Retained Intracerebral Depth Electrode after Stereotactic Electroencephalography Monitoring: A Case Report.

Stereotactic electroencephalography (SEEG) is an increasingly popular surgical modality for localizing the epileptogenic zone. Robot-guided stereotactic electrode placement has been covered in Japan by National Health Insurance since 2020. However, several surgical devices, such as the anchor bolt (a thin, hollow, metal shaft that serves as a guide screw or fixing for each electrode), have not been approved. A 14-year-old female who underwent SEEG for intractable epilepsy and required additional surgery to remove a retained depth electrode from the skull after the SEEG monitoring was finished. She had uncontrolled focal seizures consisting of nausea and laryngeal constriction at the onset. After a comprehensive presurgical evaluation, robot-guided stereotactic electrode implantation was performed to evaluate her seizures by SEEG. Nine depth electrodes were implanted through the twist drill hole. The electrodes were sutured to her skin for fixation without anchor bolts. When we attempted to remove the electrodes after 8 days of SEEG monitoring, one of the electrodes was retained. The retained electrode was removed through an additional skin incision and a small craniectomy under general anesthesia. We confirmed narrowing of the twist drill hole pathway in the internal table of the skull due to osteogenesis, which locked the electrode. This complication might be avoided if an anchor bolt had been used. This case report prompts the approval of the anchor bolts to avoid difficulty in electrode removal. Moreover, approval of a depth electrode with a thinner diameter and more consistent hardness is needed.

[Preoperative Simulation in Epilepsy Surgery].

In patients with intractable epilepsy, seizure focus resection can yield favorable seizure outcomes. First, the localization of the seizure focus is estimated by noninvasive methods such as magnetic resonance imaging(MRI), video-electroencephalography(EEG)monitoring, nuclear medicine examinations, magnetoencephalography, and neuropsychological tests. A subgroup of patients may require additional information obtained from the intracranial EEG. There are two major methods for intracranial EEG: intracranial EEG with subdural grid electrodes(SDG)and stereotactic electroencephalography. If the estimated seizure focus overlaps with the eloquent area in noninvasive studies, the margin and extent of the resection are determined by the results of intracranial EEG and functional mapping by electrical cortical stimulation. Herein, we present a case of lobe epilepsy with subtle MRI lesions in the superior temporal sulcus of the language-dominant hemisphere. The results of the SDG and functional mapping showed that the seizure onset zone overlapped with the language area. Resection of the middle and inferior temporal gyri and multiple transections of the language area resulted in Engel IIB seizure outcomes. In such cases, a thorough preoperative simulation is required to determine the best resection margin for seizure control and functional preservation.

Hippocampal volumetry to determine the resection side in patients with intractable non-lesional bilateral temporal lobe epilepsy.

Bilateral Temporal lobe epilepsy (BTLE) cases may result in poor surgical outcomes due to the difficulty in determining/localizing the epileptogenic zone. In this study, we investigated whether hippocampal volume (HV) would be useful for the determination of the best resection side in BTLE. Eighteen cases of BTLE determined by a scalp video electroencephalogram (SVEEG) underwent resection via intracranial electroencephalography (IVEEG). Patients with lesions or semiologically determined focus lateralization were excluded. In addition to SVEEG, an epilepsy protocol magnetic resonance imaging (MRI) including hippocampus fluid-attenuated inversion recovery (FLAIR) and HV, 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), single-photon emission computed tomography with 123I-iomazenil (IMZ-SPECT), and magnetoencephalography (MEG) were performed for the preoperative evaluation of the lateralization. The resection side was determined based on the IVEEG results, and the seizure outcome at two years postoperatively was classified as either a well-controlled seizure outcome (Engel class I), or residual (classes II-V). We used a Fisher's exact test to compare the concordance between the determination of the epileptic focus by each modality and the resected side where patients achieved a well-controlled seizure outcome. Seizures were well controlled in 9/18 patients after surgery. Eight out of 11 patients (72.7%), in whom the HV results (strongly atrophic side) and the resection side were matched, had well-controlled seizure outcomes (P = 0.0498). The concordance of other presurgical evaluations with the resection side was not significantly related to a well-controlled seizure outcome. HV may be a useful method to determine the optimal resection side of the epileptic focus/foci in cases of suspected BTLE.

Comparison of seizure outcomes and ADL recovery period after total or anterior corpus callosotomy in adolescent and young adults with drop attacks and severe mental retardation.

PURPOSE: The aim of this study was to evaluate seizure outcomes and postoperative neurologic complications, with an emphasis on the recovery period of activities of daily living (ADL) between anterior partial corpus callosotomy (ACC) and total corpus callosotomy (TCC) in adolescent and young adults with drop attacks and severe mental retardation. METHODS: We retrospectively reviewed the clinical records of consecutive patients with intractable epilepsy who underwent corpus callosotomy (CC) for drop attacks between 2010 and 2019 in the Department of Neurosurgery, Hiroshima University hospital, with a minimum follow-up of one year. Inclusion criteria of this study were 1) age at surgery: 11-39 years, 2) preoperative intelligence quotient <35, and 3) preoperative Barthel index (BI) ≥30. Postoperative full ADL recovery was defined as complete recovery to the preoperative BI score. We compared the postoperative days required for 1) recovery of oral intake ability, 2) discharge from our hospital, 3) returning home from any hospital, 4) returning home with full ADL recovery, and 5) seizure outcomes in patients with ACC versus those with one-stage TCC. RESULTS: Ten patients with ACC and 14 patients with one-stage TCC met the inclusion criteria. The period for returning home with full ADL recovery was a median of 15 days (range 9-45 days) after ACC, while the median was 21.5 days (range 10-62 days) after one-stage TCC (p = 0.2904). Although there was a tendency for the ADL recovery period to be longer after one-stage TCC, there were no statistically significant differences in any category of ADL recovery period. Eleven of 14 (78.6 %) patients who received a one-stage TCC showed favorable seizure outcomes, with drop attack cessation, which was significantly better than 1 of 10 (10 %) patients with ACC (p = 0.0009). CONCLUSIONS: From the viewpoint of postoperative seizure outcomes and ADL recovery period, one-stage TCC is preferred to ACC for adolescent and young adults with severe mental retardation.

Preservation of Memory Despite Unresected Contralateral Hippocampal Volume Loss After Resection of Hippocampal Sclerosis in Seizure-Free Patients.

OBJECTIVE: To determine postoperative long-term changes of hippocampal volume (HV) correlating with cognitive functions in patients who underwent surgery for hippocampal sclerosis with postoperative freedom from seizures. METHODS: We studied 1.5T magnetic resonance imaging before and after surgery in 24 patients (mean ± SD age, 36.9 ± 11.0 years) with hippocampal sclerosis. We performed serial magnetic resonance imaging at 6 months to 1 year, 1-2 years, 2-3 years, and 3-5 years postoperatively. We compared HVs of 24 patients with HVs of 14 age-matched control subjects. We analyzed correlations between consecutive HVs and seizure duration and age at surgery. We compared consecutive changes in HVs between dominant and nondominant hemispheres with concurrent cognitive functions. RESULTS: Preoperative HVs of unresected contralateral hippocampus were significantly smaller than HVs of control subjects (P < 0.01). Unresected contralateral HV changes compared with preoperative HVs were -3.6% ± 6.9%, -2.3% ± 8.5%, -3.6% ± 10.2% (P < 0.05), and -5.0% ± 9.5% (P < 0.05) at consecutive postoperative periods. Largest change in HVs at 3-5 years was significantly correlated with older age at surgery (P < 0.05). Unresected contralateral dominant 14 HVs remained consistently smaller than nondominant 10 HVs up to 5 years with statistical significance (P < 0.05). Verbal memory was preserved in 14 patients with unresected contralateral smaller dominant hippocampus. CONCLUSIONS: In seizure-free patients after hippocampal sclerosis resection , unresected contralateral HV significantly declined with older age at surgery. Visual memory was preserved regardless of side and volume loss. Despite significantly reduced HVs, verbal memory was preserved with the unresected contralateral dominant hippocampus. Earlier surgical intervention may have lower potential risk for memory decline secondary to postoperative HV loss.

Anti-seizure effect and neuronal activity change in the genetic-epileptic model rat with acute and chronic vagus nerve stimulation.

BACKGROUND: VNS showed time-dependent anti-seizure effect. However, the precise mechanism of VNS in acute and chronic anti-seizure effect has not been fully elucidated. Noda epileptic rat (NER) is genetic epilepsy model rat which exhibits spontaneous generalized tonic-clonic seizure (GTC) approximately once per 30 h and frequent dialeptic seizure (DS). We performed acute and chronic VNS on NER to focus on the acute and chronic anti-epileptic effect and neuronal activity change by VNS. METHODS: We performed acute VNS (2 h) on 22 NERs (VNS, n = 11, control, n = 11), then subsequently administered chronic (4 weeks) VNS on 10 of 22 NERs (VNS n = 5, control n = 5). We evaluated the acute and chronic anti-seizure effects of VNS on GTC and DS by behavioral and electroencephalographical observation (2 h every week). We carried out double immunofluorescence for biomarkers of short-term (c-Fos) and long-term (ΔFosB) neuronal activation to map regions in the brain that were activated by acute (VNS n = 6, control n = 6) or chronic VNS (VNS n = 5, control n = 5). Furthermore, we performed chronic VNS (4 w) on 12 NERs (VNS n = 6, control n = 6) with long-term observation (8 h a day, 5d per week) to obtain an adequate number of GTCs to elucidate the time dependent anti-epileptic effect on GTC. RESULTS: Acute VNS treatment reduced GTC seizure frequency and total duration of the DS. Chronic VNS resulted in a time-dependent reduction of DS frequency and duration. However, chronic VNS did not show time-dependent reduction of GTC frequency. There were significant c-Fos expressions in the central medial nucleus (CM), mediodorsal thalamic nucleus (MDM), locus coeruleus (LC), and nucleus of solitary tract (NTS) after acute VNS. And there were significant ΔFosB expressions in the lateral septal nucleus (LSV), medial septal nucleus (MSV), MDM, and pontine reticular nucleus caudal (PnC) after chronic VNS. Any decrease in frequency of GTCs by chronic VNS could not be confirmed even with long-term observation. CONCLUSION: We confirmed acute VNS significantly reduced the frequency of GTC and duration of DS. Chronic VNS decreased the frequency and duration of DS in a time-dependent manner. The brainstem and midline thalamus were activated after acute and chronic VNS. The forebrain was activated only after chronic VNS.

Combined surgical intervention with vagus nerve stimulation following corpus callosotomy in patients with Lennox-Gastaut syndrome.

BACKGROUND: Lennox-Gastaut syndrome (LGS) is a drug-resistant pediatric epilepsy characterized by multiple seizure types, including drop attacks (DAs). Palliative procedures such as corpus callosotomy (CC) and vagus nerve stimulation (VNS) may be effective for adequate seizure control in LGS patients who are not candidates for resective surgery. We evaluated the efficacy of the combination of these two procedures for LGS-related seizures. METHOD: Ten patients with LGS (age 3-30 years at VNS implantation) underwent CC and subsequent VNS. We evaluated surgical outcomes, particularly with respect to the efficacy of VNS on seizure reduction rates for different residual seizure types after CC. We compared clinical parameters, including sex, age, seizure duration, history, MRI findings, extent of CC, number of antiepileptic drugs, and neuropsychological states, between VNS responders and non-responders to predict satisfactory seizure outcomes with respect to residual seizures after CC. FINDINGS: VNS was effective for residual seizures regardless of seizure type (except for DAs) after CC in patients with LGS. Six of ten (60%) patients had a satisfactory seizure outcome (≥50% seizure reduction) for all residual seizure types after VNS. Two of ten (20%) patients were seizure-free at 12 months post-VNS. Even those patients that were non-responders, with respect to all seizures including DAs, after prior CC showed favorable responses to subsequent VNS. Compared to VNS, excellent seizure outcomes for DAs were achieved after CC in seven of nine (77.8%) patients with DAs. Among the clinical parameters, only conversation ability before VNS was significantly different between responders and non-responders (p = 0.033). CONCLUSION: Combined VNS and prior CC produced satisfactory seizure outcomes in LGS patients with different seizure types, including DAs. Even non-responders to prior CC responded to subsequent VNS for residual seizures, except for DAs. There is a greater likelihood that these procedures may be more feasible in patients who possess conversation ability prior to VNS.

Novel Software for Performing Leksell Stereotactic Surgery without the Use of Printing Films: Technical Note.

Hospitals in Japan have recently begun to employ the DICOM viewer system on desktop or laptop monitors. However, conventional embedding surgery for deep-brain stimulation with the Leksell stereotactic system (LSS) requires printed X-ray films for defining the coordination, coregistration of actual surgical films with the reference coordinates, and validation of the needle trajectories. While just performing these procedures on desktop or laptop monitors, the authors were able to develop novel software to facilitate complete digital manipulation with the Leksell frame without printing films. In this study, we validated the practical use of LSS, and benefit of this software in the Takanobashi Central Hospital and Kagoshima University Hospital.

Electrocorticographic-histopathologic correlations implying epileptogenicity of dysembryoplastic neuroepithelial tumor.

Based on intracranial-video electroencephalography (EEG), histopathological features, and postoperative seizure outcome, we elucidated the epileptogenicity in patients with dysembryoplastic neuroepithelial tumor (DNT). Five patients (P1-P5) pathologically diagnosed with DNT underwent intracranial-video EEG to identify the ictal onset zone and irritative zone. We evaluated the correlations of ictal onset zone and irritative zone with the magnetic resonance imaging-visible lesion (MRI-lesion) and their histopathological features. Intracranial-video EEG located the ictal onset zone adjacent to the MRI-lesion margin in four patients with complex/simple forms of DNT subcategory, and on the MRI-lesion in P3 with a nonspecific DNT form. The irritative zone extended to surrounding regions of the ictal onset zone in all patients. Histopathologically, MRI-lesions were characterized by specific glioneuronal elements, whereas the ictal onset zone and irritative zone were represented with dysplastic cortex accompanying oligodendroglia-like cells in four (P1, P2, P4, and P5) of five patients. Cortical dysplasia was identified with typical histopathologic features in the irritative zone remote from the MRI-lesion in P5. P3, with a nonspecific form, indicated prominent component of dysplastic cortex with oligodendroglia-like cells scattered in the MRI-lesion. Lesionectomy of MRI-lesion with additional cortical resections (including the ictal onset zone and irritative zone) yielded postoperative seizure freedom (Engel Class I) in P3, P4, and P5, while P1 and P2 (with only lesionectomy) experienced postoperative residual seizure (Class II and III in each patient). Our results suggest the intrinsic epileptogenicity of DNT. The topographical correlation indicated that the dysplastic cortex accompanying oligodendroglia-like cells was more epileptogenic than the specific glioneuronal elements itself. Meticulous intracranial-video EEG analysis delineating the MRI nonvisible ictal onset zone and the irritative zone may yield better seizure outcome.

Late recurrence of intractable epilepsy associated with MRI-occult pilocytic astrocytoma in the temporal lobe nine years after initial removal: a case report with surgical and late-seizure recurrence observations.

A 28-year-old male who presented a relapse of intractable epilepsy consisting of complex partial seizures with occasional secondary generalizations at the age of 26, had undergone removal of a left mesial temporal lobe tumor at another hospital at 18 years old. Pathological examination at that time revealed a low-grade astrocytoma, and the tumor was further treated by complementary adjuvant irradiation therapy. Magnetic resonance imaging (MRI) findings on admission portrayed a post-operative cavity anterior to the atrophied hippocampus on the left side with hyperintense in fluid-attenuated inversion recovery (FLAIR) images. There were no enhanced lesions in T1-weighted gadolinium images. As it was diagnosed as left mesial temporal lobe epilepsy with preoperative evaluations, the patient underwent left anterior temporal lobe resection (TLR). Intraoperative findings revealed that a small lump of grey tissue was attached to the anteromesial side of the sclerotic hippocampus. We surgically removed this and the tissue was a pilocytic astrocytoma. The patient has since remained seizure-free for 2.5 years. Seizure outcomes at postoperative 1-2 years are highly predictive of long-term outcomes after TLR for temporal lobe epilepsy (TLE). Late-seizure recurrence (> postoperative 2 years) with an initially successful outcome rarely occurs in TLR patients. This case report suggests that recurrence of even benign pilocytic astrocytomas may occur when seizure recurs in long-term follow-up.

Giant cell tumor of the temporal bone with intratumoral hemorrhage.

We report a case of hemorrhagic giant cell tumor (GCT) of the temporal bone in a 77-year-old woman. The patient suffered from sudden-onset headache and vomiting associated with left temporal hemorrhage. MRI revealed a left temporal extradural mass lesion expanding to the subtemporal fossa, showing strong hypointensity on T(2)-weighted imaging. Subsequent MRI revealed tumor growth with multiple cystic components at 1-month follow up. The tumor was found to be a GCT associated with recent intratumoral hemorrhage and abundant hemosiderin pigmentation. T(2)-weighted MRI of the GCT strongly supported hemosiderin deposition. Secondary formation of cystic components in the GCT can also reflect prior hemorrhage and indicate the progression of shape modification. A literature review revealed that hemosiderin deposition in this rare entity is not as rare as previously thought and that massive intratumoral hemorrhage may occur.

Arteriovenous malformation of the scalp: case report and review of the literature.

BACKGROUND: Arteriovenous malformations (AVMs) of the scalp are relatively rare, and their precise natural course remains to be elucidated. We encountered a patient with a scalp AVM that progressively enlarged over the course of 3 years by capturing feeders from intracranial arteries. To our knowledge, ours is the first serial angiographic depiction of the growth of a scalp AVM and the development of a de novo aneurysm in the superior temporal artery (STA) that performed as a feeder. CASE DESCRIPTION: This 21-year-old female consulted us in 1998 complaining of right tinnitus and a pulsating mass in the retroauricular region. The initial angiogram revealed an AVM in the right temporo-parietal subcutaneous space with feeders from the STA, an occipital artery, a posterior auricular artery, and a middle meningeal artery (MMA). Three years later, she complained of enlargement of the lesion, increased tinnitus, and alopecia. Repeat angiographic study revealed the presence of a nidus and the appearance of new feeders from a contralateral MMA and an ipsilateral middle cerebral artery; there was a de novo saccular aneurysm in the right STA. On the day preceding surgery, the left MMA was embolized to control intraoperative bleeding. The AVM was removed totally without any dermal complications. CONCLUSION: This case suggests that scalp AVMs can become enlarged by capturing subcutaneous or intracranial feeders, and that the consequent hemodynamic stress may induce de novo aneurysms in scalp AVMs. Capillary endothelial cells were strongly immunostained for vascular endothelial growth factor.

[Venous thromboembolism in neurosurgery].

Clinicopathological features of venous thromboembolism (VT), such as pulmonary embolism (PE) and deep venous thrombosis (DVT), associated with intracranial diseases has not been clarified sufficiently in Japan. We investigated the clinical characteristics of VT in consecutive 3,595 group of patients retrospectively, who had been admitted to our department. The occurrence rate of VT was 0.22% (8 patients). There were 2 males (0.10%) and 6 females (0.31%) with the mean age of 70.9 years old, ranging from 54 to 83 years old. Three patients were diagnosed as PE and 5 as DVT. The background of intracranial diseases included cerebrovascular disease in 5 patients, brain tumor in 2, and post-resuscitation encephalopathy in 1. The mortality rate of PE seems to be extremely high, considering that all patients with PE suffered death within 4 hours. High risk patients of VT in our series were the elderly, fat persons, and females who suffered from cerebral stroke. Immobilization scoring at 4 or 5 on the modified Rankin's Scale is also estimated to be a risk factor for VT. Patients with cerebral hemorrhage tend to develop VT in the acute stage of the clinical course and those with other intracranial diseases present VT in the chronic stage. VT is relatively rare, but is still one of the severe complications in neurosurgical management so that, once having occurred, VT has a high likelihood of resulting in death. We should discern the high risk group for VT and make proper prophylaxis depending on the patients condition.