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SUMMARYPurpose: In patients with drug-refractory focal epilepsy, nonlesional magnetic resonance imaging (MRI) or discordant data of presurgical standard investigations leads to failure generating a sufficient hypothesis for electrode implantation or epilepsy surgery. The seizure-onset zone can be further investigated by subtraction ictal singlephoton emission computed tomography (SPECT) coregistered to MRI (SISCOM). This is an observational study of a large consecutive cohort of patients undergoing prospective SISCOM to generate hypothesis for electrode implantation or site of epilepsy surgery. Methods: One hundred seventy-five consecutive patients undergoing presurgical evaluation with either nonlesional MRI or discordant data of standard investigations preventing the generation of hypothesis for seizure onset were evaluated with SISCOM. Results were compared to gold standard for seizure onset detection, either electrocorticography (ECoG) and/or postoperative outcome. Key Findings: One hundred thirty patients had successful SPECT injection. Hypothesis for electrode implantation/ site of surgery was generated in 74 patients. Forty patients had gold standard comparison. Twenty-eight patients underwent resective surgery. SISCOM was concordant to site of surgery in 82%. An additional 12 patients underwent invasive EEG monitoring but were not suitable for surgery. SISCOM was concordant multifocal in 75%. Two years postsurgical follow-up of 26 patients showed favorable outcome in 22 (Engel class I and class II). Significance: SISCOM is a highly valuable diagnostic tool to localize the seizure-onset zone in nonlesional and extratemporal epilepsies. Outcome in this patient group was unexpectedly good, even in patients with nonlesional MRI. The high correlation with ECoG and site of successful surgery is a strong indicator that outcome prediction in this patient group should be adapted accordingly, which may encourage more patients to undergo electrode implantation and subsequent successful surgery. Statistical analysis showed that SISCOM with shorter duration of seizures, focal seizures, and lesional MRI was more likely to generate implantation hypothesis. KEY WORDS: Epilepsy, Neurosurgery, Human, SPECT, MRI, EEG.Localization of the epileptogenic zone in patients with drug-refractory partial epilepsy undergoing presurgical evaluation is challenging. Standard investigations include epilepsy-dedicated magnetic resonance imaging (MRI) brain, simultaneous video-electroencephalography (EEG) long-term monitoring, and neuropsychological testing. However, in a considerable number of patients these tests might not exactly reveal the epileptogenic zone. In those cases the test results might be used to generate a hypothesis of intracranial electrode placement to further investigate the seizure-onset zone. Particularly in extratemporal epilepsies and patients with normal MRI results it is more likely that no conclusive hypothesis for seizure-onset zone can be generated and further tests are necessary.Ictal single-photon emission c...

Summary:Purpose: To analyze the role of selective middle cerebral artery (MCA) Wada tests in the presurgical workup of patients with drug-resistant focal epilepsies.Methods: Twenty MCA Wada test procedures were performed to identify eloquent cortex (a) in nine patients with hemispheric lesions involving the motor cortex (connatal MCA infarct, n ‫ס‬ 5; unilateral cortical dysplasia, n ‫ס‬ 3; Rasmussen encephalitis, n ‫ס‬ 1), (b) five patients with circumscribed neoplastic or nonneoplastic lesions adjacent to the motor cortex or classic language areas, and (c) for purely electrophysiologic reasons, in two patients with electrical status epilepticus in sleep (ESES). Sodium amobarbital and [ 99m Tc]-HMPAO were simultaneously injected via a microcatheter into the distal M1 segment (n ‫ס‬ 7), the inferior MCA trunk (n ‫ס‬ 3), or into MCA branches (n ‫ס‬ 10).Results: Co-registered single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI; n ‫ס‬ 18) showed that sodium amobarbital did not reach the target area in three procedures. Temporary neurologic deficits occurred in 12 procedures. Eleven patients were operated on with the following surgical approaches: functional hemispherectomy, n ‫ס‬ 3; partial or extended lesionectomy, n ‫ס‬ 4; anterior temporal lobectomy, n ‫ס‬ 1; and multiple subpial transsections, n ‫ס‬ 3. Seizure freedom (Engel class I) was achieved in five patients.Conclusions: Selective MCA Wada tests can contribute to risk assessment concerning postsurgical motor deficits before functional hemispherectomy. Other indications are less clear: The identification of language areas is targeted primarily by electrical-stimulation mapping after subdural grid implantations, and selective MCA Wada tests in ESES patients yet have to be validated in larger patient groups.

Summary:Purpose: To evaluate whether limbic system abnormalities associated with Ammon's horn sclerosis alter seizure outcome after selective amgydalohippocampectomy.Methods: In 45 patients with unilateral mesial temporal lobe epilepsy, histologically proven Ammon's horn sclerosis, and uneventful postoperative course, volumes of the hippocampus, hemisphere, amygdala, entorhinal cortex, mamillary body, and fornix were measured by using a T 1 -weighted 3-D gradient-echo sequence with roughly isotropic (1.17 × 1.17 × 1-mm) voxels. In addition, signal intensity of the hippocampus and of the temporal lobe white matter was visually assessed and graded on a coronal T 2 -weighted fast-spin-echo sequence with 2-mm-thick slices. Volumetric measurements and visual analysis were compared between seizure-free and non-seizure-free patients examined 12 months after surgery.Results: Hippocampal, hemispheric, entorhinal cortex, mamillary body, and fornix volumes, but not amygdalar volumes, were significantly smaller on the operated-on than on the nonoperated-on side and significantly smaller in patients compared with controls. No volume differences of the hippocampus, hemisphere, amygdala, entorhinal cortex, mamillary body, and fornix existed between seizure-free (Engel class IA) and non-seizurefree patients (Engel class IB-IV). Increased temporal lobe white matter signal was observed in 15 patients but did not alter seizure outcome.Conclusions: Limbic system abnormalities are not a surrogate marker to predict postsurgical seizure outcome in patients with unilateral Ammon's horn sclerosis.

IntroductionIn idiopathic scoliosis, biomechanical, biological and clinical views confirm that the deformity in the sagittal plane is of primary pathogenetic significance [8]. A fixed lordotic section causes rotation and increased lateral curvature of the spine as a result of the asymmetry in the coronal plane [2]. Various studies confirm that lordosis of the thoracic vertebrae is characteristic for idiopathic scoliosis in adolescents [3,8,11].The scoliotic deformity in the follow-up of scoliosis patients is usually examined using anteroposterior (AP) radiographs. An additional lateral radiograph, while providing additional information, would result in increased X-ray exposure. On the lateral X-ray projection, the mean entrance surface radiation dose for the thoracic spine is 6.1 mGy and for the lumbar spine 6.7 mGy [1]. However, monitoring the scoliotic deformity on a lateral view can provide additional information, useful, for example, for assessing the effect of brace treatment in two planes or determining further prognostic factors.The technique of MR total spine imaging developed by the authors allows visualization of the whole spine in the coronal and sagittal planes [4,5]. The present study aimed to establish whether MR total spine imaging is a reliable and useful method to image scoliosis in the sagittal plane. AbstractThe purpose of the present study was to introduce a new magnetic resonance imaging (MRI) procedure showing the whole spine in a coronal and sagittal plane, and to study the assessment of sagittal Cobb angle measurements using this technique. Prospectively we studied 32 patients (average age 14.8 years) with idiopathic scoliosis (mean thoracic Cobb angle 33°on radiograph) and 18 patients (average age 14.5 years) without scoliosis. The MRI investigation was carried out in a standard supine position. The cervical and upper thoracic spine and the lower thoracic and lumbar spine were measured on a 1.5-T Gyroscan ACS-NT Powertrak 6000 system. An algorithm was developed to combine the results of the cranial and caudal scans into a coronal and a sagittal image of the whole spine (MR total spine imaging). Measurement of the sagittal Cobb angle conducted ten times by four independent investigators revealed an intraobserver variance of 1.6°and an interobserver variance of 1.8°. In the group with scoliosis the mean sagittal Cobb angle from T4 to T12 was 12°(range -3°to 24°) and in the group without scoliosis 22°(range 16°to 30°), which was a significant difference. MR total spine imaging makes it possible to image scoliosis in the sagittal plane. On these MR projections, idiopathic thoracic scoliosis was identified by a reduced sagittal Cobb angle. MR total spine imaging would allow monitoring of scoliosis in the sagittal plane, which can reveal relevant clinical data without radiation exposure.