Mechanics-based models of concentric tube continuum robots have recently achieved a level of sophistication that makes it possible to begin to apply these robots to a variety of real-world clinical scenarios. Endonasal skull base surgery is one such application, where their small diameter and tentacle like dexterity are particularly advantageous. In this paper we provide the medical motivation for an endonasal surgical robot featuring concentric tube manipulators, and describe our model-based design and teleoperation methods, as well as a complete system incorporating image-guidance. Experimental demonstrations using a laparoscopic training task, a cadaver reachability study, and a phantom tumor resection experiment illustrate that both novice and expert users can effectively teleoperate the system, and that skull base surgeons can use the robot to achieve their objectives in a realistic surgical scenario.

Object The goals of this study were to report the clinical presentation, radiographic findings, operative strategy, and outcomes among patients with temporal bone encephaloceles and cerebrospinal fluid fistulas (CSFFs) and to identify clinical variables associated with surgical outcome. Methods A retrospective case series including all patients who underwent a middle fossa craniotomy or combined mastoid–middle cranial fossa repair of encephalocele and/or CSFF between 2000 and 2012 was accrued from 2 tertiary academic referral centers. Results Eighty-nine consecutive surgeries (86 patients, 59.3% women) were included. The mean age at time of surgery was 52.3 years, and the left side was affected in 53.9% of cases. The mean delay between symptom onset and diagnosis was 35.4 months, and the most common presenting symptoms were hearing loss (92.1%) and persistent ipsilateral otorrhea (73.0%). Few reported a history of intracranial infection (6.7%) or seizures (2.2%). Thirteen (14.6%) of 89 cases had a history of major head trauma, 23 (25.8%) were associated with chronic ear disease without prior operation, 17 (19.1%) occurred following tympanomastoidectomy, and 1 (1.1%) developed in a patient with a cerebral aqueduct cyst resulting in obstructive hydrocephalus. The remaining 35 cases (39.3%) were considered spontaneous. Among all patients, the mean body mass index (BMI) was 35.3 kg/m2, and 46.4% exhibited empty sella syndrome. Patients with spontaneous lesions were statistically significantly older (p = 0.007) and were more commonly female (p = 0.048) compared with those with nonspontaneous pathology. Additionally, those with spontaneous lesions had a greater BMI than those with nonspontaneous disease (p = 0.102), although this difference did not achieve statistical significance. Thirty-two surgeries (36.0%) involved a middle fossa craniotomy alone, whereas 57 (64.0%) involved a combined mastoid–middle fossa repair. There were 7 recurrences (7.9%); 2 patients with recurrence developed meningitis. The use of artificial titanium mesh was statistically associated with the development of recurrent CSFF (p = 0.004), postoperative wound infection (p = 0.039), and meningitis (p = 0.014). Also notable, 6 of the 7 cases with recurrence had evidence of intracranial hypertension. When the 11 cases that involved using titanium mesh were excluded, 96.2% of patients whose lesions were reconstructed with an autologous multilayer repair had neither recurrent CSFF nor meningitis at the last follow-up. Conclusions Patients with temporal bone encephalocele and CSFF commonly present with persistent otorrhea and conductive hearing loss mimicking chronic middle ear disease, which likely contributes to a delay in diagnosis. There is a high prevalence of obesity among this patient population, which may play a role in the pathogenesis of primary and recurrent disease. A middle fossa craniotomy or a combined mastoid–middle fossa approach incorporating a multilayer autologous tissue technique is a safe and reliable method of repair that may be particularly useful for large or multifocal defects. Defect reconstruction using artificial titanium mesh should generally be avoided given increased risks of recurrence and postoperative meningitis.

Background The clinical effect of radiographic contact of glioblastoma (GBM) with neurogenic zones (NZ)—the ventricular-subventricular (VSVZ) and subgranular (SGZ) zones—and the corpus callosum (CC) remains unclear and, in the case of the SGZ, unexplored. We investigated 1) if GBM contact with a NZ correlates with decreased survival; 2) if so, whether this effect is associated with a specific NZ; and 3) if radiographic contact or invasion by GBM of the CC, the largest identifiable white matter tract, is associated with decreased survival. Methods We retrospectively identified 207 adult patients who underwent cytoreductive surgery for GBM followed by chemotherapy and/or radiation. Age, preoperative Karnofsky performance status score (KPS), and extent of resection were recorded. Preoperative MRIs were blindly analyzed to calculate tumor volume and contact with VSVZ, SGZ, CC, and cortex. Overall (OS) and progression free (PFS) survivals were calculated and analyzed with multivariate Cox analyses. Results Among 207 patients, 111 had GBM contacting VSVZ (VSVZ+GBMs), 23 SGZ+GBMs, 52 CC+GBMs, and 164 cortex+GBMs. VSVZ+, SGZ+, and CC+ GBMs had significantly larger volume relative to non-contacting controls. In addition to age, KPS, gross total resection, chemotherapy, and radiation, multivariate Cox survival analyses revealed contact with VSVZ as an independent predictor of lower OS and the only predictor of lower PFS and early recurrence. Conclusions GBM contact with the VSVZ, but not SGZ, CC, or cortex, is associated with early recurrence and decreased survival. We hypothesize that the VSVZ niche has unique properties that contribute to GBM pathobiology in adults.

The ventricular-subventricular zone (V-SVZ), which lies in the walls of the lateral ventricles (LV), is the largest neurogenic niche within the adult brain. Whether radiographic contact with the LV influences survival in glioblastoma (GBM) patients remains unclear. We assimilated and analyzed published data comparing survival in GBM patients with (LV+GBM) and without (LV−GBM) radiographic LV contact. PubMed, EMBASE, and Cochrane electronic databases were searched. Fifteen studies with survival data on LV+GBM and LV−GBM patients were identified. Their Kaplan–Meier survival curves were digitized and pooled for generation of median overall (OS) and progression free (PFS) survivals and log-rank hazard ratios (HRs). The log-rank and reported multivariate HRs after accounting for the common predictors of GBM survival were analyzed separately by meta-analyses. The calculated median survivals (months) from pooled data were 12.95 and 16.58 (OS), and 4.54 and 6.25 (PFS) for LV+GBMs and LV−GBMs, respectively, with an overall log-rank HRs of 1.335 [1.204–1.513] (OS) and 1.387 [1.225–1.602] (PFS). Meta-analysis of log-rank HRs resulted in summary HRs of 1.58 [1.35–1.85] (OS, 10 studies) and 1.41 [1.22–1.64] (PFS, 5 studies). Meta-analysis of multivariate HRs resulted in summary HRs of 1.35 [1.14–1.58] (OS, 6 studies) and 1.64 [0.88–3.05] (PFS, 3 studies). Patients with GBM contacting the LV have lower survival. This effect may be independent of the common predictors of GBM survival, suggesting a clinical influence of V-SVZ contact on GBM biology.

Objective To determine the factors associated with intra- and postoperative cerebrospinal fluid (CSF) leaks in setting of endoscopic transsphenoidal sellar surgery. Study Design Retrospective cohort. Setting Tertiary referral center. Subjects and Methods This study included 806 patients who underwent endoscopic transsphenoidal sellar surgery between 2004 and 2016. The associations between CSF leaks (intra- and postoperative) and patient demographics, medical history, tumor characteristics, and intraoperative repair techniques were analyzed. Results In sum, 205 (25.4%) patients had a CSF leak: 188 (23.3%) intraoperative leaks and 38 (4.7%) postoperative leaks. Twenty-one (2.6%) patients had postoperative leaks after having repair of an intraoperative leak; 55% of patients with a postoperative leak had an intraoperative leak repaired. On multivariate analysis, body mass index (BMI), hydrocephalus, suprasellar extension, and craniopharyngioma significantly predicted intraoperative CSF leaks, while only BMI and hydrocephalus predicted postoperative CSF leaks. Patients having septal flap repairs of CSF leaks had a higher postoperative leak rate relative to other repair techniques (odds ratio, 6.37; P = .013). Rigid reconstruction did not correlate with leaks. Conclusion For this large cohort of patients undergoing endoscopic transsphenoidal sellar surgery, BMI and hydrocephalus were identified as predictors of postoperative CSF leaks, including those occurring after repair of intraoperative leak. These variables may put stress on the surgical repair of sellar defects, and consideration of these risk factors may help counsel patients and guide perioperative decision making in regard to repair strategies and CSF diversion techniques.