lesional temporal lobe epilepsy

PurposeThis study aimed to discuss the clinical features of seizure semiology and electroencephalography (EEG) in young children with lesional temporal lobe epilepsy (TLE).MethodChildren with lesional TLE received presurgical evaluation for intractable epilepsy. They were followed up for more than one year after temporal lobectomy. We reviewed the medical history and video-EEG monitoring of children with TLE to analyze the semiology of seizures and EEG findings and compared the semiology of seizures and EEG findings of childhood TLE and adult TLE.ResultsA total of 84 seizures were analyzed in 11 children (aged 23–108 months). The age of seizure onset was from 1 month to 26 months (a mean of 17.6 months). All of the patients exhibited prominent motor manifestations including epileptic spasm, tonic seizure, and unilateral clonic seizure. Seven children manifested behavioral arrest similar to an automotor seizure in adult TLE but with a shorter duration and higher frequency. The automatisms were typically orofacial, whereas manual automatisms were rarely observed. The EEG recordings revealed that diffuse discharge patterns were more common in younger children, whereas focal or unilateral patterns were more typical in older children. All of the patients were seizure-free after temporal lobectomy with more than one-year follow-up. All of the children had a mental development delay or regression; however, there was improvement after surgery, especially in those with surgery performed early.ConclusionIn contrast to TLE in adults, young children with lesional TLE probably represent a distinct nosological and probably less homogeneous syndrome. Although they had generalized clinical and electrographic features, resective epilepsy surgery should be considered as early as possible to obtain seizure control and improvement in mental development.     

Somatosensory auras in refractory temporal lobe epilepsy

PURPOSE: To determine the prevalence, manifestations, lateralizing value, and surgical prognostic value of somatosensory auras (SSAs) in patients with refractory temporal lobe epilepsy (TLE). METHODS: Eighty-one consecutive patients undergoing temporal lobectomy for refractory complex-partial seizures were screened for SSAs. The characteristics of the somatosensory phenomena, occurrence of other aura types, seizure semiology, findings of EEG and imaging studies, temporal lobe neuropathology, and postoperative seizure outcome were determined in each patient with SSAs. RESULTS: Nine (11%) of 81 patients with refractory temporal lobe seizures reported distinct SSAs as part of their habitual seizures. The most common manifestation of SSAs was tingling (eight of nine, 89%), but sensory loss (one of nine, 11%) and pain (one of nine, 11%) also were reported. Five patients had unilateral somatosensory symptoms, and four patients had bilateral somatosensory symptoms. Seizure origin was in the contralateral temporal lobe in four (80%) of five patients with unilateral SSAs, including all patients with unilateral SSAs affecting a limb. Partial temporal lobe resection produced complete seizure remission in all nine (100%) patients 1 year after surgery and in seven (78%) of nine patients 2 years after surgery. CONCLUSIONS: SSAs occur more frequently than previously appreciated in patients with refractory temporal lobe seizures and usually manifest as either unilateral or bilateral tingling. In patients with temporal lobe seizures, unilateral SSAs involving a limb suggest a seizure origin in the contralateral temporal lobe. The surgical outcome of TLE patients with SSAs is favorable. Thus the presence of SSAs should not serve as a deterrent to temporal lobe resection in patients with clearly defined TLE.     

Coexistence of temporal lobe and idiopathic generalized epilepsies.

OBJECTIVE: To assess the interrelation of idiopathic generalized epilepsy (IGE) and temporal lobe epilepsy (TLE) when they coexist in the same patient. METHODS: The authors reviewed the electroclinical features of 350 consecutive patients who had temporal resection between 1975 and 1997 at the Maudsley and King's College Hospitals, London. RESULTS: Two patients had the unusual combination of TLE and IGE (0.57%). In the first, the clinical onset of juvenile myoclonic epilepsy followed the surgical resolution of his partial seizures but had been heralded for at least 5 years by subclinical spontaneous and photically induced generalized spike-wave discharges. In the second, TLE and juvenile absence epilepsy had a long parallel course before surgery. After surgery he had no further partial seizures. CONCLUSION: These cases suggest that when an idiopathic absence or myoclonic syndrome manifests in a patient with symptomatic TLE, the phenotype may not be a merged syndrome. Rather, the two conditions can retain their inherent electroclinical profile, responsiveness to treatment, and prognosis.     

Pilomotor seizures: An autonomic semiology of limbic encephalitis?

PurposeIctal piloerection is an infrequent seizure semiology that is commonly overlooked as an ictal epileptic manifestation. Piloerection is considered to be principally caused by temporal lobe activity although frontal and hypothalamic seizure origins have been reported. The described etiology has shown a wide variety of structural causes such as mesial temporal sclerosis, tumors, posttraumatic, cavernomas and cryptogenic epilepsies.MethodsWe retrospectively reviewed the incidence of ictal piloerection in the clinical records of patients who underwent video-EEG monitoring (VEEGM) between 2007 and 2013 in a multicenter cooperative study. All patients presented refractory epilepsies and were evaluated with a protocol that included brain MRI, neuropsychology and VEEGM.ResultsA total of 766 patients were evaluated in four tertiary centers in Spain. Five patients showed piloerection as principal seizure semiology (prevalence 0.65%). The mean age at seizure onset was 39.6 years and the average epilepsy duration was 5.2 years (range 2–14) before diagnosis. Four patients were additionally examined with FDG-PET and/or SPECT-SISCOM. All presented temporal lobe epilepsy (TLE), three right-sided and two left-sided. A typical unilateral hippocampal sclerosis was described in 3 cases. The etiology detected in all cases was limbic encephalitis. Three had LGI1, one anti-Hu, and another Ma2 antibodies.ConclusionOur series describes a so far not well-recognized autoimmune association of pilomotor seizures to limbic encephalitis. This etiology should be ruled out through a comprehensive diagnostic work-up even in cases of long-lasting TLE with typical hippocampal atrophy on MRI.     

Clinical Usefulness of the Dipole Tracing Method for Localizing Interictal Spikes in Partial Epilepsy

Summary: Purpose: To clarify the clinical usefulness of the dipole tracing method in evaluation of interictal EEG spikes in patients with partial epilepsy.
Methods : Eight patients with partial epilepsy were studied. We compared the generator source of interictal spikes detected by the dipole tracing method with the results of magnetic resonance imaging (MRI), interictayictal measurement of cerebral blood flow (CBF) by single photon emission computed tomography (SPECT), interictal measurement of glucose metabolism by positron emission tomography (PET) and invasive electrocorticogram (ECoG).
Results : In 5 patients with mesial temporal lobe epilepsy (TLE), including 3 patients who underwent standard temporal lobectomy, the dipole tracing method showed results consistent with those of other examinations and better correlation with ECoG than with other noninvasive examinations. In a patient with mesial TLE who had defects in the skull due to previous surgery, the dipoles were located more laterally than expected. In a patient with frontal lobe epilepsy (FLE) who was finally proved to have an epileptogenic area in the lateral frontal area, the spike dipoles were identified in the medial side of the frontal lobe.
Conclusions : The dipole tracing method used in the present study is useful for localizing epileptogenic areas in patients with mesial TLE. However, in patients with partial skull defects and in those with FLE, the reliability of this method is still in accuracy of the lobe level.     

Hypermotor seizures in patients with temporal pole lesions

Hypermotor seizures are considered to be characteristic of frontal lobe epilepsy, with only rare occurrence in temporal lobe epilepsy. After noting hypermotor seizures in several patients with lesions involving the pole of the temporal lobe, we investigated whether temporal pole lesions were associated with hypermotor seizures. We systematically reviewed medical records, MRI images and pathological findings in consecutive patients who underwent epilepsy surgery over the preceding 10 years in our institution and identified eight patients with temporal pole lesions and intractable complex partial seizures. We analyzed all recorded seizures for semiology, classifying seizures as hypermotor or typical "psychomotor." Four patients exhibited hypermotor seizure semiology and four patients manifested typical psychomotor seizure characteristics. In patients with hypermotor seizures, scalp EEG tended to demonstrate lateral anterior temporal ictal onset, with lesser involvement of the sphenoidal electrode, while the patients with psychomotor seizures had initial inferomesial temporal rhythmic theta activity. Two patients with hypermotor seizures had implanted frontal and temporal subdural grids demonstrating orbitofrontal spread before hypermotor behavior. Patients underwent either anterior temporal lobectomy or lesionectomy. All improved considerably, with six patients seizure-free since surgery. We conclude that hypermotor seizures occur frequently in patients with temporal pole lesions. A search for temporal pole pathology is recommended for patients with hypermotor seizures and temporal epileptiform discharges. Modification of the surgical approach to include this region should be considered in patients who exhibit hypermotor seizures.     

Orbito-frontal epilepsy masquerading as temporal lobe epilepsy-a case report.

Temporal lobectomy fails to control seizures in a considerable percentage of patients who do not have hippocampal sclerosis. One theoretical reason for failure of surgery is that some of these patients may in fact have extratemporal epilepsy. We present a 28-year-old woman with clinical and scalp electroencephalogram (EEG) evidence of right temporal lobe epilepsy (TLE) supported by functional imaging with interictal positron emission tomography (PET) and ictal single-photon emission computerized tomography (SPECT). An invasive EEG monitoring was prompted by the discovery of a small right orbito-frontal lesion on MRI. Monitoring documented seizure onset at the lesion, with rapid right temporal involvement. The patient was almost seizure-free after a lesionectomy. The index of suspicion of orbito-frontal epilepsy should be high in patients with apparent TLE when the scalp EEG and neuroimaging data are not congruent, or if temporal lobe pathology cannot be identified on structural imaging.     

儿童难治性颞叶癫痫的手术治疗

目的 探讨儿童难治性颞叶癫痫术前评估和手术方法 及影响癫痫预后的因素.方法 回顾性分析2007年7月至2009年2月手术治疗的21例儿童难治性癫痫患者中得到随访的19例临床资料,主要为复杂部分性发作.多数患者有腹部不适等发作先兆和咂嘴等发作时伴随自动动作.MRI扫描15例异常.6例行PET扫描均异常.头皮脑电图示局灶痫性放电7例,多灶痫性放电12例.施行一侧颞前叶+海马、杏仁核切除术15例,一侧颞前叶、海马、杏仁核+部分额叶皮层切除术4例.结果 随访12-30个月,癫痫发作结果 ,Engel Ⅰ级13例;Ⅱ级3例;Ⅲ级1例;Ⅳ级2例.随访期间对4例进行神经心理学评估,2例明显好于术前.无永久性神经缺损并发症.术后切除标本病理诊断结果 为颞叶皮层发育不良和颞叶内侧硬化等.结论 颞叶切除治疗儿童难治性癫痫多数预后良好.该手术安全、并发症少.发作表现、EEG以及神经影像学检查对致痫灶定位相互符合时,预示预后良好.早期手术可能对患儿的神经心理学改善有帮助.     

Localizing significance of temporal intermittent rhythmic delta activity (TIRDA) in drug-resistant focal epilepsy.

OBJECTIVE: Temporal intermittent rhythmic delta activity (TIRDA) is an EEG pattern characterized by sinusoidal trains of activity, ranging from 1 to 3.5 Hz, and well localized over the temporal regions. It is considered to be an indicator of temporal lobe epilepsy (TLE), but full agreement between different authors has still not been reached. The aim of this study was therefore to assess the role of TIRDA in localizing the epileptogenic zone, which was estimated using anatomo-electro-clinical correlations obtained from non-invasive pre-surgical investigations, in a large group of patients affected by drug-resistant partial epilepsy. METHODS: The occurrence of TIRDA was investigated using a prolonged Video-EEG recording of 129 patients affected by drug-resistant partial epilepsy that underwent a non-invasive pre-surgical protocol. Patients were divided into 3 groups: TLE only, extratemporal epilepsy, and multilobar epilepsy including temporal lobe. According to the epileptogenic zone identified using anatomo-clinical-radiological correlations, 3 different subgroups of TLE were identified: mesial, lateral, and mesio-lateral. Statistical analysis was performed in order to evaluate the relationship between TIRDA and the epileptogenic zone, and neuroradiological, neuropathological, EEG interictal and ictal findings. RESULTS: The pattern of TIRDA was observed in 52 out of the 129 (40.3%) patients studied. Significant correlations were found between TIRDA and: (i) mesial and mesio-lateral TLE; (ii) mesial temporal sclerosis; (iii) interictal epileptiform discharge localized over the anterior temporal regions; and (iv) 5-9 Hz temporal ictal discharge. CONCLUSIONS: Our research shows that TIRDA plays a role in localizing the epileptogenic zone, suggesting that this pattern might be considered as an EEG marker of an epileptogenesis that involves the mesial structures of the temporal lobe. However, further studies investigating the relationship between intracranial EEG monitoring and simultaneous scalp EEG recording are needed in order to confirm our findings and improve our understanding of the significance of TIRDA.     

Postsurgical outcome in patients with auditory auras and drug-resistant epilepsy

PurposeWe assessed whether patients with auditory auras have similar outcomes after epilepsy surgery as patients without auditory auras, and hypothesized that patients with non-dominant hemisphere foci might fare better after temporal lobe surgery than patients with dominant resections.MethodsIn this retrospective study, outcome after temporal resection was assessed for patients with drug-resistant epilepsy. Preoperative demographic data, clinical data, and surgical outcome were prospectively registered in a database from 1986 through 2016. Seizure outcome was classified as either seizure-free or relapsed.ResultsData were available in 1186 patients. Forty five patients (3.8%) reported auditory auras; 42 patients (93%) had temporal lobe epilepsy (TLE), and three patients (7%) had extratemporal epilepsy. Since most patients with auditory auras had TLE and in order to have comparable groups, we selected 41 patients with auditory auras and compared them with patients without auditory auras who had temporal lobe resections (767 patients). There were no significant demographic or clinical differences between TLE patients with auditory auras and those without. Patients who had auditory auras were more likely to relapse after temporal lobe surgery than those without (p = 0.03). Among patients who had auditory auras and temporal lobe surgery, side of surgery was not related to postoperative outcome (p = 0.3).ConclusionAuditory auras are rare among patients with drug-resistant TLE. The presence of an auditory aura in a patient with drug-resistant TLE carries a worse prognosis for a postoperative seizure free outcome and this is not related to the side of surgery.     

Peri-ictal water drinking and other ictal vegetative symptoms: Localizing and lateralizing the epileptogenic zone in temporal lobe epilepsy? Two case reports and review of the literature

Peri-ictal behavior disorders can be helpful in localizing and lateralizing seizure onset in partial epilepsies, especially those originating in the temporal lobe. In this paper, we present the case of two right-handed women aged 36 and 42 years who presented with partial seizures of mesial temporal type. Both of the patients had drug resistant epilepsy and undergone presurgical evaluation tests including brain magnetic resonance imaging, video-EEG monitoring and neuropsychological testing. The two patients had hippocampal sclerosis in the right temporal lobe and exhibited PIWD behavior concomitant with right temporal lobe discharges documented during video-EEG recordings. Anterior temporal lobectomy was performed in one case with an excellent outcome after surgery. The patient was free of seizures at 3 years follow-up. We reviewed other publications of peri-ictal autonomic symptoms considered to have a lateralizing significance, such as peri-ictal vomiting, urinary urge, ictal pilo-erection. Clinicians should search for these symptoms, even if not spontaneously reported by the patient, because they are often under-estimated, both by the patients themselves and by physicians. Additionally, patients with lateralizing auras during seizures have a significantly better outcome after epilepsy surgery than those without lateralizing features.     

Preoperative evaluation for temporal lobe surgery.

Temporal lobe epilepsy (TLE), the most common form of partial epilepsy in adults is often refractory to medical treatment and in these patients epilepsy surgery is considered. Successful surgery is dependent on accurate localisation and lateralisation of the epileptogenic zone. The preoperative evaluation involves a series of assessments and investigations including detailed clinical history, interictal EEG, video-EEG monitoring, MRI, PET, SPECT, and neuropsychology and neuropsychiatric assessment. The role of each of these investigations and assessments in the preoperative evaluation is discussed. Advanced MR techniques including magnetic resonance spectroscopy, MR diffusion and MR perfusion have recently been assessed and are likely to enhance the pre-surgical evaluation of patients with TLE.The surgical outcome and preoperative investigations performed of 80 consecutive patients who underwent temporal lobe surgery between 1993 and 2002 at Royal Melbourne Hospital were reviewed. All patients had MRI, video-EEG monitoring and neuropsychology assessment and 56% a PET scan. During a mean follow-up of 5.9 years 75% had Class 1 outcome, 22% non-Class 1 outcome and 3% were lost to follow-up. The results of preoperative investigations were correlated with outcome. For interictal EEG, seizure semiology, ictal EEG, PET and neuropsychology assessment the surgical outcome of patients in whom results were concordant to side of surgery was compared with those discordant or non-lateralising. There was no significant difference. In 78 of 80 patients MRI revealed mesial temporal sclerosis or a foreign tissue lesion. The outcome was no different between these two groups. Results suggest that in patients with unilateral temporal lobe lesion on MRI and where ictal EEG is either concordant or non-lateralising, other investigations including PET, provide little additional prognostic information.