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Clinicopathological factors related to regrowth of vestibular schwannoma after incomplete resection

Clinical article

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

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.

In Journal of Neurosurgery Volume 114 (2011): Issue 5 (May 2011)

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

Clinical article

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

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.

In Journal of Neurosurgery Volume 116 (2012): Issue 3 (Mar 2012)

Free access

Visualization of cortical activation in human brain by flavoprotein fluorescence imaging

Daiju Mitsuhashi, Ryuichi Hishida, Makoto Oishi, Tetsuya Hiraishi, Manabu Natsumeda, Katsuei Shibuki, and Yukihiko Fujii

OBJECTIVE

To develop an innovative brain mapping and neuromonitoring method during neurosurgery, the authors set out to establish intraoperative flavoprotein fluorescence imaging (iFFI) to directly visualize cortical activations in human brain. The significance of iFFI was analyzed by comparison with intraoperative perfusion-dependent imaging (iPDI), which is considered the conventional optical imaging, and by performing animal experiments.

METHODS

Seven patients with intracerebral tumors were examined by iFFI and iPDI following craniotomy, using a single operative microscope equipped with a laser light source for iFFI and xenon lamp for iPDI. Images were captured by the same charge-coupled device camera. Responses to bipolar stimulation at selected points on the cortical surface were analyzed off-line, and relative signal changes were visualized by overlaying pseudocolor intensity maps onto cortical photographs. Signal changes exceeding 3 SDs from baseline were defined as significant. The authors also performed FFI and PDI on 10 mice using similar settings, and then compared signal patterns to intraoperative studies.

RESULTS

Signals acquired by iFFI exhibited biphasic spatiotemporal changes consisting of an early positive signal peak (F1) and a delayed negative signal peak (F2). In contrast, iPDI signals exhibited only 1 negative peak (P1) that was significantly delayed compared to F1 (p < 0.02) and roughly in phase with F2. Compared to F2 and P1, F1 was of significantly lower amplitude (p < 0.02) and located closer to the bipolar stimulus center (p < 0.03), whereas F2 and P1 were more widespread, irregular, and partially overlapping. In mice, the spatiotemporal characteristics of FFI and PDI resembled those of iFFI and iPDI, but the early positive signal was more robust than F1.

CONCLUSIONS

This is the first report in humans of successful intraoperative visualization of cortical activations by using iFFI, which showed rapid evoked cortical activity prior to perfusion-dependent signal changes. Further technical improvements can lead to establishment of iFFI as a real-time intraoperative tool.

In Journal of Neurosurgery Volume 137: Issue 4 (Oct 2022)

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Interactive virtual simulation using a 3D computer graphics model for microvascular decompression surgery

Clinical article

Makoto Oishi, Masafumi Fukuda, Tetsuya Hiraishi, Naoki Yajima, Yosuke Sato, and Yukihiko Fujii

Object

The purpose of this paper is to report on the authors' advanced presurgical interactive virtual simulation technique using a 3D computer graphics model for microvascular decompression (MVD) surgery.

Methods

The authors performed interactive virtual simulation prior to surgery in 26 patients with trigeminal neuralgia or hemifacial spasm. The 3D computer graphics models for interactive virtual simulation were composed of the brainstem, cerebellum, cranial nerves, vessels, and skull individually created by the image analysis, including segmentation, surface rendering, and data fusion for data collected by 3-T MRI and 64-row multidetector CT systems. Interactive virtual simulation was performed by employing novel computer-aided design software with manipulation of a haptic device to imitate the surgical procedures of bone drilling and retraction of the cerebellum. The findings were compared with intraoperative findings.

Results

In all patients, interactive virtual simulation provided detailed and realistic surgical perspectives, of sufficient quality, representing the lateral suboccipital route. The causes of trigeminal neuralgia or hemifacial spasm determined by observing 3D computer graphics models were concordant with those identified intraoperatively in 25 (96%) of 26 patients, which was a significantly higher rate than the 73% concordance rate (concordance in 19 of 26 patients) obtained by review of 2D images only (p < 0.05). Surgeons evaluated interactive virtual simulation as having “prominent” utility for carrying out the entire surgical procedure in 50% of cases. It was evaluated as moderately useful or “supportive” in the other 50% of cases. There were no cases in which it was evaluated as having no utility. The utilities of interactive virtual simulation were associated with atypical or complex forms of neurovascular compression and structural restrictions in the surgical window. Finally, MVD procedures were performed as simulated in 23 (88%) of the 26 patients .

Conclusions

Our interactive virtual simulation using a 3D computer graphics model provided a realistic environment for performing virtual simulations prior to MVD surgery and enabled us to ascertain complex microsurgical anatomy.

In Journal of Neurosurgery Volume 117 (2012): Issue 3 (Sep 2012)

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Interactive presurgical simulation applying advanced 3D imaging and modeling techniques for skull base and deep tumors

Clinical article

Makoto Oishi, Masafumi Fukuda, Naoki Yajima, Kenzo Yoshida, Machiko Takahashi, Tetsuya Hiraishi, Tetsuro Takao, Akihiko Saito, and Yukihiko Fujii

Object

In this paper, the authors' goal was to report their novel presurgical simulation method applying interactive virtual simulation (IVS) using 3D computer graphics (CG) data and microscopic observation of color-printed plaster models based on these CG data in surgery for skull base and deep tumors.

Methods

For 25 operations in 23 patients with skull base or deep intracranial tumors (meningiomas, schwannomas, epidermoid tumors, chordomas, and others), the authors carried out presurgical simulation based on 3D CG data created by image analysis for radiological data. Interactive virtual simulation was performed by modifying the 3D CG data to imitate various surgical procedures, such as bone drilling, brain retraction, and tumor removal, with manipulation of a haptic device. The authors also produced color-printed plaster models of modified 3D CG data by a selective laser sintering method and observed them under the operative microscope.

Results

In all patients, IVS provided detailed and realistic surgical perspectives of sufficient quality, thereby allowing surgeons to determine an appropriate and feasible surgical approach. Surgeons agreed that in 44% of the 25 operations IVS showed high utility (as indicated by a rating of “prominent”) in comprehending 3D microsurgical anatomies for which reconstruction using only 2D images was complicated. Microscopic observation of color-printed plaster models in 12 patients provided further utility in confirming realistic surgical anatomies.

Conclusions

The authors' presurgical simulation method applying advanced 3D imaging and modeling techniques provided a realistic environment for practicing microsurgical procedures virtually and enabled the authors to ascertain complex microsurgical anatomy, to determine the optimal surgical strategies, and also to efficiently educate neurosurgical trainees, especially during surgery for skull base and deep tumors.

In Journal of Neurosurgery Volume 119 (2013): Issue 1 (Jul 2013)

Open access

Preoperative three-dimensional multifusion imaging aiding successful microvascular decompression of a cerebellopontine angle lipoma: associated hemifacial spasm. Illustrative case

Hiroki Seto, Ryosuke Ogura, Tetsuya Hiraishi, Yoshihiro Tsukamoto, Taiki Saito, Satoshi Shibuma, Kohei Shibuya, Kouichirou Okamoto, Makoto Oishi, and Yukihiko Fujii

BACKGROUND

Cerebellopontine angle (CPA) lipoma–associated hemifacial spasm (HFS) is rare. As the removal of CPA lipomas has a high risk of worsening the neurological symptoms, surgical exploration is warranted only in selected patients. Preoperative identification of the lipoma affected site of the facial nerve, and offending artery are crucial for patient selection and successful microvascular decompression (MVD).

OBSERVATIONS

Presurgical simulation using three-dimensional (3D) multifusion imaging showed a tiny CPA lipoma wedged between the facial and auditory nerves, as well as an affected facial nerve by the anterior inferior cerebellar artery (AICA) at the cisternal segment. Although a recurrent perforating artery from the AICA anchored the AICA to the lipoma, successful MVD was achieved without lipoma removal.

LESSONS

The presurgical simulation using 3D multifusion imaging could identify the CPA lipoma, affected site of the facial nerve, and offending artery. It was helpful for patient selection and successful MVD.

In Journal of Neurosurgery: Case Lessons Volume 5 (2023): Issue 12 (Mar 2023)