Posts

Posted on

Intrathecal Morphine Following Lumbar Fusion: A Randomized, Placebo-Controlled Trial

Neurosurgery, Volume 85, Issue 2, August 2019, Pages 189–198

Despite the potential for faster postoperative recovery and the ease of direct intraoperative injection, intrathecal morphine is rarely provided in lumbar spine surgery.

OBJECTIVE: To evaluate the safety and efficacy of intrathecal morphine following lumbar fusion.

METHODS: We randomly assigned 150 patients undergoing elective instrumented lumbar fusion to receive a single intrathecal injection of morphine (0.2 mg) or placebo (normal saline) immediately prior to wound closure. The primary outcome was pain on the visual- analogue scale during the first 24 h after surgery. Secondary outcomes included respiratory depression, treatment-related side effects, postoperative opioid requirements, and length of hospital stay. An intention-to-treat, repeated-measures analysis was used to estimate outcomes according to treatment in the primary analysis.

RESULTS: The baseline characteristics of the 2 groups were similar. Intrathecal morphine reduced pain both at rest (32% area under the curves [AUCs] difference, P < .01) and with movement (22% AUCs difference, P < .02) during the initial 24 h after surgery. The risk of respiratory depression was not increased by intrathecal morphine (hazard ratio, 0.86; 95% confidence interval, 0.44 to 1.68; P = .66). Although postoperative opioid requirements were reduced with intrathecal morphine (P < .03), lengths of hospital stay were similar (P = .32). Other than a trend towards increased intermittent catheterization among patients assigned to intrathecal morphine (P = .09), treatment-related side effects did not significantly differ. The early benefits of intrathecal morphine on postoperative pain were no longer apparent after 48 h.

CONCLUSION: A single intrathecal injection of 0.2 mg of morphine safely reduces postoperative pain following lumbar fusion.

Posted on

The approach angle to the interoptic triangle limits surgical workspace when targeting the contralateral internal carotid artery

Acta Neurochirurgica (2019) 161:1535–1543

The interoptic triangle (IOT) offers a key access to the contralateral carotid artery’s ophthalmic segment (oICA) and its perforating branches (PB), the ophthalmic artery (OA), and the superior hypophyseal artery (SHA). It has been previously reported that the assessment of IOT’s size is relevant when attempting approaches to the contralateral oICA. However, previous studies have overseen that, since the oICA is a paramedian structure and a lateralized contralateral approach trajectory is then required, the real access to the oICA is further limited by the approach angle adopted by the surgeon with respect to the IOT’s plane. For this reason, we determined the surgical accessibility to the contralateral oICA and its branches though the IOT by characterizing the morphometry of this triangle relative to the optimal contralateral approach angle.

Methods We defined the “relative interoptic triangle” (rIOT) as the two-dimensional projection of the IOT to the surgeon’s view, when the microscope has been positioned with a certain angle with respect to the midline to allow the maximal contralateral oICA visualization. We correlated the surface of the rIOT to the visualization of oICA, OA, SHA, and PBs on 8 cadavers and 10 clinical datasets, using for the last a 3D-virtual reality system.

Results A larger rIOT correlated positively with the exposure of the contralateral oICA (R = 0.967, p < 0.001), OA (R = 0.92, p < 0.001), SHA (R = 0.917, p < 0.001), and the number of perforant vessels of the oICA visible (R = 0.862, p < 0.001). The exposed length of oICA, OA, SHA, and number PB observed increased as rIOT’s surface enlarged. The correlation patterns observed by virtual 3D-planning matched the anatomical findings closely.

Conclusions The exposure of contralateral oICA, OA, SHA, and PB directly correlates to rIOT’s surface. Therefore, preoperative assessment of rIOT’s surface is helpful when considering contralateral approaches to the oICA. A virtual 3D planning tool greatly facilitates this assessment.

Posted on

Probabilistic Tractography to Predict the Position of Cranial Nerves Displaced by Skull Base Tumors: Value for Surgical Strategy Through a Case Series of 62 Patients

Neurosurgery, Volume 85, Issue 1, July 2019, Pages E125–E136

Predicting the displacement of cranial nerves by tumors could make surgery safer and the outcome better. Recent advances in imaging and processing have overcome some of the limits associated with cranial nerve tractography, such as spatial resolution and fiber crossing. Among others, probabilistic algorithms yield to a more accurate depiction of cranial nerve trajectories.

OBJECTIVE: To report how cranial nerve probabilistic tractography can help the surgical strategy in a series of various skull base tumors.

METHODS: After distortion correction and region of interest seeding, a probabilistic tractography algorithm used the constrained spherical deconvolution model and attempted the reconstruction of cranial nerve trajectories in both healthy and displaced conditions.

RESULTS: Sixty-two patients were included and presented: vestibular schwannomas (n = 33); cerebellopontine angle meningiomas (n = 15); arachnoid or epidermoid cysts (n = 6); cavernous sinus and lower nerves schwannomas (n = 4); and other tumors (n = 4). For each patient, at least one ‘displaced’ cranial nerve was not clearly identified on classical anatomical MRI images. All 372 cranial nerves were successfully tracked on each healthy side; among the 175 cranial nerves considered ‘displaced’by tumors, 152 (87%) were success- fully tracked. Among the 127 displaced nerves of operated patients (n = 51), their position was confirmed intraoperatively for 118 (93%) of them. Conditions that led to tractography failure were detailed. On the basis of tractography, the surgical strategy was adjusted for 44 patients (71%).

CONCLUSION: This study reports a cranial nerve probabilistic tractography pipeline that can: predict the position of most cranial nerves displaced by skull base tumors, help the surgical strategy, and thus be a pertinent tool for future routine clinical application.

Posted on

Twenty-Five Years of Intracranial Pressure Monitoring After Severe Traumatic Brain Injury: A Retrospective, Single-Center Analysis

Neurosurgery, Volume 85, Issue 1, July 2019, Pages E75–E82

Intracranial pressure (ICP) is a clinically important variable after severe traumatic brain injury (TBI) and has been monitored, along with clinical outcome, for over 25 yr in Addenbrooke’s hospital, Cambridge, United Kingdom. This time period has also seen changes in management strategies with the implementation of protocolled specialist neurocritical care, expansion of neuromonitoring techniques, and adjustments of clinical treatment targets.

OBJECTIVE: To describe the changes in intracranial monitoring variables over the past 25 yr.

METHODS: Data from 1146 TBI patients requiring ICP monitoring were analyzed. Monitored variables included ICP, cerebral perfusion pressure (CPP), and the cerebral pressure reactivity index (PRx). Data were stratified into 5-yr epochs spanning the 25 yr from 1992 to 2017.

RESULTS: CPP increased sharply with specialist neurocritical care management (P < 0.0001) (introduction of a specific TBI management algorithm) before stabilizing from 2000 onwards. ICP decreased significantly over the 25 yr of monitoring from an average of 19 to 12 mmHg (P < 0.0001) but PRx remained unchanged. The mean number of ICP plateau waves and the number of patients developing refractory intracranial hypertension both decreased significantly. Mortality did not significantly change in the cohort (22%).

CONCLUSION: We demonstrate the evolving trends in neurophysiological monitoring over the past 25 yr from a single, academic neurocritical care unit. ICP and CPP were responsive to the introduction of an ICP/CPP protocol while PRx has remained unchanged.

Posted on

Low-Dose Gamma Knife Radiosurgery for Acromegaly

Neurosurgery, Volume 85, Issue 1, July 2019, Pages E20–E30

Remission rate is associated with higher dose of Gamma Knife Radio- surgery (GKRS; Gamma Knife: Elekta AB, Stockholm, Sweden) for acromegaly, but the dose ≥25 Gy is not always feasible when the functioning adenoma is close to optic apparatus

OBJECTIVE: To evaluate the efficacy and safety of low-dose (<25 Gy) GKRS in the treatment of patients with acromegaly.

METHODS: Single-center retrospective review of acromegaly cases treated with GKRS between June 1994 and December 2016. A total of 76 patients with the diagnosis of acromegaly who were treated with low-dose GKRS were selected for inclusion. Patients were treated with a median margin dose, isodose line, and treatment volume of 15.8 Gy, 57.5%, and 4.8 mL, respectively. Any identifiable portion of the optic apparatus was limited to a radiation dose of 10 Gy. All patients underwent full endocrine, ophthalmological, and imaging evaluation prior to and after GKRS treatments, and results of these were analyzed.

RESULTS: Biochemical remission was achieved in 33 (43.4%) patients. Actuarial remission rates were 20.3%, 49.9%, and 76.3% at 4, 8, and 12 yr, respectively. Absence of cavernous sinus invasion (P = .042) and lower baseline insulin-like growth factor-1 levels (P = .019) were significant predictors of remission. New hormone deficiencies were found in 9 (11.8%) patients. Actuarial hormone deficiency rates were 3%, 14%, and 22.2% at 4, 8, and 10 yr, respectively. Two (2.6%) patients who achieved initial remission experienced recurrence. No optic complications were encountered.

CONCLUSION: Reasonable remission and new hormone deficiency rates can be achieved with low-dose GKRS for acromegaly. These rates may be comparable to those with standard GKRS margin doses.

Posted on

The medial wall of the cavernous sinus. Part 2: Selective medial wall resection in 50 pituitary adenoma patients

J Neurosurg 131:131–140, 2019

Pituitary adenomas often invade the medial wall of the cavernous sinus (CS), but this structure is generally not surgically removed because of the risk of vascular and cranial nerve injury. The purpose of this study was to report the surgical outcomes in a large series of cases of invasive pituitary adenoma in which the medial wall of the CS was selectively removed following an anatomically based, stepwise surgical technique.

METHODS The authors’ institutional database was reviewed to identify cases of pituitary adenoma with isolated invasion of the medial wall, based on an intraoperative evaluation, in which patients underwent an endoscopic endonasal approach with selective resection of the medial wall of the CS. Cases with CS invasion beyond the medial wall were excluded. Patient complications, resection, and remission rates were assessed.

RESULTS Fifty patients were eligible for this study, 15 (30%) with nonfunctional adenomas and 35 (70%) with functional adenomas, including 16 growth hormone–, 10 prolactin-, and 9 adrenocorticotropic hormone (ACTH)–secreting tumors. The average tumor size was 2.3 cm for nonfunctional and 1.3 cm for functional adenomas. Radiographically, 11 cases (22%) were Knosp grade 1, 23 (46%) Knosp grade 2, and 16 (32%) Knosp grade 3. Complete tumor resection, based on intraoperative impression and postoperative MRI, was achieved in all cases. The mean follow-up was 30 months (range 4–64 months) for patients with functional adenomas and 16 months (range 4–30 months) for those with nonfunctional adenomas. At last follow-up, complete biochemical remission (using current criteria) without adjuvant treatment was seen in 34 cases (97%) of functional adenoma. No imaging recurrences were seen in patients who had nonfunctional adenomas. A total of 57 medial walls were removed in 50 patients. Medial wall invasion was histologically confirmed
in 93% of nonfunctional adenomas and 83% of functional adenomas. There were no deaths or internal carotid artery injuries, and the average blood loss was 378 ml. Four patients (8%) developed a new, transient cranial nerve palsy, and 2 of these patients required reoperation for blood clot evacuation and fat graft removal. There were no permanent cranial nerve palsies.

CONCLUSIONS The medial wall of the CS can be removed safely and effectively, with minimal morbidity and excellent resection and remission rates. Further follow-up is needed to determine the long-term results of this anatomically based technique, which should only be performed by very experienced endonasal skull base teams.

Posted on

The medial wall of the cavernous sinus. Part 1: Surgical anatomy, ligaments, and surgical technique for its mobilization and/or resection

J Neurosurg 131:122–130, 2019

The medial wall of the cavernous sinus (CS) is often invaded by pituitary adenomas. Surgical mobilization and/or removal of the medial wall remains a challenge.

METHODS Endoscopic endonasal dissection was performed in 20 human cadaver heads. The configuration of the medial wall, its relationship to the internal carotid artery (ICA), and the ligamentous connections in between them were investigated in 40 CSs.

RESULTS The medial wall of the CS was confirmed to be an intact single layer of dura that is distinct from the capsule of the pituitary gland and the periosteal layer that forms the anterior wall of the CS. In 32.5% of hemispheres, the medial wall was indented by and/or well adhered to the cavernous ICA. The authors identified multiple ligamentous fibers that anchored the medial wall to other walls of the CS and/or to specific ICA segments. These parasellar ligaments were clas- sified into 4 groups: 1) caroticoclinoid ligament, spanning from the medial wall and the middle clinoid toward the clinoid ICA segment and anterior clinoid process; 2) superior parasellar ligament, connecting the medial wall to the horizontal cavernous ICA and/or lateral wall of the CS; 3) inferior parasellar ligament, bridging the medial wall to the anterior wall of the CS or anterior surface of the short vertical segment of the cavernous ICA; and 4) posterior parasellar ligament, which anchors the medial wall to the short vertical segment of the cavernous ICA and/or the posterior carotid sulcus. The caroticoclinoid ligament and inferior parasellar ligament were present in most CSs (97.7% and 95%, respectively), while the superior and posterior parasellar ligaments were identified in approximately half of the CSs (57.5% and 45%, respec- tively). The caroticoclinoid ligament was the strongest and largest ligament, and it was typically assembled as a group of ligaments with a fan-like arrangement. The inferior parasellar ligament was the first to be encountered after opening the anterior wall of the CS during an interdural transcavernous approach.

CONCLUSIONS The authors introduce a classification of the parasellar ligaments and their role in anchoring the medial wall of the CS. These ligaments should be identified and transected to safely mobilize the medial wall away from the cavernous ICA during a transcavernous approach and for safe and complete resection of adenomas that selectively invade the medial wall.

Posted on

Endoscopic clipping of intraventricular aneurysms using the “wet-field” technique

J Neurosurg 131:104–108, 2019

Intraventricular hemorrhage and intracerebral aneurysms are relatively frequent complications associated with moy- amoya disease. Prevention of aneurysm rerupture is important because it significantly decreases the morbidity and mortality rates. Aneurysms arising distal to collateral flow are sometimes observed in patients with intraventricular hem- orrhage; however, the treatment of these aneurysms remains challenging because of their deep-seated location in the brain and accompanying narrow surgical corridor.

The authors describe a neuroendoscopic aneurysm clipping technique performed in 2 cases using a small-diameter tubular retractor for intraventricular aneurysms of the distal lateral posterior choroidal artery. In this technique, the surgical field was continuously irrigated with artificial CSF to keep the ventricle size intact, and aneurysm clipping was performed through a tubular retractor that was introduced with neuronavigational guidance. The patients’ postoperative courses were uneventful, and CT angiography revealed complete clipping of the aneurysms and patent parent arteries.

Endoscopic clipping using a tubular retractor is an effective and less invasive alternative for treating intraventricular aneurysms. The wet-field endoscopic technique is performed in an aqueous field and maintains an intact ventricle size, allowing for a clear surgical view and a wider, enhanced surgical field.

 

Posted on

Endovascular Treatment of Ruptured Middle Cerebral Artery Aneurysms: A Single-Arm Meta-Analysis and Systematic Review

World Neurosurg. (2019) 127:559-566

The use of endovascular treatment for ruptured middle cerebral artery (MCA) aneurysms, which have been more likely to be recommended for neurosurgical clipping because of the complex anatomic configuration, remains controversial. In the present study, the angiographic and clinical outcomes of endovascularly treated ruptured MCA aneurysms were systematically reviewed.

METHODS: Online databases, including Cochrane, Medline, Web of Science, and Embase, were retrospectively and systematically searched. The primary outcomes were the immediate complete occlusion rate, mortality, complication- related mortality, and procedure-related complication rate. Meta-analysis was performed using a random or fixed effect model based on heterogeneity.

RESULTS: A total of 14 studies with 1004 ruptured MCA aneurysms were included. The procedure-related mortality rate at discharge was 1.8% (95% confidence interval [CI], 0.9%-2.7%; I2 = 0.0%; P = 0.623). The favorable clinical outcome rate at discharge was 65.4% (95% CI, 54.8%-76.0%; I2 = 94.2%; P < 0.001) and had progressively increased to 73.2% (95% CI, 59.9%-86.5%; I2 = 80.9%; P < 0.001). The overall complication rate was 22.7% (95% CI, 15.1%- 30.3%; I2 = 75.5%; P < 0.001).

CONCLUSION: Endovascular treatment of MCA aneurysms was related to a high incidence of procedure-related complications but a low rate of procedure-related mortality. The overall angiographic and clinical outcomes were comparable and warrant further investigation comparing clipping versus coiling for ruptured MCA aneurysms.

Posted on

Need for arthrodesis following facetectomy for spinal peripheral nerve sheath tumors

J Neurosurg Spine 31:112–122, 2019

Spinal peripheral nerve sheath tumors (PNSTs) are a group of rare tumors originating from the nerve and its supporting structures. Standard surgical management typically entails laminectomy with or without facetectomy to gain adequate tumor exposure. Arthrodesis is occasionally performed to maintain spinal stability and mitigate the risk of postoperative deformity, pain, or neurological deficit. However, the factors associated with the need for instrumentation in addition to PNST resection in the same setting remain unclear.

METHODS An institutional tumor registry at a tertiary care center was queried for patients treated surgically for a primary diagnosis of spinal PNST between 2002 and 2016. An analysis focused on patients in whom a facetectomy was performed during the resection. The addition of arthrodesis at the index procedure comprised the primary outcome. The authors also recorded baseline demographics, tumor characteristics, and surgery-related variables. Logistic regression was used to identify factors associated with increased risk of fusion surgery.

RESULTS A total of 163 patients were identified, of which 56 (32 had facetectomy with fusion, 24 had facetectomy alone) were analyzed. The median age was 48 years, and 50% of the cohort was female. Age, sex, and race, as well as tumor histology and size, were evenly distributed between patients who received facetectomy alone and those who had facetectomy and fusion. On univariate analysis, total versus subtotal facetectomy (OR 9.0, 95% CI 2.01–64.2; p = 0.009) and cervicothoracic versus other spinal region (OR 9.0, 95% CI 1.51–172.9; p = 0.048) were significantly associated with increased odds of performing immediate fusion. On multivariable analysis, only the effect of total facetectomy remained statistically significant (OR 6.75, 95% CI 1.47–48.8; p = 0.025).

CONCLUSIONS The authors found that total facetectomy and cervicothoracic involvement may be highly associated with the need for concomitant arthrodesis at the time of index surgery. These findings may help surgeons to determine the best surgical planning for patients with PNST.

Posted on

Surgical or endovascular management of ruptured intracranial aneurysms: an agreement study

J Neurosurg 131:25–31, 2019

Ruptured intracranial aneurysms (RIAs) can be managed surgically or endovascularly. In this study, the authors aimed to measure the interobserver agreement in selecting the best management option for various patients with an RIA.

METHODS The authors constructed an electronic portfolio of 42 cases of RIA in which an angiographic image along with a brief clinical vignette for each patient were displayed. Undisclosed to the responders was that the RIAs had been categorized as International Subarachnoid Aneurysm Trial (ISAT) (small, anterior-circulation, non–middle cerebral artery location, n = 18) and non-ISAT (n = 22) aneurysms; the non-ISAT group also included 2 basilar apex aneurysms for which a high number of endovascular choices was expected. The portfolio was sent to 132 clinicians who manage pa- tients with RIAs and circulated to members of an American surgical association. Judges were asked to choose between surgical and endovascular management, to indicate their level of confidence in the choice of treatment on a quantitative 0–10 scale, and to determine whether they would include the patient in a randomized trial in which both treatments are compared. Eleven clinicians were asked to respond twice at least 1 month apart. Responses were analyzed using kappa statistics.

RESULTS Eighty-five clinicians (58 cerebrovascular surgeons, 21 interventional neuroradiologists, and 6 interventional neurologists) answered the questionnaire. Overall, endovascular management was chosen more frequently (n = 2136 [59.8%] of 3570 answers). The proportions of decisions to clip were significantly higher for non-ISAT (50.8%) than for ISAT (26.2%) aneurysms (p = 0.0003). Interjudge agreement was only fair (kappa 0.210, 95% CI 0.158–0.276) for all cases and judges, despite high confidence levels (mean score > 8 for all cases). Agreement was no better within sub- groups of clinicians with the same specialty, years of experience, or location of practice or across capability groups (ability to clip or coil, or both). When agreement was defined as > 80% of responders choosing the same option, agreement occurred for only 7 of 40 cases, all of which were ISAT aneurysms, for which coiling was preferred.

CONCLUSIONS Agreement between clinicians regarding the best management option was infrequent but centered around coiling for some ISAT aneurysms. Surgical clipping was chosen more frequently for non-ISAT aneurysms than for ISAT aneurysms. Patients with such an aneurysm might be candidates for inclusion in randomized trials.

Posted on

Amygdala and Hypothalamus: Historical Overview With Focus on Aggression

Neurosurgery, 85, 1: 11–30, 2019

Aggressiveness has a high prevalence in psychiatric patients and is a major health problem. Two brain areas involved in the neural network of aggressive behavior are the amygdala and the hypothalamus.

While pharmacological treatments are effective in most patients, some do not properly respond to conventional therapies and are considered medically refractory. In this population, surgical procedures (ie, stereotactic lesions and deep brain stimulation) have been performed in an attempt to improve symptomatology and quality of life.

Clinical results obtained after surgery are difficult to interpret, and the mechanisms responsible for postoperative reductions in aggressive behavior are unknown.

We review the rationale and neurobiological characteristics that may help to explain why functional neurosurgery has been proposed to control aggressive behavior.

Posted on

Cavernous angiomas: deconstructing a neurosurgical disease

J Neurosurg 131:1–13, 2019

Cavernous angioma (CA) is also known as cavernoma, cavernous hemangioma, and cerebral cavernous malformation (CCM) (National Library of Medicine Medical Subject heading unique ID D006392). In its sporadic form, CA occurs as a solitary hemorrhagic vascular lesion or as clustered lesions associated with a developmental venous anomaly. In its autosomal dominant familial form (Online Mendelian Inheritance in Man #116860), CA is caused by a heterozygous germ-line loss-of-function mutation in one of three genes—CCM1/KRIT1, CCM2/Malcavernin, and CCM3/PDCD10—causing multifocal lesions throughout the brain and spinal cord.

In this paper, the authors review the cardinal features of CA’s disease pathology and clinical radiological features. They summarize key aspects of CA’s natural history and broad elements of evidence-based management guidelines, including surgery. The authors also discuss evidence of similar genetic defects in sporadic and familial lesions, consequences of CCM gene loss in different tissues at various stages of development, and implications regarding the pathobiology of CAs.

The concept of CA with symptomatic hemorrhage (CASH) is presented as well as its relevance to clinical care and research in the field. Pathobiological mechanisms related to CA include inflammation and immune-mediated processes, angiogenesis and vascular permeability, microbiome driven factors, and lesional anticoagulant domains. These mechanisms have motivated the development of imaging and plasma biomarkers of relevant disease behavior and promising therapeutic targets.

The spectrum of discoveries about CA and their implications endorse CA as a paradigm for deconstructing a neurosurgical disease.

 

Posted on

Three-year results from a randomized trial of lumbar discectomy with annulus fibrosus occlusion in patients at high risk for reherniation

Acta Neurochirurgica (2019) 161:1389–1396

A larger defect in the annulus fibrosus following lumbar discectomy is a well-known risk factor for reherniation. Procedures intended to prevent reherniation by sealing or occluding the annular defect warrant study in high-risk patients. This study sought to determine 3-year results of lumbar discectomy with a bone-anchored annular closure device (ACD) or lumbar discectomy only (controls) in patients at high risk for reherniation.

Methods This multicenter randomized trial enrolled patients with sciatica due to lumbar intervertebral disc herniation who failed conservative treatment. Patients with large annular defects after lumbar limited microdiscectomy were intraoperatively randomly assigned to receive ACD or control. Clinical and imaging follow-up was performed at routine intervals over 3 years. Main outcomes included rate of reherniations, reoperations, and endplate changes; leg and back pain scores on a visual analogue scale; Oswestry Disability Index (ODI); Physical Component Summary (PCS) and Mental Component Summary (MCS) scores from the SF-36; and adverse events adjudicated by a data safety monitoring board.

Results Among 554 randomized patients, the modified intent-to-treat population consisted of 272 patients in which ACD implantation was attempted and 278 receiving control; device implantation was not attempted in 4 patients assigned to ACD. Outcomes at 3 years favored ACD for symptomatic reherniation (14.8% vs. 29.5%; P < 0.001), reoperation (11.0% vs. 19.3%; P = 0.007), leg pain (21 vs. 30; P < 0.01), back pain (23 vs. 30; P = 0.01), ODI (18 vs. 23; P = 0.02), PCS (47 vs. 44; P < 0.01), and MCS (52 vs. 49; P < 0.01). The frequency of all-cause serious adverse events was comparable between groups (42.3% vs. 44.5%; P = 0.61).

Conclusions The addition of a bone-anchored ACD in patients with large annular defects following lumbar discectomy reduces the risk of reherniation and reoperation, and has a similar safety profile over 3-year follow-up compared with lumbar limited discectomy only.

 

Posted on

The biophysical role of hemodynamics in the pathogenesis of cerebral aneurysm formation and rupture

Neurosurg Focus 47 (1):E11, 2019

The pathogenesis of intracranial aneurysms remains complex and multifactorial. While vascular, genetic, and epidemio- logical factors play a role, nascent aneurysm formation is believed to be induced by hemodynamic forces. Hemodynamic stresses and vascular insults lead to additional aneurysm and vessel remodeling. Advanced imaging techniques allow us to better define the roles of aneurysm and vessel morphology and hemodynamic parameters, such as wall shear stress, oscillatory shear index, and patterns of flow on aneurysm formation, growth, and rupture. While a complete understand- ing of the interplay between these hemodynamic variables remains elusive, the authors review the efforts that have been made over the past several decades in an attempt to elucidate the physical and biological interactions that govern aneurysm pathophysiology. Furthermore, the current clinical utility of hemodynamics in predicting aneurysm rupture is discussed.

Posted on

Numerical Analysis of Bifurcation Angles and Branch Patterns in Intracranial Aneurysm Formation

Neurosurgery 85 (1): E31–E39. 2019

Hemodynamic factors, especially wall shear stress (WSS), are generally thought to play an important role in intracranial aneurysm (IA) formation. IAs frequently occur at bifurcation apices, where the vessels are exposed to the impact of WSS.

OBJECTIVE: To elucidate the relationship between bifurcation geometry and WSS for IA formation.

METHODS: Twenty-one bifurcation models varying in branch angles and branch diameters were made with 3-dimensional computer-aided design software. In all models, the value of maximum WSS (WSSMAX), the area of high WSS (AREA), and the magnitude of wall shear force over AREA (|Fw |) were investigated by the steady-flow simulation of computational fluid dynamics.

RESULTS: On the basis of statistical analysis, WSSMAX tended to be high when the bifurcation angle and/or branch diameter was small. AREA and |F⃗ | significantly increase as the bifurcation and/or the branch angle became larger.

CONCLUSION: The magnitude of WSS strongly correlated with bifurcation geometry. In addition to high WSS, AREA and |F⃗ | were thought to affect IA formation. Observed bifurcation geometry may predict IA formation. Large branch angles and small branch may increase the risk of IA formation.

Posted on

Iterative Surgical Resections of Diffuse Glioma With Awake Mapping: How to Deal With Cortical Plasticity and Connectomal Constraints?

Neurosurgery 85(1):105–116. 2019

In diffuse glioma, a multistage approach with iterative tailored surgical resections can be considered.
OBJECTIVE: To compare results of iterative intrasurgical brain mappings to investigate the potential and limitation of neuroplasticity at the individual stage, and to highlight to what extent it can influence the therapeutic strategy.
METHODS: Glioma patients who underwent 2 consecutive awake surgeries with cortical and subcortical stimulation were classified into group 1 (n = 23) if cortical mappings exhibited high level of plasticity (displacement of ≥2 sites) or into group 2 (n = 19) with low level of plasticity.
RESULTS: Clinical characteristics did not differ significantly between both groups. The borders of the tumors were mostly sharp in group 1 (82.6%) and rather indistinct in group 2 (84.2%), (P = .00001). Tumor remnants were more often cortical (± subcortical) in group 1 (39.1%) and more often purely subcortical in group 2 (68.4%; P = .009). In group 1, the time needed to recover independence was significantly shorter at reoperation (37.6 h vs 78.3 h after the first surgery, P = .00003) while this difference was not significant in group 2. The iterative extents of resection (EOR) remain comparable in group 1 (94% vs 92%, P = .40) but were significantly smaller in group 2 at reoperation (94% vs 88%, P = .05).
CONCLUSION: More efficient plasticity mechanisms are facilitated by cortical tumors with sharp borders, are associated with an increase of EOR at reoperation and with earlier functional recovery. Tumoral invasion of the white matter tracts represents the main limitation of neuroplasticity: this connectomal constraint limits EOR during second surgery.

Posted on

Investigating the utility of intraoperative neurophysiological monitoring for anterior cervical discectomy and fusion: analysis of over 140,000 cases from the National (Nationwide) Inpatient Sample data set

J Neurosurg Spine 31:76–86, 2019

Intraoperative neurophysiological monitoring (IONM) is a useful adjunct in spine surgery, with proven benefit in scoliosis-correction surgery. However, its utility for anterior cervical discectomy and fusion (ACDF) is unclear, as there are few head-to-head comparisons of ACDF outcomes with and without the use of IONM. The authors sought to evaluate the impact of IONM on the safety and cost of ACDF.

METHODS This was a retrospective analysis of data from the National (Nationwide) Inpatient Sample of the Healthcare Cost and Utilization Project from 2009 to 2013. Patients with a primary procedure code for ACDF were identified, and diagnosis codes were searched to identify cases with postoperative neurological complications. The authors performed univariate and multivariate logistic regression for postoperative neurological complications with use of IONM as the in- dependent variable; additional covariates included age, sex, surgical indication, multilevel fusion, Charlson Comorbidity Index (CCI) score, and admission type. They also conducted propensity score matching in a 1:1 ratio (nearest neighbor) with the use of IONM as the treatment indicator and the aforementioned variables as covariates. In the propensity score–matched cohort, they compared neurological complications, length of stay (LOS), and hospital charges (in US dollars).

RESULTS A total of 141,007 ACDF operations were identified. IONM was used in 9540 cases (6.8%). No significant association was found between neurological complications and use of IONM on univariate analysis (OR 0.80, p = 0.39) or multivariate regression (OR 0.82, p = 0.45). By contrast, age ≥ 65 years, multilevel fusion, CCI score > 0, and a non- elective admission were associated with greater incidence of neurological complication. The propensity score–matched cohort consisted of 18,760 patients who underwent ACDF with (n = 9380) or without (n = 9380) IONM. Rates of neurological complication were comparable between IONM and non-IONM (0.17% vs 0.22%, p = 0.41) groups. IONM and non-IONM groups had a comparable proportion of patients with LOS ≥ 2 days (19% vs 18%, p = 0.15). The use of IONM was associated with an additional $6843 (p < 0.01) in hospital charges.

CONCLUSIONS The use of IONM was not associated with a reduced rate of neurological complications following ACDF. Limitations of the data source precluded a specific assessment of the effectiveness of IONM in preventing neuro- logical complications in patients with more complex pathology (i.e., ossification of the posterior longitudinal ligament or cervical deformity).

Posted on

Ruptured PICA aneurysms: presentation and treatment outcomes compared to other posterior circulation aneurysms

Acta Neurochirurgica (2019) 161:1325–1334

Aneurysms of the posterior inferior cerebellar artery (PICA) are relatively uncommon and evidence is sparse about patients presenting with ruptured PICA aneurysms. We performed an analysis of the Swiss SOS national registry to describe clinical presentation, treatment pattern, and neurological outcome of patients with ruptured PICA aneurysms compared with other ruptured posterior circulation (PC) aneurysms.

Methods This was a retrospective analysis of anonymized data from the Swiss SOS registry (Swiss Study on Aneurysmal Subarachnoid Hemorrhage; 2009–2014). Patients with ruptured PC aneurysms were subdivided into a PICA and non-PICA group. Clinical, radiological, and treatment-related variables were identified, and their impact on the neurological outcome was determined in terms of modified Rankin score at discharge and at 1 year of follow-up for the two groups.

Results Data from 1864 aneurysmal subarachnoid hemorrhage patients were reviewed. There were 264 patients with a ruptured PC aneurysm. Seventy-four PICA aneurysms represented 28% of the series; clinical and radiological characteristics at admission were comparable between the PICA and non-PICA group. Surgical treatment was accomplished in 28% of patients in the PICA group and in the 4.8% of patients in the non-PICA group. No statistically significant difference was found between the two groups in terms of complications after treatment. Hydrocephalus requiring definitive shunt was needed in 21.6% of PICA patients (p = 0.6); cranial nerve deficit was present in average a quarter of the patients in both PICA and non-PICA group with no statistical difference (p = 0.3). A more favorable outcome (66.2%) was reported in the PICA group at discharge (p < 0.05) but this difference faded over time with a similar neurological outcome at 1-year follow-up (p = 0.09) between both PICA and non- PICA group. The Kaplan-Meyer estimation showed no significant difference in the mortality rate between both groups (p = 0.08).

Conclusions In the present study, patients with ruptured PICA aneurysms had a favorable neurological outcome in more than two thirds of cases, similar to patients with other ruptured PC aneurysms. Surgical treatment remains a valid option in a third of cases with ruptured PICA aneurysms.

Proudly powered by WordPress