Citations

Objective Compare cochlear implant (CI) performance between patients with ipsilateral sporadic vestibular schwannoma (VS) and NF2-related schwannomatosis (NF2). Compare CI performance according to VS management modality. Study Design Historical cohort. Setting Tertiary academic center. Patients Forty-nine patients (52 ears) undergoing cochlear implantation in the setting of ipsilateral sporadic (n = 21) or NF2-associated VS (n = 28). Interventions CI ipsilateral to VS. Main Outcome Measures Auditory thresholds, consonant–nucleus–consonant (CNC) word scores, and AzBio sentences in quiet scores. Results Among all patients, median post-CI pure tone average was 28 dB HL (interquartile range [IQR], 21–38), CNC word score was 39% (IQR, 6–62), and AzBio sentences in quiet score was 60% (IQR, 11–83) at a median of 12.5 months postimplantation. Despite the NF2 cohort having larger tumors, when comparing patients with sporadic versus NF2-associated VS, there were no statistically significant differences in CNC word (49% [30–70] vs. 31% [0–52]) or AzBio sentences in quiet (66% [28–80] vs. 57% [5–83]) scores. Regardless of NF2 status, all patients managed with observation, and radiosurgery achieved open-set speech. In patients who underwent microsurgery, 6 (46%) of 13 with NF2 achieved open-set speech recognition compared with 4 (67%) of 6 with sporadic disease. Conclusion Select patients with VS achieve successful hearing rehabilitation with a CI. In this cohort, tumor management strategy significantly influenced CI performance, whereas differences in NF2 status exhibited less effect. Specifically, all patients managed with observation or radiosurgery achieved open-set speech perception, whereas approximately half of people with NF2-related VS and two-thirds of people with sporadic VS achieved this outcome after tumor microsurgery. When disease permits, observation and radiosurgery should be considered in patients who may later pursue a CI.

This Viewpoint discusses how recent discoveries surrounding the natural history of sporadic vestibular schwannoma provide data to support a shift in current management paradigms.

Objective In certain cases, clinicians may consider continued observation of a vestibular schwannoma after initial growth is detected. The aim of the current work was to determine if patients with growing sporadic vestibular schwannomas could be stratified by the likelihood of subsequent growth based on initial growth behavior. Study Design Slice-by-slice volumetric tumor measurements from 3,505 serial magnetic resonance imaging studies were analyzed from 952 consecutively treated patients. Setting Three tertiary-referral centers. Patients Adults with sporadic vestibular schwannoma. Interventions Wait-and-scan. Main Outcome Measures Composite end point of subsequent growth- or treatment-free survival rates, where growth is defined as an additional increase of at least 20% in tumor volume from the volume at the time of initial growth. Results Among 405 patients who elected continued observation despite documented growth, stratification, of volumetric growth rate into less than 25% (reference: n = 107), 25 to less than 50% (hazard ratio [HR], 1.39; p = 0.06; n = 96), 50 to less than 100% (HR, 1.71; p = 0.002; n = 112), and at least 100% (HR, 2.01; p < 0.001; n = 90) change per year predicted the likelihood of future growth or treatment. Subsequent growth- or treatment-free survival rates (95% confidence interval) at year 5 after detection of initial growth were 31% (21–44%) for those with less than 25% growth per year, 18% (10–32%) for those with 25 to less than 50%, 15% (9–26%) for those with 50 to less than 100%, and 6% (2–16%) for those with at least 100%. Neither patient age (p = 0.15) nor tumor volume at diagnosis (p = 0.95) significantly differed across stratification groups. Conclusions At the time of diagnosis, clinical features cannot consistently predict which tumors will ultimately display aggressive behavior. Stratification by volumetric growth rate at the time of initial growth results in a stepwise progression of increasing likelihood of subsequent growth. When considering continued observation after initial growth detection, almost 95% of patients who have tumors that double in volume between diagnosis and the first detection of growth demonstrate further tumor growth or undergo treatment if observed to 5 years.

Abstract Introduction The clival, paraclival, and craniocervical junction regions are challenging surgical targets. To approach these areas, endoscopic endonasal transclival approaches (EETCAs) and their extensions (far-medial approach and odontoidectomy) have gained popularity as they obviate manipulating and working between neurovascular structures. Although several cadaveric studies have further refined these contemporary approaches, few provide a detailed step-by-step description. Thus, we aim to didactically describe the steps of the EETCAs and their extensions for trainees. Methods Six formalin-fixed cadaveric head specimens were dissected. All specimens were latex-injected using a six-vessel technique. Endoscopic endonasal middle and inferior clivectomies, far-medial approaches, and odontoidectomy were performed. Results Using angled endoscopes and surgical instruments, an endoscopic endonasal midclivectomy and partial inferior clivectomy were performed without nasopharyngeal tissue disruption. To complete the inferior clivectomy, far-medial approach, and partially remove the anterior arch of C1 and odontoid process, anteroinferior transposition of the Eustachian–nasopharynx complex was required by transecting pterygosphenoidal fissure tissue, but incision in the nasopharynx was not necessary. Full exposure of the craniocervical junction necessitated bilateral sharp incision and additional inferior mobilization of the posterior nasopharynx. Unobstructed access to neurovascular anatomy of the ventral posterior fossa and craniocervical junction was provided. Conclusion EETCAs are a powerful tool for the skull-base surgeon as they offer a direct corridor to the ventral posterior fossa and craniocervical junction unobstructed by eloquent neurovasculature. To facilitate easier understanding of the EETCAs and their extensions for trainees, we described the anatomy and surgical nuances in a didactic and step-by-step fashion.

OBJECTIVE Chordomas are rare tumors from notochordal remnants and account for 1%–4% of all primary bone malignancies, often arising from the clivus and sacrum. Despite margin-negative resection and postoperative radiotherapy, chordomas often recur. Further, immunohistochemical (IHC) markers have not been assessed as predictive of chordoma recurrence. The authors aimed to identify the IHC markers that are predictive of postoperative long-term (≥ 1 year) chordoma recurrence by using trained multiple tree-based machine learning (ML) algorithms. METHODS The authors reviewed the records of patients who had undergone treatment for clival and spinal chordomas between January 2017 and June 2021 across the Mayo Clinic enterprise (Minnesota, Florida, and Arizona). Demographics, type of treatment, histopathology, and other relevant clinical factors were abstracted from each patient record. Decision tree and random forest classifiers were trained and tested to predict long-term recurrence based on unseen data using an 80/20 split. RESULTS One hundred fifty-one patients diagnosed and treated for chordomas were identified: 58 chordomas of the clivus, 48 chordomas of the mobile spine, and 45 chordomas sacrococcygeal in origin. Patients diagnosed with cervical chordomas were the oldest among all groups (58 ± 14 years, p = 0.009). Most patients were male (n = 91, 60.3%) and White (n = 139, 92.1%). Most patients underwent resection with or without radiation therapy (n = 129, 85.4%). Subtotal resection followed by radiation therapy (n = 51, 33.8%) was the most common treatment modality, followed by gross-total resection then radiation therapy (n = 43, 28.5%). Multivariate analysis showed that S100 and pan-cytokeratin are more likely to predict the increase in the risk of postoperative recurrence (OR 3.67, 95% CI 1.09–12.42, p= 0.03; and OR 3.74, 95% CI 0.05–2.21, p = 0.02, respectively). In the decision tree analysis, a clinical follow-up > 1897 days was found in 37% of encounters and a 90% chance of being classified for recurrence (accuracy = 77%). Random forest analysis (n = 500 trees) showed that patient age, type of surgical treatment, location of tumor, S100, pan-cytokeratin, and EMA are the factors predicting long-term recurrence. CONCLUSIONS The IHC and clinicopathological variables combined with tree-based ML tools successfully demonstrated a high capacity to identify recurrence patterns with an accuracy of 77%. S100, pan-cytokeratin, and EMA were the IHC drivers of recurrence. This shows the power of ML algorithms in analyzing and predicting outcomes of rare conditions of a small sample size.

Abstract Introduction Although many neuroanatomic atlases have been published, few have detailed complex cranial approaches and pertinent anatomic considerations in a stepwise fashion intended for rapid comprehension by neurosurgery students, residents, and fellows. Methods Five sides of formalin-fixed latex-injected specimens were dissected under microscopic magnification. The frontotemporal and orbitozygomatic approaches were performed by neurosurgical residents and fellows at different training levels with limited previous experience in anatomical dissection mentored by the senior authors (M.P.C. and M.J.L.). Meticulous surgical anatomic dissections were performed until sufficient visual and technical completion was attained, with parameters of effectively demonstrating key surgical steps for educational training purposes. Following the completion of dissection and three-dimensional photography, illustrative case examples were reviewed to demonstrate the relative benefits and optimal applications of each approach. Results The frontotemporal and orbitozygomatic approaches afford excellent access to anterior and middle skull base pathologies, as well as the exposure of the infratemporal fossa. Key considerations include head positioning, skin incision, scalp retraction, fat pad dissection and facial nerve protection, true or false MacCarty keyhole fashioning, sphenoid wing drilling and anterior clinoidectomy, completion of the craniotomy and accessory orbital osteotomy cuts, dural opening, and intradural neurovascular access. Conclusion The frontotemporal and orbitozygomatic approaches are core craniotomies that offer distinct advantages for complex cranial operations. Learning and internalizing their key steps and nuanced applications in a clinical context is critical for trainees of many levels. The orbitozygomatic craniotomy in particular is a versatile but challenging approach; operative-style laboratory dissection is an essential component of its mastery and one that will be powerfully enhanced by the current work.