Multimodality functional imaging evaluation in a patient with Rasmussen's encephalitis

Rasmussen's encephalitis (RE) is a cryptogenic progressive inflammatory disorder of the brain that causes severe neurological problems, including intractable focal epilepsy. In select patients, aggressive treatment using cerebral hemispherectomy may ameliorate the devastating cognitive decline that accompanies this disease, even if the epileptic focus appears broadly distributed. We present a case of histopathologically-confirmed RE evaluated using a multimodal process that explored the physical and functional aspects of the associated epilepsy. This process included magnetic resonance imaging, single photo emission computed tomography, electroencephalography, and magnetoencephalography (MEG). The findings indicate that functional brain imaging data may greatly assist the surgical treatment decision-making process in RE, especially when structural imaging fails to reveal definitive localizing information. In addition, MEG may provide insights about the cortical reorganization of somatosensory cortex following hemispherectomy.     

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.     

Multiphasic presentation of Rasmussen's encephalitis

Rasmussen's encephalitis is a rare, chronic inflammatory disorder of unknown cause, characterised by drug‐resistant focal epilepsy that may rarely present in adolescence or adulthood. We present a case of Rasmussen's encephalitis with prominent recurrent fluctuation in symptoms and well‐documented fluctuating changes on MRI, adding to the spectrum of diversity of Rasmussen's encephalitis.     

Ictal SPECT in Sturge-Weber syndrome

We report on a patient with right-sided Sturge-Weber syndrome (SWS), in whom earlier functional hemispherectomy failed. Subtraction of ictal and interictal single-photon-emission-computed-tomography (SPECT) superimposed on individual MRI showed a right fronto-orbital hyperperfusion, with a left-sided EEG seizure pattern. Ictal SPECT supported our assumption that right frontal originated seizure pattern propagated to left hemisphere via the remaining right frontal bridge. Right orbito-frontal resection and disconnection from corpus callosum resulted in seizure freedom.     

Ictal brain imaging in presurgical evaluation of patients with medically intractable complex partial seizures

At the Indiana University Medical Center, 99 patients with medically intractable complex partial seizures (MI-CPS) had presurgical evaluation with subsequent anterior temporal lobectomy. The majority of the patients had single photon emission tomography (SPECT) performed interictally as well as during an actual epileptic seizure (ictal scan). Decreased regional cerebral perfusion (rCP) was seen in 54/94 (57%) of the interictal scans corresponding to the eventual site of the surgery. However, ictal scans provided a higher yield; increased rCP in the temporal lobe during an actual seizure was observed in 60/82 (73%) concordant to the side of surgery. SPECT is a useful, noninvasive method of localizing the epilepti-form focus in patients with MI-CPS considered for resective surgery. Both interictal and ictal SPECT need to be performed; combined interictal hypo-perfusion and ictal hyperperfusion in the same focal area are unique to epileptogenic lesions. Ictal SPECT studies can be performed in the majority of patients during the period of continuous video/EEG monitoring with only a little additional effort. Combining the results of functional brain imaging (interictal and ictal SPECT, PET) with clinical semiology of seizures, surface and sphenoidal EEG, magnetic resonance imaging and other non-invasive tests, anterior temporal lobectomy can be recommended in approximately two-thirds of the patients without resorting to potentially dangerous intracranial EEG monitoring.     

Positron emission tomography in Rasmussen's encephalitis

This report presents unusual positron emission tomography findings in an 11-year-old male with Rasmussen's encephalitis. This patient underwent fluorine-18 fluorodeoxyglucose positron emission tomography to localize his ictal focus before surgical consideration. Positron emission tomography disclosed marked hypermetabolism in the left cerebral hemisphere and basal ganglia with subnormal right cerebral activity and crossed cerebellar diaschisis. The heterogeneous distribution of metabolism suggests a combination of areas in different stages of ictal and postictal involvement. The hypermetabolic region in the left hemisphere was larger in size and extent (now including the left frontoparietal lobe) than the sole hypermetabolic left temporal lobe on his positron emission tomography from 2 years ago. While this positron emission tomography pattern of progression appears most commonly in Rasmussen's encephalitis case studies, few serial reports exist. The complex positron emission tomography findings of this case emphasize the importance of knowing the history of recent seizures, seizure type, clinical status at time of injection, and electroencephalographic correlation before interpreting functional neuroimaging studies. Finally, positron emission tomography studies can help clarify whether patients with Rasmussen's encephalitis with dominant hemisphere involvement are appropriate candidates for surgery or not.     

发作期录像脑电监测在15例难治性颞叶癫痫患者术前定位中的价值

目的 探讨发作期录像脑电监测（IVEEG）在难治性非病变性颞叶癫痫（TLE）致痫源术前定位中的价值。方法 对15例药物难治性TLE患者术前定位资料及术后随诊情况进行分析。结果 所有患者在行长时间IVEEG监测中均捕获到临床发作。在15例患者中，有13例IVEEG显示出一侧起源的局灶爆发性节律性电活动，该放电侧均与最终切除侧相一致，且有11例患者术后效果较好。结论 IVEEG监测不仅有助于明确诊断及发作类型，更为重要的是对于大多数难治性非病变性TLE患者可提供较可靠的致痫源定侧信息。     

Ictal PET in presurgical workup of refractory extratemporal epilepsy

Ictal Pet in presurgical workup of refractory epilepsy is seldom performed and limited due to technical difficulties. In carefully selected patient subset with frequent extratemporal seizures, ictal PET depicts ‘seizure onset zone’ with high spatial resolution even within a widespread pathology. We here depict a four year old with posterior quadrant dysplasia evaluated with ictal PET.Key Words: Epilepsy, Ictal PET, presurgical workup, refractory     

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.     

Ictal SPECT in clinical perisylvian syndrome

In the congenital bilateral perisylvian syndrome, pseudobulbar symptoms, cognitive deficits and cortical malformations in the perisylvian region are typical features. We report two initially magnetic resonance imaging (MRI) negative patients from our epilepsy surgery program that shared the same seizure and ictal SPECT characteristics suggesting seizure onset localized in the perisylvian region. In one patient, reevaluation revealed perisylvian cortical malformation on MRI while in the other patient MRI was normal. In these patients, subtraction ictal SPECT coregistered with MRI (SISCOM) proved useful together with clinical data in diagnosing the patients with mild forms of perisylvian syndrome.     

Experience with immunomodulatory treatments in Rasmussen's encephalitis

The authors investigated immunomodulatory treatments in 15 patients with Rasmussen encephalitis (RE) (14 with childhood and one with adolescent onset RE). Positive time-limited responses were obtained in 11 patients using variable combinations of corticosteroids, apheresis, and high-dose IV immunoglobulins. Although surgical exclusion of the affected hemisphere is the only treatment that halts disease progression, immunomodulation can be considered when early surgery is not feasible, in late-onset patients with slower disease progression, and in the few cases of bilateral disease.     

Neuronal autoantibodies in patients with Rasmussen's encephalitis

Aim. Rasmussen's encephalitis (RE) is a rare disease with unknown pathophysiology. To disclose whether anti‐neuronal autoimmunity participates in the aetiology of RE, various neuronal autoantibodies (NAAbs) were investigated in sera of patients with RE and controls. Methods. The study included five patients who fulfilled the RE diagnostic criteria (clinical, EEG, and MRI findings) as the patient group, and 50 multiple sclerosis patients and 50 healthy subjects as the control groups. Sera were evaluated for various NAAbs by radioimmunoassay or cell‐based assays. All sera were also screened for uncharacterized antibodies to neuronal cell surface or synapse antigens by indirect immunofluorescence using hippocampal cell cultures. Results. The mean age at onset of seizures was 8.3±3.4 years (range: 4–13.5) and mean follow‐up time was 11.2±5.4 years (range: 5–19). All patients had unihemispheric atrophy of the cerebral cortex and epilepsia partialis continua. Two of the patients had moderate cognitive impairment, while the others were severely affected, as shown by neuropsychological testing. NAAb positivity was not detected in any of the patients. Conclusion. Immune aetiology is thought to have a role in RE, but the responsible players have not yet been elucidated. Our extensive antibody screening in a small number of patients does not support the presence of antigen‐specific anti‐neuronal autoimmunity in RE pathophysiology.     

Ictal source localization in presurgical patients with refractory epilepsy.

Source localization of epileptic foci using ictal spatiotemporal dipole modeling (ISDM) yields reliable anatomic information in presurgical candidates. It requires substantial resources from EEG and neuroimaging laboratories. The profile and number of patients who may benefit from it are currently unknown. The purpose of this study is to demonstrate the clinical usefulness of source localization in a prospectively analyzed series. One hundred patients (51 male and 49 female patients) with mean age of 31 years (range, 2 to 63 years) and mean duration of refractory epilepsy of 20 years (range, 1 to 49 years) were enrolled consecutively in a presurgical protocol. Ictal EEG was available in 93 patients. ISDM was performed when suitable ictal EEG files were available. The clinical applicability of ISDM was examined in three patients groups: 37 patients in whom ictal EEG recording and MRI were congruent (group I), 30 patients in whom results were not completely congruent but not incongruent (group II), and 26 patients in whom the results were incongruent (group III). ISDM could be performed in 31 of 100 patients: 11 in group I, 8 in group II, and 12 in group III. ISDM influenced decision making in none of the patients in group I, in 4 of 8 patients in group II, and in 10 of 12 patients in group III. Typically, the results of ISDM directed avoiding intracranial EEG recordings in what appeared to be unsuitable candidates for resection by clearly confirming the incongruency between ictal EEG and MRI findings. In this series of 100 presurgical candidates, ictal source localization could be performed in 31% of patients. In 14% of patients, it proved to be a key element in the surgical decision process.     

Extrarolandic electroclinical findings in the evolution of adult-onset Rasmussen's encephalitis

Rasmussen's encephalitis (RE) is a rare immunomediated disorder characterized by unilateral hemispheric atrophy, drug-resistant focal epilepsy, and progressive neurological deficits. Its onset typically occurs in childhood, though it has also been reported in adult age (A-RE) with atypical clinical features. The aim of this study was to describe the electroclinical features in a group of seven patients with A-RE.We retrospectively studied seven women aged 23–43 years (mean: 32.1 years) with a diagnosis of RE according to commonly accepted diagnostic criteria. All the patients were clinically evaluated and underwent prolonged video-EEG monitoring, laboratory investigations, and high-resolution MRI follow-up.All the patients displayed an ictal electroclinical pattern whose evolution varied. We identified an early phase characterized by polymorphic ictal electroclinical manifestations (temporal semiology in five cases, frontal in one, and parietal in the remaining case) and a late phase clinically characterized by viscerosensitive phenomena followed by somatosensitive signs, experiential symptoms, and motor signs in all the cases. In the late phase, the ictal EEG pattern was characterized by monomorphic, pseudorhythmic, repetitive slow-wave theta activity over the frontal and central regions, with ipsilateral propagation and/or secondary spreading to contralateral perisylvian structures. Patients were treated with a combination of AEDs and immunotherapy (steroids and IVIg); epilepsy surgery was performed in 3 cases.Our results show that A-RE is characterized by early and late clinical- and EEG-different features which may reflect a progressive involvement of a specific “extrarolandic” network in the advanced phase of the disease and may suggest that the electroclinical expression of RE varies according to the different stages of the pathological process.