Author: cba

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Perioperative Outcomes in Intracranial Pleomorphic Xanthoastrocytoma

Neurosurgery 80:105–111, 2017

Patients with pleomorphic xanthoastrocytoma (PXA) routinely undergo multiple procedures to ensure recurrence-free survival and are resultantly at increased risk of experiencing perioperative complications (regional, medical, and/or neurological), a combination of which has not been recorded in previous studies.

OBJECTIVE: To determine perioperative outcomes in a cohort of patients (adult and pediatric) with intracranial PXA.

METHODS: We retrospectively identified 39 patients who underwent surgery at our insti- tution for intracranial PXA between 1994 and 2011. Demographic factors were recorded along with Karnofsky Performance Status (KPS), complications, and mortality.

RESULTS: Mean patient age was 31 years at the most recent surgery. A majority of patients (24; 62%) had multiple surgeries with a mean of 2 operations per patient. Eleven PXAs (28%) were malignant (grade III or IV). Perioperative complications included permanent neurological worsening in 4 patients (10%), regional complications in 4 (10%), and medical complications in 3 (8%). Preoperative KPS was ≥70 in 34 of 38 patients (89%). Long- term postoperative KPS was ≥70 in 36 of 37 patients (97%), suggesting good functional outcomes. There was no perioperative mortality, but 7 patients (18%) died of tumor progression. Patients with malignant PXAs trended toward higher risk of regional compli- cations (3 of 11 patients [27%]; P = .06), received adjuvant therapy more often (10 of 11 patients [91%]; P < .001), had higher mortality from tumor progression (7 of 11 patients [64%]; P < .001), and were significantly larger (mean, 6.05 ± 0.73 cm standard error of the mean; n = 7; P < .01).

CONCLUSION: Both pediatric and adult PXAs may be resected with good functional outcomes. Perioperative neurological complications are relatively common, but do not affect long-term functional outcome or mortality. Malignant PXAs are higher risk for perioperative complications and, ultimately, death from tumor progression, despite increased use of adjuvant radiation and chemotherapy.

 

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A prospective randomized multicenter phase I/II clinical trial to evaluate safety and efficacy of NOVOCART disk plus autologous disk chondrocyte transplantation in the treatment of nucleotomized and degenerative lumbar disks to avoid secondary disease

Neurosurg Rev (2017) 40:155–162

NOVOCART ® Disk plus, an autologous cell compound for autologous disk chondrocyte transplantation, was developed to reduce the degenerative sequel after lumbar disk surgery or to prophylactically avoid degeneration in adjacent disks, if present. The NDisc trial is an on-going multi-center, randomized study with a sequential phase I study within the combined phase I/II trial with close monitoring of tolerability and safety.

Twenty-four adult patients were randomized and treated with the investigational medicinal product NDisc plus or the carrier material only. Rates of adverse events in Phase I of this trial were comparable with those expected in the early time course after elective disk surgery. There was one reherniation 7 months after transplantation, which corresponds to an expected reherniation rate. Immunological markers like CRP and IL-6 were not significantly elevated and there were no im- aging abnormalities. No indications of harmful material extrusion or immunological consequences due to the investigational medicinal product NDplus were observed.

Therefore, the study appears to be safe and feasible. Safety analyses of Phase I of this trial indicate a relatively low risk considering the benefits that patients with debilitating degenerative disk disease may gain.

 

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Agents for fluorescence-guided glioma surgery: a systematic review of preclinical and clinical results

Acta Neurochir (2017) 159:151–167

Fluorescence-guided surgery (FGS) is a technique used to enhance visualization of tumor margins in order to increase the extent of tumor resection in glioma surgery. In this paper, we systematically review all clinically tested fluorescent agents for application in FGS for glioma and all pre-clinically tested agents with the potential for FGS for glioma.

Methods: We searched the PubMed and Embase databases for all potentially relevant studies through March 2016. We assessed fluorescent agents by the following outcomes: rate of gross total resection (GTR), overall and progression-free survival, sensitivity and specificity in discriminating tumor and healthy brain tissue, tumor-to-normal ratio of fluorescent signal, and incidence of adverse events.

Results: The search strategy resulted in 2155 articles that were screened by titles and abstracts. After full-text screening, 105 articles fulfilled the inclusion criteria evaluating the following fluorescent agents: 5-aminolevulinic acid (5-ALA) (44 studies, including three randomized control trials), fluorescein (11), indocyanine green (five), hypericin (two), 5- aminofluorescein-human serum albumin (one), endogenous fluorophores (nine) and fluorescent agents in a pre-clinical testing phase (30). Three meta-analyses were also identified.

Conclusions: 5-ALA is the only fluorescent agent that has been tested in a randomized controlled trial and results in an improvement of GTR and progression-free survival in high-grade gliomas. Observational cohort studies and case series suggest similar outcomes for FGS using fluorescein. Molecular targeting agents (e.g., fluorophore/nanoparticle labeled with anti-EGFR antibodies) are still in the pre-clinical phase, but offer promising results and may be valuable future alternatives.

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Quantitative analysis of the trajectory of simulated basilar apex aneurysms through the internal carotid artery to assess the need for an orbitozygomatic approach

Acta Neurochir (2017) 159:85–92

The aim of this study was to identify the correlation between the location of the internal carotid artery (ICA) and the need for an orbitozygomatic approach (OZA) when approaching a basilar apex (BX) aneurysm.

Materials and methods: By imaging the virtual trajectory to access the basilar artery (BA) through the ICA, the correla- tions among the height of the BX, the height and lateral breadth of the bifurcation of the ICA, and the need for removal of the orbital rim or zygomatic arch were investigated using three-dimensional computed tomography angiography (3DCTA) data of approximately 80 random samples not lim- ited to BX aneurysms. Furthermore, the utility of 3D simula- tion to determine the need for the OZA was verified using data from five patients with BX aneurysms.

Results: The height of the bifurcation of the ICA was inversely correlated and the height of the BX was positively correlated with the need for the OZA (both p < 0.017). Among patients undergoing surgery, clipping was successfully performed without the OZA in two patients in whom the distance from the simulated skull point on the extended line from the BX through the bifurcation of the ICA was more than 4 cm from the zygoma and orbital rim.

Conclusions: It is necessary to determine the spatial relationship between the basilar artery and the ICA to decide whether the OZA is needed for surgery. Correlations of the height of the ICA and BX with the need for the OZA were not very strong individually, though they were significant. Therefore, simulation using 3DCTA appears to be important for planning the surgical approach for the treatment of BX aneurysms.

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Walking assessment after lumbar puncture in normal-pressure hydrocephalus: a delayed improvement over 3 days

J Neurosur (126) 148-157, 2017

The determination of gait improvement after lumbar puncture (LP) in idiopathic normal-pressure hydrocephalus (iNPH) is crucial, but the best time for such an assessment is unclear. The authors determined the time course of improvement in walking after LP for single-task and dual-task walking in iNPH.

METHODS: In patients with iNPH, sequential recordings of gait velocity were obtained prior to LP (time point [TP]0), 1–8 hours after LP (TP1), 24 hours after LP (TP2), 48 hours after LP (TP3), and 72 hours after LP (TP4). Gait analysis was performed using a pressure-sensitive carpet (GAITRite) under 4 conditions: walking at preferred velocity (STPS), walking at maximal velocity (STMS), walking while performing serial 7 subtractions (dual-task walking with serial 7 [DTS7]), and walking while performing verbal fluency tasks (dual-task walking with verbal fluency [DTVF]).

RESULTS: Twenty-four patients with a mean age of 76.1 ± 7.8 years were included in this study. Objective responder status moderately coincided with the self-estimation of the patients with subjective high false-positive results (83%). The extent of improvement was greater for single-task walking than for dual-task walking (p < 0.05). Significant increases in walking speed were found at TP2 for STPS (p = 0.042) and DTVF (p = 0.046) and at TP3 for STPS (p = 0.035), DTS7 (p = 0.042), and DTVF (p = 0.044). Enlargement of the ventricles (Evans Index) positively correlated with early improvement. Gait improvement at TP3 correlated with the shunt response in 18 patients.

CONCLUSIONS: Quantitative gait assessment in iNPH is important due to the poor self-evaluation of the patients. The maximal increase in gait velocity can be observed 24–48 hours after the LP. This time point is also best to predict the response to shunting. For dual-task paradigms, maximal improvement appears to occur later (48 to 72 hours). Assessment of gait should be performed at Day 2 or 3 after LP.

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Surgical treatment of long-standing overt ventriculomegaly in adults (LOVA)

Acta Neurochir (2017) 159:71–79

Longstanding overt ventriculomegaly in adults (LOVA) is characterised by chronic hydrocephalus presumed to begin during infancy, but arresting before becoming clinically detectable. Later in life clinical features of hydrocephalus ensue, typically in the 5th or 6th decades. Only a relatively small number of LOVA case series have been published, and ambiguity remains regarding optimal management. This case series describes a series of patients with LOVA treated successfully at a single neurosurgical institution using endoscopic third ventriculostomy (ETV).

Methods: A series of 14 patients were diagnosed with LOVA using established clinical and radiological criteria. All patients underwent an ETV and their clinical conditions were followed up for up to 5 years post-operatively.

Results: Fourteen patients (100 %) reported either improvement or halt of progression in their presenting symptoms 3 months after ETV; 93 % of patients (n = 13) did not require any further surgical intervention. One patient (7 %) reported deterioration in symptoms beyond 3 months post-operatively, which necessitated further surgery (ventriculoperitoneal shunt). These promising outcomes after ETV are mirrored in numerous other LOVA case series. Other works have analysed the value of CSF shunting procedures in LOVA, with mixed results. A direct, prospective comparison of outcomes after shunt procedures and ETV, with a specific focus on LOVA patients, is yet to be completed. A minority of patients fail to respond, or develop recurrence of symptoms, months or years after initial surgical intervention.

Conclusions: ETV is an attractive option for surgical treatment of LOVA. After surgical treatment for LOVA, long-term follow-up should be considered to screen for late recurrence of the condition.

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The Relationship Between Preoperative Clinical Presentation and Quantitative Magnetic Resonance Imaging Features in Patients With Degenerative Cervical Myelopathy

Neurosurgery 80:121–128, 2017

Degenerative cervical myelopathy encompasses a group of conditions resulting in progressive spinal cord injury through static and dynamic compression. Although a constellation of changes can present on magnetic resonance imaging (MRI), the clinical significance of these findings remains a subject of controversy and discussion.

OBJECTIVE: To investigate the relationship between clinical presentation and quantitative MRI features in patients with degenerative cervical myelopathy.

METHODS: A secondary analysis of MRI and clinical data from 114 patients enrolled in a prospective, multicenter study was conducted. MRIs were assessed for maximum spinal cord compression (MSCC), maximum canal compromise (MCC), signal changes, and a signal change ratio (SCR). MRI features were compared between patients with and those without myelopathy symptoms with the use of t tests. Correlations between MRI features and duration of symptoms were assessed with the Spearman ρ.

RESULTS: Numb hands and Hoffmann sign were associated with greater MSCC (P < .05); broad-based, unstable gait, impairment of gait, and Hoffmann sign were associated with greaterMCC (P<.05); andnumbhands,Hoffmann sign, Babinski sign, lower limb spasticity, hyperreflexia, and T1 hypointensitywere associated with greater SCR (P<.05). Patientswith a T2 signal hyperintensity had greater MSCC and MCC (P < .001).

CONCLUSION: MSCC was associated with upper limb manifestations, and SCR was associated with upper limb, lower limb, and general neurological deficits. Hoffmann sign occurred more commonly in patients with a greater MSCC,MCC and SCR. The Lhermitte phenomenon presented more commonly in patientswith a lower SCR and may be an early indicator of mild spinal cord involvement. Research to validate these findings is required.

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Associations of intracranial pressure with brain biopsy, radiological findings, and shunt surgery outcome in patients with suspected idiopathic normal pressure hydrocephalus

Acta Neurochir (2017) 159: 51-61

It remains unclear how intracranial pressure (ICP) measures are associated with brain biopsies and radiological markers. Here, we aim to investigate associations between ICP and radiological findings, brain biopsies, and shunt surgery outcome in patients with suspected idiopathic normal pressure hydrocephalus (iNPH).

Method

In this study, we retrospectively analyzed data from 73 patients admitted with suspected iNPH to Kuopio University Hospital. Of these patients, 71% underwent shunt surgery. The NPH registry included data on clinical and radiological examinations, 24-h intraventricular pressure monitoring, and frontal cortical biopsy.

Results

The mean ICP and mean ICP pulse wave amplitude were not associated with the shunt response. Aggregations of Alzheimer’s disease (AD)-related proteins (amyloid-β, hyperphosphorylated tau) in frontal cortical biopsies were associated with a poor shunt response (P = 0.014). High mean ICP was associated with Evans’ index (EI; P = 0.025), disproportional sylvian and suprasylvian subarachnoid spaces (P = 0.014), and focally dilated sulci (P = 0.047). Interestingly, a high pulse wave amplitude was associated with AD-related biopsy findings (P = 0.032), but the mean ICP was not associated with the brain biopsy. The ICP was not associated with medial temporal lobe atrophy, temporal horn widths, or white matter changes. ICP B waves were associated with less atrophy of the medial temporal lobe (P = 0.018) and more severe disproportionality between the sylvian and suprasylvian subarachnoid spaces (P = 0.001).

Conclusions

The EI and disproportional sylvian and suprasylvian subarachnoid spaces were associated with mean ICP. Disproportionality was also associated with ICP B waves. These associations, although rather weak, with elevated ICP in 24-h measurements, support their value in iNPH diagnostics and suggest that these radiological markers are potentially related to the pathogenesis of iNPH. Interestingly, our results suggested that elevated pulse wave amplitude might be associated with brain amyloid accumulation.

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Deadly falls: operative versus nonoperative management of Type II odontoid process fracture in octogenarians

Journal of Neurosurgery: Spine – 26(1): 4-9

Type II odontoid fracture is a common injury among elderly patients, particularly given their predisposition toward low-energy falls. Previous studies have demonstrated a survival advantage following early surgery among patients older than 65 years, yet octogenarians represent a medically distinct and rapidly growing population. The authors compared operative and nonoperative management in patients older than 79 years.

METHODS  A single-center prospectively maintained trauma database was reviewed using ICD-9 codes to identify octogenarians with C-2 cervical fractures between 1998 and 2014. Cervical CT images were independently reviewed by blinded neurosurgeons to confirm a Type II fracture pattern. Prospectively recorded outcomes included Glasgow Coma Scale (GCS) score, Abbreviated Injury Scale (AIS) score, Injury Severity Score (ISS), additional cervical fracture, and cord injury. Primary end points were mortality at 30 days and at 1 year. Statistical tests included the Student t-test, chi-square test, Fisher’s exact test, Kaplan-Meier test, and Cox proportional hazard.

RESULTS  A total of 111 patients met inclusion criteria (94 nonoperative and 17 operative [15 posterior and 2 anterior]). Mortality data were available for 100% of patients. The mean age was 87 years (range 80–104 years). Additional cervical fracture, spinal cord injury, GCS score, AIS score, and ISS were not associated with either management strategy at the time of presentation. The mean time to death or last follow-up was 22 months (range 0–129 months) and was nonsignificant between operative and nonoperative groups (p = 0.3). Overall mortality was 13% in-hospital, 26% at 30 days, and 41% at 1 year. Nonoperative and operative mortality rates were not significant at any time point (12% vs 18%, p = 0.5 [in-hospital]; 27% vs 24%, p = 0.8 [30-day]; and 41% vs 41%, p = 1.0 [1-year]). Kaplan-Meier analysis did not demonstrate a survival advantage for either management strategy. Spinal cord injury, GCS score, AIS score, and ISS were significantly associated with 30-day and 1-year mortality; however, Cox modeling was not significant for any variable. Additional cervical fracture was not associated with increased mortality. The rate of nonhome disposition was not significant between the groups.

CONCLUSIONS  Type II odontoid fracture is associated with high morbidity among octogenarians, with 41% 1-year mortality independent of intervention—a dramatic decrease from actuarial survival rates for all 80-, 90-, and 100-year-old Americans. Poor outcome is associated with spinal cord injury, GCS score, AIS score, and ISS.

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The ‘Lumbar Fusion Outcome Score’ (LUFOS): a new practical and surgically oriented grading system for preoperative prediction of surgical outcomes after lumbar spinal fusion in patients with degenerative disc disease and refractory chronic axial low back pain

Neurosurg Review (40) pp 67–81, 2017

In order to evaluate the predictive effect of non-invasive preoperative imaging methods on surgical outcomes of lumbar fusion for patients with degenerative disc disease (DDD) and refractory chronic axial low back pain (LBP), the authors conducted a retrospective review of 45 patients with DDD and refractory LBP submitted to anterior lumbar interbody fusion (ALIF) at a single center from 2007 to 2010.

Surgical outcomes – as measured by Visual Analog Scale (VAS/back pain) and Oswestry Disability Index (ODI) – were evaluated pre-operatively and at 6 weeks, 3 months, 6 months, and 1 year post-operatively. Linear mixed-effects models were generated in order to identify possible preoperative imaging characteristics (including bone scan/99mTc scintigraphy increased endplate uptake, Modic endplate changes, and disc degeneration graded according to Pfirrmann classification) which may be predictive of long-term surgical outcomes .

After controlling for confounders, a combined score, the Lumbar Fusion Outcome Score (LUFOS), was developed. The LUFOS grading system was able to stratify patients in two general groups (Non-surgical: LUFOS 0 and 1; Surgical: LUFOS 2 and 3) that presented significantly different surgical outcomes in terms of estimated marginal means of VAS/back pain (p = 0.001) and ODI (p = 0.006) beginning at 3 months and continuing up to 1 year of follow-up.

In conclusion, LUFOS has been devised as a new practical and surgically oriented grading system based on simple key parameters from non-invasive preoperative imaging exams (magnetic resonance imaging/MRI and bone scan/99mTc scintigraphy) which has been shown to be highly predictive of surgical outcomes of patients undergoing lumbar fusion for treatment for refractory chronic axial LBP.

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Efficacy, complications and cost of surgical interventions for idiopathic intracranial hypertension: a systematic review of the literature

Acta Neurochirurgica 2017 (159) 33–49

To define the efficacy, complication profile and cost of surgical options for treating idiopathic intracranial hypertension (IIH) with respect to the following endpoints: vision and headache improvement, normal CSF pressure restoration, papilloedema resolution, relapse rate, operative complications, cost of intervention and quality of life.

Methods

A systematic review of the surgical treatment of IIH was carried out. Cochrane Library, MEDLINE and EMBASE databases were systematically searched from 1985 to 2014 to identify all relevant manuscripts written in English. Additional studies were identified by searching the references of retrieved papers and relative narrative reviews.

Results

Forty-one (41) studies were included (36 case series and 5 case reports), totalling 728 patients. Three hundred forty-one patients were treated with optic nerve sheath fenestration (ONSF), 128 patients with lumboperitoneal shunting (LPS), 72 patients with ventriculoperitoneal shunting (VPS), 155 patients with venous sinus stenting and 32 patients with bariatric surgery. ONSF showed considerable efficacy in vision improvement, while CSF shunting had a superior headache response. Venous sinus stenting demonstrated satisfactory results in both vision and headache improvement along with the best complication profile and low relapse rate, but longer follow-up periods are needed. The complication rate of bariatric surgery was high when compared to other interventions and visual outcomes have not been reported adequately. ONSF had the lowest cost.

Conclusions

No surgical modality proved to be clearly superior to any other in IIH management. However, in certain contexts, a given approach appears more justified. Therefore, a treatment algorithm has been formulated, based on the extracted evidence of this review. The traditional treatment paradigm may need to be re-examined with sinus stenting as a first-line treatment modality.

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Comparing clinical outcomes of repeat discectomy versus fusion for recurrent disc herniation utilizing the N2QOD

J Neurosurg Spine 26:39–44, 2017

Recurrent lumbar disc herniation (RLDH) is a significant cause of morbidity in patients undergoing lumbar discectomy and has been reported to occur in up to 18% of cases. While repeat discectomy is often successful in treating these patients, concern over repeat RLDH may lead surgeons to advocate instrumented fusion even in the absence of instability. The authors’ goal was to compare clinical outcomes for patients undergoing repeat discectomy versus instrumented fusion for RLDH.

Methods The authors used the National Neurosurgery Quality and Outcomes Database (N2QOD) to assess outcomes of patients who underwent repeat discectomy versus instrumented fusion at a single institution from 2012 to 2015. Primary outcomes included Oswestry Disability Index (ODI) score, visual analog scale (VAS) score, and quality-adjusted life year (QALY) measures. Secondary outcomes included hospital length of stay, discharge status, and hospital charges.

Results The authors identified 25 repeat discectomy and 12 instrumented fusion patients with 3- and 12-month follow-up records. The groups had similar ODI and VAS scores and QALY measurements at 3 and 12 months. Patients in the instrumented fusion group had significantly longer hospitalizations (3.7 days vs 1.0 days, p < 0.001) and operative times (229.6 minutes vs 82.7 minutes, p < 0.001). They were also more likely to be female (p = 0.020) and to be discharged to inpatient rehabilitation instead of home (p = 0.036). Hospital charges for the instrumented fusion group were also significantly higher ($54,458.29 vs $11,567.05, p < 0.001). Rates of reoperation were higher in the repeat discectomy group (12% vs 0%), but the difference was not statistically significant (p = 0.211).

Conclusions Repeat discectomy and instrumented fusion result in similar clinical outcomes at short-term follow-up. Patients undergoing repeat discectomy had significantly shorter operative times and length of stay, and they incurred dramatically lower hospital charges. They were also less likely to require acute rehabilitation postoperatively. Further research is needed to compare these two management strategies.

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A randomized controlled trial comparing autologous cranioplasty with custom-made titanium cranioplasty

J Neurosurg 126:81–90, 2017

Autologous bone is usually used to reconstruct skull defects following decompressive surgery. However, it is associated with a high failure rate due to infection and resorption. The aim of this study was to see whether it would be cost-effective to use titanium as a primary reconstructive material.

Methods Sixty-four patients were enrolled and randomized to receive either their own bone or a primary titanium cranioplasty. All surgical procedures were performed by the senior surgeon. Primary and secondary outcome measures were assessed at 1 year after cranioplasty.

Results There were no primary infections in either arm of the trial. There was one secondary infection of a titanium cranioplasty that had replaced a resorbed autologous cranioplasty. In the titanium group, no patient was considered to have partial or complete cranioplasty failure at 12 months of follow-up (p = 0.002) and none needed revision (p = 0.053). There were 2 deaths unrelated to the cranioplasty, one in each arm of the trial. Among the 31 patients who had an autologous cranioplasty, 7 patients (22%) had complete resorption of the autologous bone such that it was deemed a complete failure. Partial or complete autologous bone resorption appeared to be more common among young patients than older patients (32 vs 45 years old, p = 0.013). The total cumulative cost between the 2 groups was not significantly different (mean difference A$3281, 95% CI $-9869 to $3308; p = 0.327).

Conclusions Primary titanium cranioplasty should be seriously considered for young patients who require reconstruction of the skull vault following decompressive craniectomy. Clinical trial registration no.: ACTRN12612000353897 (anzctr.org.au)

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Image-guided resection of aggressive sacral tumors

Neurosurg Focus 42 (1):E15, 2017

The aim of this study was to identify and discuss operative nuances utilizing image guidance in the surgical management of aggressive sacral tumors.

Methods: The authors report on their single-institution, multi-surgeon, retrospective case series involving patients with pathology-proven aggressive sacral tumors treated between 2009 and 2016. They also reviewed the literature to identify articles related to aggressive sacral tumors, their diagnosis, and their surgical treatment and discuss the results together with their own experience. Information, including background, imaging, treatment, and surgical pearls, is organized by tumor type.

Results: Review of the institutional records identified 6 patients with sacral tumors who underwent surgery between 2009 and 2016. All 6 patients were treated with image-guided surgery using cone-beam CT technology (O-arm). The surgical technique used is described in detail, and 2 illustrative cases are presented. From the literature, the authors compiled information about chordomas, chondrosarcomas, giant cell tumors, and osteosarcomas and organized it by tumor type, providing a detailed discussion of background, imaging, and treatment as well as surgical pearls for each tumor type.

Conclusions: Aggressive sacral tumors can be an extremely difficult challenge for both the patient and the treating physician. The selected surgical intervention varies depending on the type of tumor, size, and location. Surgery can have profound risks including neural compression, lumbopelvic instability, and suboptimal oncological resection. Focusing on the operative nuances for each type can help prevent many of these complications. Anecdotal evidence is provided that utilization of image-guided surgery to aid in tumor resection at our institution has helped reduce blood loss and the local recurrence rate while preserving function in both malignant and aggressive benign tumors affecting the sacrum.

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Passive language mapping combining real-time oscillation analysis with cortico-cortical evoked potentials for awake craniotomy

J Neurosurg 125:1580–1588, 2016

Electrocortical stimulation (ECS) is the gold standard for functional brain mapping; however, precise functional mapping is still difficult in patients with language deficits. High gamma activity (HGA) between 80 and 140 Hz on electrocorticography is assumed to reflect localized cortical processing, whereas the cortico-cortical evoked potential (CCEP) can reflect bidirectional responses evoked by monophasic pulse stimuli to the language cortices when there is no patient cooperation. The authors propose the use of “passive” mapping by combining HGA mapping and CCEP recording without active tasks during conscious resections of brain tumors.

Methods Five patients, each with an intraaxial tumor in their dominant hemisphere, underwent conscious resection of their lesion with passive mapping. The authors performed functional localization for the receptive language area, using real-time HGA mapping, by listening passively to linguistic sounds. Furthermore, single electrical pulses were delivered to the identified receptive temporal language area to detect CCEPs in the frontal lobe. All mapping results were validated by ECS, and the sensitivity and specificity were evaluated.

Results Linguistic HGA mapping quickly identified the language area in the temporal lobe. Electrical stimulation by linguistic HGA mapping to the identified temporal receptive language area evoked CCEPs on the frontal lobe. The combination of linguistic HGA and frontal CCEPs needed no patient cooperation or effort. In this small case series, the sensitivity and specificity were 93.8% and 89%, respectively.

Conclusions The described technique allows for simple and quick functional brain mapping with higher sensitivity and specificity than ECS mapping. The authors believe that this could improve the reliability of functional brain mapping and facilitate rational and objective operations. Passive mapping also sheds light on the underlying physiological mechanisms of language in the human brain.

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Natural history of colloid cysts of the third ventricle

J Neurosurg 125:1420–1430, 2016

Colloid cysts are rare, histologically benign lesions that may result in obstructive hydrocephalus and death. Understanding the natural history of colloid cysts has been challenging given their low incidence and the small number of cases in most reported series. This has complicated efforts to establish reliable prognostic factors and surgical indications, particularly for asymptomatic patients with incidental lesions. Risk factors for obstructive hydrocephalus in the setting of colloid cysts remain poorly defined, and there are no grading scales on which to develop standard management strategies.

Methods The authors performed a single-center retrospective review of all cases of colloid cysts of the third ventricle treated over nearly 2 decades at Washington University. Univariate analysis was used to identify clinical, imaging, and anatomical factors associated with 2 outcome variables: symptomatic clinical status and presentation with obstructive hydrocephalus. A risk-prediction model was defined using bootstrapped logistic regression. Predictive factors were then combined into a simple 5-point clinical scale referred to as the Colloid Cyst Risk Score (CCRS), and this was evaluated with receiver-operator characteristics.

Results The study included 163 colloid cysts, more than half of which were discovered incidentally. More than half of the incidental cysts (58%) were followed with surveillance neuroimaging (mean follow-up 5.1 years). Five patients with incidental cysts (8.8%) progressed and underwent resection. No patient with an incidental, asymptomatic colloid cyst experienced acute obstructive hydrocephalus or sudden neurological deterioration in the absence of antecedent trauma. Nearly half (46.2%) of symptomatic patients presented with hydrocephalus. Eight patients (12.3%) presented acutely, and there were 2 deaths due to obstructive hydrocephalus and herniation. The authors identified several factors that were strongly correlated with the 2 outcome variables and defined third ventricle risk zones where colloid cysts can cause obstructive hydrocephalus. No patient with a lesion outside these risk zones presented with obstructive hydrocephalus. The CCRS had significant predictive capacity for symptomatic clinical status (area under the curve [AUC] 0.917) and obstructive hydrocephalus (AUC 0.845). A CCRS ≥ 4 was significantly associated with obstructive hydrocephalus (p < 0.0001, RR 19.4).

Conclusions Patients with incidentally discovered colloid cysts can experience both lesion enlargement and symptom progression or less commonly, contraction and symptom regression. Incidental lesions rarely cause acute obstructive hydrocephalus or sudden neurological deterioration in the absence of antecedent trauma. Nearly one-half of patients with symptomatic colloid cysts present with obstructive hydrocephalus, which has an associated 3.1% risk of death. The CCRS is a simple 5-point clinical tool that can be used to identify symptomatic lesions and stratify the risk of obstructive hydrocephalus. External validation of the CCRS will be necessary before objective surgical indications can be established. Surgical intervention should be considered for all patients with CCRS ≥ 4, as they represent the high-risk subgroup.

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Lateral interbody fusion combined with open posterior surgery for adult spinal deformity

J Neurosurg Spine 25:697–705, 2016

Lateral interbody fusion (LIF) with percutaneous screw fixation can treat adult spinal deformity (ASD) in the coronal plane, but sagittal correction is limited. The authors combined LIF with open posterior (OP) surgery using facet osteotomies and a rod-cantilever technique to enhance lumbar lordosis (LL). It is unclear how this hybrid strategy compares to OP surgery alone. The goal of this study was to evaluate the combination of LIF and OP surgery (LIF+OP) for ASD.

Methods All thoracolumbar ASD cases from 2009 to 2014 were reviewed. Patients with < 6 months follow-up, prior fusion, severe sagittal imbalance (sagittal vertical axis > 200 mm or pelvic incidence-LL > 40°), and those undergoing anterior lumbar interbody fusion were excluded. Deformity correction, complications, and outcomes were compared between LIF+OP and OP-only surgery patients.

Results LIF+OP (n = 32) and OP-only patients (n = 60) had similar baseline features and posterior fusion levels. On average, 3.8 LIFs were performed. Patients who underwent LIF+OP had less blood loss (1129 vs 1833 ml, p = 0.016) and lower durotomy rates (0% vs 23%, p = 0.002). Patients in the LIF+OP group required less ICU care (0.7 vs 2.8 days, p < 0.001) and inpatient rehabilitation (63% vs 87%, p = 0.015). The incidence of new leg pain, numbness, or weakness was similar between groups (28% vs 22%, p = 0.609). All leg symptoms resolved within 6 months, except in 1 OP-only patient. Follow-up duration was similar (28 vs 25 months, p = 0.462). LIF+OP patients had significantly less pseudarthrosis (6% vs 27%, p = 0.026) and greater improvement in visual analog scale back pain (mean decrease 4.0 vs 1.9, p = 0.046) and Oswestry Disability Index (mean decrease 21 vs 12, p = 0.035) scores. Lumbar coronal correction was greater with LIF+OP surgery (mean [± SD] 22° ± 13° vs 14° ± 13°, p = 0.010). LL restoration was 22° ± 13°, intermediately between OP-only with facet osteotomies (11° ± 7°, p < 0.001) and pedicle subtraction osteotomy (29° ± 10°, p = 0.045).

Conclusions LIF+OP is an effective strategy for ASD of moderate severity. Compared with the authors’ OP-only operations, LIF+OP was associated with faster recovery, fewer complications, and greater relief of pain and disability.

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Fractal Analysis for the Differentiation of Brain Tumors Using 3-Tesla Magnetic Resonance Susceptibility-Weighted Imaging

Neurosurgery 79:839–846, 2016

Susceptibility-weighted imaging (SWI) of brain tumors provides information about neoplastic vasculature and intratumoral micro- and macrobleedings. Low- and high-grade gliomas can be distinguished by SWI due to their different vascular characteristics. Fractal analysis allows for quantification of these radiological differences by a computer-based morphological assessment of SWI patterns.

OBJECTIVE: To show the feasibility of SWI analysis on 3-T magnetic resonance imaging to distinguish different kinds of brain tumors.

METHODS: Seventy-eight patients affected by brain tumors of different histopathology (low- and high-grade gliomas, metastases, meningiomas, lymphomas) were included. All patients underwent preoperative 3-T magnetic resonance imaging including SWI, on which the lesions were contoured. The images underwent automated computation, extracting 2 quantitative parameters: the volume fraction of SWI signals within the tumors (signal ratio) and the morphological self-similar features (fractal dimension [FD]). The results were then correlated with each histopathological type of tumor.

RESULTS: Signal ratio and FD were able to differentiate low-grade gliomas from grade III and IV gliomas, metastases, and meningiomas (P , .05). FD was statistically different between lymphomas and high-grade gliomas (P , .05). A receiver-operating characteristic analysis showed that the optimal cutoff value for differentiating low- from highgrade gliomas was 1.75 for FD (sensitivity, 81%; specificity, 89%) and 0.03 for signal ratio (sensitivity, 80%; specificity, 86%).

CONCLUSION: FD of SWI on 3-T magnetic resonance imaging is a novel image biomarker for glioma grading and brain tumor characterization. Computational models offer promising results that may improve diagnosis and open perspectives in the radiological assessment of brain tumors.

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Laser Interstitial Thermal Therapy for Mesial Temporal Lobe Epilepsy

Neurosurgery 79:S83–S91, 2016

Approximately one-third of patients with epilepsy do not achieve adequate seizure control through medical management alone. Mesial temporal lobe epilepsy (MTLE) is one of the most common forms of medically refractory epilepsy referred for surgical management. Stereotactic laser amygdalohippocampotomy using magnetic resonance–guided laser interstitial thermal therapy (MRg-LITT) is an important emerging therapy for MTLE.

Initial published reports support MRg-LITT as a less invasive surgical option with a shorter hospital stay and fewer neurocognitive side effects compared with craniotomy for anterior temporal lobectomy with amygdalohippocampectomy and selective amygdalohippocampectomy.

We provide a historical overview of laser interstitial thermal therapy development and the technological advancements that led to the currently available commercial systems. Current applications of MRg-LITT for MTLE, reported outcomes, and technical issues of the surgical procedure are reviewed. Although initial reports indicate that stereotactic laser amygdalohippocampotomy may be a safe and effective therapy for medically refractory MTLE, further research is required to establish its long-term effectiveness and its cost/benefit profile.

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Contribution of Lordotic Correction on C5 Palsy Following Cervical Laminectomy and Fusion

Neurosurgery 79:816–822, 2016

C5 palsy is a well-reported complication of cervical spine surgery. The implication of sagittal cervical alignment parameters and their changes after surgery on the incidence of C5 palsy remains unclear.

OBJECTIVE: We review cervical alignment changes in our cases of C5 palsy after cervical laminectomy and fusion.

METHODS: Cases of C5 palsy were retrospectively compared with a control group. Preoperative and postoperative upright plain film radiographs were analyzed in blinded fashion.

RESULTS: Spine registry analysis identified 148 patients who underwent cervical laminectomy and fusion by the senior author over 5 years. There were 18 (12%) cases complicated by postoperative C5 palsy. Nine of these 18 patients had prerequisite upright films and were compared with a randomly constructed case control group of 20 patients. There were no statistically significant differences between the 2 groups in age, proportion of males, and preoperative Nurick score. Measures of sagittal alignment did not differ significantly between the 2 groups on preoperative and postoperative imaging. When comparing the amount of alignment change between preoperative and postoperative upright imaging, however, patients with C5 palsy had a statistically higher amount of average C4-C5 Cobb angle change (22.53 vs 0.78; P = .01). Logistic regression analysis demonstrated that lordotic change in both C4-C5 and C2-C7 Cobb angles were associated with development of palsy.

CONCLUSION: Lordotic cervical correction, as measured on upright imaging, was statistically larger in patients who had C5 palsy. The role of deformity correction in C5 palsy deserves further study and may inform intraoperative decision making.

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