Influence of Epilepsy and Temporal Lobe Resection on Olfactory Function

Summary: Olfactory auras accompany some cases of epilepsy. Several aspects of olfactory function, including sensitivity, also may be altered. We reviewed the literature on these topics, as well as studies evaluating the influences of temporal lobe resection and other seizure management procedures on olfactory function. We concluded that: (a) despite several studies, the prevalence of olfactory auras in epilepsy is unknown, with estimates ranging from <1% to >30%; (b) epilepsy appears to cause a generalized decrease in olfactory functioning, although increased sensitivity may occur in some epileptic patients at some time in the preictal period; (c) other sensory modalities are also affected by the epileptic process which, in some cases, involve limbic-related temporal lobe structures; (d) many of the olfactory deficits previously attrib-uted to temporal lobe resection actually exist preoperatively; (e) a tastehlavor confusion exists in the reporting of taste auras; (0 unpleasant auras are associated with hyperresponsiveness of neurons, which may explain why most epilepsy-related olfactory auras are described as "bad"; and (g) interesting parallels exist between the effects of the neuroendocrine system on seizure activity and olfactory function.     

Might the olfactory bulb be an origin of olfactory auras in focal epilepsy?

Olfactory auras (phantosmia) are an infrequent phenomenon in complex focal seizures generated in the mesial temporal lobe. It is generally assumed that all such auras arise from epileptic foci in the entorhinal cortex, amygdala or rostral insula, all of which have major afferent projections from the olfactory bulb or mainly from its relay, the anterior olfactory nucleus. The histological morphology, synaptic circuitry, and foetal development of the olfactory bulb are unique. The olfactory system is the only special sensory system that does not project to the thalamus because its bulb and tract incorporate an intrinsic thalamic equivalent: axonless granular and periglomerular neurons and the anterior olfactory nucleus. The olfactory bulb exhibits continuous synaptic turnover throughout life. Other brain structures with synaptic plasticity (neocortex, hippocampus, and amygdala) are epileptogenic; synaptically stable structures (brainstem, cerebellum, and basal ganglia) are not epileptogenic. Electrophysiological and neuropathological data of the olfactory bulb in epilepsy are sparse. We propose an alternative hypothesis, first hinted in 1954 by Penfield and Jasper, that some epileptic olfactory auras are primarily generated by the olfactory bulb and secondarily mediated by the amygdala and entorhinal cortex.     

Temporal Lobe Epilepsy Subtypes: Differential Patterns of Cerebral Perfusion on Ictal SPECT

Summary: Purpose : We studied cerebral perfusion patterns in the various subtypes of TLE, as determined by pathology and good outcome after temporal lobectomy (as confirmation of temporal origin).
Methods : We studied clinical features and ictal technetium ^99m hexamethyl-propyleneamineoxime (99mTc-HM-PAO) single-photon emission-computed tomography (SPECT) in four subgroups of patients with intractable temporal lobe epilepsy (TLE) treated with surgery: hippocampal sclerosis (group 1, n = 10), foreign-tissue lesion in mesial temporal lobe (group 2, n = 8), foreign-tissue lesion in lateral temporal lobe (group 3, n = 7), and normal temporal lobe tissue with good surgical outcome (group 4, n = 5).
Results : No major clinical differences in auras, complex partial seizures or postictal states were identified among the groups. Ictal SPECT showed distinct patterns of cerebral perfusion in these subtypes of TLE. In groups 1 and 2, hyperperfusion was seen in the ipsilateral mesial and lateral temporal regions. In group 3, hyperperfusion was seen bilaterally in the temporal lobes with predominant changes in the region of the lesion. Hyperperfusion was restricted to the ipsilateral anteromesial temporal region in group 4. Ipsilateral temporal hyperperfusion in mesial onset seizures can be explained by known anatomic projections between mesial structures and ipsilateral temporal neocortex. Bilateral temporal hyperperfusion in lateral onset seizures can be explained by the presence of anterior commissural connections between lateral temporal neocortex and the contralateral amygdala.
Conclusions : We conclude that the perfusion patterns seen on ictal SPECT are helpful for subclassification of temporal lobe seizures, whereas clinical features are relatively unhelpful. These perfusion patterns provide an insight into preferential pathways of seizure propagation in the subtypes of TLE.     

Preoperative amygdala fMRI in temporal lobe epilepsy

Purpose:   Anterior temporal lobe resections (ATLR) benefit 70% of patients with refractory mesial temporal lobe epilepsy (TLE), but may be complicated by emotional disturbances. We used functional magnetic resonance imaging (fMRI) to investigate the role of the amygdala in processing emotions in TLE and whether this may be a potential preoperative predictive marker for emotional disturbances following surgery.
Methods:   We studied 54 patients with refractory mesial TLE due to hippocampal sclerosis (28 right, 26 left) and 21 healthy controls using a memory encoding fMRI paradigm, which included viewing fearful and neutral faces. Twenty-one TLE patients (10 left, 11 right) subsequently underwent ATLR. Anxiety and depression were assessed preoperatively and 4 months postoperatively using the Hospital Anxiety and Depression Scale.
Results:   On viewing fearful faces, healthy controls demonstrated left lateralized, while right TLE patients showed bilateral amygdala activation. Left TLE patients had significantly reduced activation in left and right amygdalae compared to controls and right TLE patients. In right TLE patients, left and right amygdala activation was significantly related to preoperative anxiety and depression levels, and preoperative right amygdala activation correlated significantly with postoperative change of anxiety and depression scores, characterized by greater increases in anxiety and depression in patients with greater preoperative activation. No such correlations were seen for left TLE patients.
Discussion:   The fearful face fMRI paradigm is a reliable method for visualizing amygdala activation in controls and patients with mesial TLE. Activation of the right amygdala preoperatively was predictive of emotional disturbances following right ATLR.     

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.     

Foramen ovale electrodes in the preoperative evaluation of temporal lobe epilepsy in children

Purpose:  Foramen ovale electrodes (FOEs) can localize the epileptogenic zone in adults with mesial temporal lobe epilepsy (TLE). Our aim was to investigate the feasibility and safety of using FOEs to investigate refractory TLE in children.
Methods:  Thirty-eight children with seizure semiology and video-EEG (electroencephalography) consistent with medically refractory TLE, and/or the presence of a lesion in the temporal lobe, had FOEs inserted. Complications occurring during the monitoring and up to 3 months after surgery and the long-term seizure outcome were registered.
Results:  Forty electrodes were placed in 38 patients. The mean age of the patients was 9.8 years (range 2.3–15.4 years). FOEs confirmed a unilateral mesial temporal lobe seizure onset in 14 patients, onset in both FOEs and lateral electrodes in two patients, and onset in the anterior temporal electrodes in only one patient. Six patients had seizures recorded but were not considered surgical candidates; four patients had no seizures recorded, and 11 patients were further investigated with depth electrodes. One patient (2.6%) developed a hematoma in the cheek, and in two patients the electrodes were extracranial but could still be used for recording. Twenty-eight children had a temporal resection; 25 were Engel class I at follow-up.
Discussion:  FOEs are safe to use in children and provide valuable information on the mesial temporal lobe structures in the preoperative investigation of pediatric TLE. Patient selection for FOE investigation is, however, essential for a conclusive result.     

Olfactory Prodromal Symptoms and Unilateral Olfactory Dysfunction Are Associated in Patients with Right Mesial Temporal Lobe Epilepsy

Summary: Purpose: We report a patient with mesial temporal lobe epilepsy (MTLE) with olfactory prodromal symptoms manifested as an unpleasant smell of onions, who was found to have an ipsilateral deficit of olfactory naming (olfactory agnosia).
Methods and Results : Preoperative olfactory testing revealed a selective right-sided olfactory deficit for naming of odors. Olfactory threshold was within the normal range. The patient has been seizure free after selective amygdalohippocampectomy for 4 months. No olfactory prodromal events have occurred since surgery. Olfactory testing 3 months after resection showed that right-sided odor naming was still impaired.
Conclusions : We conclude that olfactory prodromal symptoms may be associated with unilateral olfactory dysfunction, and lateralization of seizure origin may be possible by unilateral olfactory testing.     

Entorhinal cortex MRI assessment in temporal,extratemporal, and idiopathic generalized epilepsy

PURPOSE: We previously showed a reduction in the volume of the entorhinal cortex (EC) ipsilateral to the seizure focus in patients with intractable temporal lobe epilepsy (TLE). The purpose of this study was to examine the specificity of EC atrophy in epilepsy. METHODS: We performed volumetric measurement of the EC on high-resolution magnetic resonance imaging (MRI) in patients with TLE (n = 70), extratemporal lobe epilepsy (ETE; n = 18), and idiopathic generalized epilepsy (IGE; n = 20). EC volumes of epilepsy patients were compared with those of 48 age- and sex-matched normal controls. Within the TLE group, 63 patients were selected prospectively with hippocampal atrophy ipsilateral to the seizure focus. The remaining seven patients were chosen retrospectively based on normal volumetric MRI of the hippocampus and amygdale, as well as normal histopathologic examination of the resected tissue. RESULTS: Compared with normal controls, EC volume was smaller ipsilateral but not contralateral to the seizure focus in patients with TLE (p < 0.001). No difference in the EC volumes ipsilateral and contralateral to the seizure focus was seen in patients with ETE and IGE compared with normal controls. The individual analysis showed that the EC was atrophic in 73% of TLE patients with hippocampal atrophy. Three of the seven TLE patients with normal volumetric MRI of the hippocampus and amygdala and normal histopathologic examination had EC atrophy ipsilateral to the seizure focus. In no patient with ETE or IGE was the EC found to be atrophic. CONCLUSIONS: EC atrophy ipsilateral to the seizure focus appears to be specific to mesial temporal lobe structural damage associated with TLE.     

The localizing value of the abdominal aura and its evolution: a study in focal epilepsies.

OBJECTIVE: To evaluate the localizing value of abdominal aura and its evolution into other seizure types. METHODS: The seizures of 491 consecutive patients with focal epilepsies were prospectively classified according to a recently introduced semiologic seizure classification. All patients underwent prolonged EEG video monitoring and MRI scan. Two hundred twenty-three patients (45%) had temporal lobe epilepsies (TLE); 113 patients (23%) had extratemporal epilepsies; and for 155 (32%) patients, the epilepsy could not be localized to one lobe. RESULTS: Abdominal auras were more frequent with TLE (117 of 223 patients, 52%) than in extratemporal epilepsy (13 of 113 patients, 12%, p < 0.0001) and more frequent in mesial TLE (70 of 110 patients, 64%) than in neocortical TLE (16 of 41 patients, 39%, p = 0.007). No preponderance to one side existed. Abdominal auras were followed by ictal oral and manual automatisms (automotor seizure) in at least one seizure evolution in all patients with TLE (117 patients, 100%). In contrast, only two patients with extratemporal epilepsy (2 of 13 patients, 15%, p < 0.0001) had abdominal auras evolving into automotor seizures. An abdominal aura is associated with TLE with a probability of 73.6%. The evolution of an abdominal aura into an automotor seizure, however, increases the probability of TLE to 98.3%. CONCLUSIONS: These results demonstrate that evolution of abdominal aura into automotor seizure permits differentiation between temporal lobe epilepsy and extratemporal epilepsy, showing that analysis of seizure evolution provides more localizing information than does the frequency of particular seizure types.     

Type of preoperative aura may predict postsurgical outcome in patients with temporal lobe epilepsy and mesial temporal sclerosis

PurposeAs the initial symptoms of epileptic seizures, many types of auras have significant localizing or lateralizing value. In this study, we hypothesized that the type of aura may predict postsurgical outcome in patients with medically refractory temporal lobe epilepsy (TLE) and mesial temporal sclerosis (MTS).MethodsIn this retrospective study, all patients with a clinical diagnosis of medically refractory TLE due to unilateral mesial temporal sclerosis who underwent epilepsy surgery at the Jefferson Comprehensive Epilepsy Center were recruited. Patients were prospectively registered in a database from 1986 through 2014. Postsurgical outcome was classified into two groups: seizure freedom or relapse. Outcome was compared between seven groups of patients according to their preoperative auras.ResultsTwo hundred thirty-seven patients were studied. The chance of becoming free of seizures after surgery in patients with abdominal aura was 65.1%, while in other patients, this was 43.3% (P = 0.01). In two-by-two comparisons, no other significant differences were observed.ConclusionPatients with medically refractory TLE–MTS who reported abdominal auras preceding their seizures fared better postoperatively with regard to seizure control compared with those who did not report auras, which may indicate bitemporal dysfunction, and to patients with other auras, which may indicate a widespread epileptogenic zone in the latter group of patients.     

Typical and atypical perfusion patterns in periictal SPECT of patients with unilateral temporal lobe epilepsy

PURPOSE: To characterize perfusion patterns of periictal single-photon emission tomography (SPECT) in patients with unilateral temporal lobe epilepsy (TLE) and to determine their relationship to the epileptogenic zone (EZ). METHODS: We studied periictal SPECT scans of 53 patients after anterior mesial temporal lobectomy who had good seizure outcome after surgery. Ictal SPECT scans were performed during video-EEG monitoring. Typical SPECT patterns consisted of ipsilateral ictal hyperperfusion or ipsilateral postictal hypoperfusion. Atypical ictal patterns included normal scans, bilateral temporal hyperperfusion, or contralateral patterns. These perfusion patterns were retrospectively analyzed searching for concordance rate with the EZ. RESULTS: We obtained 51 ictal and two early postictal scans. In the typical group, 40 (75.4%) patients had ipsilateral ictal temporal lobe hyperperfusion, and one (1.9%) patient had ipsilateral postictal temporal lobe hypoperfusion. Twelve (22.7%) patients exhibited atypical perfusion patterns: seven (13.2%) patients had bitemporal ictal hyperperfusion (four cases showed asymmetric temporal lobe changes), four (7.6%) patients had contralateral hyperperfusion, and one (1.9%) patient had a normal SPECT scan. All four patients with bitemporal asymmetric hyperperfusions showed greater perfusion lateralized to the side of the EZ. Three of the four patients who had contralateral hyperperfusion also had a complex postictal-like pattern in the ipsilateral temporal lobe consisting of anteromesial hyperperfusion with adjacent lateral hypoperfusion. CONCLUSIONS: This study analyzed typical and atypical perfusion patterns in unilateral TLE, and suggested that not only typical, but also some atypical perfusion patterns may contribute to the lateralization of EZ.     

Lack of aura experience correlates with bitemporal dysfunction in mesial temporal lobe epilepsy

The diagnostic value of lack of aura experience in patients with temporal lobe epilepsy (TLE) is unclear. PURPOSE: To evaluate possible factors of bitemporal dysfunction in patients with mesial TLE who did not experience an aura in electroencephalography EEG/video monitoring for epilepsy surgery. METHODS: Ictal scalp EEG propagation patterns of 347 seizures of 58 patients with mesial temporal lobe sclerosis or non-lesional mesial TLE, interictal epileptiform discharges (IED), presence of unilateral mesial temporal lobe sclerosis in visual magnetic resonance imaging (MRI) analysis, prose memory performance, history or not of an aura, and postictal memory or absence of an aura were analyzed. The ictal EEG was categorized as follows. EEG seizure: (a) remaining regionalized, (b) non-lateralized, (c) showing later switch of lateralization or bitemporal asynchronous ictal patterns. RESULTS: Absent aura in monitoring was significantly correlated with absence of unitemporal MRI sclerosis (P=0.004), bitemporal IED (P=0.008), and propagation of the ictal EEG to the contralateral temporal lobe (P=0.001). Other historical data and interictal prose memory performance were not significantly correlated with absent aura. Ten of 11 patients without aura in monitoring also had absent or rare auras in their history. CONCLUSIONS: Lack of aura experience strongly correlates with indicators of bitemporal dysfunction such as bitemporal interictal sharp waves and bitemporal ictal propagation in scalp EEG, and absence of lateralized MRI sclerosis in patients with mesial TLE. The fact that absent auras are not correlated with episodic memory suggests a transient memory deficit, probably because of rapid propagation to the contralateral mesial temporal lobe.     

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

ObjectivesWe investigated the clinical features associated with olfactory auras in patients with drug-resistant epilepsy and also hypothesized that this type of aura may predict worse postsurgical outcome in patients with drug-resistant temporal lobe epilepsy (TLE).MethodsIn this retrospective analysis, data from all patients with drug-resistant epilepsy who underwent epilepsy surgery were reviewed. Patients were prospectively registered in a database from 1986 through 2016. We assessed outcome in the first 5 years after surgery to produce a Kaplan–Meier estimate of seizure recurrence. Post-surgical outcome was classified into two groups; 1) seizure-free, with or without auras; or 2) relapse of complex partial or secondarily generalized seizures. We also investigated the clinical features of patients with TLE and olfactory auras compared with those without olfactory auras.ResultsWe studied 1186 patients. Thirty-seven patients (3.1%) reported olfactory auras with their seizures. Thirty-two patients had temporal lobe surgery. Intracranial video-EEG recording was performed in four patients. Three patients with lateral temporal neocortical seizures reported olfactory auras with their seizures; two of them were seizure-free after surgery. There were no significant clinical differences between patients with TLE and olfactory auras compared with those without. Seizure outcome after surgery was not significantly different between these two groups (p = 0.3; Cox–Mantel test).ConclusionThe rarity of olfactory auras makes it difficult to propose new diagnostic and treatment strategies. A multicenter approach, which can enroll more patients, is needed to devise better therapies for patients with drug-resistant epilepsy and this symptom.     

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.     

Hyperkinetic seizures in patients with temporal lobe epilepsy: clinical features and outcome after temporal lobe resection

Purpose: Temporal lobe epilepsy (TLE) is usually associated with automatisms. Hyperkinetic seizures are supposed to be unusual. Because we witnessed several patients with TLE and ictal hyperkinetic symptoms, we retrospectively assessed the number, clinical findings, and seizure outcome in such patients who had undergone temporal lobe resection. Methods: We reviewed medical history, video–electroencephalography (EEG) recording and neuroimaging of adult patients who underwent epilepsy surgery for TLE at the Kork Epilepsy Center over the last 20 years with a minimum postoperative follow‐up of 12 months. Key Findings: Among 294 patients who were resected exclusively in the temporal region, we identified 17 (6%) who presented with hyperkinetic semiology such as violent vocalization, complex movements of the proximal segments of the limbs, rotation of the trunk, pelvic thrusting, or early tonic or dystonic posturing. Most of the patients had a preceding aura. Ictal EEG activity was located in the corresponding temporal region, usually with a wide distribution over temporal electrodes with fast spread to unilateral frontal electrodes and to the contralateral side. Neuroimaging revealed extended lesions in the temporal lobe involving mesial and neocortical structures. Most of the patients underwent classical anterior temporal lobe resection including amygdalo‐hippocampectomy. Fourteen patients (82%) became completely seizure‐free (Engel class Ia). Histopathology showed mainly focal cortical dysplasia plus hippocampal sclerosis. Significance: Hyperkinetic seizure semiology may occasionally occur in patients with TLE and is, therefore, no contradiction to the hypothesis of TLE if scalp EEG patterns and neuroimaging findings correspond. The postoperative seizure outcome is favorable in such patients and not different from outcome data in classical TLE.     

Ictal fear auras after selective amygdalohippocampectomy: the use of ictal SPECT and scalp EEG in the presurgical reevaluation

The perception of fear aura in complex partial seizures is linked to epileptic discharges within mesial temporal lobe structures. Although selective amygdalohippocampectomy often leads to favorable seizure control, persistence of fear auras after surgery can hamper quality of life significantly. We describe two patients with persistent fear auras after selective amygdalohippocampectomy who had to be reevaluated for a second operative procedure. In one patient, ictal SPECT revealed focal hyperperfusion within the left temporal pole. In the other patient, localization of the focus was possible with ictal scalp EEG, which revealed closely time-related focal theta activity in the right frontotemporal electrodes. Both patients underwent a second surgery leading to complete remission. The persistence of fear auras after selective amygdalohippocampectomy provides an example of involvement of a complex neuronal network in the generation of this emotional state during mesiotemporal lobe seizures. Ictal SPECT or ictal scalp EEG may be valuable in identifying the involved areas and in guiding the surgeon to render these patients seizure free.     

Nuclear Magnetic Resonance Imaging, a New Approach to the Investigation of Refractory Temporal Lobe Epilepsy

Nuclear magnetic resonance is a noninvasive technique of imaging the brain using signals produced by magnetic fields and radiowaves. Sixteen patients with refractory temporal lobe epilepsy (TLE) had magnetic resonance imaging (MRI) during investigation for possible surgical management. These images plus those of 10 normal controls, were interpreted blind and the results from the TLE patients compared to the EEG and computerized tomographic (CT) scan findings. Fourteen patients compared with one normal control had one or more of the following: small temporal lobe, small mesial temporal structures, small hemisphere, and focal mesial temporal prolonged spin-spin relaxation time. These findings correlated with the electrographically determined seizure focus in 11 patients. Enlarged or asymmetrical temporal horns were seen with equal frequency in patients and controls and did not correlate with the seizure focus. CT scans were less likely to show these changes than MRI. Correlation of the MRI changes with histopathology of resected temporal lobes was poor. MRI reveals structural and possibly functional alterations which may aid in the localization of the seizure focus in the temporal lobes of patients with refractory complex partial seizures.     

Postictal diffusion-weighted imaging for the localization of focal epileptic areas in temporal lobe epilepsy

PURPOSE: Diffusion-weighted MR imaging (DWI) is a novel technique to delineate focal areas of cytotoxic edema of various etiologies. We hypothesized that DWI may also detect the epileptogenic region and adjacent areas during the ictal and early postictal periods in patients with temporal lobe epilepsy (TLE). METHODS: We studied patients with intractable TLE (n = 9), due to hippocampal sclerosis (HS, n = 7), left mesial temporal lobe tumor (n = 1), and of unknown etiology (n = 1). Informed consent was obtained before inclusion in the study. All patients with single short seizures were scanned immediately after EEG-documented seizures (between 45 and 150 min); one of two patients in status was scanned 14 h after cessation of seizures. DWI results were analyzed visually and by calculating apparent diffusion coefficient (ADC) maps. RESULTS: We found significant decreases in ADC postictally in one of six patients with TLE due to HS and single short seizures. One patient with an incompletely resected temporal lobe tumor also exhibited ADC abnormalities. One patient in focal status epilepticus revealed a decrease in ADC, and one patient with a continuous aura had no DWI abnormality. CONCLUSIONS: Postictal DWI technique may occasionally help delineate epileptic areas in some patients with TLE. Yield is low in patients with HS and single short seizures: it may be higher in patients with tumor or status epilepticus.     

Effects of illness duration on memory processing of patients with temporal lobe epilepsy

PURPOSE: To examine the effects of illness duration on the neural processing of memory in patients with temporal lobe epilepsy (TLE) by using functional MRI. METHODS: Twenty-three TLE patients (16 left, seven right) performed a complex visual scene-encoding task during functional MRI. Region-of-interest (ROI) analyses were used to quantity functional activation in the mesial temporal and frontal lobes. The patients' verbal and visual memory performances were evaluated by standardized neuropsychological tests. Analyses included group comparison and correlations of duration of epilepsy with functional activation and memory performance. RESULTS: Compared with normal controls, TLE patients demonstrated reduced activation bilaterally in the mesial temporal lobe (p=0.003), and the reduction was more pronounced on the ipsilateral side of the seizure focus. Moreover, a longer duration of illness was associated with fewer voxels activated in both the left (p=0.038) and right (p=0.017) mesial temporal lobe. Furthermore, the duration of illness was found to be significantly and negatively correlated with both verbal (p=0.020) and visual (p=0.000) memory functioning. CONCLUSIONS: TLE seems to affect the memory processes in the mesial temporal lobes progressively (i.e., the longer the duration of illness, the lower the brain activation). In turn, the reduction of brain activation negatively affects memory functioning. Finally, the reduction is not limited to the side of seizure but also is observed in the contralateral hemisphere.     

颞叶内侧结构弥散张量成像及白质纤维束成像在颞叶癫痫诊断中的应用价值

目的 通过磁共振弥散张量成像(DTI)及白质纤维束示踪(DTT)技术定量分析颞叶癫痫患者双侧颞叶内侧结构弥散参数值及局部纤维束变化特点,评价DTI技术对颞叶癫痫的诊断价值.方法 对广州医学院第二附属医院自2010年12月至2011年2月临床诊断为颞叶癫痫的16例患者和20例健康志愿者进行常规MRI及DTI扫描,测量双侧颞叶杏仁体、海马及颞叶皮质的部分各向异性(FA)、相对各向异性(RA)、表观弥散系数(ADC)等数值并进行统计学分析,同时应用DTT技术观察癫痫患者局部纤维束与正常对照者的差异.结果 正常对照者双侧颞叶内侧各结构FA、RA、ADC值比较差异均无统计学意义(P＞0.05).颞叶癫痫患侧、对侧与正常对照者颞叶内侧各结构FA、RA、ADC值比较差异均有统计学意义(P＜0.05),其中ADC值呈颞叶癫痫患侧＞颞叶癫痫对侧＞正常对照者的变化趋势,以海马尾部变化最为显著;而FA、RA值呈颞叶癫痫患侧＜颞叶癫痫对侧＜正常对照者的变化趋势,并且杏仁体、海马体部变化较海马尾部更显著.结论 DTI技术能充分了解癫痫患者颞叶内侧结构的弥散参数值及纤维束变化特点,有助于癫痫病灶定位的准确诊断,同时加深对颞叶内侧结构整体变化的了解亦有助于术前的整体评估及提高手术疗效.