Faculty Profiles - OOISHI Makoto

Papers - OOISHI Makoto

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Pharyngeal motor evoked potentials elicited by transcranial electrical stimulation for intraoperative monitoring during skull base surgery. International journal

Masafumi Fukuda, Makoto Oishi, Tetsuya Hiraishi, Akihiko Saito, Yukihiko Fujii

Journal of neurosurgery 116 ( 3 ) 605 - 10 2012.3

Language：English Publishing type：Research paper (scientific journal)

OBJECT: The purpose of this study was to determine whether monitoring of pharyngeal motor evoked potentials (PhMEPs) elicited by transcranial electrical stimulation during skull base tumor surgery might be useful for predicting postoperative swallowing deterioration. METHODS: The authors analyzed PhMEPs in 21 patients during 22 surgical procedures for the treatment of skull base tumors. Corkscrew electrodes positioned at C3 or C4 and Cz were used to deliver supramaximal stimuli (220-550 V). Pharyngeal MEPs were recorded from the posterior wall of the pharynx through a modified endotracheal tube. The correlation between the final/baseline PhMEP ratio and postoperative swallowing function was examined. RESULTS: Postoperative swallowing function was significantly (p < 0.05), although not strongly (r = -0.47), correlated with the final/baseline PhMEP ratio. A PhMEP ratio < 50% was recorded during 4 of 22 procedures; in all 4 of these cases, the patients experienced postoperative deterioration of swallowing function. After 18 procedures, the PhMEP ratios remained > 50%; nevertheless, after 4 (22.2%) of these 18 procedures, patients showed deterioration of swallowing function. CONCLUSIONS: Intraoperative PhMEP monitoring can be useful for predicting swallowing deterioration following skull base surgery, especially in patients with swallowing disturbances that are mainly due to reduction in the motor functions of the pharyngeal muscles.

DOI： 10.3171/2011.10.JNS111343

Near-infrared spectroscopic study and the Wada test for presurgical evaluation of expressive and receptive language functions in glioma patients: with a case report of dissociated language functions. International journal

Yosuke Sato, Takeo Uzuka, Hiroshi Aoki, Manabu Natsumeda, Makoto Oishi, Masafumi Fukuda, Yukihiko Fujii

Neuroscience letters 510 ( 2 ) 104 - 9 2012.2

Language：English Publishing type：Research paper (scientific journal)

Near-infrared spectroscopy (NIRS) has proven to be useful for the evaluation of language lateralization in healthy subjects, infants, and epileptic patients. This study for the first time investigated the expressive and receptive language functions separately, using NIRS in presurgical glioma patients. We also describe a special case with dissociated pattern of language functions. Ten glioma patients were examined. Using NIRS, the hemodynamic changes during a verb generation task or story listening task were measured in the cerebral hemisphere on either side covering the language areas. Following the NIRS study, the Wada test was performed in all the patients. The NIRS study revealed increases of oxyhemoglobin and decreases of deoxyhemoglobin in the language areas elicited by both tasks. In 9 patients, who were all right-handed, the expressive and receptive language functions were lateralized to the left hemisphere. The results of the NIRS study were completely consistent with those of the Wada test. In the remaining 1 patient with a right sided insular glioma, who was right-handed, the NIRS study revealed stronger activation of the right inferior frontal region during the verb generation task, and stronger activation of the left superior temporal region during the story listening task. This dissociated language function was validated by the Wada test and the postoperative neurological course. These results demonstrate that a NIRS study using our technique is extremely valuable for preoperative assessment of the language functions and exemplifies how a preoperative NIRS study can allow detection of unforeseen language lateralization.

DOI： 10.1016/j.neulet.2012.01.011

Monitoring of abnormal muscle response and facial motor evoked potential during microvascular decompression for hemifacial spasm. International journal

Masafumi Fukuda, Makoto Oishi, Tetsuro Takao, Tetsuya Hiraishi, Yosuke Sato, Yukihiko Fujii

Surgical neurology international 3 118 - 118 2012

Language：English Publishing type：Research paper (scientific journal)

BACKGROUND: To determine whether the monitoring of abnormal muscle response (AMR) and facial motor evoked potential (FMEP) during microvascular decompression (MVD) for hemifacial spasm (HFS) might be useful for predicting the postoperative clinical course and final outcomes. METHODS: We analyzed 45 HFS patients who underwent both AMR and FMEP monitoring during MVD. Patients were divided into two groups on the basis of post-MVD disappearance (group AMR-A) or persistence (group AMR-B) of AMR. With regard to FMEPs, patients were classified into one of the two groups according to the ratio of the final to baseline FMEP amplitudes recorded for the orbicularis oculi muscle: one group with a ratio of <50% (group FMEP-A), and the other with a ratio of ≥50% (group FMEP-B). RESULTS: Twenty-one of the 26 (81%) patients in group AMR-A were assigned to group FMEP-A, whereas 9 of the 17 (53%) patients in group AMR-B were assigned to FMEP-B (P < 0.05). In 38 of the 40 (95%) patients in whom the AMRs disappeared or persisted at amplitudes <50% that at the baseline, HFS had subsided at the final follow-up. Forty of the 42 (95%) patients whose FMEP amplitude ratios indicated reduction in the amplitudes from the baseline, had complete relief of the symptoms. Nineteen of the 20 (95%) patients whose AMRs disappeared after MVD experienced immediate relief of their symptoms after the operation. With regard to 14 of the 20 (70%) patients whose AMRs persisted at the final recordings, the symptoms of HFS improved over time and eventually subsided (P < 0.001). CONCLUSIONS: Intraoperative monitoring of both AMR and FMEP during MVD may be useful in predicting the postoperative outcomes in HFS patients. The AMR-related findings may help to predict whether HFS disappears immediately after surgery or some time later.

DOI： 10.4103/2152-7806.102328

[Depiction of the cranial nerves around the cavernous sinus by 3D reversed FISP with diffusion weighted imaging (3D PSIF-DWI)].

Go Ishida, Makoto Oishi, Shinya Jinguji, Yuichiro Yoneoka, Mitsuya Sato, Yukihiko Fujii

No shinkei geka. Neurological surgery 39 ( 10 ) 953 - 61 2011.10

Language：Japanese Publishing type：Research paper (scientific journal)

To evaluate the anatomy of cranial nerves running in and around the cavernous sinus, we employed three-dimensional reversed fast imaging with steady-state precession (FISP) with diffusion weighted imaging (3D PSIF-DWI) on 3-T magnetic resonance (MR) system. After determining the proper parameters to obtain sufficient resolution of 3D PSIF-DWI, we collected imaging data of 20-side cavernous regions in 10 normal subjects. 3D PSIF-DWI provided high contrast between the cranial nerves and other soft tissues, fluid, and blood in all subjects. We also created volume-rendered images of 3D PSIF-DWI and anatomically evaluated the reliability of visualizing optic, oculomotor, trochlear, trigeminal, and abducens nerves on 3D PSIF-DWI. All 20 sets of cranial nerves were visualized and 12 trochlear nerves and 6 abducens nerves were partially identified. We also presented preliminary clinical experiences in two cases with pituitary adenomas. The anatomical relationship between the tumor and cranial nerves running in and around the cavernous sinus could be three-dimensionally comprehended by 3D PSIF-DWI and the volume-rendered images. In conclusion, 3D PSIF-DWI has great potential to provide high resolution "cranial nerve imaging", which visualizes the whole length of the cranial nerves including the parts in the blood flow as in the cavernous sinus region.

Spatiotemporal dynamics of epileptiform propagations: Imaging of human brain slices Reviewed

Hiroki Kitaura, Tetsuya Hiraishi, Hiroatsu Murakami, Hiroshi Masuda, Masafumi Fukuda, Makoto Oishi, Masae Ryufuku, Yong-Juan Fu, Hitoshi Takahashi, Shigeki Kameyama, Yukihiko Fujii, Katsuei Shibuki, Akiyoshi Kakita

NEUROIMAGE 58 ( 1 ) 50 - 59 2011.9

Language：English Publishing type：Research paper (scientific journal) Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE

Seizure activities often originate from a localized region of the cerebral cortex and spread across large areas of the brain. The properties of these spreading abnormal discharges may account for clinical phenotypes in epilepsy patients, although the manner of their propagation and the underlying mechanisms are not well understood. In the present study we performed flavoprotein fluorescence imaging of cortical brain slices surgically resected from patients with partial epilepsy caused by various symptomatic lesions. Elicited neural activities in the epileptogenic tissue spread horizontally over the cortex momentarily, but those in control tissue taken from patients with brain tumors who had no history of epilepsy demonstrated only localized responses. Characteristically, the epileptiform propagation comprised early and late phases. When the stimulus intensity was changed gradually, the early phase showed an all-or-none behavior, whereas the late phase showed a gradual increase in the response. Moreover, the two phases were propagated through different cortical layers, suggesting that they are derived from distinct neural circuits. Morphological investigation revealed the presence of hypertrophic neurons and loss of dendritic spines, which might participate in the aberrant activities observed by flavoprotein fluorescence imaging. These findings indicate that synchronized activities of the early phase may play a key role in spreading abnormal discharges in human cortical epilepsies. (C) 2011 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.neuroimage.2011.05.046

Intraoperative facial nerve motor evoked potential monitoring during skull base surgery predicts long-term facial nerve function outcomes. International journal

Masafumi Fukuda, Makoto Oishi, Tetsuya Hiraishi, Akihiko Saito, Yukihiko Fujii

Neurological research 33 ( 6 ) 578 - 82 2011.7

Language：English Publishing type：Research paper (scientific journal)

OBJECTIVES: This study was designed to clarify whether facial nerve motor evoked potentials (FNMEPs) elicited by transcranial electrical stimulation during skull base surgery are useful for predicting long-term facial nerve function. METHODS: We analyzed FNMEP findings in 35 patients with skull base tumors. Mean follow-up was 24.4 months. Corkscrew electrodes positioned at C3 or C4 and Cz were used to deliver supramaximal stimuli. FNMEPs were recorded from the orbicularis oculi and oris muscles. RESULTS: The correlation between the final-to-baseline FNMEP ratio and initial or long-term facial nerve function was examined. Initial post-operative facial nerve function correlated significantly with the FNMEP ratios in the orbicularis oculi (r = -0.53, P < 0.005) and orbicularis oris (r = -0.80, P < 0.001) muscles. The correlations between FNMEP ratios and facial nerve function remained significant during long-term follow-up (orbicularis oculi muscle: r = -0.43, P < 0.05; orbicularis oris muscle: r = -0.71, P < 0.001). All patients in whom the FNMEP ratio in the orbicularis oculi muscles remained above 50% were assigned to the satisfactory facial nerve function (House-Brackmann Grades i and ii) group at the final examination. DISCUSSION: FNMEP monitoring can predict facial nerve function not only immediately after surgery but also long-term.

DOI： 10.1179/016164110X12700393823697

Usefulness of motor-evoked potential monitoring during coil embolization of anterior choroidal artery aneurysms: technical reports. International journal

Tetsuya Hiraishi, Masafumi Fukuda, Makoto Oishi, Kazuhiko Nishino, Junsuke Shinbo, Takatoshi Sorimachi, Yasushi Ito, Yukihiko Fujii

Neurological research 33 ( 4 ) 360 - 2 2011.5

Language：English Publishing type：Research paper (scientific journal)

OBJECTIVES: To determine whether transcranial motor-evoked potential (TCMEP) monitoring is useful for detecting blood flow insufficiency in the anterior choroidal artery (AChA) and reflects motor function during coil embolization of AChA aneurysms. METHODS: We analysed MEP findings in seven patients who underwent coil embolization for AChA aneurysms. Corkscrew electrodes positioned at C3 and C4 were used to deliver supra-maximal stimuli (230-550 V). TCMEPs were recorded from the brachioradialis, abductor pollicis brevis, anterior tibialis, and abductor hallucis muscles during all endovascular surgery procedures. RESULTS: Three of seven patients showed transient decreases in TCMEP amplitudes obtained from the lower extremities after coil insertion into the aneurysms, although digital subtraction angiography (DSA) showed no blood flow insufficiency in the AChAs. In two of these three patients, extraction of the coils resulted in recovery of TCMEP amplitudes. In the other patient, the amplitude recovered gradually during repeated TCMEP recordings. One of the three patients experienced transient hemiparesis and aphasia 3 hours after treatment. No patients experienced permanent morbidity post-operatively. DISCUSSION: Decreases in TCMEP amplitude during endovascular treatment for AChA aneurysms are likely to reflect motor dysfunction due to a subtle blood flow insufficiency in the AChA, not detectable by DSA. TCMEP monitoring is a simple and safe monitoring method during coil embolization of AChA aneurysms.

DOI： 10.1179/016164110X12807570

Clinicopathological factors related to regrowth of vestibular schwannoma after incomplete resection. International journal

Masafumi Fukuda, Makoto Oishi, Tetsuya Hiraishi, Manabu Natsumeda, Yukihiko Fujii

Journal of neurosurgery 114 ( 5 ) 1224 - 31 2011.5

Language：English Publishing type：Research paper (scientific journal)

OBJECT: The authors retrospectively analyzed various clinicopathological factors to determine which are related to regrowth during a long-term follow-up period in patients who underwent incomplete vestibular schwannoma (VS) resection. METHODS: This study involved 74 patients (25 men and 49 women) in whom a VS was treated surgically via the lateral suboccipital approach, and who had postoperative follow-up periods exceeding 5 years. The mean follow-up was 104.1 months (range 60-241 months), and the mean patient age at surgery was 48.1 years (range 19-75 years). The tumors ranged in size from 0 mm (localized within the internal auditory canal) to 56 mm (28.3 ± 12.2 mm [mean ± SD]). RESULTS: Gross-total resection (GTR) was performed in 41 (55%) of the 74 patients; subtotal resection ([STR]; 90-99%) in 25 (34%); and partial resection ([PR]; < 90%) in 8 (11%). Regrowth rates in the GTR, STR, and PR groups were 2.4% (1 of 41 cases), 52% (13 of 25), and 62.5% (5 of 8), respectively, and the times to regrowth ranged from 6 to 76 months (median 31.9 months). The regrowth-free survival curves differed significantly between the complete (GTR) and incomplete (STR and PR) resection groups. Eighteen (54.5%) of the 33 patients who underwent incomplete resection showed evidence of regrowth during follow-up. Univariate and multivariate analyses of various factors revealed that both the thickness of the residual tumor, based on MR imaging after surgery, and the MIB-1 index were positively related to residual tumor regrowth. The receiver operating characteristic curves, plotted for both the thickness of the residual tumor and the MIB-1 index, identified the optimal cutoff points for these values as 7.4 mm (sensitivity 83.3%, specificity 86.7%) and 1.6 (sensitivity 83.3%, specificity 66.7%), respectively. CONCLUSIONS: Greater residual tumor thickness, based on MR imaging after the initial surgery, and a higher MIB-1 index are both important factors related to postoperative tumor regrowth in patients who have undergone incomplete VS resection. These patients require frequent neuroimaging investigation during follow-up to assure early detection of tumor regrowth.

DOI： 10.3171/2010.11.JNS101041

Transarterial embolisation for refractory bilateral chronic subdural hematomas in a case with dentatorubral-pallidoluysian atrophy Reviewed

Yoshihiro Tsukamoto, Makoto Oishi, Junnsuke Shinbo, Yukihiko Fujii

ACTA NEUROCHIRURGICA 153 ( 5 ) 1145 - 1147 2011.5

Presurgical simulation with advanced 3-dimensional multifusion volumetric imaging in patients with skull base tumors. International journal

Makoto Oishi, Masafumi Fukuda, Go Ishida, Akihiko Saito, Tetsuya Hiraishi, Yukihiko Fujii

Neurosurgery 68 ( 1 Suppl Operative ) 188 - 99 2011.3

Language：English Publishing type：Research paper (scientific journal)

BACKGROUND: Despite recent diagnostic and technical advancements in the field of neurosurgery, surgical treatment for tumors in the skull base region, ie, skull base tumors (SBTs), remains a challenge. OBJECTIVE: To validate the utility of presurgical simulation for the treatment of SBTs by 3-dimensional multifusion volumetric imaging (3D MFVI), including volume rendering and image fusion, to combine data from various imaging modalities. METHODS: We performed presurgical simulation using 3D MFVI for 21 SBTs (acoustic neurinomas, jugular neurinomas, meningiomas, chordomas, and others) in 20 patients. We collected targeted data from computed tomography, magnetic resonance imaging, computed tomography or magnetic resonance angiography, and digital subtraction angiography and combined these data using image-analyzing software. The simulations were used to assess the 3D relationships among the microsurgical anatomical components, the appropriate surgical approach, and the resectable parts of the tumor. Finally, we compared the results of the simulation with the operative results. RESULTS: In all patients, the 3D MFVI techniques enabled adequate visualization of the microsurgical anatomy and facilitated presurgical simulation, thereby allowing the surgeons to determine an appropriate and feasible surgical approach. All procedures to open the bone window were performed in accordance with the simulations, except for the surgical exposure of the acoustic canal for 2 acoustic neurinomas. In 3 of the 21 cases, tumor removal could not be performed according to the simulations because of unexpected bleeding or other restrictions. CONCLUSION: The 3D MFVI technique was of a sufficiently high quality to enable visualization of the 3D microsurgical anatomy. This promising method can facilitate determination of the most appropriate approach and safe and precise surgical procedures for SBTs.

DOI： 10.1227/NEU.0b013e318207b3ad

[Depiction of the trigeminal nerve deviated by a tumor lesion, using probabilistic diffusion tensor tractography].

Go Ishida, Makoto Oishi, Masafumi Fukuda, Mitsuya Sato, Yukihiko Fujii

No shinkei geka. Neurological surgery 39 ( 3 ) 255 - 62 2011.3

Language：Japanese Publishing type：Research paper (scientific journal)

We attempted presurgical visualization of the trigeminal nerve deviated by tumor compression using the probabilistic diffusion tractography (PDT) technique, which is used to analyze diffusion tensor imaging (DTI) data. We acquired DTI data of 3 patients with a tumor lesion around the trigeminal nerve (2 patients with trigeminal neurinomas and 1 with epidermoid) using the 3T magnetic resonance imaging system. The DTI data was analyzed by PDT using the Diffusion Toolbox, and the software of FMRIB (FDT; www.fmrib.ox.ac.uk/fsl). In all 3 patients, PDT allowed successful visualization of the trigeminal nerve which is further distal to the trigeminal ganglion, even when heavy T2-weighted imaging and conventional fiber-tracking analysis of the DTI data revealed only the cisternal segment of the nerves. Especially in 2 cases with the tumor mainly located in the Meckel's cave, the location of the nerve was determined only by PDT. All these findings obtained by PDT were concordant with the intraoperative observation of the actual nerves. In conclusion, PDT is a useful technique for visualization of the trigeminal nerve even when it is severely deviated by tumor compression, and this technique could have potential for evaluating other cranial nerves in surgical cases with a tumor in the skull base.

Trigeminal neuralgia associated with the specific bridging pattern of transverse pontine vein: diagnostic value of three-dimensional multifusion volumetric imaging. International journal

Makoto Oishi, Masafumi Fukuda, Yoshiyuki Noto, Tadashi Kawaguchi, Tetsuya Hiraishi, Yukihiko Fujii

Stereotactic and functional neurosurgery 89 ( 4 ) 226 - 33 2011

Language：English Publishing type：Research paper (scientific journal)

OBJECTIVES: We report the specific bridging pattern of a transverse pontine vein (TPV) associated with trigeminal neuralgia (TN), which was evaluated by 3-dimensional (3D) multifusion volumetric imaging (MFVI). METHODS: In 3 cases with TN (V1 or V1-2 territory), constructive interference in steady state (CISS) imaging confirmed no arterial compression but indicated a vein draining into Meckel's cave. Virtual endoscopic (VE) analysis for CISS images and 3D MFVI (in 2 cases) including venous information was obtained by a multidetector row computed tomography (MDCT) system. Additionally, we investigated the bridging pattern of veins around Meckel's cave on 3D MFVI of 50 cerebellopontine angle (CPA) regions without any lesions. RESULTS: In all 3 patients, VE of CISS or 3D MFVI identified a bridging vein from the TPV causing the focal deformity of the trigeminal nerve near Meckel's cave. All those patients achieved a pain-free state after surgically coagulating and cutting the vein. In investigating 3D MFVI of 50 CPA regions, this type of the bridging vein was found in 4 (8%) including the presented 2 cases. CONCLUSIONS: The specific bridging pattern of the TPV draining into Meckel's cave can be associated with TN. The 3D MFVI analysis using venous information obtained by MDCT was useful to evaluate surgical anatomy including the offending vein which can be missed.

DOI： 10.1159/000326778

Prediction of the microsurgical window for skull-base tumors by advanced three-dimensional multi-fusion volumetric imaging.

Makoto Oishi, Masafumi Fukuda, Go Ishida, Akihiko Saito, Tetsuya Hiraishi, Yukihiko Fujii

Neurologia medico-chirurgica 51 ( 3 ) 201 - 7 2011

Language：English Publishing type：Research paper (scientific journal)

The surgery of skull base tumors (SBTs) is difficult due to the complex and narrow surgical window that is restricted by the cranium and important structures. The utility of three-dimensional multi-fusion volumetric imaging (3-D MFVI) for visualizing the predicted window for SBTs was evaluated. Presurgical simulation using 3-D MFVI was performed in 32 patients with SBTs. Imaging data were collected from computed tomography, magnetic resonance imaging, and digital subtraction angiography. Skull data was processed to imitate actual bone resection and integrated with various structures extracted from appropriate imaging modalities by image-analyzing software. The simulated views were compared with the views obtained during surgery. All craniotomies and bone resections except opening of the acoustic canal in 2 patients were performed as simulated. The simulated window allowed observation of the expected microsurgical anatomies including tumors, vasculatures, and cranial nerves, through the predicted operative window. We could not achieve the planned tumor removal in only 3 patients. 3-D MFVI afforded high quality images of the relevant microsurgical anatomies during the surgery of SBTs. The intraoperative déjà-vu effect of the simulation increased the confidence of the surgeon in the planned surgical procedures.

Fiber tract visualization and intraoperative functional neuronavigation Reviewed

Yukihiko Fujii, Hitoshi Matsuzawa, Makoto Oishi, Takeo Uzuka, Tsutomu Nakada

Japanese Journal of Neurosurgery 20 ( 4 ) 247 - 253 2011

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Congress of Neurological Surgeons

Visualization of neural fibers using diffusion tensor imaging (DTI) is becoming an indispensable tool in neurosurgery. Currently, two techniques, three-dimensional anisotropy contrast (3DAC) imaging and tractography, are frequently utilized. 3DAC images provide three-dimensional fiber-directional information in true color contrast and exquisitely high anatomical resolution sensitive to physiological anisotropism. Images are obtained by performing processes in image form (pictorial mathematics) without the necessity of eigenvalue estimation. Hence, image quality is identical to conventional magnetic resonance images such as T1 weighted and T2 weighted images. 3DAC has been shown to provide images with extraordinary contrast to detect not only major neural tracts but also fine neural fibers and nuclei, including in the brainstem and spinal cord. Tractography is widely used in neurosurgical settings, especially for presurgical planning to identify neural tracts. The direction of the largest diffusion determined by DTI parallels the dominant fiber orientation in each voxel, representing the mean longitudinal direction of neural fibers, which can be utilized for fiber tract tracing, i. e., tractography. Tractography is generally performed in two different ways, i. e., by deterministic or probabilistic methods. Advantages of the latter method over the former include the ability to clearly represent uncertainty and to reconstruct crossing fibers in the data, though the former is computationally intensive because of its requirement of thousands of iterations. There is widespread misunderstanding that tractography images actually represent real tracts and their pathology. In order to avoid such a potentially serious mistake, clinicians should clearly understand that, unlike 3DAC, tractography is in fact an artificial image. Recently, functional neuronavigation, i. e., intraoperative navigation integrated with preoperative functional images, was introduced into neurosurgical practice. Functional neuronavigation combined with visualization of thefiber tract is also expected to significantly reduce postoperative neurological deficits. In this venue, accuracy ofthe navigation is critical. It is, therefore, imperative that neurosurgeons understand the pros and cons of each of the techniques to be incorporated. The most reliable scenario will be the combination of intraoperative images, such as computed tomographic images and magnetic resonance images, appropriately integrated with functional data obtained preoperatively.

DOI： 10.7887/jcns.20.247

[Effects of abnormal muscle response monitoring on manipulation of microvascular decompression].

Masafumi Fukuda, Makoto Oishi, Tetsuya Hiraishi, Yukihiko Fujii

No shinkei geka. Neurological surgery 38 ( 6 ) 531 - 8 2010.6

Language：Japanese Publishing type：Research paper (scientific journal)

OBJECTIVE: Intraoperative abnormal muscle response (AMR) monitoring is used as an indicator of postoperative outcome in patients with hemifacial spasm (HFS). We investigated whether AMR findings influence manipulation of microvascular decompression and improve the postoperative results. MATERIALS AND METHODS: Subjects were 102 HFS patients who underwent AMR monitoring during surgery. The value of AMR monitoring was classified into four categories: a guiding, a confirming, an indirect confirming, or an inconclusive role. The relationship between AMR monitoring results and surgical outcome was analyzed. RESULTS: The overall cure rate was 92.2%. A guiding role of AMR monitoring was apparent in 13.7% of patients, and a confirming role was demonstrated in 53.9% of patients. The cure rate was 92.9% in patients defined as guiding, and 96.4% in patients defined as confirming cases. When the AMR remained disappearance until completion of decompression in patients assigned in indirect confirming, 13 of 15 patients (86.7%) experienced resolution postoperatively. In patients defined as inconclusive cases, 14 of 16 patients (87.5%) in whom AMR still presented but its amplitude decreased at the end of surgery experienced complete resolution. CONCLUSIONS: This study demonstrates that meticulous evaluation of AMR findings intraoperatively can help to improve the results of surgery. We believe that intraoperative AMR monitoring is useful in microvascular decompression for HFS.

Facial nerve motor-evoked potential monitoring during microvascular decompression for hemifacial spasm. International journal

Masafumi Fukuda, Makoto Oishi, Tetsuya Hiraishi, Yukihiko Fujii

Journal of neurology, neurosurgery, and psychiatry 81 ( 5 ) 519 - 23 2010.5

Language：English Publishing type：Research paper (scientific journal)

OBJECTIVE: To determine whether monitoring facial nerve motor-evoked potentials (FNMEPs) elicited by transcranial electrical stimulation during microvascular decompression (MVD) for hemifacial spasm (HFS) is useful for predicting postoperative outcome. METHODS: The authors analysed FNMEP findings in 25 patients with HFS. Corkscrew electrodes positioned at C3 or C4 and Cz were used to deliver supramaximal stimuli (152-450 V). FNMEPs were recorded from the orbicularis oculi, mentalis and oris muscles. Differences in amplitude or response duration between the final (at dural closure) and baseline FNMEP were evaluated. Final-to-baseline FNMEPs ratios (shown as percentages) obtained from the three muscles were examined. RESULTS: In the orbicularis oculi muscles, both duration and amplitude in the final FNMEP were significantly reduced compared with the baseline FNMEP (p<0.001 and p<0.0005, respectively). The FNMEP ratio obtained from the orbicularis oculi muscle (44.8+/-25.4%) was significantly lower than the other two muscles (95.8+/-51.2% for the mentalis muscle and 84.5+/-34.6% for the orbicularis oris muscle; p<0.0001). In one patient who showed the same degree of symptoms immediately after surgery as in the preoperative state, neither LSRs nor FNMEP from the orbicularis oculi muscle changed. CONCLUSIONS: The FNMEP amplitude from the orbicularis oculi muscle decreased after MVD in HFS patients whose symptoms were resolved postoperatively, thus suggesting normalisation of facial nerve excitability. FNMEP monitoring during MVD surgery as well as LSR monitoring could predict postoperative outcome in HFS patients.

DOI： 10.1136/jnnp.2009.181495

Long-term outcomes after surgical treatment of jugular foramen schwannoma. International journal

Masafumi Fukuda, Makoto Oishi, Akihiko Saito, Yukihiko Fujii

Skull base : official journal of North American Skull Base Society ... [et al.] 19 ( 6 ) 401 - 8 2009.11

Language：English Publishing type：Research paper (scientific journal)

The purpose of this article is to clarify long-term outcomes following surgery for jugular foramen schwannomas. Fifteen adult patients underwent surgery, predominantly via the lateral suboccipital approach, for jugular foramen schwannomas between December 1987 and May 2007. All information was collected retrospectively from patient medical records at a university hospital. The main outcome measures were tumor regrowth and IX-X nerve function at median 84.3 months (range, 12 to 166 months) following surgery. Near total removal was achieved in 10 patients, and the remaining 5 patients had subtotal removal. Tumor regrowth was observed in 9 of 15 patients at 6 to 89 months (mean, 31.2 months) after surgery. The actual tumor control rate was 70.0 +/- 12.8% at 5 years. Fourteen of 15 patients exhibited IX-X nerve dysfunction immediately after surgery, but 8 of these 14 patients experienced amelioration of the symptoms at the final follow-up period. No patients required additional treatment. We found in our study that for jugular foramen schwannoma, tumor volume should be reduced as much as possible to avoid severe IX-X nerve damages postoperatively. If a small amount of tumor remains, long-term follow-up is necessary.

DOI： 10.1055/s-0029-1220197

[Presurgical evaluaton for lateral suboccipital craniotomy using contrast-enhanced CT volumetric imaging].

Makoto Oishi, Masafumi Fukuda, Akihiko Saito, Tetsuya Hiraishi, Yukihiko Fuji

No shinkei geka. Neurological surgery 37 ( 5 ) 459 - 65 2009.5

Language：Japanese Publishing type：Research paper (scientific journal)

To safely and precisely accomplish lateral suboccipital craniotomy (LSOC), we have presurgically evaluated the three-dimensional (3-D) relationships of various vascular structures and cranial landmarks in the occipito-cervical region by volumetric imaging of 3-D contrast enhanced computed tomography (CECT). The 3-D anatomies visualized by adjusting the window width, window level, and opacity level of the specific CT value for each structure were an occpital artery (OA), mastoid and posterior condylar emissary veins (MEV and PCEV), which were useful in dissecting muscles and exposing the cranial surface, and the relationship of the transverse-sigmoid sinus CTSS) and the asterion, which was necessary and decisive for making a key burr hole to perform craniotomy. The morphologic analysis for our 48 cases with cerebello-pontine angle tumor or neurovascular compression syndrome showed running patterns of OA, varieties of MEV and PCEV in their sizes and connections, right dominance of TSS, and the various relationship between the TSS and the asterion. Especially, the exact location of the TSS compared to the astenon was found to be inferior in 56%, right below in 38%, and superior in 6%. In conclusion, presurgical evaluation using volumetric imaging of 3-D CECT is a convenient and valuable method for obtaining the anatomic information required for performing LSOC safely and precisely in individual patients.

Three-dimensional visualization of neurovascular compression: presurgical use of virtual endoscopy created from magnetic resonance imaging. International journal

Tetsuro Takao, Makoto Oishi, Masafumi Fukuda, Go Ishida, Mitsuya Sato, Yukihiko Fujii

Neurosurgery 63 ( 1 Suppl 1 ) ONS139-45; discussion ONS145-6 2008.7

Language：English Publishing type：Research paper (scientific journal)

OBJECTIVE: To assess the usefulness of presurgical simulation of microvascular decompression (MVD) by virtual endoscopy (VE), a new tool to analyze three-dimensionally reconstructed magnetic resonance data sets in patients with trigeminal neuralgia or hemifacial spasm (HFS). METHODS: In 17 patients (10 with trigeminal neuralgia and seven with HFS) determined to be candidates for MVD, we performed presurgical simulation of MVD using VE. We used constructive interference in steady-state imaging and magnetic resonance angiography to obtain the original images. VE findings were compared with surgical findings. RESULTS: The three-dimensional relations between visible structures seen on VE were consistent with intraoperative findings in all patients. In total, 20 (91%) of 22 neurovascular compression sites in all 17 patients were correctly delineated on VE, with the exception of two small branches identified as offending vessel in two patients with HFS. Perforators that were not apparent on VE limited our ability to accomplish transpositioning of the offending vessels as simulated. The positions of structures that can affect individual surgical approaches, such as the petrosal vein, cerebellar flocculus, and vertebral artery, were also adequately predicted on VE. All patients had excellent surgical outcomes. CONCLUSION: Presurgical VE in patients with trigeminal neuralgia or HFS is a novel technique that provides excellent visualization of the three-dimensional relations between neurovascular structures and allows simulation of MVD.

DOI： 10.1227/01.neu.0000335028.77779.7c

[Facial nerve motor evoked potentials elicited by transcranial electrical stimulation for intraoperative monitoring].

Masafumi Fukuda, Makoto Oishi, Akihiko Saito, Tetsuro Takao, Yukihiko Fujii

No shinkei geka. Neurological surgery 36 ( 4 ) 315 - 21 2008.4

Language：Japanese Publishing type：Research paper (scientific journal)

OBJECTIVE: To determine whether monitoring facial nerve motor evoked potentials (FNMEPs) elicited by transcranial electrical stimulation during skull base tumor surgery is useful for predicting facial nerve outcome. METHODS: We analyzed FNMEP findings in 31 patients with skull base tumor. Surgery was performed twice in 2 of the 31 patients because of tumor regrowth. FNMEP monitoring was conducted 33 times in the present study. Corkscrew electrodes positioned at C3 or C4 and Cz were used to deliver supramaximal stimuli (140-550V). FNMEPs were recorded from the orbicularis oculi and oris muscles. Correlation between the final-to-baseline FNMEP ratio and postoperative facial nerve function (House & Brackmann grade) was examined. RESULTS: Valid FNMEPs were obtained in 26 of the 33 (78.8%) recordings from the orbicularis oculi muscle and in 31 of the 33 (93.9%) recordings from the orbicularis oris muscle. Facial nerve function correlated significantly with the FNMEP ratios in the orbicularis oculi (r = -0.52 N=26, p < 0.01) and orbicularis oris (r = -0.60, N=31, p < 0.001) muscles. An FNMEP ratio of -50% consistently predicted immediate postoperative facial palsy, although the degree of palsy differed among the patients. CONCLUSIONS: Intraoperative FNMEP monitoring is useful for predicting facial nerve function after skull base surgery.

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