Neurosurgery Blog


Daily bibliographic review of the Neurosurgery Department. La Fe University Hospital. Valencia, Spain

Preserving normal facial nerve function and improving hearing outcome in large vestibular schwannomas with a combined approach

Acta Neurochir (2017) 159:1197–1211

To perform planned subtotal resection followed by gamma knife surgery (GKRS) in a series of patients with large vestibular schwannoma (VS), aiming at an optimal functional outcome for facial and cochlear nerves.

Methods Patient characteristics, surgical and dosimetric features, and outcome were collected prospectively at the time of treatment and during the follow-up.

Results A consecutive series of 32 patients was treated between July 2010 and June 2016. Mean follow-up after surgery was 29 months (median 24, range 4–78). Mean presurgical tumor volume was 12.5 cm3 (range 1.47–34.9). Postoperative status showed normal facial nerve function (House– Brackmann I) in all patients. In a subgroup of 17 patients with serviceable hearing before surgery and in which cochlear nerve preservation was attempted at surgery, 16 (94.1%) retained serviceable hearing. Among them, 13 had normal hearing (Gardner–Robertson class 1) before surgery, and 10 (76.9%) retained normal hearing after surgery. Mean duration between surgery and GKRS was 6.3 months (range 3.8–13.9). Mean tumor volume at GKRS was 3.5 cm3 (range 0.5–12.8), corresponding to mean residual volume of 29.4% (range 6– 46.7) of the preoperative volume. Mean marginal dose was 12 Gy (range 11–12). Mean follow-up after GKRS was 24 months (range 3–60). Following GKRS, there were no new neurological deficits, with facial and hearing functions remaining identical to those after surgery in all patients. Three patients presented with continuous growth after GKRS, were considered failures, and benefited from the same combined approach a second time.

Conclusion Our data suggest that large VS management, with planned subtotal resection followed by GKRS, might yield an excellent clinical outcome, allowing the normal facial nerve and a high level of cochlear nerve functions to be retained. Our functional results with this approach in large VS are comparable with those obtained with GKRS alone in small- and medium-sized VS. Longer term follow-up is necessary to fully evaluate this approach, especially regarding tumor control.


Trigeminal nerve contrast enhancement after radiosurgery

J Neurosurg 127:219–225, 2017

Contrast enhancement of the retrogasserian trigeminal nerve on MRI scans frequently develops after radiosurgical ablation for the management of medically refractory trigeminal neuralgia (TN). The authors sought to evaluate the clinical significance of this imaging finding in patients who underwent a second radiosurgical procedure for recurrent TN.

METHODS During a 22-year period, 360 patients underwent Gamma Knife stereotactic radiosurgery (SRS) as their first surgical procedure for TN at the authors’ center. The authors retrospectively analyzed the data from 59 patients (mean age 72 years, range 33–89 years) who underwent repeat SRS for recurrent pain at a median of 30 months (range 6–146 months) after the first SRS. The isocenter was 4 mm, and the median maximum doses for the first and second procedures were 80 Gy and 70 Gy, respectively. A neuroradiologist and a neurosurgeon blinded to the treated side evaluated the presence of nerve contrast enhancement on MRI series at the time of the repeat procedure. The authors correlated the presence of this imaging change with clinical outcomes. Pain outcomes and development of trigeminal sensory dysfunction were evaluated with the Barrow Neurological Institute (BNI) Pain Scale and BNI Numbness Scale, respectively. The mean length of follow-up after the second SRS was 58 months (95% CI 49–68 months).

RESULTS At the time of the repeat SRS, contrast enhancement of the trigeminal nerve on MRI scans was observed in 31 patients (53%). Five years after the SRS, patients with this enhancement had lower actuarial rates of complete pain relief after the repeat SRS (27% [95% CI 7%–47%]) than patients without the enhancement (76% [95% CI 58%–94%]) (p < 0.001). At the 5-year follow-up, patients with the contrast enhancement also had a higher risk for trigeminal sensory loss after repeat SRS (75% [95% CI 59%–91%]) than patients without contrast enhancement (26% [95% CI 10%–42%]) (p = 0.001). Dysesthetic pain after repeat SRS was observed for 8 patients with and for 2 patients without contrast enhancement.

CONCLUSIONS Trigeminal nerve contrast enhancement on MRI scans observed at the time of a repeat SRS for TN was associated with less satisfactory pain control and more frequently detected facial sensory loss. Residual contrast enhancement at the time of a repeat SRS may warrant consideration of dose reduction or further separation of the radiosurgical targets.

Contemporary analysis of the intraoperative and perioperative complications of neurosurgical procedures performed in the sitting position

J Neurosurg 127:182–188, 2017

Historically, performing neurosurgery with the patient in the sitting position offered advantages such as improved visualization and gravity-assisted retraction. However, this position fell out of favor at many centers due to the perceived risk of venous air embolism (VAE) and other position-related complications. Some neurosurgical centers continue to perform sitting-position cases in select patients, often using modern monitoring techniques that may improve procedural safety. Therefore, this paper reports the risks associated with neurosurgical procedures performed in the sitting position in a modern series.

METHODS The authors reviewed the anesthesia records for instances of clinically significant VAE and other complications for all neurosurgical procedures performed in the sitting position between January 1, 2000, and October 8, 2013. In addition, a prospectively maintained morbidity and mortality log of these procedures was reviewed for instances of subdural or intracerebral hemorrhage, tension pneumocephalus, and quadriplegia. Both overall and specific complication rates were calculated in relation to the specific type of procedure.

RESULTS In a series of 1792 procedures, the overall complication rate related to the sitting position was 1.45%, which included clinically significant VAE, tension pneumocephalus, and subdural hemorrhage. The rate of any detected VAE was 4.7%, but the rate of VAE requiring clinical intervention was 1.06%. The risk of clinically significant VAE was highest in patients undergoing suboccipital craniotomy/craniectomy with a rate of 2.7% and an odds ratio (OR) of 2.8 relative to deep brain stimulator cases (95% confidence interval [CI] 1.2–70, p = 0.04). Sitting cervical spine cases had a comparatively lower complication rate of 0.7% and an OR of 0.28 as compared with all cranial procedures (95% CI 0.12–0.67, p < 0.01). Sitting cervical cases were further subdivided into extradural and intradural procedures. The rate of complications in intradural cases was significantly higher (OR 7.3, 95% CI 1.4–39, p = 0.02) than for extradural cases. The risk of VAE in intradural spine procedures did not differ significantly from sitting suboccipital craniotomy/craniectomy cases (OR 0.69, 95% CI 0.09–5.4, p = 0.7). Two cases (0.1%) had to be aborted intraoperatively due to complications. There were no instances of intraoperative deaths, although there was a single death within 30 days of surgery.

CONCLUSIONS In this large, modern series of cases performed in the sitting position, the complication rate was low. Suboccipital craniotomy/craniectomy was associated with the highest risk of complications. When appropriately used with modern anesthesia techniques, the sitting position provides a safe means of surgical access.

Long-term clinical and radiographic outcomes of the Prestige LP artificial cervical disc replacement at 2 levels

J Neurosurg Spine 27:7–19, 2017

The aim of this study was to assess long-term clinical safety and effectiveness in patients undergoing anterior cervical surgery using the Prestige LP artificial disc replacement (ADR) prosthesis to treat degenerative cervical spine disease at 2 adjacent levels compared with anterior cervical discectomy and fusion (ACDF).

METHODS A prospective, randomized, controlled, multicenter FDA-approved clinical trial was conducted at 30 US centers, comparing the low-profile titanium ceramic composite-based Prestige LP ADR (n = 209) at 2 levels with ACDF (n = 188). Clinical and radiographic evaluations were completed preoperatively, intraoperatively, and at regular postoperative intervals to 84 months. The primary end point was overall success, a composite variable that included key safety and efficacy considerations.

RESULTS At 84 months, the Prestige LP ADR demonstrated statistical superiority over fusion for overall success (observed rate 78.6% vs 62.7%; posterior probability of superiority [PPS] = 99.8%), Neck Disability Index success (87.0% vs 75.6%; PPS = 99.3%), and neurological success (91.6% vs 82.1%; PPS = 99.0%). All other study effectiveness measures were at least noninferior for ADR compared with ACDF. There was no statistically significant difference in the overall rate of implant-related or implant/surgical procedure–related adverse events up to 84 months (26.6% and 27.7%, respectively). However, the Prestige LP group had fewer serious (Grade 3 or 4) implant- or implant/surgical procedure–related adverse events (3.2% vs 7.2%, log hazard ratio [LHR] and 95% Bayesian credible interval [95% BCI] -1.19 [-2.29 to -0.15]). Patients in the Prestige LP group also underwent statistically significantly fewer second surgical procedures at the index levels (4.2%) than the fusion group (14.7%) (LHR -1.29 [95% BCI -2.12 to -0.46]). Angular range of motion at superior- and inferior-treated levels on average was maintained in the Prestige LP ADR group to 84 months.

CONCLUSIONS The low-profile artificial cervical disc in this study, Prestige LP, implanted at 2 adjacent levels, maintains improved clinical outcomes and segmental motion 84 months after surgery and is a safe and effective alternative to fusion.

The Cost of Brain Surgery: Awake vs Asleep Craniotomy for Perirolandic Region Tumors

Neurosurgery 81:307–314, 2017

Cost effectiveness has become an important factor in the health care system, requiring surgeons to improve efficacy of procedures while reducing costs. An awake craniotomy (AC) with direct cortical stimulation (DCS) presents one method to resect eloquent region tumors; however, some authors assert that this procedure is an expensive alternative to surgery under general anesthesia (GA) with neuromonitoring.

OBJECTIVE: To evaluate the cost effectiveness and clinical outcomes between AC and GA patients.

METHODS: Retrospective analysis of a cohort of 17 patients with perirolandic gliomas who underwent an AC with DCS were case-control matched with 23 patients with perirolandic gliomas who underwent surgery under GA with neuromonitoring (ie, motor-evoked potentials, somatosensory-evoked potentials, phase reversal). Inpatient costs, qualityadjusted life years (QALY), extent of resection, and neurological outcome were compared between the groups.

RESULTS: Total inpatient expense per patient was $34 804 in the AC group and $46 798 in the GA group (P = .046). QALY score for the AC group was 0.97 and 0.47 for the GA group (P = .041). The incremental cost per QALY for the AC group was $82 720 less than the GA group. Postoperative Karnofsky performance status was 91.8 in the AC group and 81.3 in the GA group (P=.047). Length of hospitalization was 4.12 days in the AC group and 7.61 days in the GA group (P = .049).

CONCLUSION: The total inpatient costs for awake craniotomies were lower than surgery under GA. This study suggests better cost effectiveness and neurological outcome with awake craniotomies for perirolandic gliomas.

Relationship of A1 segment hypoplasia to anterior communicating artery aneurysm morphology and risk factors for aneurysm formation

J Neurosurg 127:89–95, 2017

Hypoplasia of the A1 segment of the anterior cerebral artery is frequently observed in patients with anterior communicating artery (ACoA) aneurysms. The effect of this anatomical variant on ACoA aneurysm morphology is not well understood.

METHODS Digital subtraction angiography images were reviewed for 204 patients presenting to the authors’ institution with either a ruptured or an unruptured ACoA aneurysm. The ratio of the width of the larger A1 segment to the smaller A1 segment was calculated. Patients with an A1 ratio greater than 2 were categorized as having A1 segment hypoplasia. The relationship of A1 segment hypoplasia to both patient and aneurysm characteristics was then assessed.

RESULTS Of 204 patients that presented with an ACoA aneurysm, 34 (16.7%) were found to have a hypoplastic A1. Patients with A1 segment hypoplasia were less likely to have a history of smoking (44.1% vs 62.9%, p = 0.0410). ACoA aneurysms occurring in the setting of a hypoplastic A1 were also found to have a larger maximum diameter (mean 7.7 vs 6.0 mm, p = 0.0084). When considered as a continuous variable, increasing A1 ratio was associated with decreasing aneurysm dome-to-neck ratio (p = 0.0289). There was no significant difference in the prevalence of A1 segment hypoplasia between ruptured and unruptured aneurysms (18.9% vs 10.7%; p = 0.1605).

CONCLUSIONS Our results suggest that a hypoplastic A1 may affect the morphology of ACoA aneurysms. In addition, the relative lack of traditional risk factors for aneurysm formation in patients with A1 segment hypoplasia argues for the importance of hemodynamic factors in the formation of ACoA aneurysms in this anatomical setting.


Surgical treatment of intraforaminal/extraforaminal lumbar disc herniations

Acta Neurochir (2017) 159:1273–1281

Several disc disease nomenclatures and approaches for LDH exist. The traditional midline bonedestructive procedures together with approaches requiring extreme muscular retraction are being replaced by muscle sparing, targeted, stability-preserving surgical routes. The increasing speculation on LDHs and the innovative corridors described to treat them have lead to an extensive production of papers frequently treating the same topic but adopting different terminologies and reporting contradictory results.

Methods The review of such literature somehow confounding gave us the chance to regroup by surgical corridors the vast amount of approaches for LDH differently renamed over time. Likewise, LDHs were simplified in intra-foraminal (ILDH), extra-foraminal (ELDH), and intra−/extra-foraminal (IELDH) in relation to precise anatomical boundaries and extent of bulging disc.

Results Through the analysis of the papers, it was possible to identify ideal surgical corridors for ILDHs, ELDHs, and IELDHs, distinguishing for each approach the exposure provided and the technical advantages/disadvantages in terms of muscle trauma, biomechanical stability, and nerve root preservation. A significant disproportion was noted between studies discussing traditional midline approaches or variants of the posterolateral route and those investigating pros and cons of simple or combined alternative corridors. Although rarely discussed, these latter represent valuable strategies particularly for the challenging IELDHs, thanks to the optimal compromise between herniation exposure and bone-muscle preservation.

Conclusions The integration of adequate mastery of traditional approaches together with a greater confidence through unfamiliar surgical corridors can improve the development of combined mini-invasive procedures, which seem promising for future targeted LDH excisions.

A New Classification for Pathologies of Spinal Meninges, Part 1: Dural Cysts, Dissections, and Ectasias

Neurosurgery 81:29–44, 2017

The clinical significance of pathologies of the spinal dura is often unclear and their management controversial.

OBJECTIVE: To classify spinal dural pathologies analogous to vascular aneurysms, present their symptoms and surgical results.

METHODS: Among 1519 patients with spinal space-occupying lesions, 66 patients demonstrated dural pathologies. Neuroradiological and surgical features were reviewed and clinical data analyzed.

RESULTS: Saccular dural diverticula (type I, n = 28) caused by defects of both dural layers, dissections between dural layers (type II, n = 29) due to defects of the inner layer, and dural ectasias (type III, n = 9) related to structural changes of the dura were distinguished. For all types, symptoms consisted of local pain followed by signs of radiculopathy or myelopathy, while one patient with dural ectasia presented a low-pressure syndrome and 10 patients with dural dissections additional spinal cord herniation. Type I and type II pathologies required occlusion of their dural defects via extradural (type I) or intradural (type II) approaches. For type III pathologies of the dural sac no surgerywas recommended. Favorable results were obtained in all 14 patients with type I and 13 of 15 patients with type II pathologies undergoing surgery.

CONCLUSION: The majority of dural pathologies involving root sleeves remain asymptomatic, while those of the dural sac commonly lead to pain and neurological symptoms. Type I and type II pathologies were treated with good long-term results occluding their dural defects, while ectasias of the dural sac (type III) were managed conservatively.


Optimization of Microelectrode Recording in Deep Brain Stimulation Surgery Using Intraoperative Computed Tomography

WORLD NEUROSURGERY 103: 168-173, JULY 2017

Microelectrode recording (MER) is used to confirm targeting accuracy during deep brain stimulation (DBS) surgery. We describe a technique using intraoperative computed tomography (CT) extrapolation (iCTE) to predetermine and adjust the trajectory of the guide tube to improve microelectrode targeting accuracy. We hypothesized that this technique would decrease the number of MER tracks and operative time, while increasing the recorded length of the subthalamic nucleus (STN).

– METHODS: Thirty-nine patients with Parkinson’s disease who underwent STN DBS before the iCTE method were compared with 33 patients undergoing STN DBS using iCTE. Before dural opening, a guide tube was inserted and rested on dura. Intraoperative computed tomography (iCT) was performed, and a trajectory was created along the guide tube and extrapolated to the target using targeting software. If necessary, headstage adjustments were made to correct for error. The guide tube was inserted, and MER was performed. iCT was performed with the microelectrode tip at the target. Coordinates were compared with planned/ adjusted track coordinates. Radial error between the MER track and the planned/adjusted track was calculated. Cases before and after implementation of iCTE were compared to determine the impact of iCTE on operative time, number of MER tracks and recorded STN length.

– RESULTS: The use of iCTE reduced the average radial MER track error from 1.90  0.12 mm (n[54) to 0.84  0.09 mm (n[49) (P < 0.001) while reducing the operative time for bilateral lead placement from 272  9 minutes (n [ 30) to 233  10 minutes (n [ 24) (P < 0.001). The average MER tracks per hemisphere was reduced from 2.24  0.13 mm (n[66) to 1.75  0.09 mm (n[63) (P < 0.001), whereas the percentage of hemispheres requiring a single MER track for localization increased from 29% (n [ 66) to 43% (n [ 63). The average length of recorded STN increased from 4.01  0.3 mm (n [ 64) to 4.75  0.28 mm (n [ 56) (P < 0.05).

-CONCLUSION: iCTE improves microelectrode accuracy and increases the first-pass recorded length of STN, while reducing operative time. Further studies are needed to determine whether this technique leads to less morbidity and improved clinical outcomes.


Results of the ANSWER Trial Using the PulseRider for the Treatment of Broad-Necked, Bifurcation Aneurysms

Neurosurgery 81:56–65, 2017

The safety and probable benefit of the PulseRider (Pulsar Vascular, Los Gatos, California) for the treatment of broad-necked, bifurcation aneurysms was studied in the context of the prospective, nonrandomized, single arm clinical trial— the Adjunctive Neurovascular Support of Wide-neck aneurysm Embolization and Reconstruction (ANSWER) Trial.

OBJECTIVE: To present the results of the United States cases employing the PulseRider device as part of the ANSWER clinical trial.

METHODS: Aneurysms treated with the PulseRider device among sites enrolling in the ANSWER trial were prospectively studied and the results are summarized. Aneurysms arising at either the carotid terminus or basilar apex thatwere relatively broad neckedwere considered candidates for inclusion into the ANSWER study.

RESULTS: Thirty-four patients were enrolled (29 female and 5 male) with a mean age of 60.9 years (27 basilar apex and 7 carotid terminus).Mean aneurysm height ranged from 2.4 to 15.9 mm with a mean neck size of 5.2 mm (range 2.3-11.6 mm). In all patients, the device was delivered and deployed. Immediate Raymond I or II occlusion was achieved in 82.4% and progressed to 87.9% at 6-month follow-up. A modified Rankin Score of 2 or less was seen in 94% of patients at 6 months.

CONCLUSION: The results from the ANSWER trial demonstrate that the PulseRider device is safe and offers probable benefit as for the treatment of bifurcation aneurysms arising at the basilar apex or carotid terminus. As such, it represents a useful addition to the armamentarium of the neuroendovascular specialist.

Is less always better? Keyhole and standard subtemporal approaches

J Neurosurg 127:157–164, 2017

The subtemporal approach is one of the surgical routes used to reach the interpeduncular fossa. Keyhole subtemporal approaches and zygomatic arch osteotomy have been proposed in an effort to decrease the amount of temporal lobe retraction. However, the effects of these modified subtemporal approaches on temporal lobe retraction have never been objectively validated.

METHODS A keyhole and a classic subtemporal craniotomy were executed in 4 fresh-frozen silicone-injected cadaver heads. The target was defined as the area bordered by the superior cerebellar artery, the anterior clinoid process, supraclinoid internal carotid artery, and the posterior cerebral artery. Once the target was fully visualized, the authors evaluated the amount of temporal lobe retraction by measuring the distance between the base of the middle fossa and the temporal lobe. In addition, the volume of the surgical and anatomical corridors was assessed as well as the surgical maneuverability using navigation and 3D moldings. The same evaluation was conducted after a zygomatic osteotomy was added to the two approaches.

RESULTS Temporal lobe retraction was the same in the two approaches evaluated while the surgical corridor and the maneuverability were all greater in the classic subtemporal approach.

CONCLUSIONS The zygomatic arch osteotomy facilitates the maneuverability and the surgical volume in both approaches, but the temporal lobe retraction benefit is confined to the lateral part of the middle fossa skull base and does not result in the retraction necessary to expose the selected target.

The force pyramid: a spatial analysis of force application during virtual reality brain tumor resection

J Neurosurg 127:171–181, 2017

Virtual reality simulators allow development of novel methods to analyze neurosurgical performance. The concept of a force pyramid is introduced as a Tier 3 metric with the ability to provide visual and spatial analysis of 3D force application by any instrument used during simulated tumor resection. This study was designed to answer 3 questions: 1) Do study groups have distinct force pyramids? 2) Do handedness and ergonomics influence force pyramid structure? 3) Are force pyramids dependent on the visual and haptic characteristics of simulated tumors?

METHODS Using a virtual reality simulator, NeuroVR (formerly NeuroTouch), ultrasonic aspirator force application was continually assessed during resection of simulated brain tumors by neurosurgeons, residents, and medical students. The participants performed simulated resections of 18 simulated brain tumors with different visual and haptic characteristics. The raw data, namely, coordinates of the instrument tip as well as contact force values, were collected by the simulator. To provide a visual and qualitative spatial analysis of forces, the authors created a graph, called a force pyramid, representing force sum along the z-coordinate for different xy coordinates of the tool tip.

RESULTS Sixteen neurosurgeons, 15 residents, and 84 medical students participated in the study. Neurosurgeon, resident and medical student groups displayed easily distinguishable 3D “force pyramid fingerprints.” Neurosurgeons had the lowest force pyramids, indicating application of the lowest forces, followed by resident and medical student groups. Handedness, ergonomics, and visual and haptic tumor characteristics resulted in distinct well-defined 3D force pyramid patterns.

CONCLUSIONS Force pyramid fingerprints provide 3D spatial assessment displays of instrument force application during simulated tumor resection. Neurosurgeon force utilization and ergonomic data form a basis for understanding and modulating resident force application and improving patient safety during tumor resection.


Protocol for motor and language mapping by navigated TMS in patients and healthy volunteers

Acta Neurochir (2017) 159:1187–1195

Navigated transcranial magnetic stimulation (nTMS) is increasingly used for preoperative mapping of motor function, and clinical evidence for its benefit for brain tumor patients is accumulating. In respect to language mapping with repetitive nTMS, literature reports have yielded variable results, and it is currently not routinely performed for presurgical language localization. The aim of this project is to define a common protocol for nTMS motor and language mapping to standardize its neurosurgical application and increase its clinical value.

Methods: The nTMS workshop group, consisting of highly experienced nTMS users with experience of more than 1500 preoperative nTMS examinations, met in Helsinki in January 2016 for thorough discussions of current evidence and personal experiences with the goal to recommend a standardized protocol for neurosurgical applications.

Results: nTMS motor mapping is a reliable and clinically validated tool to identify functional areas belonging to both normal and lesioned primary motor cortex. In contrast, this is less clear for language-eloquent cortical areas identified by nTMS. The user group agreed on a core protocol, which enables comparison of results between centers and has an excellent safety profile. Recommendations for nTMS motor and language mapping protocols and their optimal clinical integration are presented here.

Conclusion: At present, the expert panel recommends nTMS motor mapping in routine neurosurgical practice, as it has a sufficient level of evidence supporting its reliability. The panel recommends that nTMS language mapping be used in the framework of clinical studies to continue refinement of its protocol and increase reliability.

Clinical Experience and Results of Microsurgical Resection of Arteriovenous Malformation in the Presence of Space-Occupying Intracerebral Hematoma

Neurosurgery 81:75–86, 2017

Management of ruptured arteriovenous malformations (AVMs) with a mass-producing intracerebral hematoma (ICH) represents a surgical dilemma.

OBJECTIVE: To evaluate the clinical outcome and obliteration rates of microsurgical resection of AVM when performed concomitantly with evacuation of an associated spaceoccupying ICH.

METHODS: Data of patients with AVMwere collected prospectively. Cases were identified in which an AVM was resected and an associated space-occupying ICH was evacuated at the same time, and divided into “group 1,” in which the surgery was performed acutely within 48 h of presentation (secondary to elevated intracranial pressure); and “group 2,” in which selected patients were operated upon in the presence of a liquefying ICH in the “subacute”stage. Clinical outcomes were assessed using themodified Rankin Scale, with a score of 0 to 2 considered a good outcome. Obliteration rateswere assessed using postoperative angiography.

RESULTS: From 2001 to 2015, 131 patients underwent microsurgical resection of an AVM, of which 65 cases were included. In “group 1” (n = 21; Spetzler-Ponce class A = 13, class B = 5, and class C = 3), 11 of 21 (52%) had a good outcome and in 18 of 19 (95%) of those who had a postoperative angiogramthe AVMswere completely obliterated. In “group 2”(n=44; Spetzler-Ponce class A=33, class B=9, and class C=2), 31 of 44 (93%) had a good outcome and 42 of 44 (95%) were obliterated with a single procedure. For supratentorial AVMs, the ICH cavity was utilized to provide an operative trajectory to a deep AVM in 11 cases, and in 26 cases the ICH cavity was deep to the AVM and hence facilitated the deep dissection of the nidus.

CONCLUSION: In selected patients the presence of a liquefying ICH cavity may facilitate the resection of AVMs when performed in the subacute stage resulting in a good neurological outcome and high obliteration rate.

Preoperative planning of hemangioblastoma using 3D imaging


J Neurosurg 127:139–147, 2017

Successful resection of hemangioblastoma depends on preoperative assessment of the precise locations of feeding arteries and draining veins. Simultaneous 3D visualization of feeding arteries, draining veins, and surrounding structures is needed.

The present study evaluated the usefulness of high-resolution 3D multifusion medical imaging (hr-3DMMI) for preoperative planning of hemangioblastoma. The hr-3DMMI combined MRI, MR angiography, thin-slice CT, and 3D rotated angiography. Surface rendering was mainly used for the creation of hr-3DMMI using multiple thresholds to create 3D models, and processing took approximately 3–5 hours. This hr-3DMMI technique was used in 5 patients for preoperative planning and the imaging findings were compared with the operative findings. Hr-3DMMI could simulate the whole 3D tumor as a unique sphere and show the precise penetration points of both feeding arteries and draining veins with the same spatial relationships as the original tumor.

All feeding arteries and draining veins were found intraoperatively at the same position as estimated preoperatively, and were occluded as planned preoperatively. This hr-3DMMI technique could demonstrate the precise locations of feeding arteries and draining veins preoperatively and estimate the appropriate route for resection of the tumor. Hr-3DMMI is expected to be a very useful support tool for surgery of hemangioblastoma.

Impact of Weekend Presentation on Short-Term Outcomes and Choice of Clipping vs Coiling in Subarachnoid Hemorrhage

Neurosurgery 81:87–91, 2017

Presentation on a weekend is commonly associated with higher mortality and a decreased likelihood of receiving invasive procedures.

OBJECTIVE: To determine whether weekend presentation influences mortality, discharge destination, or type of treatment received (clip vs coil) in subarachnoid hemorrhage (SAH).

METHODS: We performed a serial cross-sectional retrospective study using the Nationwide Inpatient Sample. All adult discharges with a primary diagnosis of SAH (ICD-9-CM 435) from 2005 to 2010 were included, and records with trauma or arteriovenous malformation were excluded. Unadjusted and adjusted associations between weekend presentation and 3 outcomes (in-hospital mortality, discharge destination, and treatment with clip vs coil) were estimated using chi-square tests and multilevel logistic regression.

RESULTS: A total of 46 093 admissions for nontraumatic SAH were included in the sample; 24.6% presented on a weekend, 68.9% on a weekday, and 6.5% had unknown day of presentation. Weekend admission was not a significant predictor of inpatient mortality (25.4% weekend vs 24.9% weekday; P = .44), or a combined poor outcome measure of mortality or discharge to long-term acute care or hospice (30.3% weekend vs 29.4% weekday; P = .23). Among those treated for aneurysm obliteration, the proportion of clipped vs coiled did not change with weekend vs weekday presentation (21.5% clipped with weekend presentation vs 21.6% weekday, P = .95; 21.5% coiled with weekend presentation vs 22.4% weekday, P = .19).

CONCLUSION: Presentation with nontraumatic SAH on a weekend did not influence mortality, discharge destination, or type of treatment received (clip vs coil) compared with weekday presentation.


Perpetuation of errors in illustrations of cranial nerve anatomy

J Neurosurg 127:192–198, 2017

For more than 230 years, anatomical illustrations have faithfully reproduced the German medical student Thomas Soemmerring’s cranial nerve (CN) arrangement. Virtually all contemporary atlases show the abducens, facial, and vestibulocochlear nerves (CNs VI–VIII) all emerging from the pontomedullary groove, as originally depicted by Soemmerring in 1778.

Direct observation at microsurgery of the cerebellopontine angle reveals that CN VII emerges caudal to the CN VIII root from the lower lateral pons rather than the pontomedullary groove. Additionally, the CN VI root lies in the pontomedullary groove caudal to both CN VII and VIII in the vast majority of cases.

In this high-resolution 3D MRI study, the exit location of CN VI was caudal to the CN VII/VIII complex in 93% of the cases. Clearly, Soemmerring’s rostrocaudal numbering system of CN VI-VII-VIII (abducens-facial-vestibulocochlear CNs) should instead be VIII-VII-VI (vestibulocochlear- facial-abducens CNs). While the inaccuracy of the CN numbering system is of note, what is remarkable is that generations of authors have almost universally chosen to perpetuate this ancient error. No doubt some did this through faithful copying of their predecessors. Others, it could be speculated, chose to depict the CN relationships incorrectly rather than run contrary to long-established dogma.

This study is not advocating that a universally recognized numbering scheme be revised, as this would certainly create confusion. The authors do advocate that future depictions of the anatomical arrangements of the brainstem roots of CNs VI, VII, and VIII ought to reflect actual anatomy, rather than be contorted to conform with the classical CN numbering system.


Endoscopic approach via the interhemispheric fissure: the role of an endoscope in a surgical case of multiple falcine lesions

Acta Neurochir (2017) 159:1243–1246

For treating a patient with multiple falcine and parasagittal lesions, we believe that it is beneficial to resect the maximum possible number of lesions during one operation, even if some lesions are asymptomatic. This practice can potentially reduce the total number of operations during a patient’s lifetime.

Methods We provide an introduction of a concurrent endoscopic approach via the interhemispheric fissure.

Conclusions Applying this endoscopic approach concurrently with conventional microscopic surgery can enable the safe resection of as many lesions as possible during one operation.

Evolution of Sagittal Imbalance Following Corrective Surgery for Sagittal Plane Deformity

Neurosurgery 81:129–134, 2017

Sagittal balance in adult spinal deformity is a major predictor of quality of life. A temporary loss of paraspinalmuscle force and somatic pain following spine surgery may limit a patient’s ability to maintain posture.

OBJECTIVE: To assess the evolution of sagittal balance and clinical outcomes during recovery from adult spinal deformity surgery.

METHODS: Retrospective review of a prospective observational database identified a consecutive series of patients with sagittal vertical axis (SVA) > 40mm undergoing adult deformity surgery. Radiographic parameters and clinical outcomes were measured out to 2 yr after surgery.

RESULTS: A total of 113 consecutive patients met inclusion criteria. Mean preoperative SVA was 90.3 mm, increased to 104.6mm in the first week, then gradually reduced at each follow-up interval to 59.2mm at 6wk, 45.0mm at 3mo, 38.6mm at 6mo, and 34.1mm at 1 yr (all P < .05). SVA did not change between 1 and 2 yr. Pelvic incidence-lumbar lordosis (PI-LL) corrected immediately from 25.3◦ to 8.5◦ (16.8◦ change; P < .01) and a decreased pelvic tilt from 27.6◦ to 17.6◦ (10◦ change; P < .01). No further change was noted in PILL. Pelvic tilt increased to 20.2◦ (P = .01) at 6wk and held steady through 2 yr. Mean Visual Analog Scale, Oswestry Disability Index, and Short Form-36 scores all improved; pain rapidly improved, whereas disability measures improved as SVA improved.

CONCLUSION: Radiographic assessment of global sagittal alignment did not fully reflect surgical correction of sagittal balance until 6 months after adult deformity surgery. Sagittal balance initially worsened then steadily improved at each interval over the first year postoperatively. At 1 yr, all clinical and radiographic measures outcomes were significantly improved.


Transdural arterial recruitment to brain arteriovenous malformation

J Neurosurg 127:51–58, 2017

The occurrence of transdural arterial recruitment (TDAR) in association with brain arteriovenous malformation (bAVM) is uncommon, and the reason for TDAR is not understood. The aim of this cohort study was to examine patient and bAVM characteristics associated with TDAR and the implications of TDAR on management.

METHODS A prospective surgical database of bAVMs was examined. Cases previously treated elsewhere or incompletely examined by digital subtraction angiography (DSA) assessment were excluded. Three studies of this cohort were performed, as follows: characteristics associated with TDAR, the relationship between TDAR and neurological deficits unassociated with hemorrhage (NDUH), and the impact of TDAR on outcome from surgery. Regression models were performed.

RESULTS Of 769 patients with complete DSA who had no previous treatment, 51 (6.6%) were found to have TDAR. The presence of TDAR was associated with increasing age (p < 0.01; OR 1.05; 95% CI 1.02–1.07); presentation with NDUH (p < 0.01; OR 2.71; 95% CI 1.29–5.71); increasing size of the bAVM (p < 0.01; OR 1.57; 95% CI 1.29–1.91); and combined supply from both anterior and posterior circulations (p = 0.02; OR 2.37; 95% CI 1.17–4.78). Further analysis of TDAR cases comparing those with and without NDUH found an association of larger size (6.6 cm [2.9 SD] compared with 4.7 cm [1.8 SD]; p < 0.01) and combined supply from both anterior and posterior circulations (relative risk 2.5; 95% CI 1.0–6.2; p = 0.04) to be associated with an NDUH presentation. For the 632 patients undergoing surgery there was an increased risk of complications (where this produced a new permanent neurological deficit at 12 months represented by a modified Rankin Scale score of > 1) with the following variables: size; location in eloquent brain; deep venous drainage; increasing age; and no presentation with hemorrhage. The presence of TDAR was not associated with an increased risk of complications from surgery.

CONCLUSIONS The authors found that TDAR occurs in older patients with larger bAVMs, and that TDAR is also more likely to be associated with bAVMs presenting with NDUH. The likely explanation for the presence of TDAR is a secondary recruitment arising as a consequence of shear stress, rather than a primary vascular supply present from the earliest development of the bAVM.

Neurosurgery Department. “La Fe” University Hospital. Valencia, Spain


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