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BACKGROUND AND OBJECTIVES: Surgical resections for lesions associated with intractable temporal lobe epilepsy (TLE) offers good seizure outcomes.However, the necessity of hippocampectomy in addition to lesionectomy is controversial, especially when the hippocampus is not involved by the lesion. Lesionectomy alone, preserving the hippocampus by an appropriate surgical approach, might offer good seizure outcomes while maintaining neurocognitive function. In the present study, the aims were to examine the surgical strategy for lesions associated with TLE and to present how to select surgical approaches to preserve the hippocampus. METHODS: A total of 22 consecutive lesion-associated TLE patients who underwent lesionectomy alone were retrospectively reviewed. The surgical approach, transsylvian, transorbital, subtemporal, supracerebellar transtentorial, or transcortical approach, was selected based on the location of the lesion. Postoperative seizure outcomes were classified by the Engel classification. Neurocognitive outcomes were assessed before and after surgery if possible. The pathology, the extent of resection, and lesion recurrence were reviewed. RESULTS: The transsylvian approach was selected in six patients, the transorbital approach in one patient, the subtemporal approach in three patients, the supracerebellar transtentorial approach in five patients, and the transcortical approach in seven patients. Eighteen of 22 (81.8 %) patients achieved Engel's class I or II good seizure outcomes. No patients had neurocognitive deterioration after surgery. Twelve patients had various types of brain tumors, and ten patients had non-tumorous lesions. Gross total resection was achieved in 21 patients. All patients had no recurrence. CONCLUSION: For patients with lesion-associated TLE, lesionectomy alone by the appropriate surgical approach offers satisfactory seizure outcomes while preserving hippocampus.

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PURPOSE: Coherence analysis in electroencephalography (EEG) allows measurement of the degree of consistency of amplitude between pairs of electrodes. Theoretically, disconnective epilepsy surgery should decrease coherence between corresponding areas. The study aimed to evaluate postoperative changes in interhemispheric coherence values after corpus callosotomy (CC). METHODS: Non-lesional, drug-resistant, generalized epilepsy patients who underwent total CC were retrospectively collected. To evaluate coherence, we divided the scalp interictal EEG into "baseline" and "discharge" states after excluding periods with artifacts. Interhemispheric coherence values were obtained between eight pairs of symmetrically opposite scalp electrodes in six different frequency bands. We analyzed both pre- and postoperative EEG sessions and calculated the percentage of difference (POD) in coherence values. RESULTS: We collected 13 patients and analyzed 2496 interhemispheric coherence values. Preoperative coherence values differed significantly between baseline and discharge states (p = 0.0003), but postoperative values did not (p = 0.11). For baseline state, coherence values were decreased after CC and median POD was - 22.3% (p < 0.0001). Delta frequency showed the most decreased POD (-44.3%, p = 0.0009). Median POD was lowest in the Fp1-Fp2 pair of electrodes. For discharge state, coherence values were decreased after CC and median POD was - 24.7% (p < 0.0001). Delta frequency again showed the most decreased POD (-55.9%, p = 0.0016). Median POD was lowest in the F7-F8 pair. CONCLUSION: After total CC, interhemispheric coherence decreased significantly in both baseline and discharge states. The most decreased frequency band was the delta band, which may be used as a representative frequency band in future studies.

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Anterior callosotomy to about 20 mm has been considered relatively safe empirically. The present study aimed to compare cognitive function before and after resection of tumors in the anterior part of the lateral ventricle. We analyzed 6 patients with intraventricular tumors located in the anterior horn or body of the lateral ventricle who underwent surgical excision via interhemispheric transcallosal approach at Osaka City University Hospital between March 2015 and August 2018. And clinical and imaging studies, neuropsychological function using MMSE, WAIS-III and WMS-R and surgical complications were retrospectively reviewed based on the medical records at our institution. As a result, 4 patients achieved gross total resection of the tumor and 2 patients achieved subtotal resection. 4 patients showed hydrocephalus, which disappeared in each case within 6 months after tumor resection. Mean length of callosotomy was 16.9 mm (range, 15.5-26.1 mm). One patient showed postoperative transient deficits including aphasia, microphonia, ballism in all extremities and hemiplegia, and another patient experienced subjective difficulty when talking. These symptoms disappeared within 3 months after tumor resection. Scores from the MMSE and WAIS-III showed no significant postoperative deterioration. Performance intelligence quotient (P = 0.04), full intelligence quotient (P = 0.04) and perceptual organization (P = 0.03) of WAIS-III were significantly improved after surgery compared with preoperatively. In conclusion, anterior corpus callosotomy of about 20 mm for intraventricular tumor in the anterior horn or body of the lateral ventricle might have little effect on cognitive function in the chronic phase, although the influence of hydrocephalus cannot be ignored.

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STUDY DESIGN: Clinical case series. OBJECTIVE: To present a surgical technique and results of posterior direct reduction of lateral atlantoaxial joints for rigid pediatric atlantoaxial subluxation (AAS) using a fulcrum lever technique. SUMMARY OF BACKGROUND DATA: The surgical treatment of pediatric rigid AAS is still technically challenging. Several factors contribute to the surgical difficulty, such as small vertebrae, incomplete bone formation, dysplasia, the difficulty of reduction and external fixation are considered as a surgical daunting challenge. Herein, the surgical technique of posterior direct reduction of lateral atlantoaxial joints for rigid pediatric AAS using a fulcrum lever technique is presented. METHODS: This retrospective study included 10 pediatric patients with rigid AAS who underwent posterior direct reduction of bilateral C1/2 facet joints via a fulcrum lever technique. The indication for surgery was the presence of neurological symptoms and spinal cord atrophy with an intramedullary high signal at the C1 level on T2-weighted magnetic resonance (MR) images. The surgical procedure consisted of three steps: (1) opening and distraction of the C1/2 facet joints and placement of tricortical bone as a spacer and fulcrum; (2) placement of C1 and C2 screws; and finally, (3) compression between the C1 posterior arch and C2 lamina and constructing C1/2 fusion. All patients underwent the neurological and radiological evaluations before and after surgery. RESULTS: Eight of 10 patients demonstrated genetic disorders, either Down syndrome or chondrodysplasia punctate. Besides, all cases documented congenital anomaly of the odontoid process. Bilateral C1 lateral mass screws were successfully placed in all cases. No evidence of postoperative neurovascular complications. Radiological evaluation showed the corrections and bony fusions of C1/2 facet joint in all cases. CONCLUSION: The fulcrum lever technique for rigid pediatric AAS can be one of the effective surgical solutions to this challenging pediatric spinal disorder. LEVEL OF EVIDENCE: 4.

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Calcifying pseudoneoplasms of the neuraxis (CAPNON) are rare pathological lesions that can present anywhere in the central nervous system. Symptoms vary depending on the location, though they often include seizures, especially in intracranial and supratentorial lesions. A case of intracranial supratentorial CAPNON presenting with drug-resistant left temporal lobe epilepsy is reported. The patient had a history of drug-resistant focal seizures for over 36 years. The lesion was located in the left mesial temporal lobe, but hippocampal sclerosis and hippocampal invasion were not apparent. The lesion was removed without hippocampectomy, and the patient has been seizure-free for one year.

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BACKGROUND: Schwannomas not related to cranial nerves are rare. Here, we present a case of a schwannoma that originated from the falx cerebri and review reported cases in the literature. CASE DESCRIPTION: A 36-year-old male experienced generalized seizures following right hemiparesis predominantly in his lower extremity. Magnetic resonance imaging revealed a round tumor attached to the falx cerebri on the left side. Radiologically, the tumor appeared to be a falx meningioma. We performed gross total removal of the tumor. Pathology showed a schwannoma that originated from the falx cerebri. Right hemiparesis disappeared soon after surgery. CONCLUSION: Although distinguishing a schwannoma of the falx cerebri from a falx meningioma and metastasis is difficult preoperatively, inclusion of schwannoma of the falx cerebri in the differential diagnosis is important, especially when the patient is relatively young and/or the tumor lacks a dural tail sign.

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OBJECTIVE: We reviewed our experience with salvage surgery following failed gamma knife radiosurgery (GKS) for vestibular schwannomas. METHODS: The study comprised 18 patients with unilateral vestibular schwannomas. The median prescribed radiation dose was 12 Gy (range, 10-12.5 Gy). Nine patients had regrowth after GKS, and 9 had regrowth after surgical resection plus GKS. The median interval between GKS and surgical resection was 26 months (range: 4-66 months). The maximum tumor diameter of all patients ranged 25-43 mm (median 35.5 mm). The tumor was removed subtotally in 2 patients and partially in the other 16 patients. The median follow-up period after surgical resection was 60 months (range: 12-144 months). RESULTS: Among the 17 patients with preoperative preserved facial nerve function (House-Brackmann [HB] grade I-III), 14 of them (82%) had an HB score of grade I at the last follow-up. There were no differences in facial nerve preservation between those with failed GKS and those with failed GKS plus surgery (78% vs. 100%, P = 0.156). At the post-salvage surgery follow-up, the residual tumor was unchanged or decreased in 15 patients (83%) and increased in 3 patients (17%). CONCLUSION: A surgical indication after GKS should be carefully considered because of the natural regression of transient tumor expansion with time, and surgical resection is limited to subtotal or partial removal for functional preservation. Careful follow-up is necessary in patients with tumor regrowth several years after GKS due to delayed radiation effects.

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