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The cochlea in skull base surgery: an anatomy study

Jian Wang, Fumitaka Yoshioka, Wonil Joo, Noritaka Komune, Vicent Quilis-Quesada and Albert L. Rhoton Jr.

OBJECTIVE

The object of this study was to examine the relationships of the cochlea as a guide for avoiding both cochlear damage with loss of hearing in middle fossa approaches and injury to adjacent structures in approaches directed through the cochlea.

METHODS

Twenty adult cadaveric middle fossae were examined using magnifications of ×3 to ×40.

RESULTS

The cochlea sits below the floor of the middle fossa in the area between and below the labyrinthine segment of the facial nerve and greater petrosal nerve (GPN) and adjacent to the lateral genu of the petrous carotid. Approximately one-third of the cochlea extends below the medial edge of the labyrinthine segment of the facial nerve, geniculate ganglion, and proximal part of the GPN. The medial part of the basal and middle turns are the parts at greatest risk in drilling the floor of the middle fossa to expose the nerves in middle fossa approaches to the internal acoustic meatus and in anterior petrosectomy approaches. Resection of the cochlea is used selectively in extending approaches through the mastoid toward the lateral edge of the clivus and front of the brainstem.

CONCLUSIONS

An understanding of the location and relationships of the cochlea will reduce the likelihood of cochlear damage with hearing loss in approaches directed through the middle fossa and reduce the incidence of injury to adjacent structures in approaches directed through the cochlea.

In Journal of Neurosurgery Publish Before Print

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Diffusivity parameters of diffusion tensor imaging and apparent diffusion coefficient as imaging markers for predicting the treatment response of patients with trigeminal neuralgia

Yu-Li Lee, Shu-Tian Chen, Jen-Tsung Yang, Hsu-Huei Weng, Hsueh-Lin Wang and Yuan-Hsiung Tsai

OBJECTIVE

Trigeminal neuralgia (TN) is facial pain that is usually caused by neurovascular compression syndrome and is characterized by suddenly intense and paroxysmal pain. Radiofrequency lesioning (RFL) is one of the major treatments for TN, but the treatment response for RFL is sometimes inconsistent, and the recurrence of TN is not uncommon. This study aimed to estimate the outcome predictors of TN treated with RFL by using the parameters of diffusion tensor imaging (DTI).

METHODS

Fifty-one patients with TN who were treated with RFL were enrolled in the study. MRI was performed in all patients within 1 week before surgery. The visual analog scale was used to evaluate symptom severity at three time points: before, 1 week after, and 3 months after RFL. The involved cisternal segment of the trigeminal nerves was manually selected, and the histograms of each of the diffusivity metrics—including the apparent diffusion coefficient (ADC), fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD)—were measured. The differences in the means, as well as the kurtosis and skewness of each of the diffusivity metrics between the nonrecurrent and recurrent groups, were then analyzed using the Mann-Whitney U-test.

RESULTS

There were significantly lower kurtosis values (a broader peak of the distributional curves) for both FA and ADC in the recurrent group (p = 0.0004 and 0.015, respectively), compared to the nonrecurrent group. The kurtoses of AD and RD, as well as the mean and skewness of all other diffusivity metrics, did not show significant differences between the two groups.

CONCLUSIONS

The pretreatment diffusivity metrics of DTI and ADC may be feasible imaging biomarkers for predicting the outcome of TN after RFL. A clarification of the kurtosis value of FA and ADC is helpful for determining the prognosis of patients after RFL.

In Journal of Neurosurgery Publish Before Print

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The effect of preoperative embolization and flow dynamics on resection of brain arteriovenous malformations

Grace F. Donzelli, Jeffrey Nelson, David McCoy, Charles E. McCulloch, Steven W. Hetts, Matthew R. Amans, Christopher F. Dowd, Van V. Halbach, Randall T. Higashida, Michael T. Lawton, Helen Kim and Daniel L. Cooke

OBJECTIVE

Preoperative embolization of brain arteriovenous malformations (AVMs) is performed to facilitate resection, although its impact on surgical performance has not been clearly defined. The authors tested for associations between embolization and surgical performance metrics.

METHODS

The authors analyzed AVM cases resected by one neurosurgeon from 2006 to 2017. They tested whether cases with and without embolization differed from one another with respect to patient and AVM characteristics using t-tests for continuous variables and Fisher’s exact tests for categorical variables. They used simple and multivariable regression models to test whether surgical outcomes (blood loss, resection time, surgical clip usage, and modified Rankin Scale [mRS] score) were associated with embolization. Additional regression analyses integrated the peak arterial afferent contrast normalized for the size of the region of interest (Cmax/ROI) into models as an additional predictor.

RESULTS

The authors included 319 patients, of whom 151 (47%) had preoperative embolization. Embolized AVMs tended to be larger (38% with diameter > 3 cm vs 19%, p = 0.001), less likely to have hemorrhaged (48% vs 63%, p = 0.013), or be diffuse (19% vs 29%, p = 0.045). Embolized AVMs were more likely to have both superficial and deep venous drainage and less likely to have exclusively deep drainage (32% vs 17% and 12% vs 23%, respectively; p = 0.002). In multivariable analysis, embolization was not a significant predictor of blood loss or mRS score changes, but did predict longer operating times (+29 minutes, 95% CI 2–56 minutes; p = 0.034) and increased clip usage (OR 2.61, 95% CI 1.45–4.71; p = 0.001). Cmax/ROI was not a significant predictor, although cases with large Cmax/ROI tended to have longer procedure times (+25 minutes per doubling of Cmax/ROI, 95% CI 0–50 minutes; p = 0.051).

CONCLUSIONS

In this series, preoperative embolization was associated with longer median resection times and had no association with intraoperative blood loss or mRS score changes.

In Journal of Neurosurgery Publish Before Print

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Increasing the accuracy of 3D EEG implantations

Roman Rodionov, Aidan O’Keeffe, Mark Nowell, Michele Rizzi, Vejay N. Vakharia, Victoria Wykes, Sofia H. Eriksson, Anna Miserocchi, Andrew W. McEvoy, Sebastien Ourselin and John S. Duncan

OBJECTIVE

The accuracy of stereoelectroencephalography (SEEG) electrode implantation is an important factor in maximizing its safety. The authors established a quality assurance (QA) process to aid advances in implantation accuracy.

METHODS

The accuracy of three consecutive modifications of a frameless implantation technique was quantified in three cohorts comprising 22, 8, and 23 consecutive patients. The modifications of the technique aimed to increase accuracy of the bolt placement.

RESULTS

The lateral shift of the axis of the implanted bolt at the level of the planned entry point was reduced from a mean of 3.0 ± 1.6 mm to 1.4 ± 0.8 mm. The lateral shift of the axis of the implanted bolt at the level of the planned target point was reduced from a mean of 3.8 ± 2.5 mm to 1.6 ± 0.9 mm.

CONCLUSIONS

This QA framework helped to isolate and quantify the factors introducing inaccuracy in SEEG implantation, and to monitor ongoing accuracy and the effect of technique modifications.

In Journal of Neurosurgery Publish Before Print

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Intraoperative ultrasound visualization of paravertebral anatomy in the retroperitoneal space during lateral lumbar spine surgery

Hidetoshi Nojiri, Kei Miyagawa, Hiroto Yamaguchi, Masato Koike, Yoshiyuki Iwase, Takatoshi Okuda and Kazuo Kaneko

OBJECTIVE

Lumbar surgery via a lateral approach is a minimally invasive and highly useful procedure. However, care must be taken to avoid its potentially fatal complications of intestinal and vascular injuries. The object of this study was to evaluate the usefulness of intraoperative ultrasound in improving the safety of lateral lumbar spine surgery.

METHODS

A transvaginal ultrasound probe was inserted into the operative field, and the intestinal tract, kidney, psoas muscle, and vertebral body were identified using B-mode ultrasound. The aorta, vena cava, common iliac vessels, and lumbar arteries and their associated branches were identified using the color Doppler mode.

RESULTS

The study cohort comprised 100 patients who underwent lateral lumbar spine surgery, 92 via a left-sided approach. The intestinal tract and kidney lateral to the psoas muscle on the anatomical approach pathway were visualized in 36 and 26 patients, respectively. A detachment maneuver displaced the intestinal tract and kidneys in an anteroinferior direction, enabling confirmation of the absence of organ tissues above the psoas. In all patients, the major vessels anterior to the vertebral bodies and the lumbar arteries and associated branches in the psoas on the approach path were clearly visualized in the Doppler mode, and their orientation, location, and positional relationship with regard to the vertebral bodies, intervertebral discs, and psoas were determined.

CONCLUSIONS

When approaching the lateral side of the lumbar spine in the retroperitoneal space, intraoperative ultrasound allows real-time identification of the blood vessels surrounding the lumbar spine, intestinal tract, and kidney in the approach path and improves the safety of surgery without increasing invasiveness.

In Journal of Neurosurgery: Spine Publish Before Print

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Intrauterine closure of myelomeningocele is associated with superior long-term quality of life than postnatal closure: a single-center study

Nishit Mummareddy, Michael C. Dewan, Anna Huang, Jade Basem, Kelly A. Bennett, Chevis N. Shannon and John C. Wellons III

OBJECTIVE

The Management of Myelomeningocele Study (MOMS) established several important benefits of myelomeningocele fetal closure, including decreased need for shunting at 30 months. However, the effects of fetal closure on long-term quality of life (QOL) have not been studied. In this study, the authors aimed to analyze the differences in long-term QOL between children treated with intrauterine repair and those treated with postnatal repair.

METHODS

Caregivers of children treated with either intrauterine or postnatal closure at a tertiary acute care hospital between 1997 and 2003 were contacted to participate. The Pediatric Quality of Life Inventory (PedsQL 4.0) and a surgical history questionnaire were administered over the phone. Responses to the QOL survey were reverse scored and linearly transformed to a 0–100 scale, with a higher score indicating better QOL. The Mann-Whitney U-test was used to analyze differences in means.

RESULTS

Seventy-four children had MMC repair between 1997 and 2003. Twenty-three (31%) of the patients’ families responded to the PedsQL 4.0 questionnaire. Of these 23 children, 11 had intrauterine closure and 12 had postnatal closure. The intrauterine group did not differ in age (median [IQR] 17 years [14–17 years] vs 15 years [14–19 years], p = 0.926), sex (27.3% vs 41.7% male, p = 0.469), or lesion level (p = 0.199) from the postnatal group. Fewer patients in the intrauterine group underwent neurosurgical procedures than those in the postnatal group (55.6% vs 100%, p = 0.018). However, of the children receiving neurosurgical procedures, there was no difference in the number of procedures between the intrauterine and postnatal groups (median [IQR] 4 [2–10.5] vs 2.5 [1.75–6.25], p = 0.458). There was no difference in the percentage of children receiving nonneurosurgical procedures between the two groups (100% vs 100%, p > 0.99). Children who underwent intrauterine closure had significantly higher psychosocial health (median [IQR] 70.0 [56.7–83.3] vs 55.0 [42.1–60.0], p = 0.015) as well as total QOL (median [IQR] 56.5 [55.4–81.5] vs 49.5 [32.9–59.0], p = 0.019) than children with postnatal closure. Physical health was not significantly different between the two groups (median [IQR] 62.5 [37.5–78.1] vs 39.1 [18.8–59.4], p = 0.108).

CONCLUSIONS

Relative to postnatal closure, children who underwent intrauterine closure of MMC demonstrated better long-term QOL as measured by psychosocial and overall QOL metrics. Given that not all medical and socioeconomic confounders were adjusted for due to the low sample size, validation of these results in a larger population and across multiple centers is needed.

In Journal of Neurosurgery: Pediatrics Publish Before Print

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Is supratotal resection achievable in low-grade gliomas? Feasibility, putative factors, safety, and functional outcome

Marco Rossi, Federico Ambrogi, Lorenzo Gay, Marcello Gallucci, Marco Conti Nibali, Antonella Leonetti, Guglielmo Puglisi, Tommaso Sciortino, Henrietta Howells, Marco Riva, Federico Pessina, Pierina Navarria, Ciro Franzese, Matteo Simonelli, Roberta Rudà and Lorenzo Bello

OBJECTIVE

Surgery for low-grade gliomas (LGGs) aims to achieve maximal tumor removal and maintenance of patients’ functional integrity. Because extent of resection is one of the factors affecting the natural history of LGGs, surgery could be extended further than total resection toward a supratotal resection, beyond tumor borders detectable on FLAIR imaging. Supratotal resection is highly debated, mainly due to a lack of evidence of its feasibility and safety. The authors explored the intraoperative feasibility of supratotal resection and its short- and long-term impact on functional integrity in a large cohort of patients. The role of some putative factors in the achievement of supratotal resection was also studied.

METHODS

Four hundred forty-nine patients with a presumptive radiological diagnosis of LGG consecutively admitted to the neurosurgical oncology service at the University of Milan over a 5-year period were enrolled. In all patients, a policy was adopted to perform surgery according to functional boundaries, aimed at achieving a supratotal resection whenever possible, without any patient or tumor a priori selection. Feasibility, general safety, and tumor or patient putative factors possibly affecting the achievement of a supratotal resection were analyzed. Postsurgical patient functional performance was evaluated in five cognitive domains (memory, language, praxis, executive functions, and fluid intelligence) using a detailed neuropsychological evaluation and quality of life (QOL) examination.

RESULTS

Total resection was feasible in 40.8% of patients, and supratotal resection in 32.3%. The achievement of a supratotal versus total resection was independent of age, sex, education, tumor volume, deep extension, location, handedness, appearance of tumor border, vicinity to eloquent sites, surgical mapping time, or surgical tools applied. Supratotal resection was associated with a long clinical history and histological grade II, suggesting that reshaping of brain networks occurred. Although a consistent amount of apparently MRI-normal brain was removed with this approach, the procedure was safe and did not carry additional risk to the patient, as demonstrated by detailed neuropsychological evaluation and QOL examination. This approach also improved seizure control.

CONCLUSIONS

Supratotal resection is feasible and safe in routine clinical practice. These results show that a long clinical history may be the main factor associated with its achievement.

In Journal of Neurosurgery Publish Before Print

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Letter to the Editor. Is 7-Tesla MRI necessary in the assessment of microstructural injury to visual pathways due to pituitary adenomas?

Xiaopeng Guo, Shun Yao and Bing Xing

In Journal of Neurosurgery Publish Before Print

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Letter to the Editor. Resting-state functional MRI for functional neurosurgery: seeing the light?

Constantin Tuleasca, Jean Régis, Elena Najdenovska, Tatiana Witjas, Nadine Girard, Jean-Philippe Thiran, Meritxell Bach Cuadra, Marc Levivier and Dimitri Van De Ville

In Journal of Neurosurgery Publish Before Print

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Long-term clinical and visual outcomes after surgical resection of pediatric pilocytic/pilomyxoid optic pathway gliomas

Eveline Teresa Hidalgo, Svetlana Kvint, Cordelia Orillac, Emily North, Yosef Dastagirzada, Jamie Chiapei Chang, Gifty Addae, Tara S. Jennings, Matija Snuderl and Jeffrey H. Wisoff

OBJECTIVE

The choice of treatment modality for optic pathway gliomas (OPGs) is controversial. Chemotherapy is widely regarded as first-line therapy; however, subtotal resections have been reported for decompression or salvage therapy as first- and second-line treatment. The goal of this study was to further investigate the role and efficacy of resection for OPGs.

METHODS

A retrospective chart review was performed on 83 children who underwent surgical treatment for OPGs between 1986 and 2014. Pathology was reviewed by a neuropathologist. Clinical outcomes, including progression-free survival (PFS), overall survival (OS), and complications, were analyzed.

RESULTS

The 5- and 10-year PFS rates were 55% and 46%, respectively. The 5- and 10-year OS rates were 87% and 78%, respectively. The median extent of resection was 80% (range 30%–98%). Age less than 2 years at surgery and pilomyxoid features of the tumor were found to be associated with significantly lower 5-year OS. No difference was seen in PFS or OS of children treated with surgery as a first-line treatment compared with children with surgery as a second- or third-line treatment. Severe complications included new disabling visual deficit in 5%, focal neurological deficit in 8%, and infection in 2%. New hormone deficiency occurred in 22% of the children.

CONCLUSIONS

Approximately half of all children experience a long-term benefit from resection both as primary treatment and as a second-line therapy after failure of primary treatment. Primary surgery does not appear to have a significant benefit for children younger than 2 years or tumors with pilomyxoid features. Given the risks associated with surgery, an interdisciplinary approach is needed to tailor the treatment plan to the individual characteristics of each child.

In Journal of Neurosurgery: Pediatrics Publish Before Print