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Masaki Iwasaki, Nobukazu Nakasato, Hiroyoshi Suzuki and Teiji Tominaga

A 34-year-old man presented with intractable temporal lobe epilepsy. Three-tesla magnetic resonance imaging revealed increased T2 signal intensity and volume loss limited to the CA4 region of the right hippocampus. A right anterior temporal lobectomy and amygdalohippocampectomy were performed. Histological examination of the hippocampus disclosed severe neuron loss limited to the CA4 region, consistent with the preoperative imaging, which is a pattern known as endfolium sclerosis. Close inspection of the internal hippocampal anatomy with high-field MR imaging is useful in patients with temporal lobe epilepsy, because endfolium sclerosis may be associated with less chance of seizure freedom after temporal lobectomy.

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Naoki Ikegaya, Akio Takahashi, Takanobu Kaido, Yuu Kaneko, Masaki Iwasaki, Nobutaka Kawahara and Taisuke Otsuki

Surgical treatment of the insula is notorious for its high probability of motor complications, particularly when resecting the superoposterior part. Ischemic damage to the pyramidal tract in the corona radiata has been regarded as the cause of these complications, resulting from occlusion of the perforating arteries to the pyramidal tract through the insular cortex. The authors describe a strategy in which a small piece of gray matter is spared at the bottom of the periinsular sulcus, where the perforating arteries pass en route to the pyramidal tract, in order to avoid these complications. This method was successfully applied in 3 patients harboring focal cortical dysplasia in the posterior insula and frontoparietal operculum surrounding the periinsular sulcus. None of the patients developed permanent postoperative motor deficits, and seizure control was achieved in all 3 cases. The method described in this paper can be adopted for functional preservation of the pyramidal tract in the corona radiata when resecting epileptogenic pathologies involving insular and opercular regions.

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Yutaro Takayama, Naoki Ikegaya, Keiya Iijima, Yuiko Kimura, Norihiro Muraoka, Yuu Kaneko, Tetsuya Yamamoto and Masaki Iwasaki

OBJECTIVE

Intractable epilepsy patients with ulegyria could be candidates for resective surgery. Complete resection of ulegyria in the epileptogenic hemisphere is associated with favorable seizure outcome, although the risk of postoperative functional deficits is higher. The authors evaluated the extent of resection and postsurgical outcomes in epilepsy patients with ulegyria who underwent intracranial electroencephalography (iEEG) monitoring prior to resection to clarify the efficacy of iEEG-guided partial resection of ulegyria.

METHODS

Ten consecutive epilepsy patients with ulegyria (7 males and 3 females, age range at surgery 7–34 years) underwent iEEG prior to resective surgery between 2011 and 2017 with a minimum follow-up of 12 months (range 12–72 months). The diagnosis of ulegyria was based on the typical pattern of cortical atrophy especially at the bottom of the sulcus on MRI. An iEEG study was indicated after comprehensive preoperative evaluations, including high-field MRI, long-term video-EEG, magnetoencephalography, and FDG-PET. The resection planning was based on iEEG analysis. Total lesionectomy was not always performed, as preservation of cortical function was prioritized.

RESULTS

Ulegyria was seen in the occipital and/or parietal lobe in 9 patients and bilaterally in 5 patients. Ictal EEG onset involved the temporal neocortex in 6 patients. Intracranial electrodes were implanted unilaterally in all except 1 patient with bilateral lesions. The extent of MRI lesion was covered by the electrodes. Seizure onset zones (SOZs) and irritative zones (IZs) were identified in all patients. SOZs and IZs were completely resected in 8 patients but were only partially removed in the remaining 2 patients because the eloquent cortices and the epileptogenic zones overlapped. Ulegyria of the epileptogenic side was totally resected in 1 patient. Seizure freedom was achieved in 4 patients, including 3 after partial lesionectomy. Extended resection of the temporal neocortex was performed in 4 patients, although postoperative seizure freedom was achieved only in 1 of these patients. Visual field deficit was seen in 4 patients. Three of 5 patients with bilateral lesions achieved seizure freedom after unilateral resective surgery.

CONCLUSIONS

Intracranial EEG–guided partial lesionectomy provides a reasonable chance of postoperative seizure freedom with a lower risk of functional deficits. Patients with bilateral ulegyria should not be excluded from consideration as surgical candidates.

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Tomohiro Kawaguchi, Toshihiro Kumabe, Ryuta Saito, Masayuki Kanamori, Masaki Iwasaki, Yoji Yamashita, Yukihiko Sonoda and Teiji Tominaga

Object

Maximum resection of gliomas with minimum surgical complications usually leads to optimum outcomes for patients. Radical resection of insulo-opercular gliomas is still challenging, and selection of ideal patients can reduce risk and obtain better outcomes.

Methods

This retrospective study included 83 consecutively treated patients with newly diagnosed gliomas located at the insulo-opercular region and extending to the sylvian fissure around the primary motor and somatosensory cortices. The authors selected 4 characteristics as surgical indicators: clear tumor boundaries, negative enhancement, intact lenticulostriate arteries, and intact superior extremity of the central insular sulcus.

Results

Univariate analysis showed that tumors with clear boundaries were associated with higher rates of gross-total resection than were tumors with ambiguous boundaries (75.7% vs 19.6%). Tumors with negative enhancement compared with enhanced tumors were associated with lower frequency of tumor progression (32.0% vs 81.8%, respectively) and lower rates of surgical complications (14.0% vs 45.5%, respectively). Tumors with intact lenticulostriate arteries were associated with higher rates of gross-total resection than were tumors with involved lenticulostriate arteries (67.3% vs 11.8%, respectively). Tumors with intact superior extremity of the central insular sulcus were associated with higher rates of gross-total resection (57.4% vs 20.7%, respectively) and lower rates of surgical complications (18.5% vs 41.4%, respectively) than were tumors with involved anatomical structures. Multivariate analysis showed that clear tumor boundaries were independently associated with gross-total resection (p < 0.001). Negative enhancement was found to be independently associated with surgical complications (p = 0.005), overall survival times (p < 0.001), and progression-free survival times (p = 0.004). Independent associations were also found between intact lenticulostriate arteries and gross-total resection (p < 0.001), between intact lenticulostriate arteries and progression-free survival times (p = 0.026), and between intact superior extremity of the central insular sulcus and gross-total resection (p = 0.043). Among patients in whom all 4 indicators were present, prognosis was good (5-year survival rate 93.3%), resection rate was maximal (gross-total resection 100%), and surgical complication rate was minimal (6.7%). Also among these patients, overall rates of survival (p = 0.003) and progression-free survival (p = 0.005) were significantly higher than among patients in whom fewer indicators were present.

Conclusions

The authors propose 4 simple indicators that can be used to identify ideal candidates for radical resection of insulo-opercular gliomas, improve the outcomes, and promote maximum resection without introducing neurological complications. The indicators are clear tumor boundaries, negative enhancement, intact lenticulostriate arteries, and intact superior extremity of the central insular sulcus.

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Masaki Iwasaki, Mitsugu Uematsu, Yuko Sato, Tojo Nakayama, Kazuhiro Haginoya, Shin-ichiro Osawa, Hisashi Itabashi, Kazutaka Jin, Nobukazu Nakasato and Teiji Tominaga

Object

Corpus callosotomy is usually intended to alleviate—not to achieve total control of—epileptic seizures. A few patients experience complete seizure control after callosotomy, but the associated clinical factors are unknown. The object of this study was to investigate clinical factors associated with long-term seizure remission after total corpus callosotomy in patients with infantile or early childhood onset epilepsy.

Methods

Thirteen consecutive patients with infantile or early childhood onset epilepsy underwent 1-stage total corpus callosotomy for alleviation of seizures. Their age at surgery ranged from 1 year and 5 months to 24 years (median 7 years). Eleven patients had West syndrome at the onset of disease, and the other 2 had Lennox-Gastaut syndrome. All patients suffered from spasms, axial tonic seizures, or atonic seizures. Six patients had proven etiology of epilepsy, including tuberous sclerosis, polymicrogyria, trauma, and Smith-Magenis syndrome. The association between postoperative seizure freedom and preoperative factors including age at surgery, no MRI abnormalities, proven etiology, and focal electroencephalographic epileptiform discharges was examined.

Results

Postoperative seizure freedom was achieved in 4 of 13 patients for a minimum of 12 months. All 4 patients had no MRI abnormalities and no identified etiology. None of the 8 patients with MRI abnormality, 6 patients with known etiology of epilepsy, or 4 patients aged older than 10 years at surgery achieved seizure freedom. Two of the 7 patients with focal electroencephalographic abnormalities became seizure free. Absence of MRI abnormalities was significantly associated with postoperative seizure freedom (p < 0.01).

Conclusions

Complete seizure remission is achieved after total corpus callosotomy in a subgroup of patients with intractable epilepsy following West syndrome or Lennox-Gastaut syndrome. One-stage total corpus callosotomy at a young age may provide a higher rate of seizure freedom, especially for patients with no MRI abnormalities and no identified etiology of epilepsy.

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Kiyoshi Gomi, Mio Tanaka, Mariko Yoshida, Susumu Ito, Masaki Sonoda, Fuminori Iwasaki, Tetsu Niwa, Noriko Aida, Hisato Kigasawa and Yukichi Tanaka

The authors report on a case of histiocytic sarcoma (HS) in a pediatric patient presenting with a solitary tumor in the cerebellum, with the aim of providing insight into primary HS in the CNS, which is especially rare. A 17-month-old Japanese girl presented with a 2-week history of progressive gait disturbance. Brain MRI revealed a 4.7 × 4.3 × 4.3–cm well-demarcated solitary mass in the right hemisphere of the cerebellum, initially suggestive of medulloblastoma, ependymoma, or anaplastic astrocytoma. On intraoperative inspection the cerebellar tumor showed intensive dural attachment and was subtotally removed. Histological and immunohistochemical findings were consistent with HS. The patient subsequently received chemotherapy, and her preoperative neurological symptoms improved. Primary HS in the CNS usually demonstrates an aggressive clinical course and is currently considered to have a poor prognosis. The possibility of this rare tumor should be included in the differential diagnosis of localized cerebellar tumors in the pediatric age group.

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Akihito Minamide, Munehito Yoshida, Hiroshi Yamada, Yukihiro Nakagawa, Masaki Kawai, Kazuhiro Maio, Hiroshi Hashizume, Hiroshi Iwasaki and Shunji Tsutsui

Object

The authors undertook this study to document the clinical outcomes of microendoscopic laminotomy, a minimally invasive decompressive surgical technique using spinal endoscopy for lumbar decompression, in patients with lumbar spinal stenosis (LSS).

Methods

A total of 366 patients were enrolled in the study and underwent microendoscopic laminotomy between 2007 and 2010. Indications for surgery were single- or double-level LSS, persistent neurological symptoms, and failure of conservative treatment. Microendoscopy provided wide visualization through oblique lenses and allowed bilateral decompression via a unilateral approach, through partial resection of the base of the spinous process, thereby preserving the supraspinous and interspinous ligaments and contralateral musculature. Clinical symptoms and signs of low-back pain were evaluated prior to and following surgical intervention by applying the Japanese Orthopaedic Association (JOA) scoring system, Roland-Morris Disability Questionnaire (RMDQ), Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ), and 36-Item Short Form Health Survey (SF-36). These items were evaluated preoperatively and 2 years postoperatively.

Results

Effective circumferential decompression was achieved in all patients. The 2-year follow-up evaluation was completed for 310 patients (148 men and 162 women; mean age 68.7 years). The average recovery rate based on the JOA score was 61.3%. The overall results were excellent in 34.9% of the patients, good in 34.9%, fair in 21.7%, and poor in 8.5%. The mean RMDQ score significantly improved from 11.3 to 4.8 (p < 0.001). In all categories of both JOABPEQ and SF-36, scores at 2 years' follow-up were significantly higher than those obtained before surgery (p < 0.001). Twelve surgery-related complications were identified: dural tear (6 cases [1.9%]), wrong-level operation (1 [0.3%]), transient neuralgia (4 [1.3%]), and infection (1 [0.3%]). All patients recovered, and there were no serious postoperative complications.

Conclusions

Microendoscopic laminotomy is a safe and very effective minimally invasive surgical technique for the treatment of degenerative LSS.

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Hitoshi Fukuda, Alexander I. Evins, Koichi Iwasaki, Itaro Hattori, Kenichi Murao, Yoshitaka Kurosaki, Masaki Chin, Philip E. Stieg, Sen Yamagata and Antonio Bernardo

OBJECTIVE

Occipital artery–posterior inferior cerebellar artery (OA-PICA) bypass is a technically challenging procedure for posterior fossa revascularization. The caudal loop of the PICA is considered the optimal site for OA-PICA anastomosis, however its absence can increase the technical difficulty associated with this procedure. The use of the far-lateral approach for accessing alternative anastomosis sites in OA-PICA bypass in patients with absent or unavailable caudal loops of PICA is evaluated.

METHODS

A morphometric analysis of OA-PICA bypass with anastomosis on each segment of the PICA was performed on 5 cadaveric specimens through the conventional midline foramen magnum and far-lateral approaches. The difficulty level associated with anastomoses at each segment was qualitatively assessed in each approach for exposure and maneuverability by multiple surgeons. A series of 8 patients who underwent OA-PICA bypass for hemodynamic ischemia or ruptured dissecting posterior fossa aneurysms are additionally reviewed and described, and the clinical significance of the caudal loop of PICA is discussed.

RESULTS

Anastomosis on the caudal loop could be performed more superficially than on any other segment (p < 0.001). A far-lateral approach up to the medial border of the posterior condylar canal provided a 13.5 ± 2.2–mm wider corridor than the conventional midline foramen magnum approach, facilitating access to alternative anastomosis sites. The far-lateral approach was successfully used for OA-PICA bypass in 3 clinical cases whose caudal loops were absent, whereas the midline foramen magnum approach provided sufficient exposure for caudal loop bypass in the remaining 5 cases.

CONCLUSIONS

The absence of the caudal loop of the PICA is a major contributing factor to the technical difficulty of OA-PICA bypass. The far-lateral approach is a useful surgical option for OA-PICA bypass when the caudal loop of the PICA is unavailable.

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Naoki Ikegaya, Masaki Iwasaki, Yuu Kaneko, Takanobu Kaido, Yuiko Kimura, Tetsuya Yamamoto, Noriko Sumitomo, Takashi Saito, Eiji Nakagawa, Kenji Sugai, Masayuki Sasaki, Akio Takahashi and Taisuke Otsuki

OBJECTIVE

Cognitive risk associated with insular cortex resection is not well understood. The authors reviewed cognitive and developmental outcomes in pediatric patients who underwent resection of the epileptogenic zone involving the insula.

METHODS

A review was conducted of 15 patients who underwent resective epilepsy surgery involving the insular cortex for focal cortical dysplasia, with a minimum follow-up of 12 months. The median age at surgery was 5.6 years (range 0.3–13.6 years). Developmental/intelligence quotient (DQ/IQ) scores were evaluated before surgery, within 4 months after surgery, and at 12 months or more after surgery. Repeated measures multivariate ANOVA was used to evaluate the effects on outcomes of the within-subject factor (time) and between-subject factors (resection side, anterior insular resection, seizure control, and antiepileptic drug [AED] reduction).

RESULTS

The mean preoperative DQ/IQ score was 60.7 ± 22.8. Left-side resection and anterior insular resection were performed in 9 patients each. Favorable seizure control (International League Against Epilepsy class 1–3) was achieved in 8 patients. Postoperative motor deficits were observed in 9 patients (permanent in 6, transient in 3). Within-subject changes in DQ/IQ were not significantly affected by insular resection (p = 0.13). Postoperative changes in DQ/IQ were not significantly affected by surgical side, anterior insular resection, AED reduction, or seizure outcome. Only verbal function showed no significant changes before and after surgery and no significant effects of within-subject factors.

CONCLUSIONS

Resection involving the insula in children with impaired development or intelligence can be performed without significant reduction in DQ/IQ, but carries the risk of postoperative motor deficits.