sEVD—smartphone-navigated placement of external ventricular drains

Acta Neurochirurgica (2020) 162:513–521

Currently, the trajectory for insertion of an external ventricular drain (EVD) is mainly determined using anatomical landmarks. However, non-assisted implantations frequently require multiple attempts and are associated with EVD malpositioning and complications. The authors evaluated the feasibility and accuracy of a novel smartphone-guided, angleadjusted technique for assisted implantations of an EVD (sEVD) in both a human artificial head model and a cadaveric head.

Methods After computed tomography (CT), optimal insertion angles and lengths of intracranial trajectories of the EVDs were determined. A smartphone was calibrated to the mid-cranial sagittal line. Twenty EVDs were placed using both the premeasured data and smartphone-adjusted insertion angles, targeting the center of the ipsilateral ventricular frontal horn. The EVD positions were verified with post-interventional CT.

Results All 20 sEVDs (head model, 8/20; cadaveric head, 12/20) showed accurate placement in the ipsilateral ventricle. The sEVD tip locations showed a mean target deviation of 1.73° corresponding to 12 mm in the plastic head model, and 3.45° corresponding to 33mm in the cadaveric head. The mean duration of preoperative measurements on CT data was 3 min, whereas sterile packing, smartphone calibration, drilling, and implantation required 9 min on average.

Conclusions By implementation of an innovative navigation technique, a conventional smartphone was used as a protractor for the insertion of EVDs. Our ex vivo data suggest that smartphone-guided EVD placement offers a precise, rapidly applicable, and patient-individualized freehand technique based on a standard procedure with a simple, cheap, and widely available multifunctional device.

Implementation of cisternostomy as adjuvant to decompressive craniectomy for the management of severe brain trauma

Acta Neurochirurgica (2020) 162:469–479

Objective To evaluate the value of an adjuvant cisternostomy (AC) to decompressive craniectomy (DC) for the management of patients with severe traumatic brain injury (sTBI).

Methods A single-center retrospective quality control analysis of a consecutive series of sTBI patients surgically treated with AC or DC alone between 2013 and 2018. A subgroup analysis, “primary procedure” and “secondary procedure”, was also performed. We examined the impact of AC vs. DC on clinical outcome, including long-term (6 months) extended Glasgow outcome scale (GOS-E), the duration of postoperative ventilation, and intensive care unit (ICU) stay, mortality, Glasgow coma scale at discharge, and time to cranioplasty. We also evaluated and analyzed the impact of AC vs. DC on post-procedural intracranial pressure (ICP) and brain tissue oxygen (PbO2) values as well as the need for additional osmotherapy and CSF drainage.

Results Forty patients were examined, 22 patients in the DC group, and 18 in the AC group. Compared with DC alone, AC was associated with significant shorter duration of mechanical ventilation and ICU stay, as well as better Glasgow coma scale at discharge. Mortality rate was similar. At 6-month, the proportion of patients with favorable outcome (GOS-E ≥ 5) was higher in patients with AC vs. DC [10/18 patients (61%) vs. 7/20 (35%)]. The outcome difference was particularly relevant when AC was performed as primary procedure (61.5% vs. 18.2%; p = 0.04). Patients in the AC group also had significant lower average postsurgical ICP values, higher PbO2 values and required less osmotic treatments as compared with those treated with DC alone.

Conclusion Our preliminary single-center retrospective data indicate that AC may be beneficial for the management of severe TBI and is associated with better clinical outcome. These promising results need further confirmation by larger multicenter clinical studies. The potential benefits of cisternostomy should not encourage its universal implementation across trauma care centers by surgeons that do not have the expertise and instrumentation necessary for cisternal microsurgery. Training in skull base and vascular surgery techniques for trauma care surgeons would avoid the potential complications associated with this delicate procedure.

Double-blind randomized clinical trial of vancomycin in spinal arthrodesis: no effects on surgical site infection

J Neurosurg Spine 32:473–480, 2020

Surgical site infection (SSI) results in high morbidity and mortality in patients undergoing spinal fusion. Using intravenous antibiotics in anesthesia induction reduces the rate of postoperative infection, but it is not common practice to use them topically, despite recent reports that this procedure helps reduce infection. The objective of this study was to determine whether the topical use of vancomycin reduces the rate of postoperative SSI in patients undergoing thoracolumbar fusion.

METHODS A randomized, double-blind clinical trial in a single hospital was performed comparing vancomycin and placebo in thoracolumbar fusion patients.

RESULTS A total of 96 patients were randomized to placebo or vancomycin treatment. The mean patient age was 43 ± 14.88 years, 74% were male, and the most common etiology was fall from height (46.9%). The overall rate of postoperative SSI was 8.3%, and no difference was found between the groups: postoperative infection rates in the vancomycin and placebo groups were 8.2% and 8.5% (relative risk [RR] of SSI not using vancomycin 1.04, 95% confidence interval [CI] 0.28–3.93, p = 0.951), respectively. Patients with diabetes mellitus had higher SSI rates (RR 8.98, 95% CI 1.81–44.61, p = 0.007).

CONCLUSIONS This is the first double-blind randomized clinical trial to evaluate the effects of topical vancomycin on postoperative infection rates in thoracolumbar fusion patients, and the results did not differ significantly from placebo. Clinical trial registration no.: RBR-57wppt (ReBEC; http://www.ensaiosclinicos.gov.br/)

 

Topping-off technique for stabilization of lumbar degenerative instabilities in 322 patients

J Neurosurg Spine 32:366–372, 2020

Semi-rigid instrumentation (SRI) was introduced to take advantage of the concept of load sharing in surgery for spinal stabilization. The authors investigated a topping-off technique in which interbody fusion is not performed in the uppermost motion segment, thus creating a smooth transition from stabilized to free motion segments. SRI using the topping-off technique also reduces the motion of the adjacent segments, which may reduce the risk of adjacent segment disease (ASD), a frequently observed sequela of instrumentation and fusion, but this technique may also increase the possibility of screw loosening (SL). In the present study the authors aimed to systematically evaluate reoperation rates, clinical outcomes, and potential risk factors and incidences of ASD and SL for this novel approach.

METHODS The authors collected data for the first 322 patients enrolled at their institution from 2009 to 2015 who underwent surgery performed using the topping-off technique. Reoperation rates, patient satisfaction, and other outcome measures were evaluated. All patients underwent pedicle screw–based semi-rigid stabilization of the lumbar spine with a polyetheretherketone (PEEK) rod system.

RESULTS Implantation of PEEK rods during revision surgery was performed in 59.9% of patients. A median of 3 motion segments (range 1–5 segments) were included and a median of 2 motion segments (range 0–4 segments) were fused. A total of 89.4% of patients underwent fusion, 73.3% by transforaminal lumbar interbody fusion (TLIF), 18.4% by anterior lumbar interbody fusion (ALIF), 3.1% by extreme lateral interbody fusion (XLIF), 0.3% by oblique lumbar interbody fusion (OLIF), and 4.9% by combined approaches in the same surgery. Combined radicular and lumbar pain according to a visual analog scale was reduced from 7.9 ± 1.0 to 4.0 ± 3.1, with 56.2% of patients indicating benefit from surgery. After maximum follow-up (4.3 ± 1.8 years), the reoperation rate was 16.4%.

CONCLUSIONS The PEEK rod concept including the topping-off principle seems safe, with at least average patient satisfaction in this patient group. Considering the low rate of first-tier surgeries, the presented results seem at least comparable to those of most other series. Follow-up studies are needed to determine long-term outcomes, particularly with respect to ASD, which might be reduced by the presented approach.

Usefulness of Timed Up and Go (TUG) Test for Prediction of Adverse Outcomes in Patients Undergoing Thoracolumbar Spine Surgery

Neurosurgery 2019 DOI:10.1093/neuros/nyz480

Spine surgery rates have increased and the high postoperativemorbidity in these patients result in increased costs. Consequently, it is essential to identify patients at risk of adverse outcomes.

OBJECTIVE: To assess whether preoperative Timed Up and Go (TUG) test performance can predict high-grade postoperative complications.

METHODS: A prospective cohort study of patients undergoing elective thoracolumbar spine surgery in a tertiary care hospital between 2017 and 2018. Patients were assessed preoperatively and assigned to the slow-TUG group if unable to perform or test performance time was ≥18.4 s. Primary outcome: high-grade postoperative complications. Secondary outcomes: overall complications, length of stay (LOS), discharge to healthcare facility, readmission and emergency department (ED) presentation. Patients were followed-up until 6 wk after surgery.

RESULTS: One hundred three patients (mean age 62.95 ± 10.97 yr) were enrolled. Slow- TUG group were more likely to be classified as American Society of Anaesthesiology (ASA) class 3 (74.1% vs 47.4%, P=.02), non-independent (25.9% vs 5.3%, P<.01), and frail (92.3% vs 42.1%, P < .01). TUG was an independent predictor of high-grade complications (adjusted odds ratio (OR): 4.97, 95% CI: 1.18-22.47), overall complications (OR: 3.77, 95% CI: 1.33-11.81), discharge to a skilled-nursing facility (OR: 3.2, 95% CI: 1.00-10.70), readmission within 6 wk of surgery (OR: 9.14, 95% CI: 2.39-41.26) and LOS (adjusted incident rate ratio (IRR): 1.45, 95% CI: 1.16-1.80).

CONCLUSION: Compared to traditional risk factors, TUG is an important predictor of adverse postoperative outcomes and may be used preoperatively to identify high-risk thoracolumbar surgery patients.

 

Subperiosteal versus subdural drainage after burr hole evacuation of chronic subdural hematoma: systematic review and meta-analysis

Acta Neurochirurgica (2020) 162:489–498

The evidence for subperiosteal drainage (SPD) versus subdural drainage (SDD) in chronic subdural hematoma (CSDH) remains controversial, and most surgeons prefer to use SDD over SPD.We aimto assess the latest evidence on the use of SPD compared to SDD in patients with CSDH undergoing burr hole evacuation.

Methods We performed a systematic literature search on topics that assesses the use of SPD compared to SDD in patients with CSDH up until November 2019 from PubMed, EuropePMC, Cochrane Central Database, ScienceDirect, ProQuest, and ClinicalTrials.gov. The primary outcome was recurrent CSDH, and the secondary outcomes were mortality, surgical morbidities, and modified Rankin Score (mRS).

Results There were a total of 3241 subjects from 10 studies. SPD was shown to reduce recurrent CSDH (OR 0.66 [0.52, 0.84], p < 0.001; I2: 17%, p = 0.30) compared to SDD. Recurrent CSDH was lower in SPD group in subgroup analysis at 3-months (OR 0.63 [0.49, 0.81]; I2: 68%, p = 0.04) and 6-months (OR 0.66 [0.51, 0.85], p = 0.001; I2: 77%, p = 0.01) follow-up. However, there was no difference in CSDH recurrence upon subgroup analysis of RCTs. Similar mortality was demonstrated between SPD and SDD group (p = 0.13). The occurrence of parenchymal injury/new neurological deficit was significantly lower in SPD group (OR 0.26 [0.14, 0.51], p < 0.001; I2: 49%, p = 0.08). The rate of seizure, (p = 0.57), postoperative bleeding (p = 0.29), and infection (p = 0.25) were shown to be similar in both SPD and SDD group. Overall, the rate of surgical morbidity was significantly lower in SPD group (OR 0.61 [0.44, 0.85], p = 0.003; I2: 16%, p = 0.25). mRS at the end of follow-up was similar in SPD and SDD group (p = 0.12).

Conclusion SPD was associated with less CSDH recurrence, but similar rate of mortality, seizures, postoperative bleeding, and infections compared to SDD. The rate of parenchymal injury/new neurological deficit was lower in the SPD group.

The striking effects of deep cerebellar stimulation on generalized fixed dystonia

J Neurosurg 132:712–716, 2020

Cerebellar neuromodulation could influence the pathological abnormalities of movement disorders through several connections between the cerebellum and the basal ganglia or other cortices. In the present report, the authors demonstrate the effects of cerebellar deep brain stimulation (DBS) on a patient with severe generalized fixed dystonia (FD) that was refractory to bilateral pallidotomy and intrathecal baclofen therapy.

A previously healthy 16-year-old girl presented with generalized FD. Bilateral pallidotomy and intrathecal baclofen therapy had failed to resolve her condition, following which she received DBS through the bilateral superior cerebellar peduncle (SCP) and dentate nucleus (DN). Ipsilateral stimulation of the SCP or DN improved the FD, and the ability of DBS administered via the SCP to relax muscles was better than that of DN DBS.

A considerable improvement of generalized FD, from a bedridden state to a wheelchairbound state, was observed in the patient following 6 months of chronic bilateral DBS via the SCP; moreover, the patient was able to move her arms and legs. The findings in the present case suggest that neuromodulation of deep cerebellar structures is a promising treatment for FD that is refractory to conventional treatments.

The endoscopic transpterional port approach: anatomy, technique, and initial clinical experience

J Neurosurg 132:884–894, 2020

The evolution of microsurgical and endoscopic techniques has allowed the development of less invasive transcranial approaches. The authors describe a purely endoscopic transpterional port craniotomy to access lesions involving the cavernous sinus and the anterolateral skull base.

METHODS Through single- or dual-port incisions and with direct endoscopic visualization, the authors performed an endoscopic transpterional port approach (ETPA) using a 4-mm straight endoscope in 8 sides of 4 formalin-fixed cadaveric heads injected with colored latex. A main working port incision is made just below the superior temporal line and behind the hairline. An optional 0.5- to 1-cm second skin port incision is made on the lateral supraorbital region, allowing multiangle endoscopic visualization and maneuverability. A 1.5- to 2-cm craniotomy centered over the pterion is done through the main port, which allows an extradural exposure of the cavernous sinus region and extra/intradural exposure of the frontal and temporal cranial fossae. The authors present a pilot surgical series of 17 ETPA procedures and analyze the surgical indications and clinical outcomes retrospectively.

RESULTS The initial stage of this work on cadavers provided familiarity with the technique, standardized its steps, and showed its anatomical limits. The clinical ETPA was applied to gain access into the cavernous sinus, as well as for aneurysm clipping and meningioma resection. Overall, perioperative complications occurred in 1 patient (6%), there was no mortality, and at last follow-up all patients had a modified Rankin Scale score of 0 or 1.

CONCLUSIONS The ETPA provides a less invasive, focused, and direct route to the cavernous sinus, and to the frontal and temporal cranial fossae, and it is feasible in clinical practice for selected indications with good results.

Anterior Cervical Discectomy and Fusion in the Outpatient Ambulatory Surgery Setting: Analysis of 2000 Consecutive Cases

Neurosurgery 2019 DOI:10.1093/neuros/nyz514

In an effort to improve efficiency of care, ambulatory surgery centers (ASCs) have emerged as lower-cost options. Anterior cervical discectomy and fusion (ACDF) is one of the most prevalent spine surgeries performed and rarely requires overnight stays in the hospital, supporting its migration to the ASC. Recent analyses have called into question the safety of outpatient ACDF, potentially slowing its adoption. ASC-ACDF studies have largely been limited to small series, precluding an accurate assessment of safety.

OBJECTIVE: To analyze 2000 ASC-ACDF cases, describe patient selection and perioperative protocol, and report associated safety profile.

METHODS: A total of 2000 patients who underwent 1 to 3 level ACDF in a single ASC from 2006 to 2018 were included in this retrospective analysis. Patients were observed in a 4-h postanesthesia care unit (PACU) with a multimodal pain management regiment. Data were collected on patient demographics, comorbidities, operative details, and 30- and 90-d morbidity.

RESULTS: Of the 2000 patients, 10 (0.5%) required transfer to an inpatient setting within the 4-h observation. Reasons for transfer included hematoma (2), pain control (2), cerebrospinal fluid leak (1), and medical complications (5). Six patients (0.3%) underwent reoperation within 30 d. All-cause 30-d readmission was 1.9%.

CONCLUSION: An analysis of 2000 ACDF patients in an ASC setting with a standardized perioperative protocol demonstrates that surgical complications occur at a low rate (<1%) and can be appropriately diagnosed and managed in a 4-h PACU. In an effort to decrease healthcare costs, surgeons can safely perform ACDFs in an ASC utilizing patient selection criteria and perioperative management protocols similar to those reported here.

Ten-year analysis of saccular aneurysms in the Barrow Ruptured Aneurysm Trial

J Neurosurg 132:771–776, 2020

The authors present the 10-year results of the Barrow Ruptured Aneurysm Trial (BRAT) for saccular aneurysms. The 1-, 3-, and 6-year results of the trial have been previously reported, as have the 6-year results with respect to saccular aneurysms. This final report comparing the safety and efficacy of clipping versus coiling is limited to an analysis of those patients presenting with subarachnoid hemorrhage (SAH) from a ruptured saccular aneurysm.

METHODS In the study, 362 patients had saccular aneurysms and were randomized equally to the clipping and the coiling cohorts (181 each). The primary outcome analysis was based on the assigned treatment group; poor outcome was defined as a modified Rankin Scale (mRS) score > 2 and was independently adjudicated. The extent of aneurysm obliteration was adjudicated by a nontreating neuroradiologist.

RESULTS There was no statistically significant difference in poor outcome (mRS score > 2) or deaths between these 2 treatment arms during the 10 years of follow-up. Of 178 clip-assigned patients with saccular aneurysms, 1 (< 1%) was crossed over to coiling, and 64 (36%) of the 178 coil-assigned patients were crossed over to clipping. After the initial hospitalization, 2 of 241 (0.8%) clipped saccular aneurysms and 23 of 115 (20%) coiled saccular aneurysms required retreatment (p < 0.001). At the 10-year follow-up, 93% (50/54) of the clipped aneurysms were completely obliterated, compared with only 22% (5/23) of the coiled aneurysms (p < 0.001). Two patients had documented rebleeding, both died, and both were in the assigned and treated coiled cohort (2/83); no patient in the clipped cohort (0/175) died (p = 0.04). In 1 of these 2 patients, the hemorrhage was not from the target aneurysm but from an incidental basilar artery aneurysm, which was coiled at the same time.

CONCLUSIONS There was no significant difference in clinical outcomes between the 2 assigned treatment groups as measured by mRS outcomes or deaths. Clinical outcomes in the patients with posterior circulation aneurysms were better in the coiling group at 1 year, but after 1 year this difference was no longer statistically significant. Rates of complete aneurysm obliteration and rates of retreatment favored patients who actually underwent clipping compared with those who underwent coiling. Clinical trial registration no.: NCT01593267 (clinicaltrials.gov)

Kambin’s triangle: definition and new classification schema

J Neurosurg Spine 32:390–398, 2020

Kambin’s triangle is an anatomical corridor used to access critical structures in a variety of spinal procedures. It is considered a safe space because it is devoid of vascular and neural structures of importance. Nonetheless, there is currently significant variation in the literature regarding the exact dimensions and anatomical borders of Kambin’s triangle. This confusion was originally caused by leaving the superior articular process (SAP) unassigned in the description of the working triangle, despite Kambin identifying that structure in his original report. The SAP is the most relevant structure to consider when accessing the transforaminal corridor. Leaving the SAP unassigned has led to an open-handed application of the term “Kambin’s triangle.” That single eponym currently has two potential meanings, one meaning for endoscopic surgeons working through a corridor in the intact spine and a second meaning for surgeons accessing the disc space after a complete or partial facetectomy. Nevertheless, an anatomical corridor should have one consistent definition to clearly communicate techniques and use of instrumentation performed through that space. As such, the authors propose a new surgically relevant classification of this corridor. Assigning the SAP a border requires adding another dimension to the triangle, thereby transforming it into a prism. The term “Kambin’s prism” indicates the assignment of a border to all relevant anatomical structures, allowing for a uniform definition of the 3D space. From there, the classification scheme considers the expansion of the corridor and the extent of bone removal, with a particular focus on the SAP.

Natural history of ventriculomegaly in adults: a cluster analysis

J Neurosurg 132:741–748, 2020

Chronic ventriculomegaly in the absence of raised intracranial pressure (ICP) is a known entity in adult hydrocephalus practice. The natural history and indication for treatment is, however, poorly defined. A highly heterogeneous group, some adults with ventriculomegaly are asymptomatic, while others have life-threatening deteriorations. The authors hypothesized that the various presentations can be subtyped and represent different stages of decompensation. A cluster analysis was performed on a cohort of patients with chronic ventriculomegaly with the aim of elucidating typical clinical characteristics and outcomes in chronic ventriculomegaly in adults.

METHODS Data were collected from 79 patients with chronic ventriculomegaly referred to a single center, including demographics, presenting symptoms, and 24-hour ICP monitoring (ICPM). A statistical cluster analysis was performed to determine the presence of subgroups.

RESULTS Four main subgroups and one highly dissimilar group were identified. Patients with ventriculomegaly commonly have a perinatal event followed by one of four main presentations: 1) incidental ventriculomegaly with or without headache; 2) highly symptomatic presentation (including reduced consciousness) and raised ICP; 3) early presenting with symptoms of headache and nausea (with abnormal pulsatility); and 4) late presenting with features common to normal pressure hydrocephalus. Each symptomatic group has characteristic radiological features, ICPM, and responses to treatment.

CONCLUSIONS Cluster analysis has identified subgroups of adult patients with ventriculomegaly. Such groups may represent various degrees of decompensation. Surgical interventions may not be equally effective across the subgroups, presenting an avenue for further research. The identified subtypes provide further insight into the natural history of this lesser studied form of hydrocephalus.

Postoperative Hearing Preservation in Patients Undergoing Retrosigmoid Craniotomy for Resection of Vestibular Schwannomas: A Systematic Review of 2034 Patients

Neurosurgery 2019 DOI:10.1093/neuros/nyz147

Vestibular schwannomas (VS) are benign tumors derived from Schwann cells ensheathing the vestibulocochlear nerve. The retrosigmoid (RS) surgical approach is useful to resect tumors of multiple sizes while affording the possibility of preserving postoperative hearing.

OBJECTIVE: To conduct a systematic review of published literature investigating hearing preservation rates in patients who underwent the RS approach for VS treatment.

METHODS: The PubMed, Scopus, and Embase databases were surveyed for studies that reported preoperative and postoperative hearing grades on VS patients who underwent RS treatment. Hearing preservation rates were calculated, and additional patient demographic data were extracted. Tumor size data were stratified to compare hearing preservation rates after surgery for intracanalicular, small (0-20 mm), and large (>20 mm) tumors.

RESULTS: Of 383 deduplicated articles, 26 studies (6.8%) met eligibility criteria for a total of 2034 patients with serviceable preoperative hearing, for whom postoperative hearing status was evaluated. Aggregate hearing preservation was 31% and 35% under a fixed and random effects model, respectively. A mixed effects model was used to determine hearing preservation rates depending on tumor size, which were determined to be 57%, 37%, and 12% for intracanalicular, small, and large tumors, respectively. Significant crossstudy heterogeneity was found (I2 = 93%, τ 2 = .964, P < .01; Q = 287.80, P = < .001), with rates of hearing preservation ranging from 0% to 100%.

CONCLUSION: Tumor size may have an effect on hearing preservation rates, but multiple factors should be considered. Discussion of a patient’s expectations for hearing preservation is critical when deciding on VS treatment plans.

Efficacy and safety of middle meningeal artery embolization in the management of refractory or chronic subdural hematomas: a systematic review and meta-analysis

Acta Neurochirurgica (2020) 162:499–507

Refractory or chronic subdural hematomas (cSDH) constitute a challenging entity that neurosurgeons face frequently nowadays. Middle meningeal artery embolization (MMAE) has emerged in the recent years as a promising treatment option. However, solid evidence that can dictate management guidelines is still lacking.

Methods We conducted a systematic review and meta-analysis (MA) in compliance with the PRISMA guidelines to evaluate the efficacy and safety of MMAE compared with conventional treatments for refractory or cSDH. Databases were searched up to March 2019. Using a random-effects model, meta-analyses of proportions and risk difference were conducted recurrence, need for surgical rescue, and complications.

Results Eleven studies (177 patients) were included. Majority (116, 69%) were males with a weighted mean age of 71 + −19.5 years. Meta-analysis of proportions showed treatment failure to be 2.8%, need for surgical rescue 2.7%, and embolization-related complications 1.2%. Meta-analysis of risk-difference between embolized and non-embolized patients showed a 26% (p < 0.001, 95% CI 21%–31%, I2 = 0) lower risk of hematoma recurrence in MMAE. Similarly, in the embolized group, the need for surgical rescue was 20% less (p < 0.001, 95% CI = 12%–27%, I2 = 12.4), and complications were 3.6% less (p = 0.008, 95% CI 1%–6%, I2 = 0) compared to conventional groups.

Conclusions Although MMAE appears to be a promising treatment for refractory or cSDH, drawing definitive conclusions remains limited by paucity of data and small sample sizes. Multicenter, randomized, prospective trials are needed to compare embolization to conventional treatments like watchful waiting, medical management, or surgical evacuation. More extensive research on MMAE could begin a new era in the minimally invasive management of cSDH.

A New Piece of the Puzzle to Understand Cervical Sagittal Alignment: Utilizing a Novel Angle δ to Describe the Relationship among T1 Vertebral Body Slope, Cervical Lordosis, and Cervical Sagittal Alignment

Neurosurgery 2019 DOI:10.1093/neuros/nyz088

Cervical alignment has become increasingly important in the planning of spine surgery. A relationship between the slope of T1 (T1S), the cervical lordosis (CL), and the overall cervical sagittal vertical axis (cSVA) has previously been demonstrated, but the exact nature of this relationship is poorly understood. In this study, we derive theoretical and empirical equations to better understand how T1S and CL affect cSVA. The first equation was developed on a theoretical basis using inherent trigonometric relationships of the cervical spine. By treating the cervical spine as the arc of a circumference, and by taking into account the cervical height (CH), the geometric relationship between theT1S, CL, and cSVA was described via a trigonometric identity utilizing a novel angle δ subtended by the CH and cSVA (δ = T1S-CL/2). The second equation was developed on an empiric basis by performing a multiple linear regression on data obtained from a retrospective review of a large multicenter deformity database. The theoretical equation determined that the value of cSVA could be expressed as: cSVA = CH ∗ tan(π/180 ∗ (T 1S −CL/2)) . The empirical equation determined that value of cSVA could be expressed as: cSVA = (1.1 ∗ T 1) −(0.43 ∗ CL) + 6.69. In both, the sagittal alignment of the head over the shoulders is directly proportional to the T1S and inversely proportional to CL/2. These 2 equations may allow surgeons to better understand how the CL compensates for the T1S, to accurately predict the postoperative cSVA, and to customize cervical interbody grafts by taking into consideration each individual patient’s specific cervical spine parameters.

Incidental Low-Grade Gliomas: Single-Institution Management Based on Clinical, Surgical, and Molecular Data

Neurosurgery 2019 DOI:10.1093/neuros/nyz114

Incidentally discovered diffuse low-grade gliomas (iLGG) are poorly documented in the literature. They are diagnosed by chance during radiological examinations.

OBJECTIVE: To review a cohort of patients with iLGG surgically treated in our institution, analyzing clinical, molecular, and surgical aspects.

METHODS: Clinical, radiological, and treatment data of iLGGwere retrieved and compared with those of symptomatic diffuse LGGs (sLGG). Histological and molecular review was carried out as well. The extent of resection was evaluated on preoperative and postoperative T2-weighted magnetic resonance imaging.

RESULTS: Thirty-four iLGG cases were identified within a monoinstitutional cohort of 332 patients operated for low-grade gliomas from 2000 to 2017. Clinically, patients with iLGG had higher preoperative karnofsky performance scale (KPS) (P = .003), smaller tumor volume (P=.0001), lower frequency of eloquent areas involvement (P=.0001), and higher rate of complete resection (P = .0001) compared to those with sLGG. No differences in the molecular profile and O6-methylguanine-DNA-methyltransferase promoter methylation were detected between iLGG and sLGG. Importantly, patients with iLGG had longer overall survival than those with sLGG (P = .0001), even when a complete surgical resection was achieved (P = .001).

CONCLUSION: Although the therapeutic strategy of iLGG is still a matter of debate, our data support the safety and the effectiveness of early surgical resection. The favorable prognosis of iLGG may be due to the higher practicability of extensive resection, noneloquent tumor location, and smaller tumor volume.

Staged Laser Interstitial Thermal Therapy (LITT) Treatments to Left Insular Low-Grade Glioma

Neurosurgery 2019 DOI:10.1093/neuros/nyz120

Low-grade insular gliomas remain challenging tumors for aggressive resection because of the numerous functional and vascular structures surrounding them. Because of the potential morbidities associated with open surgical resection, less invasive techniques may confer a more optimal balance between cytoreduction and surgical complications. For this reason, we evaluated the use of laser interstitial thermal therapy (LITT) for resection of a dominant hemisphere oligodendroglioma World Health Organization (WHO) grade II in a 68-yr-old patient by use of multiple staged surgeries for its resection.

CLINICAL PRESENTATION: Patient KK was a 68-yr-old female who was found to have a large, left-sided insular mass that was shown to be an oligodendroglioma WHO grade II, positive for codeletion 1p/19q and IDH1 mutant on biopsy. Over the course of 3 mo, KK underwent 2 stages of LITT, targeting different areas of the 5-cmtumor. The 60-d magnetic resonance imaging (MRI) demonstrated a reduction in size of the tumor from5.2×3.3×2.4 cm to 3.6 × 1.9 × 1.4 cm. She returned for a second stage targeting the anterior portion of the tumor. KK did well postoperatively and went on to postsurgical chemoradiation. At the
2-yr follow-up, the lesion showed near resolution on MRI.

CONCLUSION: This case report demonstrates successful use of LITT for staged surgeries to treat a left hemisphere-dominant insular lesion. This establishes the use of LITT as a viable, minimally invasive option to treat tumors that are difficult to access or pose concerns for increased morbidity through an open surgery.

Endoscopic Transnasal Trans-Sphenoidal Approach for Pituitary Adenomas: A Comparison to the Microscopic Approach Cohort by Propensity Score Analysis

Neurosurgery DOI:10.1093/neuros/nyz201

Despite some evidence for the adoption of endoscopic transnasal transsphenoidal surgery (ETSS) for pituitary adenomas, the advantages of this technique over the traditional approach have not been robustly confirmed.

OBJECTIVE: To compare ETSS with the microscopic sublabial trans-septal transsphenoidal surgery (MTSS) for pituitary adenomas.

METHODS: We retrospectively reviewed 2 cohorts of ETSS and MTSS performed at our institution from 1995 to 2017. Patient characteristics, surgical data, and outcomes were recorded prospectively. We performed a univariate and multivariable analysis to determine the best surgical approach. To improve the quality of the results, we matched the distribution of patient characteristics between groups by propensity score (PS) method.

RESULTS: A total of 187 procedures (90 MTSS, 97 ETSS) were reviewed. We found better results in the ETSS group in terms of gross total resection (P = .002) and hormone-excess secretion control (P=.014). There was also a lower incidence of cerebrospinal fluid leakage (P = .039), transitory diabetes insipidus (P = .028), and postoperative hypopituitarism (P = .045), as well as a shorter hospital length of stay (P < .001). After PS matching, we confirmed by multivariable logistic regression analysis an increased odds ratio of gross total resection for the ETSS (3.910; 95% CI 1.720-8.889; P= .001).

CONCLUSION: By PS method, our results suggest that the ETSS provides advantages over the traditional MTSS approach for tumor resection. Better control of secreting tumors and a lower rate of most complications also support the selection of the ETSS approach for the treatment of pituitary adenomas.

Deep brain stimulation of the globus pallidus internus versus the subthalamic nucleus in isolated dystonia

J Neurosurg 132:721–732, 2020

Surgical procedures involving deep brain stimulation (DBS) of the globus pallidus internus (GPi) or subthalamic nucleus (STN) are well-established treatments for isolated dystonia. However, selection of the best stimulation target remains a matter of debate. The authors’ objective was to compare the effectiveness of DBS of the GPi and the STN in patients with isolated dystonia.

METHODS In this matched retrospective cohort study, the authors searched an institutional database for data on all patients with isolated dystonia who had undergone bilateral implantation of DBS electrodes in either the GPi or STN in the period from January 30, 2014, to June 30, 2017. Standardized assessments of dystonia and health-related quality of life using the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) and SF-36 were conducted before and at 1, 6, and 12 months after surgery. No patients were lost to the 6-month follow-up; 5 patients were lost to the 12-month follow-up.

RESULTS Both GPi (14 patients) and STN (16 patients) stimulation produced significant improvement in dystonia and quality of life in all 30 patients found in the database search. At the 1-month follow-up, however, the percentage improvement in the BFMDRS total movement score was significantly (p = 0.01) larger after STN DBS (64%) than after GPi DBS (48%). At the 12-month follow-up, the percentage improvement in the axis subscore was significantly (p = 0.03) larger after GPi DBS (93%) than after STN DBS (83%). Also, the total amount of electrical energy delivered was significantly (p = 0.008) lower with STN DBS than with GPi DBS (124 ± 52 vs 192 ± 65 mJ, respectively).

CONCLUSIONS The GPi and STN are both effective targets in alleviating dystonia and improving quality of life. However, GPi stimulation may be better for patients with axial symptoms. Moreover, STN stimulation may produce a larger clinical response within 1 month after surgery and may have a potential economic advantage in terms of lower battery consumption.

Posterior foraminotomy versus anterior decompression and fusion in patients with cervical degenerative disc disease with radiculopathy

J Neurosurg Spine 32:344–352, 2020

The long-term efficacy of posterior foraminotomy compared with anterior cervical decompression and fusion (ACDF) for the treatment of degenerative disc disease with radiculopathy has not been previously investigated in a population-based cohort.

METHODS All patients in the national Swedish Spine Register (Swespine) from January 1, 2006, until November 15, 2017, with cervical degenerative disc disease and radiculopathy were assessed. Using propensity score matching, patients treated with posterior foraminotomy were compared with those undergoing ACDF. The primary outcome measure was the Neck Disability Index (NDI), a patient-reported outcome score ranging from 0% to 100%, with higher scores indicating greater disability. A minimal clinically important difference was defined as > 15%. Secondary outcomes were assessed with additional patient-reported outcome measures (PROMs).

RESULTS A total of 4368 patients (2136/2232 women/men) met the inclusion criteria. Posterior foraminotomy was performed in 647 patients, and 3721 patients underwent ACDF. After meticulous propensity score matching, 570 patients with a mean age of 54 years remained in each group. Both groups had substantial decreases in their NDI scores; however, after 5 years, the difference was not significant (2.3%, 95% CI −4.1% to 8.4%; p = 0.48) between the groups. There were no significant differences between the groups in EQ-5D or visual analog scale (VAS) for neck and arm scores. The secondary surgeries on the index level due to restenosis were more frequent in the foraminotomy group (6/100 patients vs 1/100), but on the adjacent segments there was no difference between groups (2/100).

CONCLUSIONS In patients with cervical degenerative disc disease and radiculopathy, both groups demonstrated clinical improvements at the 5-year follow-up that were comparable and did not achieve a clinically important difference from one another, even though the reoperation rate favored the ACDF group. This study design obtains population-based results, which are generalizable.