Ictal SPECT in Nonlesional Extratemporal Epilepsy

Summary:  Purpose: Ictal single-photon emission computed tomography (SPECT) may be a reliable indicator of the ictal onset zone in patients with intractable partial epilepsy who are being considered for epilepsy surgery. The rationale for the illustrated case report is to evaluate the use of an innovation in SPECT imaging in a patient with nonlesional extratemporal epilepsy.
Methods: We investigated the presurgical evaluation and operative outcome in a patient with intractable partial epilepsy. The ictal semiology indicated a "hypermotor" seizure with bipedal automatism. The electroclinical correlation and magnetic resonance imaging (MRI) did not suggest the appropriate localization of the epileptogenic zone. A subtraction periictal SPECT coregistered to MRI (SISCOM) was peformed.
Results: SISCOM revealed a region of localized hyperperfusion in the right supplementary sensorimotor area. Chronic intracranial EEG monitoring confirmed the relationship between the localized SISCOM alteration and the ictal onset zone. The patient was rendered seizure free after surgical treatment.
Conclusions: SISCOM may be used to identify potential candidates for surgical treatment of nonlesional extratemporal epilepsy. Periictal imaging may also alter the strategy for intracranial EEG recordings and focal cortical resection.     

Parietal Lobe Lesional Epilepsy: Electroclinical Correlation and Operative Outcome

Summary: We retrospectively studied ictal behavior, extracranial EEG, and operative outcome in 10 consecutive patients with intractable partial epilepsy of presumed parietal lobe origin who received a lesionectomy, i.e., resection of the neuroimaging-identified abnormality, at the Mayo Clinic. Nine patients had a pathologically verified foreign-tissue lesion, e.g., tumor or vascular malformation, and 1 patient had gliosis. All patients with foreign-tissue lesions were rendered seizure-free. The patient with gliosis experienced a reduction in seizure tendency. There were no operative complications. The most common seizure type was a simple partial seizure with visual, motor, or sensory symptoms (n = 8). Complex partial seizures (n = 5) and secondarily generalized tonic-clonic seizures (GTC, n = 2) were also observed. The ictal behavior was often nonspecific although useful in identifying lateralization of the epileptogenic zone. Extracranial interictal and ictal EEG changes were unreliable markers of the parietal lobe origin of seizure activity. Lesionectomy without chronic intracranial monitoring or functional mapping may be an effective and safe alternative surgical procedure in patients with partial epilepsy related to parietal lobe lesions.     

Interictal, unifocal spikes in refractory extratemporal epilepsy predict ictal origin and postsurgical outcome.

OBJECTIVES: To evaluate the significance of exclusively unifocal, unilateral, interictal epileptiform patterns on scalp electroencephalography (EEG) in surgical candidates with medically intractable extratemporal epilepsy. METHODS: We reviewed 126 patients with refractory extratemporal partial seizures who underwent epilepsy surgery at our center. All were followed for at least 2 years after resections. Surgery was based on ictal EEG recordings. We examined ictal onsets and surgical outcome in subjects whose preoperative, interictal scalp EEGs during long-term monitoring (LTM) demonstrated only unilateral, well-defined focal discharges, and outcome in patients whose interictal EEGs during LTM showed bilateral, non-localized, or multifocal epileptiform patterns. RESULTS: We found that 26 subjects exhibited only unilateral, unifocal, interictal epileptiform patterns. In all 26 cases (100%) clinical seizures arose from the regions expected by the interictal findings (P<0.0001, Sign test). At last follow-up 77% (20/26) of these patients were seizure-free, while 23% (6/26) had >75% reduction in seizures. This compares to the remaining patients, of whom 34% (34/100) were seizure-free, 41% (41/100) had >75% reduction in seizures, and 25% (25/100) had <75% reduction in seizures (P=0.0001, Fisher's Exact test). CONCLUSIONS: Strictly unifocal, interictal epileptiform patterns on scalp EEG, though seen in a minority of subjects, may be an important, independent factor in evaluating subjects with intractable extratemporal, localization-related epilepsy for surgical therapy. This finding is highly predictive of both ictal onsets and successful postsurgical outcome.     

Surgical outcome and predictive factors in adult patients with intractable epilepsy and focal cortical dysplasia

OBJECTIVES: To determine the surgical outcome and prognostic factors in adult patients with intractable epilepsy and focal cortical dysplasia (FCD). MATERIALS AND METHODS: We retrospectively studied the operative outcome in 21 consecutive adult patients with FCD who underwent surgical treatment for intractable partial epilepsy. RESULTS: The mean age at surgery was 32.7 years (range, 18-58 years). The median post-operative follow-up was 2.5 years. The FCD was extratemporal in 11 patients, involved the temporal lobe in 10 patients, and was multilobar in eight patients. Eleven patients (52%) were rendered seizure-free, four patients (19%) had >95% reduction in seizures, and two patients (10%) had an 80-94% reduction in seizures. A seizure-free outcome was associated with shorter duration of epilepsy (P = 0.02). CONCLUSION: Adult patients with FCD may be candidates for surgical treatment of intractable partial epilepsy. Most individuals have neocortical, extrahippocampal seizures and approximately 50% of patients are rendered seizure-free.     

Commentary: How Has Neuroimaging Improved Patient Care?

Summary: Neuroimaging has significantly altered the management of patients with partial epilepsy. Magnetic resonance imaging (MRI) has been demonstrated to be a reliable and accurate indicator of the common pathologic findings underlying a partial seizure disorder. Intracranial mass lesions have been shown to be highly coherent with the localization of the epileptogenic zone. An MRI-identified epileptogenic lesion affects the selection of patients for epilepsy surgery and alters the diagnostic evaluation and the operative strategy. The results of the MRI preoperatively have prognostic importance in patients undergoing surgical treatment for partial epilepsy. Patients with lesional epileptic syndromes are considered favorable candidates for surgical ablative treatment. Hippo-campal volume studies may predict the neurocognitive outcome in patients undergoing temporal lobe surgery. The use of MRI has resulted in a reduction in chronic intracranial EEG monitoring at most epilepsy centers, especially in patients with lesional pathology. MRI may be a reasonable initial "screening" procedure in selected patients with intractable partial epilepsy before consideration of a presurgical evaluation. A classification of partial epilepsy is proposed, based on the results of MRI, that may be useful for patients being considered for surgical treatment. Importantly, preoperative MRI must be correlated with the electrophysiologic studies and ictal semiology before decision-making regarding surgical therapy.     

脑穿通畸形相关性癫(癎)的手术治疗(附12例分析)

目的 评价外科切除致(癎)皮质治疗脑穿通畸形相关性顽固性癫(癎)的疗效.方法 回顾性分析12例脑穿通畸形病人的临床特征、电生理数据、术中所见及致(癎)皮质切除后的癫(癎)发作情况.本组均为部分性发作,继发全面性发作9例,复杂部分性发作3例.长程视频脑电图(VEEG)显示:发作间期VEEG异常与囊肿位置吻合7例,分布弥散5例;发作期VEEG异常6例,其中5例与囊肿位置吻合.对术前VEEG和术中皮质脑电图(ECoG)显示的间期异常区、可能的症状区、硬化皮质和磁共振流体抑制翻转复原序列(MRI-flair像)上的高信号区等予以切除.结果 随访6个月～7年,本组均获Engel Ⅰ级控制,其中2例仍有先兆发作.无并发症发生.结论 在脑穿通畸形病人中,致(癎)灶不仅涉及电生理异常区(包括术前VEEG及术中ECoG异常区),也可能涉及解剖异常区(包括术前MRI-flair像上的高信号区及术中所见硬化皮质).这些异常区的充分切除和功能区的确切保护为脑穿通畸形性顽固性癫(癎)的外科治疗提供了一个有效的办法.     

难治性枕叶癫痫的术前定位与手术治疗

目的探讨难治性枕叶癫痫的术前定位与手术方法。方法对经手术治疗且随访时间6个月以上的9例枕叶癫痫患者的临床资料进行回顾性分析。采用发作症状评估、影像学检查、长程视频头皮脑电图监测、颅内电极脑电图记录等方法综合术前定位。根据术前定位确定的致痫灶部位与范围采用不同的手术方法。7例病人采用颅内电极置入术来精确定位。局部枕叶皮层切除2例,枕叶大部或全部切除4例,全枕叶或后头部脑叶离断3例;同期经枕入路切除或离断颞叶内结结构3例。结果术后随访6个月至2年,术后癫痫无发作6例,发作1次1例,发作减少90%以上2例。结论难治性枕叶癫痫经手术治疗可以取得较好的疗效,颅内电极脑电图记录有助于致痫灶准确定位,并指导术中切除部位与功能保护。     

Combining advanced neuroimaging techniques in presurgical workup of non-lesional intractable epilepsy.

PURPOSE: The rationale for this case report is to assess the degree of congruency between the results of several advanced functional, metabolic, and structural neuroimaging techniques used in patients with MRI-negative focal epilepsy. METHODS: We investigated the presurgical evaluation and post-operative outcome of a patient with intractable, extratemporal epilepsy. Because the habitual seizures in this patient could be easily induced, six, advanced, neurodiagnostic techniques were successively applied (SISCOM, ictal FDG-PET, ictal fMRI, postictal diffusion-weighted imaging, voxel-based morphometry, and MRS imaging). RESULTS: The findings for the neuroimaging methods investigated, within the left central region, were fairly congruent. Subsequent, invasive EEG recordings revealed a seizure-onset zone at the site where most of the neuroimaging had shown abnormal findings. The surgical removal of the epileptogenic zone, as defined by concordant neuroimaging and SEEG data, resulted in seizure-free postoperative outcome. Histopathological findings revealed mild focal cortical dysplasia. CONCLUSION: Great efforts should be made to combine most of the advanced neuroimaging methods in the preoperative assessment of non-lesional epilepsy surgery candidates.     

Surgical treatment of epilepsy in pediatric patients

Surgery has become an accepted treatment modality for carefully selected adults with intractable focal epilepsy. More recently, increasing numbers of pediatric patients with intractable epilepsy are also being referred for surgical consideration. Key elements of surgical candidacy include medically intractable focal epilepsy, a localized epileptogenic zone, and a low risk for new postoperative neurologic deficits. The most common etiologies of the epilepsies in pediatric surgical candidates are malformation of cortical development and low grade tumor but some patients with childhood onset temporal lobe epilepsy due to hippocampal sclerosis also present for early surgery. Based on results from several recent pediatric surgical series, the chance for favorable seizure outcome after surgery is not adversely affected by young age, with seizure-free postoperative outcome reported for 60% to 65% of infants, 59% to 67% of children, and 69% of adolescents, compared to 64% reported in a large, predominantly adult series. Some subgroups of patients have higher percentages of seizure-free outcome, including those with hippocampal sclerosis or low grade tumor. In addition to seizures, developmental issues are also a major concern in children with intractable epilepsy. Few quantitative data are available, but some anecdotal experience suggests that surgical relief of catastrophic epilepsy may result in resumption of developmental progression after surgery, although the rate of development often remains abnormal. In one series, best developmental outcomes were seen in patients with earliest surgery and highest level of preoperative development. For each patient, the timing of surgery must be carefully considered, based on a full assessment of the relative risks and benefits, derived from a detailed presurgical evaluation.     

Paediatric epilepsy surgery in the posterior cortex: a study of 62 cases

Past surgical series have emphasized the diagnostic complexity of posterior cortex epilepsy. Available data are sparse, especially in children, and most published series report a high number of surgical failures and post‐operative neurological deficits. In this article, we present a paediatric cohort of 62 children who underwent surgery for drug resistant posterior cortex epilepsy before the age of 16 years with a mean post‐operative follow‐up of 6.94 years (range: 2–16). Mean age at epilepsy onset was 3.2 years and 28 children (45%) had onset before 1 year of age. The mean age at surgery was 7.9 years (range: 1–16). Daily seizures were present in 63% of children. MRI was positive in 58 cases (93.5%) and invasive stereo‐EEG was judged mandatory in 24/62 (39%) of patients. Surgery was confined to the parietal lobe in 11 children, the occipital lobe in 8, the occipito‐parietal region in four, the occipito‐temporal region in 18, and involved both the temporal and parietal lobes in the remaining 21. Following surgery, 53 subjects (85.5%) remained seizure‐free and among those who underwent a SEEG procedure, 75% achieved seizure freedom. Focal cortical dysplasia was the most frequent histopathological diagnosis (50%), followed by tumoural (24%) and gliotic lesions (14.5%). An older age at epilepsy onset, the presence of a rather restricted epileptogenic area, and a complete resection of the epileptogenic zone were predictive of a favourable surgical outcome. These results demonstrate that a good surgical outcome is possible in children with drug resistant posterior cortex epilepsy. Accurate analysis of the chronology of ictal semiology and electrophysiological features, viewed in the context of the complete electroclinical pattern, provides a topographical orientation for posterior cortex epilepsy and, together with the presence of a lesion detectable on imaging, may improve the rate of surgical success of posterior cortex epilepsy at paediatric age.     

Extratemporal surface EEG features do not preclude successful surgical outcomes in drug-resistant epilepsy patients with unitemporal MRI lesions

Of 47 patients with onset of intractable partial seizures and temporal lobe MRI lesions, subjected to presurgical evaluation and temporal lobe surgery, we identified eight (mean age: 24 years; range: 7-52 years) demonstrating surface interictal and/or ictal EEG features suggestive of an extratemporal localisation. All eight patients underwent surgery aiming to predominantly resect the lesion, without extending to the extratemporal region. The patients were prospectively followed (mean follow-up duration: 38 months; range: 12-66 months) and all achieved excellent postoperative seizure control. Extratemporal surface interictal/ictal EEG features were more often encountered in tumoural and focal cortical dysplasia cases, compared with medial temporal sclerosis cases, and were most frequently localised over frontopolar and suprasylvian-pericentral locations. We postulate that propagation of interictal/ictal activity from the epileptogenic region of the temporal lobe to extratemporal neocortical areas, perhaps utilising the temporal pole and insula as intermediary nodes of a common epileptogenic network, accounts for the presence of our cohort's discordant lesion and EEG features.     

Surgical treatment for musicogenic epilepsy

We report a patient with medically intractable musicogenic epilepsy (ME) who was treated with surgery. Using the non-invasive methods of ictal and interictal electroencephalography (EEG), MRI, interictal single photon emission computed tomography and clinical manifestations, we first localized the musicogenic seizures (MS). The ictal onset zone was then further localized using intracranial EEG to the middle part of the left superior temporal gyrus. Surgical resection of the epileptogenic zone was then performed. The patient had two seizures within 2 weeks post-operatively, but has then had no seizures during the following year (Engel class II). The results suggest that patients who have medically intractable ME combined with unilateral ictal onset zones should be considered for the surgical treatment of epilepsy.     

Pediatric epilepsy surgery in focal lesions and generalized electroencephalogram abnormalities

Generalized abnormalities on scalp electroencephalograms (EEG) are not uncommon in children with partial epilepsy in whom a dominant focus of interictal and ictal abnormalities concordant to the brain lesion usually clarifies surgical candidacy. Children with exclusively generalized or multiregional EEG abnormalities and mental retardation are usually not considered surgical candidates, even when brain lesions are seen on imaging. Of 176 pediatric epilepsy surgeries at our center, we describe 10 children with exclusively generalized and multiregional interictal and ictal EEG abnormalities who had resection of a focal lesion seen on brain MRI. Surgical decisions were strengthened by clinical data. Surgery was offered as a last resort because of catastrophic epilepsy and treatment failures. At 26 months' mean postoperative follow-up, eight had no seizures, and two had infrequent seizures. Six months after surgery, generalized electroencephalographic abnormalities had resolved in all. We conclude that generalized and multiregional EEG abnormalities in the absence of dominant focus may not preclude epilepsy surgery in children with a congenital or acquired lesion seen on MRI. Generalized EEG abnormalities are likely secondary phenomena that resolve after surgery. Maladaptive neural plasticity and secondary epileptogenesis are potential mechanisms that mask an epileptogenic lesion with generalized EEG abnormalities.     

颅内电极置入与脑功能区定位技术在功能区难治性癫疒间手术的应用

目的探讨颅内电极埋藏与脑功能区定位技术在功能区起始的难治性癫疒间手术的评估价值。方法回顾性分析7例难治性癫疒间的临床资料,头皮视频脑电图长程监测均考虑致疒间灶可能累及功能区,故行颅内电极置入术,再行皮质电极视频脑电图长程监测,记录发作间期和发作期脑电图,以判断致疒间皮质,并采用皮质电刺激行脑功能区定位,在指导术中尽可能切除致疒间皮质的同时,最大限度保护脑功能。结果癫疒间发作起始区切除2例,癫疒间起始区部分切除加周围皮质热灼5例。随访6个月~1年,术后运动及语言功能均保护良好6例,对侧肢体出现短暂运动障碍后恢复1例。结论颅内电极埋藏与脑功能区定位技术是功能区难治性癫疒间手术必要评估手段,有助于术前明确脑功能区和皮质放电区域,以及两者之间的关系,指导设计手术方式,最大限度提高病人术后生活质量。     

Nichtinvasives Protokoll für die epilepsiechirurgische Behandlung fokaler Epilepsien

We present a non-invasive epilepsy surgery protocol, which includes EEG-video-monitoring, magnetic resonance imaging (MRI), interictal positron emission tomography (PET) and ictal single photon emission computerized tomography (SPECT). According to this non-invasive protocol 50 of 173 patients with medically intractable focal epilepsy underwent resective surgery. The localization of the epileptogenic zone was based on the congruence of the localizing results of EEG-video-monitoring, MRI, interictal PET and ictal SPECT. 46 (92%) of the patients had temporal and 4 (8%) had extratemporal epilepsies. 78% (n = 39) of all patients operated according to our non-invasive protocol were postoperatively completely or almost seizure free. Extramesiotemporal resections could be carried out without invasive EEG-recording if the epileptogenic zone was not adjacent to the eloquent cortex. We conclude from our results that in a considerable number of patients with medically intractable particularly temporal focal epilepsies, resective epilepsy surgery can be based on non-invasive EEG-evaluations and the risk of invasive recordings can be avoided.     

Individually tailored extratemporal epilepsy surgery in children: Anatomo-electro-clinical features and outcome predictors in a population of 53 cases

Surgery for refractory extratemporal lobe epilepsy (ETLE) in the pediatric age group has been reported to be associated with a high percentage of failure and relapse. We performed a retrospective study of 53 consecutive patients with epilepsy onset before 12years of age, who underwent, mostly at a pediatric age, an individually tailored ETLE surgery (32 in frontal and 21 in posterior cerebral areas) for pharmacoresistant seizures; these patients were selected and followed by a single national tertiary care pediatric center. Mean age at seizure onset was 3.14years, and mean age at surgery was 11.23years. Complete seizure freedom was achieved in 75% of the subjects. Short duration of illness before surgery, MRI features, no invasive pre-surgical evaluation, a localized interictal and ictal pattern as well as the presence of ictal fast activity on scalp EEG, localized interictal fast rhythms and absence of a diffuse initial ictal modification during SEEG, a complete resection of the epileptogenic zone, a type II FCD, and the absence of acute postoperative seizures correlated in a statistically significant way with a seizure-free outcome. We conclude that the seizure outcome of ETLE surgery in a carefully selected pediatric population can be excellent.     

Chronic Intracranial EEG Monitoring for Localizing the Epileptogenic Zone: An Electroclinical Correlation

Summary: Purpose: To evaluate the diagnostic yield and identify predictive factors of the surgical outcome in patients with intractable partial epilepsy undergoing chronic intracranial EEG monitoring (CIEM).
Methods: The clinical, magnetic resonance imaging (MRI) and electrophysiologic data of 108 patients that underwent CIEM were retrospectively reviewed. The discharge pattern and spatial extent of the initial ictal discharge were determined by blinded visual inspection and computerized analysis.
Results: The main predictive indicator for epilepsy surgery outcome in patients that underwent CIEM was the presurgical MRI findings. Most patients with hippocampal atrophy or complete lesionectomy were rendered seizure free after epilepsy surgery (83 and 80%, respectively), whereas only a small minority of patients with partial lesipectomy or no detected MRI lesion had seizure–free operative outcomes (21 and 22%, respectively). Multifocal independent initiation of the initial ictal discharge was associated with a poor surgical outcome. In contrast, the pattern and local spatial extent of the initial ictal discharge observed with CIEM failed to predict the surgical outcome.
Conclusions: The main predictor of the surgical outcome in patients that underwent CIEM was the MRI findings, whereas CIEM had only limited use in localizing the epileptogenic zone in the absence of an MRI lesion. The reported findings indicate a low specificity of CIEM in defining the site of seizure onset, which in turn significantly impairs the reliability of CIEM in delineating the epileptogenic zone for epilepsy surgery. Further studies are required to define the indications and patient sub–populations who can benefit from CIEM before epilepsy surgery.     

Positron emission tomography in presurgical localization of epileptic foci

The success of cortical resection for intractable epilepsy of neocortical origin is highly dependent on the accurate presurgical delineation of the regions responsible for generating seizures. In addition to EEG and structural imaging studies, functional neuroimaging such as positron emission tomography (PET) can assist lateralization and localization of epileptogenic cortical areas. In the presented studies, objectively delineated focal PET abnormalities have been analyzed in patients (mostly children) with intractable epilepsy, using two different tracers: 2-deoxy-2-[18F]fluoro-D-glucose (FDG), that measures regional brain glucose metabolism, and [11C]flumazenil (FMZ), that binds to GABAA receptors. The PET abnormalities were correlated with scalp and intracranial EEG findings, structural brain abnormalities, as well as surgical outcome data. In patients with extratemporal foci and no lesion on MRI, FMZ PET was more sensitive than FDG PET for identification of the seizure onset zone defined by intracranial EEG monitoring. In contrast, seizures commonly originated from the border of hypometabolic cortex detected by FDG PET suggesting that such areas are most likely epileptogenic, and should be addressed if subdural EEG is applied to delineate epileptic cortex. In patients with cortical lesions, perilesional cortex with decreased FMZ binding was significantly smaller than corresponding areas of glucose hypometabolism, and correlated well with spiking cortex. Extent of perilesional hypometabolism, on the other hand, showed a correlation with the life-time number of seizures suggesting a seizure-related progression of brain dysfunction. FMZ PET proved to be also very sensitive for detection of dual pathology (coexistence of an epileptogenic cortical lesion and hippocampal sclerosis). This has a major clinical importance since resection of both the cortical lesion and the atrophic hippocampus is required to achieve optimal surgical results. Finally, the author demonstrated that in patients with neocortical epilepsy, FDG PET abnormalities correctly regionalize the epileptogenic area, but their size is not related to the extent of epileptogenic tissue to be removed. In contrast, complete resection of cortex with decreased FMZ binding predicts good surgical outcome suggesting that application of FMZ PET can improve surgical results in selected patients with intractable epilepsy of neocortical origin.     

Dynamic changes of ictal high-frequency oscillations in neocortical epilepsy: using multiple band frequency analysis

PURPOSE: To characterize the spatial and temporal course of ictal high-frequency oscillations (HFOs) recorded by subdural EEG in children with intractable neocortical epilepsy. METHODS: We retrospectively studied nine children (four girls, five boys; 4-17 yr) who presented with intractable extrahippocampal localization-related epilepsy and who underwent extraoperative video subdural EEG (1000 Hz sampling rate) and cortical resection. We performed multiple band frequency analysis (MBFA) to evaluate the frequency, time course, and distribution of ictal HFOs. We compared ictal HFO changes before and after clinical onset and postsurgical seizure outcomes. RESULTS: Seventy-eight of 79 seizures showed HFOs. We observed wide-band HFOs ( approximately 250 Hz, approximately 120 electrodes) in six patients either with partial seizures alone (three patients) or with epileptic spasms (three patients). Three patients with partial seizures that secondarily generalized had wide-band HFOs ( approximately 170 Hz) before clinical onset and sustained narrow-band HFOs (60-164 Hz) with electrodecremental events after clinical onset ( approximately 28 electrodes). In four postoperatively seizure-free patients, more electrodes recorded higher-frequency HFOs inside the resection area than outside before and after clinical seizure onset. In five patients with residual seizures, electrodes recorded more HFOs that were of higher or equal frequency outside the surgical area than inside after clinical onset. CONCLUSION: For partial seizures alone and epileptic spasms, more electrodes recorded only wide-band HFOs; for partial seizures that secondarily generalized, fewer electrodes recorded wide-band HFOs, but in these seizures electrodes also recorded subsequent sustained narrow-band ictal HFOs. Resection of those brain regions having electrodes with ictal, higher HFOs resulted in postsurgical seizure-free outcomes.     

Type II focal cortical dysplasia: electroclinical phenotype and surgical outcome related to imaging

Purpose: Type II focal cortical dysplasia (TTFCD), a highly epileptogenic lesion with severe epilepsy curable by surgery, is missed by magnetic resonance imaging (MRI) in about one third of cases. Little is known about the electroclinical presentation in these MRI‐negative patients and a poor surgical outcome is frequently reported. We compared the clinical and neurophysiologic features in MRI‐negative and MRI‐positive cases in order to better identify candidates for surgery. Methods: Among 62 consecutive TTFCD patients (38 male, 24 female; 7–52 years old; 22 children) operated for intractable epilepsy, 25 (40%) presented negative MRI findings. We compared the history of epilepsy; the type, frequency, and distribution of seizures; neurologic examination cognitive and psychiatric impairment; interictal‐ictal electroencephalography (EEG) and stereo‐EEG (SEEG) data, fluorodeoxyglucose positron emission tomography (FDG‐PET) data, neuropathologic findings; and surgical outcome in the MRI‐negative and the MRI‐positive groups. Key Findings: Severe partial epilepsy beginning in childhood, high seizure frequency including status epilepticus, stereotyped seizures suggestive of precise brain localization, extratemporal location and functional area involvement were characteristic and similarly found in both groups. On EEG, pseudorhythmic activity was found in about 40% of patients in each group. SEEG recordings demonstrated the typical pattern characterizing TTFCD in both groups. FDG‐PET had a localization value in 84% of the MRI‐negative cases and helped to delineate the dysplastic cortex in 65% of the MRI‐positive cases. The combination of imaging and neurophysiologic data allowed us to perform safe and restricted resections, limited to a single gyrus in more than half of all cases. In addition, we were able to avoid invasive monitoring in most MRI‐positive cases and even in some selected MRI‐negative cases. The proportion of patients with a favorable surgical outcome was comparable in both groups (88% in MRI‐negative and 94% in MRI‐positive cases). The main difference between the groups was a significantly higher frequency of sleep‐related epilepsy in the MRI‐negative group (p = 0.028). This phenotypic characteristic provides a new argument for TTFCD in MRI‐negative extratemporal epilepsy. Significance: These results lead us to consider that children or adult patients in whom electroclinical data suggest TTFCD, are highly suitable for surgery, especially for cryptogenic sleep‐related epilepsy.