Clinical outcomes of normal pressure hydrocephalus in 116 patients: objective versus subjective assessment

J Neurosurg 132:1757–1763, 2020

Objective assessment tests are commonly used to predict the response to ventriculoperitoneal (VP) shunting in patients with normal pressure hydrocephalus (NPH). Whether subjective reports of improvement after a lumbar drain (LD) trial can predict response to VP shunting remains controversial. The goal in this study was to compare clinical characteristics, complication rates, and shunt outcomes of objective and subjective LD responders who underwent VP shunt placement.

METHODS This was a retrospective review of patients with NPH who underwent VP shunt placement after clinical improvement with the LD trial. Patients who responded after the LD trial were subclassified into objective LD responders and subjective LD responders. Clinical characteristics, complication rates, and shunt outcomes between the 2 groups were compared with chi-square test of independence and t-test.

RESULTS A total of 116 patients received a VP shunt; 75 were objective LD responders and 41 were subjective LD responders. There was no statistically significant difference in patient characteristics between the 2 groups, except for a shorter length of stay after LD trial seen with subjective responders. The complication rates after LD trial and VP shunting were not significantly different between the 2 groups. Similarly, there was no significant difference in shunt response between objective and subjective LD responders. The mean duration of follow-up was 1.73 years.

CONCLUSIONS Reports of subjective improvement after LD trial in patients with NPH can be a reliable predictor of shunt response. The currently used objective assessment scales may not be sensitive enough to detect subtle changes in symptomatology after LD trial.

Alternative customized instrumentation and technique for percutaneous balloon compression rhizotomy for trigeminal neuralgia

J Neurosurg 132:1938–1941, 2020

Trigeminal neuralgia is a debilitating disease that can be treated effectively by a number of modalities. Percutaneous balloon compression rhizotomy of the gasserian ganglion is an important technique that can be offered as a primary or secondary strategy after failure of medical therapy. However, the commercial kit for this procedure was discontinued in the United States in early 2016 and therefore is not currently available. The authors describe a low-cost, effective solution for continuing to offer this procedure using equipment already available in most hospitals.

METHODS The authors provide a detailed equipment list with step-by-step instructions on how to prepare all the necessary items and perform a percutaneous balloon compression rhizotomy.

RESULTS The custom “homemade” kit and technique described have been utilized successfully since June 2016 in 34 patients. The kit is a low-cost alternative, and its application does not add any operative time beyond that required for the previously commercially available kit.

CONCLUSIONS Percutaneous balloon compression rhizotomy of the gasserian ganglion is an important technique that should be readily available to patients who are not medically fit for microvascular decompression and need immediate relief of their pain. The alternative kit described here can be assembled easily using equipment that is readily available in most hospitals.

Prognostic Factors for Adjacent Segment Disease After L4-L5 Lumbar Fusion

Neurosurgery 86:835–842, 2020

Adjacent segment disease (ASD) is an important consideration during decision making for lumbar spinal fusion. OBJECTIVE: To identify risk factors for development of ASD after L4-L5 fusion and differences in incidence between rostral and caudal ASD.

METHODS: We retrospectively reviewed all consecutive patients at a single institution who underwent first-time spinal fusion at the L4-L5 level for degenerative spinal disease over a 10-yr period, using posterolateral pedicular screw fixation with or without posterior interbody fusion. ASD was defined as clinical and radiographic evidence of degenerative spinal disease requiring reoperation at the level rostral (L3-L4) or caudal (L5-S1) to the index fusion.

RESULTS: Among 131 identified patients, the incidence of ASD requiring reoperation was 25.2% (n = 33). Twenty-four cases (18.3% of the entire cohort) developed rostral ASD (segment L3-L4), 3 cases (2.3%) developed caudal (L5-S1), and 6 cases (4.6%) developed bilateral ASD (both rostral and caudal). Cumulatively, the incidence of caudal ASD was significantly lower than rostral ASD (P<.001). Following multivariate logistic regression for factors associated with ASD reoperation, decompression of segments outside the fusion construct was associated with higher ASD rates (odds ratio [OR] = 2.68, P = .039), as was female gender (OR = 3.55, P = .011), whereas older age was associated with lower ASD incidence (OR = 0.95, P = .011).

CONCLUSION: When considering posterior L4-L5 fusion, surgeons should refrain from prophylactic procedures in the L5-S1 level, without clinical indications, because ASD incidence on that segment is reassuringly low.

Surgical outcomes of anterior cerebellopontine angle meningiomas using the anterior transpetrosal approach compared with the lateral suboccipital approach

Acta Neurochirurgica (2020) 162:1243–1248

Anterior transpetrosal approach (ATPA) and lateral suboccipital approach (LSO) are the major surgical approaches for cerebellopontine angle (CPA) meningiomas. Particularly, anterior CPA meningiomas are challenging lesions to be treated surgically. To date, only a few studies have directly compared the outcomes of both approaches focusing on the anterior CPA meningiomas.

Methods For the comparative analysis, anterior CPA meningiomas that were eligible for both APTA and LSO were collected in our hospital from April 2005 to March 2017. Anterior CPA meningiomas targeted for this study were defined as follows: (1) without cavernous sinus, clivus, and middle cranial fossa extension, (2) the posterior edge is 1 cm behind the posterior wall of the internal auditory canal, and (3) the inferior edge is above the jugular tuberculum. Based on these criteria, the operative outcomes of 17 patients and 13 patients who were operated via ATPA and LSO were evaluated.

Results The complication rate of the LSO group was significantly higher than that of the ATPA group (30.7% vs. 0%, p = 0.033). The removal rate did not differ between the ATPA and LSO groups (97.35% vs. 99.23%, p = 0.12). The operative time was significantly shorter in the LSO group than in the ATPA group (304.3 min vs. 405.8 min, p = 0.036).

Conclusions Although the LSO is more widely used for CPA meningiomas, ATPA is also considered for these anterior CPA meningiomas.

Petroclival meningiomas: long-term outcomes of multimodal treatments and management strategies based on 30 years of experience at a single institution

J Neurosurg 132:1675–1682, 2020

A thorough investigation of the long-term outcomes and chronological changes of multimodal treatments for petroclival meningiomas is required to establish optimal management strategies. The authors retrospectively reviewed the long-term clinical outcomes of patients with petroclival meningioma according to various treatments, including various surgical approaches, and they suggest treatment strategies based on 30 years of experience at a single institution.

METHODS Ninety-two patients with petroclival meningiomas were treated surgically at the authors’ institution from 1986 to 2015. Patient demographics, overall survival, local tumor control rates, and functional outcomes according to multimodal treatments, as well as chronological change in management strategies, were evaluated. The mean clinical and radiological follow-up periods were 121 months (range 1–368 months) and 105 months (range 1–348 months), respectively.

RESULTS A posterior transpetrosal approach was most frequently selected and was followed in 44 patients (48%); a simple retrosigmoid approach, undertaken in 30 patients, was the second most common. The initial extent of resection and following adjuvant treatment modality were classified into 3 subgroups: gross-total resection (GTR) only in 13 patients; non-GTR treatment followed by adjuvant radiosurgery or radiation therapy (non-GTR+RS/RT) in 56 patients; and non-GTR without adjuvant treatment (non-GTR only) in 23 patients. The overall progression-free survival rate was 85.8% at 5 years and 81.2% at 10 years. Progression or recurrence rates according to each subgroup were 7.7%, 12.5%, and 30.4%, respectively.

CONCLUSIONS The authors’ preferred multimodal treatment strategy, that of planned incomplete resection and subsequent adjuvant radiosurgery, is a feasible option for the management of patients with large petroclival meningiomas, considering both local tumor control and postoperative quality of life.

 

Thirty-Day Hospital Readmission and Surgical Complication Rates for Shunting in Normal Pressure Hydrocephalus: A Large National Database Analysis

Neurosurgery 86:843–850, 2020

Research on age-related complications secondary to shunts in normal pressure hydrocephalus (NPH) is primarily limited to single-center studies and small cohorts.

OBJECTIVE: To determine the rates of hospital readmission and surgical complications, and factors that predict them, following shunt surgery for NPH in a large healthcare network.

METHODS: Surgical procedures, complications, and readmissions for adults undergoing ventricular shunting for NPH were determined using de-identified claims from a privately insured United States healthcare network in years 2007-2014. Univariate and multivariate statistics were used to determine factors that predict poor surgical outcomes. The primary outcome variable was surgical complications or readmissions (composite variable for any major perioperative complication or 30-d readmission).

RESULTS: The 30-d readmission rate for 974 patients with NPH who underwent ventricular shunting was 7.29%; the most common reasons for readmission were shunt-related complications, infection, hemorrhage, altered mental status, and cardiopulmonary and musculoskeletal problems. The perioperative complication rate was 21.15%, including intraparenchymal hemorrhage (5.85%) and extra-axial (subdural or epidural) hematoma (5.54%). The overall rate of having a surgical complication or 30-d readmission was 25.15%. Age did not predict surgical complication or 30-d readmission. Preoperative comorbidities independently associated with poor outcome were myocardial infarction within 1 yr (OR = 3.984, 95% CI = 1.105-14.368); existing cerebrovascular disease (odds ratio [OR] = 2.206, 95% CI = 1.544-3.152); and moderate/severe renal disease (OR = 2.000, 95% CI = 1.155-3.464).

CONCLUSION: The rate of complications or readmission within 30 d of ventricular shunting for NPH is 25.15%. Preoperative comorbidities of myocardial infarction within 1 yr, cerebrovascular disease, and moderate/severe renal disease are independent risk factors for poor outcome.

Development of the Subdural Hematoma in the Elderly (SHE) score to predict mortality

J Neurosurg 132:1616–1622, 2020

The purpose of this study was to describe the development of a novel prognostic score, the Subdural Hematoma in the Elderly (SHE) score. The SHE score is intended to predict 30-day mortality in elderly patients (those > 65 years of age) with an acute, chronic, or mixed-density subdural hematoma (SDH) after minor, or no, prior trauma.

METHODS The authors used the Prognosis Research Strategy group methods to develop the clinical prediction model. The training data set included patients with acute, chronic, and mixed-density SDH. Based on multivariate analyses from a large data set, in addition to review of the extant literature, 3 components to the score were selected: age, admission Glasgow Coma Scale (GCS) score, and SDH volume. Patients are given 1 point if they are over 80 years old, 1 point for an admission GCS score of 5–12, 2 points for an admission GCS score of 3–4, and 1 point for SDH volume > 50 ml. The sum of points across all categories determines the SHE score.

RESULTS The 30-day mortality rate steadily increased as the SHE score increased for all SDH acuities. For patients with an acute SDH, the 30-day mortality rate was 3.2% for SHE score of 0, and the rate increased to 13.1%, 32.7%, 95.7%, and 100% for SHE scores of 1, 2, 3, and 4, respectively. The model was most accurate for acute SDH (area under the curve [AUC] = 0.94), although it still performed well for chronic (AUC = 0.80) and mixed-density (AUC = 0.87) SDH.

CONCLUSIONS The SHE score is a simple clinical grading scale that accurately stratifies patients’ risk of mortality based on age, admission GCS score, and SDH volume. Use of the SHE score could improve counseling of patients and their families, allow for standardization of clinical treatment protocols, and facilitate clinical research studies in SDH.

 

Characterizing tumor invasiveness of glioblastoma using multiparametric magnetic resonance imaging

J Neurosurg 132:1465–1472, 2020

The objective of this study was to characterize the abnormalities revealed by diffusion tensor imaging (DTI) using MR spectroscopy (MRS) and perfusion imaging, and to evaluate the prognostic value of a proposed quantitative measure of tumor invasiveness by combining contrast-enhancing (CE) and DTI abnormalities in patients with glioblastoma.

METHODS Eighty-four patients with glioblastoma were recruited preoperatively. DTI was decomposed into isotropic (p) and anisotropic (q) components. The relative cerebral blood volume (rCBV) was calculated from the dynamic susceptibility contrast imaging. Values of N-acetylaspartate, myoinositol, choline (Cho), lactate (Lac), and glutamate + glutamine (Glx) were measured from multivoxel MRS and normalized as ratios to creatine (Cr). Tumor regions of interest (ROIs) were manually segmented from the CE T1-weighted (CE-ROI) and DTI-q (q-ROI) maps. Perfusion and metabolic characteristics of these ROIs were measured and compared. The relative invasiveness coefficient (RIC) was calculated as a ratio of the characteristic radii of CE-ROI and q-ROI. The prognostic significance of RIC was tested using Kaplan-Meier and multivariate Cox regression analyses.

RESULTS The Cho/Cr, Lac/Cr, and Glx/Cr in q-ROI were significantly higher than CE-ROI (p = 0.004, p = 0.005, and p = 0.007, respectively). CE-ROI had significantly higher rCBV values than q-ROI (p < 0.001). A higher RIC was associated with worse survival in a multivariate overall survival (OS) model (hazard ratio [HR] 1.40, 95% confidence interval [CI] 1.06–1.85, p = 0.016) and progression-free survival (PFS) model (HR 1.55, 95% CI 1.16–2.07, p = 0.003). An RIC cutoff value of 0.89 significantly predicted shorter OS (median 384 vs 605 days, p = 0.002) and PFS (median 244 vs 406 days, p = 0.001).

CONCLUSIONS DTI-q abnormalities displayed higher tumor load and hypoxic signatures compared with CE abnormalities, whereas CE regions potentially represented the tumor proliferation edge. Integrating the extents of invasion visualized by DTI-q and CE images into clinical practice may lead to improved treatment efficacy.

Utility of a Quantitative Approach Using Diffusion Tensor Imaging for Prognostication Regarding Motor and Functional Outcomes in Patients With Surgically Resected Deep Intracranial Cavernous Malformations

Neurosurgery 86:665–675, 2020

Resection of deep intracranial cavernous malformations (CMs) is associated with a higher risk of neurological deterioration and uncertainty regarding clinical outcomes.

OBJECTIVE: To examine diffusion tractography imaging (DTI) data evaluating the corticospinal tract (CST) in relation to motor and functional outcomes in patients with surgically resected deep CMs.

METHODS: Perilesional CST was characterized as disrupted, displaced, or normal. Mean fractional anisotropy (FA) values were obtained for whole ipsilateral CST and in 3 regions: subcortical (proximal), perilesional, and distally. Mean FA values in anatomically equivalent regions in the contralateral CST were obtained. Clinical and radiological data were collected independently.Multivariable regression analysis was used for statistical analysis.

RESULTS: A total of 18 patients [brainstem (15) and thalamus/basal ganglia (3); median follow-up: 270 d] were identified over 2 yr. The CST was identified preoperatively as disrupted (6), displaced (8), and normal (4). Five of 6 patientswith disruption hadweakness. Higher preoperative mean FA values for distal ipsilateral CST segmentwere associated with better preoperative lower (P < .001), upper limb (P = .004), postoperative lower (P = .005), and upper limb (P < .001) motor examination. Preoperative mean FA values for distal ipsilateral CST segment (P = .001) and contralateral perilesional CST segment (P < .001) were negatively associated with postoperative modified Rankin scale scores.

CONCLUSION: Lower preoperative mean FA values for overall and defined CST segments corresponded to worse patient pre- and postoperative motor examination and/or functional status. FA value for the distal ipsilateral CST segment has prognostic potential with respect to clinical outcomes.

Impact of aneurysm shape and neck configuration on cerebral infarction during microsurgical clipping of intracranial aneurysms

J Neurosurg 132:1539–1547, 2020

Cerebral infarction is a significant cause of morbidity and mortality related to microsurgical clipping of intracranial aneurysms. The objective of this study was to determine the impact of aneurysm shape and neck configuration on cerebral infarction after aneurysm surgery.

METHODS The authors retrospectively reviewed consecutive cases of ruptured and unruptured aneurysms treated with microsurgical clipping at their institution between 2010 and 2018. Three-dimensional reconstructions from preoperative computed tomography and digital subtraction angiography were used to determine aneurysm shape (regular/complex) and neck configuration (regular/irregular). Morphological and procedure-related risk factors for cerebral infarction were identified using univariate and multivariate statistical analyses.

RESULTS Among 243 patients with 252 aneurysms (148 ruptured, 104 unruptured), the overall cerebral infarction rate was 17.1%. Infarction tended to occur more often in aneurysms with complex shape (p = 0.084). Likewise, aneurysms with an irregular neck had a significantly higher rate of infarction (37.5%) than aneurysms with regular neck configuration (10.1%, p < 0.001). Aneurysms with an irregular neck were associated with a higher rate of intraoperative rupture (p = 0.003) and temporary parent artery occlusion (p = 0.037). In the multivariate analysis, irregular neck configuration was identified as an independent risk factor for infarction (OR 4.2, 95% CI 1.9–9.4, p < 0.001), whereas the association between aneurysm shape and infarction was not significant (p = 0.966).

CONCLUSIONS Irregular aneurysm neck configuration represents an independent risk factor for cerebral infarction during microsurgical clipping of both ruptured and unruptured aneurysms.

Effect of decompressive craniectomy in the postoperative expansion of traumatic intracerebral hemorrhage: a propensity score–based analysis

J Neurosurg 132:1623–1635, 2020

Traumatic intracerebral hemorrhage (TICH) represents approximately 13%–48% of the lesions after a traumatic brain injury (TBI), and hemorrhagic progression (HP) occurs in 38%–63% of cases. In previous studies, decompressive craniectomy (DC) has been characterized as a risk factor in the HP of TICH; however, few studies have focused exclusively on this relationship. The object of the present study was to analyze the relationship between DC and the growth of TICH and to reveal any correlation with the size of the craniectomy, degree of cerebral parenchymal herniation (CPH), or volumetric expansion of the TICH.

METHODS The authors retrospectively analyzed the records of 497 adult patients who had been consecutively admitted after suffering a severe or moderate closed TBI. An inclusion criterion was presentation with one or more TICHs on the initial or control CT. Demographic, clinical, radiological, and treatment variables were assessed for associations.

RESULTS Two hundred three patients presenting with 401 individual TICHs met the selection criteria. TICH growth was observed in 281 cases (70.1%). Eighty-two cases (20.4%) underwent craniectomy without TICH evacuation. In the craniectomy group, HP was observed in 71 cases (86.6%); in the noncraniectomy group (319 cases), HP occurred in 210 cases (65.8%). The difference in the incidence of HP between the two groups was statistically significant (OR 3.41, p < 0.01). The mean area of the craniectomy was 104.94 ± 27.5 cm2, and the mean CPH distance through the craniectomy was 17.85 ± 11.1 mm. The mean increase in the TICH volume was greater in the groups with a craniectomy area > 115 cm2 and CPH > 25 mm (16.12 and 14.47 cm3, respectively, p = 0.01 and 0.02). After calculating the propensity score (PS), the authors followed three statistical methods—matching, stratification, and inverse probability treatment weighting (IPTW)—thereby obtaining an adequate balance of the covariates. A statistically significant relationship was found between HP and craniectomy (OR 2.77, p = 0.004). This correlation was confirmed with the three methodologies based on the PS with odds greater than 2.

CONCLUSIONS DC is a risk factor for the growth of TICH, and there is also an association between the size of the DC and the magnitude of the volume increase in the TICH.

 

Cognitive dysfunction and subjective symptoms in patients with arachnoid cyst before and after surgery

Acta Neurochirurgica (2020) 162: 1041–1050

Arachnoid cysts are congenital, benign lesions in the brain and are often incidental radiological findings. Frequently, the arachnoid cysts are left untreated; however, recent studies have shown that arachnoid cysts can cause cognitive dysfunction that affect quality of life. Moreover, the function can improve after surgical decompression. Hence, there is controversy regarding symptomatology and treatment effects of arachnoid cysts. The aim of the study was to analyse if arachnoid cysts can cause cognitive impairment and subjective symptoms and if these impairments are reversible after surgical treatment.

Material and methods Twenty-one consecutive patients with radiologically confirmed supratentorial arachnoid cysts were cognitively evaluated using a battery of seven neuropsychological tests. Twelve of these patients underwent surgery and were evaluated before and after surgery. The patients were also evaluated with neuropsychological testing after surgery. Further information was extracted from the medical records. The cognitive test results were compared to standard population values using z-test, and the test results from the surgically treated patients were compared before and after surgery using paired t-test.

Results The surgically treated patients had a statistically significant improvement of neurocognitive test results after surgery in six out of the seven tests (p < 0.05). The total patient group showed lower mean values in all tests when compared to standard population. Statistical significance was, however, only detected in two of the seven tests. All surgically treated patients reported diminished symptoms after surgery.

Conclusions The patients with arachnoid cysts presented with cognitive dysfunction compared to the normal population which improved after surgical decompression. Arachnoid cysts should not be considered asymptomatic unless thoroughly evaluated with clinical and neuropsychological work-up.

Timing of intraventricular infusion test for diagnosing idiopathic normal pressure hydrocephalus

Acta Neurochirurgica (2020) 162: 1011–1017

Infusion tests, which measure resistance to outflow (Rout), are used in selecting patients suspected for idiopathic normal pressure hydrocephalus (iNPH) for shunt surgery. Infusion tests can be performed through an external ventricular drain (EVD). A 24-hour time gap from EVD insertion to an infusion test is a routine practice at our department due to concerns that the surgical procedure might influence the test results in the immediate postoperative period. The objective of the study was to investigate if timing of an intraventricular infusion test influences the results of the test in patients suspected for iNPH.

Methods Ten patients scheduled for an intraventricular infusion test were included. Measurements of baseline intracranial pressure (ICP) and plateau ICP were obtained during constant rate intraventricular infusion test performed at two time points (1 and 24 h after EVD insertion) and Rout was calculated from these measures and compared within patients.

Results Eight patients completed both infusion tests. In one of the 18 infusion tests performed, it was not possible to define an ICP plateau and this infusion test was excluded, leaving 7 paired infusion tests.Median Rout was 12.9 mmHg/ml/min (range 7.0–22.0) 1 h after EVD insertion and 11.3 mmHg/ml/min (range 7.8–18.1) after 24 h. Overall, there were no statistically significant differences in Rout (P = 0.83), baseline ICP (P = 0.70), or plateau ICP (P = 0.81) between the recordings performed 1 h and 24 h after EVD insertion. For two of the seven patients with paired infusion tests, there was poor agreement between Rout values at 1 and 24 h.

Conclusion Overall, Rout estimates do not change significantly between 1 and 24 h after EVD insertion.We therefore propose that infusion tests can be performed shortly after surgery to reduce the period of indwelling EVD and duration of hospitalization.

Stereotactic Radiosurgery for Cavernous Sinus Versus Noncavernous Sinus Dural Arteriovenous Fistulas: Outcomes and Outcome Predictors

Neurosurgery 86:676–684, 2020

Dural arteriovenous fistulas (DAVFs) can be categorized based on location.

OBJECTIVE: To compare stereotactic radiosurgery (SRS) outcomes between cavernous sinus (CS) and non-CS DAVFs and to identify respective outcome predictors.

METHODS: This is a retrospective study of DAVFs treated with SRS between 1988 and 2016 at 10 institutions. Patients’ variables, DAVF characters, and SRS parameters were included for analyses. Favorable clinical outcome was defined as angiography-confirmed obliterationwithout radiological radiation-induced changes (RIC) or post-SRS hemorrhage.Other outcomes were DAVFs obliteration and adverse events (including RIC, symptomatic RIC, and post-SRS hemorrhage).

RESULTS: The overall study cohort comprised 131 patients, including 20 patients with CS DAVFs (15%) and 111 patients with non-CS DAVFs (85%). Rates of favorable clinical outcome were comparable between the 2 groups (45% vs 37%, P = .824). Obliteration rate after SRS was higher in the CS DAVFs group, even adjusted for baseline difference (OR = 4.189, P = .044). Predictors of favorable clinical outcome included higher maximum dose (P = .014) for CS DAVFs. Symptomatic improvement was associated with obliteration in non-CS DAVFs (P = .005), but symptoms improved regardless of whether obliteration was confirmed in CS DAVFs. Non-CS DAVFs patients with adverse events after SRS were more likely to be male (P = .020), multiple arterial feeding fistulas (P = .018), and lower maximum dose (P = .041).

CONCLUSION: After SRS, CSDAVFs are more likely to obliterate than non-CS ones. Because these 2 groups have different total predictors for clinical and radiologic outcomes after SRS, they should be considered as different entities.

Shunt infusion studies: impact on patient outcome, including health economics

Acta Neurochirurgica (2020) 162: 1019–1031

The diagnosis of shunt malfunction is often not straightforward. We have explored, in symptomatic shunted patients with hydrocephalus or pseudotumour cerebri syndrome (PTCS), the accuracy of CSF infusion tests in differentiating a functioning shunt from one with possible problems, and the health economic consequences.

Methods Participants: hydrocephalus/PTCS patients with infusion tests performed from January 2013 until December 2015. We followed patients up after 6 and 12 months from the test to determine whether they had improved, had persisting symptoms or had required urgent revision. We calculated the total cost savings of revision versus infusion tests and standard protocol of revision and ICP monitoring versus infusion tests.

Results Three hundred sixty-five shunt infusion tests had been performed where a shunt prechamber/reservoir was present. For hydrocephalus patients, more than half of the tests (~ 55%, 155 out of 280) showed no shunt malfunction versus 125 with possible malfunction (ages 4 months to 90 years old). For PTCS patients aged 10 to 77 years old, 47 had possible problems and 38 no indication for shunt malfunction. Overall, > 290 unnecessary revisions were avoided over 3 years’ time. Two hundred fifty eight (> 85%) of those non-surgically managed, remained well, did not deteriorate and did not require surgery. No infections were associated with infusion studies. For Cambridge, the overall savings from avoiding revisions was £945,415 annually.

Conclusions Our results provide evidence of the importance of shunt testing in vivo to confirm shunt malfunction. Avoiding unnecessary shunt revisions carries a strong health benefit for patients that also translates to a significant financial benefit for the National Health Service and potentially for other healthcare systems worldwide.

A comparison of indirect and direct targeted STN DBS in the treatment of Parkinson’s disease

Acta Neurochirurgica (2020) 162: 1067–1076

Deep brain stimulation (DBS) in the subthalamic nucleus (STN) is used in advanced Parkinson’s disease (PD) for reducing motor fluctuations and the side effects of antiparkinsonian medication (APM). The development of neuroimaging has enabled the direct targeting of the STN. The aim of this study is to evaluate the outcome in patients with PD using STN DBS when changing from atlas-based indirect targeting method (iTM) to direct MRI-based targeting (dTM) assuming dTMis superior.

Methods Twenty-five consecutive PD patients underwent dTM STN DBS surgery from 2014 to 2017 with follow-up for 1 year. The neuroimaging, surgical method, outcome in Unified Parkinson’s Disease Rating Scale (UPDRS) scores, and reduction of APM are described and compared with the results of an earlier iTM STN DBS study.

Results Twelve months after a dTM STN DBS, significant improvement (p < 0.001) was seen in six out of seven parameters of UPDRS when patients had medication (medON) and stimulation (stimON). The activities of daily living (UPDRSII) and motor scores (UPDRSIII) improved by 41% and 62%, respectively. Dyskinesias and fluctuations were both reduced by 81%. In dTM STN DBS group, the levodopa equivalent dose (LED) and the total daily levodopa equivalent dose (LEDD) were significantly decreased by 62% and 55%, respectively, compared with the baseline (p < 0.001). Five patients (20%) were without levodopa medication 12 months after the operation.

Conclusions The development of surgical technique based on advanced neuroimaging has improved the outcome of PD STN DBS.

Role of Resistivity Index Analysis in the Prediction of Hemodynamically Significant Venous Sinus Stenosis in Patients With Idiopathic Intracranial Hypertension

Neurosurgery 86:631–636, 2020

The resistivity index (RI) in cerebral venous sinus stenosis (VSS) has not been studied in patients with idiopathic intracranial hypertension (IIH).

OBJECTIVE: To evaluate the role of RI measured by quantitative magnetic resonance venogram (QMRV) as a noninvasive tool in the diagnosis of venous hypertension associated with VSS in IIH.

METHODS:Retrospective evaluation of 13 consecutive IIH patients who underwent venous sinus stenting at our institution between 2013 and 2018. Patients’demographics, clinical presentation, cerebral mean venous sinus pressure (MVP), and RI both pre- and poststenting were recorded. The baseline RI was also compared to a control group.

RESULTS: Among 13 patients of IIH, 11 had unilateral VSS in dominant sinus, whereas 2 had bilateral VSS. RI was significantly higher in IIH patients compared to the control group in the superior sagittal (SSS) and transverse sinuses (TS) (0.21 vs 0.11, P=.01 and 0.22 vs 0.13, P=.03, respectively). The MVP (in mm Hg) decreased significantly after venous sinus stenting in the SSS (41.9 to 22.5, P < .001) and TS (39.4 to 19.5, P < .001), which was also associated with a significant reduction of the RI (0.22 vs 0.17, P < .01 in SSS and 0.23 vs 0.17, P = .03 in TS) poststenting.

CONCLUSION: RI calculated using QMRV can serve as a noninvasive tool to aid in the diagnosis of hemodynamically significant VSS. The study had a small sample size, and larger multicenter studies would be required to validate the results further.

Impact of Extent of Resection on Incidence of Postoperative Complications in PatientsWith Glioblastoma

Neurosurgery 86:625–630, 2020

Extent of resection (EOR) is well established as correlating with overall survival in patients with glioblastoma (GBM). The impact of EOR on reported quality metrics such as patient safety indicators (PSIs) and hospital-acquired conditions (HACs) is unknown.

OBJECTIVE: To perform a retrospective study to evaluate possible associations between EOR and the incidence of PSIs and HACs.

METHODS: We queried all patients diagnosed with GBM who underwent surgical resection at our institution between January 2011 and May 2017. Pre- and postoperative magnetic resonance imageswere analyzed for EOR. Each chart was reviewed to determine the incidence of PSIs and HACs.

RESULTS: A total of 284 patients met the inclusion criteria. EOR ranged from 39.00 to 100%, with a median of 99.84% and a mean of 95.7%. There were 16 PSI, and 13 HAC, events. There were no significant differences in the rates of PSIs or HACs when compared between patients stratified by gross total resection (EOR ≥ 95%) and subtotal resection (EOR < 95%). The odds of encountering a PSI or HAC were 2.5 times more likely in the subtotal resection group compared to the gross total resection group (P = .58). After adjusting for confounders, the odds of encountering a PSI or HAC in the subtotal resection group were 3.9 times greater than for the gross total resection group (P < .05).

CONCLUSION: Gross total resection of GBM is associated with a decreased incidence of PSIs and HACs, as compared to subtotal resection.

Percutaneous glycerol rhizotomy for trigeminal neuralgia in patients with multiple sclerosis

J Neurosurg 132:1405–1413, 2020

The prevalence of trigeminal neuralgia (TN) in patients with multiple sclerosis (MS-TN) is higher than in the general population (idiopathic TN [ITN]). Glycerol rhizotomy (GR) is a percutaneous lesioning surgery commonly performed for the treatment of medically refractory TN. While treatment for acute pain relief is excellent, long-term pain relief is poorer. The object of this study was to assess the efficacy of percutaneous retrogasserian GR for the treatment of MS-TN versus ITN.

METHODS A retrospective chart review was performed, identifying 219 patients who had undergone 401 GR procedures from 1983 to 2018 at a single academic institution. All patients were diagnosed with medically refractory MS-TN (182 procedures) or ITN (219 procedures). The primary outcome measures of interest were immediate pain relief and time to pain recurrence following initial and repeat GR procedures. Secondary outcomes included medication usage and presence of periprocedural hypesthesia.

RESULTS The initial pain-free response rate was similar between groups (p = 0.726): MS-TN initial GR 89.6%; MS-TN repeat GR 91.9%; ITN initial GR 89.6%; ITN repeat GR 87.0%. The median time to recurrence after initial GR was similar between MS-TN (2.7 ± 1.3 years) and ITN (2.1 ± 0.6 years) patients (p = 0.87). However, there was a statistically significant difference in the time to recurrence after repeat GR between MS-TN (2.3 ± 0.5 years) and ITN patients (1.2 ± 0.2 years; p < 0.05). The presence of periprocedural hypesthesia was highly predictive of pain-free survival (p < 0.01).

CONCLUSIONS Patients with MS-TN achieve meaningful pain relief following GR, with an efficacy comparable to that following GR in patients with ITN. Initial and subsequent GR procedures are equally efficacious.

Clinical Evaluation of Cingulum Bundle Connectivity for Neurosurgical Hypothesis Development

Neurosurgery 86:724–735, 2020

The cingulum bundle (CB) has long been a target for psychiatric neurosurgical procedures, but with limited understanding of the brain networks being impacted. Recent advances in human tractography could provide a foundation to better understand the effects of neurosurgical interventions on the CB; however, the reliability of tractography remains in question.

OBJECTIVE: To evaluate the ability of different tractography techniques, derived from typical, human diffusion-weighted imaging (DWI) data, to characterize CB connectivity described in animalmodels. This will help validate the clinical applicability of tractography, and generate insight on current and future neurosurgical targets for psychiatric disorders.

METHODS: Connectivity of the CB in 15 healthy human subjects was evaluated using DWI based tractography, and compared to tract-tracing findings from nonhuman primates. Brain regions of interestwere defined to coincide with the animalmodel. Tractographywas performed using 3 techniques (FSL probabilistic, Camino probabilistic, and Camino deterministic). Differences in connectivity were assessed, and the CB segment with the greatest connectivity was determined.

RESULTS: Each tractography technique successfully reproduced the animal tracing model with amean accuracy of 72%(68-75%, P<.05).Additionally, one region of the CB, the rostral dorsal segment, had significantly greater connectivity to associated brain structures than all other CB segments (P< .05).

CONCLUSION: Noninvasive, in vivo human analysis of the CB, using clinically available DWI for tractography, consistently reproduced the results of an animal tract-tracing model. This suggests that tractography of the CB can be used for clinical applications, which may aid in neurosurgical targeting for psychiatric disorders.