Namiko Nishida

Deep brain stimulation of the posterior hypothalamus activates the histaminergic system to exert antiepileptic effect in rat pentylenetetrazol model.

Deep brain stimulation (DBS) is a promising therapy for intractable epilepsy, yet the optimum target and underlying mechanism remain controversial. We used the rat pentylenetetrazol (PTZ) seizure model to evaluate the effectiveness of DBS to three targets: two known to be critical for arousal, the histaminergic tuberomammillary nucleus (TMN) and the orexin/hypocretinergic perifornical area (PFN), and the anterior thalamic nuclei (ATH) now in clinical trial. TMN stimulation provided the strong protection against the seizure, and PFN stimulation elicited a moderate effect yet accompanying abnormal behavior in 25% subjects, while ATH stimulation aggravated the seizure. Power density analysis showed EEG desynchronization after DBS on TMN and PFN, while DBS on ATH caused no effect with the same stimulation intensity. EEG desynchronization after TMN stimulation was inhibited in a dose-dependent manner by pyrilamine, a histamine H(1) receptor selective antagonist, while the effect of PFN stimulation was inhibited even at a low dose. In parallel, in vivo microdialysis revealed a prominent increase of histamine release in the frontal cortex after TMN stimulation, a moderate level with PFN and none with ATH. Furthermore, antiepileptic effect of DBS to TMN was also blocked by an H(1) receptor antagonist. This study clearly indicates that EEG desynchronization and the activation of the histaminergic system contributed to the antiepileptic effects caused by DBS to the posterior hypothalamus.

Evidence for a wide distribution of negative motor areas in the perirolandic cortex

OBJECTIVE The perirolandic regions were studied by extensive electrical stimulation to clarify the topography and somatotopic distribution of negative motor areas (NMAs) and examine the clinical significance of these areas. METHODS We evaluated the cortical function elicited by electrical stimulation in 30 patients with tumors or intractable epilepsy. The somatotopic distribution of NMAs was examined by localizing these regions using Talairachs bicommissural reference system. NMAs within the lesions of two patients were removed under local anesthesia. RESULTS We obtained negative motor responses following the stimulation of 30 electrodes in 15 patients. On the lateral brain surface, the majority of NMAs for the upper extremities were distributed broadly throughout the premotor cortex, while NMAs for the tongue were only found in the inferior frontal gyrus of the dominant hemisphere. During removal of the NMAs within the lesions of two patients, we documented transient hand clumsiness in one patient. CONCLUSIONS NMAs were widely distributed throughout the perirolandic area, as well as the previously reported regions in the inferior frontal gyrus. These areas likely function in the control of skilled movements; dysfunction of such movements transiently follows resection of these regions, but is subsequently well compensated for after surgery. SIGNIFICANCE The localization and consequences of resection of NMAs suggests their clinical significance in motor control.

Fibers from the dorsal premotor cortex elicit motor-evoked potential in a cortical dysplasia.

OBJECTIVE To identify the fibers originating from the dorsal premotor cortex (dorsal PMC) that contribute to motor-evoked potentials (MEP), we have applied integrated functional neuronavigation and awake surgery during removal of an epileptic cortical dysplasia located in the right premotor cortex. METHODS Chronic subdural electrodes were employed for functional mapping during a routine invasive evaluation for intractable epilepsy. After the fibers originating from the dorsal PMC were plotted into the tractography-integrated functional neuronavigation, subcortical MEPs and clinical symptoms were examined during resection of the epileptogenic dorsal PMC. RESULTS During removal of the epileptogenic area, MEPs were elicited by electrical stimulation of the fibers originating from the dorsal PMC, which were separated from the pyramidal tracts from the precentral gyrus. Resection of the dorsal PMC and its fibers caused a transient dysmetric movement of the left toe without motor weakness. CONCLUSION Functional corticospinal tract fibers originating from the dorsal PMC can be defined and removed safely under local anesthesia with the aid of integration of functional neuronavigation and subcortical electrical stimulation.

Update on Deep Brain Stimulation for Dyskinesia and Dystonia: A Literature Review

Deep brain stimulation (DBS) has been an established surgical treatment option for dyskinesia from Parkinson disease and for dystonia. The present article deals with the timing of surgical intervention, selecting an appropriate target, and minimizing adverse effects. We provide an overview of current evidences and issues for dyskinesia and dystonia as well as emerging DBS technology.

A nonspecific form of dysembryoplastic neuroepithelial tumor presenting with intractable epilepsy

We report here an intractable epilepsy case with fairly typical clinicoradiological features of dysembryoplastic neuroepithelial tumor (DNT), which means onset of seizures at a young age accompanying a medial temporal cystic lesion enclosed in cortical dysplasia (CD). The medial cystic lesion was composed of two morphologically distinct components; one was oligo-like and the other showed some tendency toward neuronal and glial differentiation, even though they were morphologically different from a so-called specific glioneural element (SGE). Epileptiform discharges were detected not only on the medial lesion but also on the lateral inferior temporal gyrus, which was confirmed as CD. According to both histopathological and clinical features, we named the lesion a nonspecific form of DNT.

Coaxial interleaved stimulation of the thalamus and subthalamus for treatment of Holmes tremor

Holmes tremor is often treated with multiple deep brain stimulation (DBS) electrodes. The authors describe a novel technique to suppress the tremors by effectively utilizing a single electrode. A 16-year-old boy presented with severe right arm tremor following a midbrain injury. A DBS electrode was implanted into the ventral oralis nucleus of the thalamus (VO) and the subthalamic region. While individual stimulation of each target was ineffective, an interleaved dual stimulation of both targets has been effective for 6 years. Coaxial interleaved stimulation of the VO and the subthalamic region is useful for treating Holmes tremor. The video can be found here: https://youtu.be/tSwGh3vy68c .

Idiopathic hematomyelia as a rare cause of epiconus syndrome.

Department of Neurosurgery, Tazuke Kofukai Medical Research Institute and Kitano Hospital, 2-4-20 Ohgimachi, Kita, Osaka 530-8480, Japan Department of Orthopedic Surgery, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo, Kyoto 606-8507, Japan Department of Pathology, Tazuke Kofukai Medical Research Institute and Kitano Hospital, 2-4-20 Ohgimachi, Kita, Osaka 530-8480, Japan

Phase I/II Study of Temozolomide Plus Nimustine Chemotherapy for Recurrent Malignant Gliomas: Kyoto Neuro-oncology Group

The objective of this phase I/II study was to examine the efficacy and toxicity profile of temozolomide (TMZ) plus nimustine (ACNU). Patients who had received a standard radiotherapy with one or two previous chemo-regimens were enrolled. In phase I, the maximum-tolerated dose (MTD) by TMZ (150 mg/m2/day) (Day 1–5) plus various doses of ACNU (30, 35, 40, 45 mg/m2/day) (Day 15) per 4 weeks was defined on a standard 3 + 3 design. In phase II, these therapeutic activity and safety of this regimen were evaluated. Forty-nine eligible patients were enrolled. The median age was 50 years-old. Eighty percent had a KPS of 70–100. Histologies were glioblastoma (73%), anaplastic astrocytoma (22%), anaplastic oligodendroglioma (4%). In phase I, 15 patients were treated at four cohorts by TMZ plus ACNU. MTD was TMZ (150 mg/m2) plus ACNU (40 mg/m2). In phase II, 40 patients were treated at the dose of cohort 3 (MTD). Thirty-five percent of patients experienced grade 3 or 4 toxicities, mainly hematologic. The overall response rate was 11% (4/37). Sixty-eight percent (25/37) had stable disease. Twenty-two percent (8/37) showed progression. Progression-free survival (PFS) rates at 6 and 12 months were 24% (95% CI, 12–35%) and 8% (95% CI, 4–15%). Median PFS was 13 months (95% CI, 9.2–17.2 months). Overall survival (OS) at 6 and 12 were 78% (95% CI, 67–89%) and 49% (95% CI, 33–57%). Median OS was 11.8 months (95% CI, 8.2–14.5 months). This phase I/II study showed a moderate toxicity in hematology and may has a promising efficacy in OS, without inferiority in PFS.

Bridging veins and veins of the brainstem in microvascular decompression surgery for trigeminal neuralgia and hemifacial spasm

OBJECTIVE In microvascular decompression surgery for trigeminal neuralgia and hemifacial spasm, the bridging veins are dissected to provide the surgical corridors, and the veins of the brainstem may be mobilized in cases of venous compression. Strategy and technique in dissecting these veins may affect the surgical outcome. The authors investigated solutions for minimizing venous complications and reviewed the outcome for venous decompression. METHODS The authors retrospectively reviewed their surgical series of microvascular decompression for trigeminal neuralgia and hemifacial spasm in patients treated between 2005 and 2017. Surgical strategies included preservation of the superior petrosal vein and its tributaries, thorough dissection of the arachnoid sleeve that enveloped these veins, cutting of the inferior petrosal vein over the lower cranial nerves, and mobilization or cutting of the veins of the brainstem that compressed the nerve roots. The authors summarized the patient characteristics, operative findings, and postoperative outcomes according to the vascular compression types as follows: artery alone, artery and vein, and vein alone. They analyzed the data using chi-square and 1-way ANOVA tests. RESULTS The cohort was composed of 121 patients with trigeminal neuralgia and 205 patients with hemifacial spasm. The superior petrosal vein and its tributaries were preserved with no serious complications in all patients with trigeminal neuralgia. Venous compression alone and arterial and venous compressions were observed in 4% and 22%, respectively, of the patients with trigeminal neuralgia, and in 1% and 2%, respectively, of those with hemifacial spasm (p < 0.0001). In patients with trigeminal neuralgia, 35% of those with artery and venous compressions and 80% of those with venous compression alone had atypical neuralgia (p = 0.015). The surgical cure and recurrence rates of trigeminal neuralgias with venous compression were 60% and 20%, respectively, and with arterial and venous compressions the rates were 92% and 12%, respectively (p < 0.0001, p = 0.04). In patients with hemifacial spasm who had arterial and venous compressions, their recurrence rate was 60%, and that was significantly higher compared to other compression types (p = 0.0008). CONCLUSIONS Dissection of the arachnoid sleeve that envelops the superior petrosal vein may help to reduce venous complications in surgery for trigeminal neuralgia. Venous compression may correlate with worse prognosis even with thorough decompression, in both trigeminal neuralgia and hemifacial spasm.

Indocyanine Green Videoangiography for Surgery of a Ruptured Dissecting Aneurysm in the Precommunicating Anterior Cerebral Artery: A Technical Case Report

BACKGROUND AND IMPORTANCE Indocyanine green videoangiography (ICG-VA) is an important intraoperative adjunct for saccular aneurysm surgery, but its efficacy in surgery for dissecting aneurysms has rarely been reported. The authors describe the usefulness of preclipping ICG-VA in a rare case of a ruptured dissecting aneurysm located at the precommunicating (A1) segment of the anterior cerebral artery. CLINICAL PRESENTATION A 52-year-old woman, with no history of connective tissue diseases or vascular disorders, presented with sudden headache and convulsion. The CT scan showed that the patient had subarachnoid hemorrhage. Angiography showed a dissecting aneurysm in the left A1 segment of the anterior cerebral artery. Thus, the patient underwent trapping of the dissecting aneurysm. ICG-VA was used as an intraoperative adjunct before and after clipping. The preclipping ICG-VA showed the heterogeneously bright dissecting aneurysm and branching arteries even in the presence of hematoma. CONCLUSION Preclipping ICG-VA may enhance the advantage of direct surgery for dissecting aneurysm by allowing visualization of the extent of the dissected vascular wall and the related branching arteries. ICG-VA can be an indispensable adjunct to minimize the compromise from the surgical treatment for intracranial dissecting aneurysms.