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Daniel T. Nagasawa, Zachary A. Smith, Nicole Cremer, Christina Fong, Daniel C. Lu and Isaac Yang

Spinal cord ependymomas are rare neoplasms, comprising approximately 5% of all CNS tumors and 15% of all spinal cord tumors. Although surgery was once reserved for diagnosis alone, the evolution of surgical practices has elevated resection to the treatment of choice for these lesions. While technological advances continue to improve the capacity for gross-total resections and thus decrease the risk of recurrence, ependymoma spinal surgery still contains a variety of potential complications. The presence of neurological deficits and deterioration are not uncommonly associated with spinal cord ependymoma surgery, including sensory loss, dorsal column dysfunction, dysesthetic syndrome, and bowel and bladder dysfunction, particularly in the immediate postoperative period. Surgical treatment may also lead to wound complications and CSF leaks, with increased risk when radiotherapy has been involved. Radiation therapy may also predispose patients to radiation myelopathy and ultimately result in neurological damage. Additionally, resections of spinal ependymomas have been associated with postoperative spinal instability and deformities, particularly in the pediatric population. Despite the advances in microsurgical techniques and intraoperative cord monitoring modalities, there remain a number of serious complications related to the treatment of spinal ependymoma tumors. Identification and acknowledgment of these potential problems may assist in their prevention, early detection, and increased quality of life for patients afflicted with this disease.

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Cort D. Lawton, Daniel T. Nagasawa, Isaac Yang, Richard G. Fessler and Zachary A. Smith

Glioblastoma multiforme (GBM) is one of the most common and aggressive primary brain tumors, composing 12%–20% of all intracranial tumors in adults. Average life expectancy is merely 12–14 months following initial diagnosis. Patients with this neoplasm have one of the worst 5-year survival rates among all cancers despite aggressive multimodal treatment consisting of maximal tumor resection, radiation therapy, and adjuvant chemotherapy. With recent advancements in management strategies, there has been improvement in the overall trend in patient outcomes; however, recurrence remains nearly inevitable. While most tumors recur locally, metastases to distal locations have become more common. Specifically, the last decade has seen an increased incidence of spinal metastases, representing an emerging complication in patients with intracranial GBM. However, the literature regarding prevention strategies and the presentation of spinal metastases has remained scarce. As local control of primary lesions continues to improve, more cases of spinal metastases are likely to be seen. In this review the authors present a new case of metastatic GBM to the L-5 nerve root, and they summarize previous cases of intracranial GBM with leptomeningeal spinal metastatic disease. They also characterize key features of this disease presentation and discuss areas of future investigation necessary for enhanced prevention and treatment of this complication.

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Winward Choy, Won Kim, Daniel Nagasawa, Stephanie Stramotas, Andrew Yew, Quinton Gopen, Andrew T. Parsa and Isaac Yang

Meningiomas are mostly benign, slow-growing tumors of the CNS that originate from arachnoidal cap cells. While monosomy 22 is the most frequent genetic abnormality found in meningiomas, a multitude of other aberrant chromosomal alterations, signaling pathways, and growth factors have been implicated in its pathogenesis. Losses on 22q12.2, a region encoding the tumor suppressor gene merlin, represent the most common genetic alterations in early meningioma formation. Malignant meningioma progression, however, is associated with more complex karyotypes and greater genetic instability. Cytogenetic studies of atypical and anaplastic meningiomas revealed gains and losses on chromosomes 9, 10, 14, and 18, with amplifications on chromosome 17. However, the specific gene targets in a majority of these chromosomal abnormalities remain elusive.

Studies have also implicated a myriad of aberrant signaling pathways involved with meningioma tumorigenesis, including those involved with proliferation, angiogenesis, and autocrine loops. Understanding these disrupted pathways will aid in deciphering the relationship between various genetic changes and their downstream effects on meningioma pathogenesis.

Despite advancements in our understanding of meningioma pathogenesis, the conventional treatments, including surgery, radiotherapy, and stereotactic radiosurgery, have remained largely stagnant. Surgery and radiation therapy are curative in the majority of lesions, yet treatment remains challenging for meningiomas that are recurrent, aggressive, or refractory to conventional treatments. Future therapies will include combinations of targeted molecular agents as a result of continued progress in the understanding of genetic and biological changes associated with meningiomas.

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Taemin Oh, Daniel T. Nagasawa, Brendan M. Fong, Andy Trang, Quinton Gopen, Andrew T. Parsa and Isaac Yang

Unfavorable outcomes such as facial paralysis and deafness were once unfortunate probable complications following resection of acoustic neuromas. However, the implementation of intraoperative neuromonitoring during acoustic neuroma surgery has demonstrated placing more emphasis on quality of life and preserving neurological function. A modern review demonstrates a great degree of recent success in this regard. In facial nerve monitoring, the use of modern electromyography along with improvements in microneurosurgery has significantly improved preservation. Recent studies have evaluated the use of video monitoring as an adjunctive tool to further improve outcomes for patients undergoing surgery. Vestibulocochlear nerve monitoring has also been extensively studied, with the most popular techniques including brainstem auditory evoked potential monitoring, electrocochleography, and direct compound nerve action potential monitoring. Among them, direct recording remains the most promising and preferred monitoring method for functional acoustic preservation. However, when compared with postoperative facial nerve function, the hearing preservation is only maintained at a lower rate. Here, the authors analyze the major intraoperative neuromonitoring techniques available for acoustic neuroma resection.

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Lawrance K. Chung, Nolan Ung, Marko Spasic, Daniel T. Nagasawa, Panayiotis E. Pelargos, Kimberly Thill, Brittany Voth, Daniel Hirt, Quinton Gopen and Isaac Yang

OBJECTIVE

Superior semicircular canal dehiscence (SSCD) is a rare disorder characterized by the formation of a third opening in the inner ear between the superior semicircular canal and the middle cranial fossa. Aberrant communication through this opening causes a syndrome of hearing loss, pulsatile tinnitus, disequilibrium, and autophony. This study analyzed the clinical outcomes of a single-institution series of patients with SSCD undergoing surgical repair by the same otolaryngologist and neurosurgeon.

METHODS

All patients who underwent SSCD repair at the University of California, Los Angeles, between March 2011 and November 2014 were included. All patients had their SSCD repaired via middle fossa craniotomy by the same otolaryngologist and neurosurgeon. Outcomes were analyzed with Fisher's exact test.

RESULTS

A total of 18 patients with a mean age of 56.2 years (range 27–84 years) and an average follow-up of 5.0 months (range 0.2–21.8 months) underwent 21 cases of SSCD repair. Following treatment, all patients (100%) reported resolution in ≥ 1 symptom associated with SSCD. Autophony (p = 0.0005), tinnitus (p = 0.0059), and sound- and/or pressure-induced dizziness (p = 0.0437) showed significant symptomatic resolution. Following treatment, 29% (2/7) of patients developed imbalance, 20% (1/5) of patients developed sound- and/or pressure-induced dizziness, and 18% (2/11) of patients developed aural fullness. Among patients with improved symptoms following surgical repair, none reported recurrence of symptoms at subsequent follow-up visits.

CONCLUSIONS

SSCD remains an underdiagnosed and undertreated condition. Surgical repair of SSCD using a middle fossa craniotomy is associated with a high rate of symptom resolution. Continued investigation using a larger patient cohort and longer-term follow-up could further demonstrate the effectiveness of using middle fossa craniotomy for SSCD repair.