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Nobuhiro Mikuni, Takeshi Satow, Junya Taki, Namiko Nishida, Rei Enatsu and Nobuo Hashimoto

✓ Difficulty swallowing due to damage of the vagus nerve is one of the most devastating complications of surgery in and around the medulla oblongata; therefore, intraoperative anatomical and functional evaluation of this nerve is crucial. The authors applied endotracheal tube surface electrodes to record electromyography (EMG) activity from vocal cords innervated by the vagus nerve. The vagal nucleus or rootlet was electrically stimulated during surgery and vocalis muscle EMG activities were displayed by auditory and visual signals. This technique was used successfully to identify the vagus motor nerve and evaluate its integrity during surgery. The advantages of this method compared with the use of needle electrodes include safe simple electrode placement and stable recording during surgery. In cases involving a pontine cavernoma pressing the nucleus or a jugular foramen tumor encircling the rootlet, this method would be particularly valuable. Additional studies with a larger number of patients are needed to estimate the significance of this method as a means of functional monitoring to predict clinical function.

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Shunya Ohtaki, Yukinori Akiyama, Aya Kanno, Shouhei Noshiro, Tomo Hayase, Michiaki Yamakage and Nobuhiro Mikuni

OBJECTIVE

Motor evoked potentials (MEPs) are a critical indicator for monitoring motor function during neurological surgery. In this study, the influence of depth of anesthesia on MEP response was assessed.

METHODS

Twenty-eight patients with brain tumors who underwent awake craniotomy were included in this study. From a state of deep anesthesia until the awake state, MEP amplitude and latency were measured using 5-train electrical bipolar stimulations on the same site of the precentral gyrus each minute during the surgery. The depth of anesthesia was evaluated using the bispectral index (BIS). BIS levels were classified into 7 stages: < 40, and from 40 to 100 in groups of 10 each. MEP amplitude and latency of each stage were compared. The deviation of the MEP measurements, which was defined as a fluctuation from the average in every BIS stage, was also considered.

RESULTS

A total of 865 MEP waves in 28 cases were evaluated in this study. MEP amplitude was increased and latency was decreased in accordance with the increases in BIS level. The average MEP amplitudes in the > 90 BIS level was approximately 10 times higher than those in the < 40 BIS level. Furthermore, the average MEP latencies in the > 90 BIS level were 1.5–3.1 msec shorter than those in the < 60 BIS level. The deviation of measured MEP amplitudes in the > 90 BIS level was significantly stabilized in comparison with that in the < 60 BIS level.

CONCLUSIONS

MEP amplitude and latency were closely correlated with depth of anesthesia. In addition, the deviation in MEP amplitude was also correlated with depth of anesthesia, which was smaller during awake surgery (high BIS level) than during deep anesthesia. Therefore, MEP measurement would be more reliable in the awake state than under deep anesthesia.

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Kotoe Kamata, Satoshi Hagihira, Takashi Maruyama, Yoshihiro Muragaki and Makoto Ozaki

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Tomohiro Murakami, Izumi Koyanagi, Takahisa Kaneko, Akihiro Yoneta, Yoshiko Keira, Masahiko Wanibuchi, Tadashi Hasegawa and Nobuhiro Mikuni

Hyperhidrosis is caused by a sympathetic dysfunction of the central or peripheral nervous system. Intramedullary spinal cord lesions can be a cause of hyperhidrosis. The authors report a rare case of intramedullary thoracic spinal cord ganglioglioma presenting as hyperhidrosis. This 16-year-old boy presented with abnormal sweating on the right side of the neck, chest, and the right arm that had been occurring for 6 years. Neurological examination revealed mild motor weakness of the right lower extremity and slightly decreased sensation in the left lower extremity. Hyperhidrosis was observed in the right C3–T8 dermatomes. Magnetic resonance imaging showed an intramedullary tumor at the right side of the spinal cord at the T2–3 level. The tumor showed partial enhancement after Gd administration. The patient underwent removal of the tumor via hemilaminectomy of T2–3. Only subtotal resection was achieved because the margins of the tumor were unclear. Histopathological examination revealed ganglioglioma. Hyperhidrosis gradually improved after surgery. Hyperhidrosis is a rare clinical manifestation of intramedullary spinal cord tumors, and only a few cases have been reported in the literature. The location of the tumor origin, around the right gray matter of the lateral spinal cord, may account for the hyperhidrosis as the initial symptom in this patient. Physicians should examine the spinal cord using MRI studies when a patient has hyperhidrosis with some motor or sensory symptoms of the extremities.

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Nobuhiro Mikuni, Tsutomu Okada, Namiko Nishida, Junya Taki, Rei Enatsu, Akio Ikeda, Yukio Miki, Takashi Hanakawa, Hidenao Fukuyama and Nobuo Hashimoto

Object

The utility of subcortical electrical stimulation and fiber tracking were compared to estimate the pyramidal tract near brain tumors.

Methods

In 22 patients, the white matter at the bottom of a tumor was electrically stimulated near the fiber tracking of the pyramidal tract shown on a neuronavigation system. The distance between the center of the fiber tracking of these tracts and the stimulated region was measured and defined as the motor evoked potential (MEP) response. The MEP was consistently produced at distances less than 7 mm (six patients), but was consistently absent at distances more than 13 mm (seven patients) from the fiber tracking of the pyramidal tracts. In the nine patients in whom the distance was between 8 and 12 mm, an MEP was elicited when stimulation was applied at the level of the corona radiata. Motor function was preserved or even improved with appropriate tumor resection in all patients.

Conclusions

The anteroposteriorly running superior longitudinal fasciculus could cause complications in the fiber tracking of upper-extremity motor pathways at the level of the corona radiata. During resection of tumors located near the corona radiata, subcortical electrical stimulation should be applied at some distance from the pyramidal tract, as estimated by fiber tracking.

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Hime Suzuki, Takeshi Mikami, Tomoyoshi Kuribara, Kazuhisa Yoshifuji, Katsuya Komatsu, Yukinori Akiyama, Hirofumi Ohnishi, Kiyohiro Houkin and Nobuhiro Mikuni

OBJECTIVE

Medullary streaks detected on fluid-attenuated inversion recovery (FLAIR) imaging have been considered to be reflected ischemic regions in pediatric moyamoya disease. The purpose of this study was to evaluate these medullary streaks both clinically and radiologically and to discuss associated pathophysiological concerns.

METHODS

The authors retrospectively reviewed data from 14 consecutive pediatric patients with moyamoya disease treated between April 2009 and June 2016. Clinical and radiological features and postoperative imaging changes were analyzed. In 4 patients, hyperintense medullary streaks on FLAIR imaging (HMSF) at the level of the centrum semiovale were detected.

RESULTS

The HMSF were coincident with hyperintense medullary streaks on a T2-weighted image, though they were not completely coincident with the vasculature on either a T2*-weighted image or contrast-enhanced CT. Analysis revealed significantly higher values in terms of MR angiography scores, number of flow voids of the basal ganglia, and the presence of the medullary artery in the group with HMSF than in those without. In contrast, the presence of white matter damage was significantly less frequent in the HMSF group. All HMSF disappeared after surgery, and the mean apparent diffusion coefficient at the same level was significantly reduced postoperatively.

CONCLUSIONS

Although HMSF should be associated with collateral circulation in moyamoya disease, other factors may be involved, including stagnated cerebrospinal fluid or vasogenic edema that is relevant to the impaired state of the white matter. Findings in this study provide insight into the pathophysiological basis of the perivascular space in moyamoya disease.

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Shunya Ohtaki, Masahiko Wanibuchi, Yuko Kataoka-Sasaki, Masanori Sasaki, Shinichi Oka, Shouhei Noshiro, Yukinori Akiyama, Takeshi Mikami, Nobuhiro Mikuni, Jeffery D. Kocsis and Osamu Honmou

OBJECTIVE

Glioma is a major class of brain tumors, and glioblastoma (GBM) is the most aggressive and malignant type. The nature of tumor invasion makes surgical removal difficult, which results in remote recurrence. The present study focused on glioma invasion and investigated the expression of actin, alpha cardiac muscle 1 (ACTC1), which is 1 of 6 actin families implicated in cell motility.

METHODS

mRNA expression of ACTC1 expression was analyzed using quantitative real-time polymerase chain reaction (qRT-PCR) in 47 formalin-fixed, paraffin-embedded glioma tissues that were graded according to WHO criteria: Grade I (n = 4); Grade II (n = 12); Grade III (n = 6); and Grade IV (n = 25). Survival was analyzed using the Kaplan-Meier method. The relationships between ACTC1 expression and clinical features such as radiological findings at the time of diagnosis and recurrence, patient age, Karnofsky Performance Scale status (KPS), and the MIB-1 index were evaluated.

RESULTS

The incidence of ACTC1 expression as a qualitative assessment gradually increased according to WHO grade. The hazard ratio for the median overall survival (mOS) of the patients with ACTC1-positive high-grade gliomas as compared with the ACTC1-negative group was 2.96 (95% CI, 1.03–8.56). The mOS was 6.28 years in the ACTC1-negative group and 1.26 years in the positive group (p = 0.037). In GBM patients, the hazard ratio for mOS in the ACTC1-positive GBMs as compared with the ACTC1-negative group was 2.86 (95% CI 0.97–8.45). mOS was 3.20 years for patients with ACTC1-negative GBMs and 1.08 years for patients with ACTC1-positive GBMs (p = 0.048). By the radiological findings, 42.9% of ACTC1-positive GBM patients demonstrated invasion toward the contralateral cerebral hemisphere at the time of diagnosis, although no invasion was observed in ACTC1-negative GBM patients (p = 0.013). The recurrence rate of GBM was 87.5% in the ACTC1-positive group; in contrast, none of the ACTC1-negative patients demonstrated distant recurrence (0.007). No remarkable relationship was demonstrated among ACTC1 expression and patient age, KPS, and the MIB-1 index.

CONCLUSIONS

ACTC1 may serve as a novel independent prognostic and invasion marker in GBM.

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Kei Miyata, Hirofumi Ohnishi, Kunihiko Maekawa, Takeshi Mikami, Yukinori Akiyama, Satoshi Iihoshi, Masahiko Wanibuchi, Nobuhiro Mikuni, Shuji Uemura, Katsutoshi Tanno, Eichi Narimatsu and Yasufumi Asai

OBJECT

In patients with severe traumatic brain injury (TBI), a randomized controlled trial revealed that outcomes did not significantly improve after therapeutic hypothermia (TH) or normothermia (TN). However, avoiding pyrexia, which is often associated with intracranial disorders, might improve clinical outcomes. The objective of this study was to compare neurological outcomes among patients with moderate and severe TBI after therapeutic temperature modulation (TTM) in the absence of other interventions.

METHODS

Data from 1091 patients were obtained from the Japan Neurotrauma Data Bank Project 2009, a cohort observational study. Patients with cardiac arrest, those with a Glasgow Coma Scale score of 3 and dilated fixed pupils, and those whose cause of death was injury to another area of the body were excluded, leaving 687 patients aged 16 years or older in this study. The patients were divided into 2 groups: the TTM group underwent TN (213 patients) or TH (82 patients), and the control group (392 patients) did not receive TTM. The primary end point for this study was the rate of poor outcome at hospital discharge, and the secondary end point was in-hospital death. Out of the 208 total items in the database, 29 variables that could potentially affect outcome were matched using the propensity score (PS) method in order to reduce selection bias and balance the baseline characteristics.

RESULTS

From each group, 141 patients were extracted using the PS-matching process. Among the patients in the TTM group, 29 had undergone TH and 112 had undergone TN. In a log-rank test using Kaplan-Meier survival curves, no significant differences in patient outcome or death were observed between the 2 groups (poor outcome, p = 0.83; death, p = 0.18). A Cox proportional-hazards regression analysis established the HR for poor outcome and mortality at 1.03 (95% CI 0.78–1.36, p = 0.83) and 1.34 (95% CI 0.87–2.07, p = 0.18), respectively.

CONCLUSIONS

There was no clear improvement in neurological outcomes after TTM in patients with moderate or severe TBI. To elucidate the role of TTM in patients with these injuries, a prospective study is needed with long-term follow-up using specific target temperatures.

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Nobuhiro Mikuni, Tsutomu Okada, Rei Enatsu, Yukio Miki, Takashi Hanakawa, Shin-ichi Urayama, Kenichiro Kikuta, Jun A. Takahashi, Kazuhiko Nozaki, Hidenao Fukuyama and Nobuo Hashimoto

Object

The authors evaluated the clinical impact of combining functional neuronavigation with subcortical electrical stimulation to preserve motor function following the removal of brain tumors.

Methods

Forty patients underwent surgery for treatment of brain tumors located near pyramidal tracts that had been identified by fiber tracking. The distances between the electrically stimulated white matter and the pyramidal tracts were measured intraoperatively with tractography-integrated functional neuronavigation, and correlated with subcortical motor evoked potentials (MEPs) and clinical symptoms during and after resection of the tumors.

Motor function was preserved after appropriate tumor resection in all cases. In 18 of 20 patients, MEPs were elicited from the subcortex within 1 cm of the pyramidal tracts as measured using intraoperative neuronavigation. During resection, improvement of motor weakness was observed in two patients, whereas transient mild motor weakness occurred in two other patients. In 20 patients, the distances between the stimulated subcortex and the estimated pyramidal tracts were more than 1 cm, and MEPs were detected in only three of these patients following stimulation.

Conclusions

Intraoperative functional neuronavigation and subcortical electrical stimulation are complementary techniques that may facilitate the preservation of pyramidal tracts around 1 cm of resected tumors.