Cannabis Use is Associated With Higher Rates of Pseudarthrosis Following TLIF: A Multi-Institutional Matched-Cohort Study.

STUDY DESIGN: This was a retrospective cohort study. OBJECTIVE: To compare the rates of pseudarthrosis in patients undergoing 1 to 3 level transforaminal lumbar interbody fusion (TLIF) procedures between cannabis users and noncannabis users. SUMMARY OF BACKGROUND DATA: Recreational use of cannabis is common, though it remains poorly studied and legally ambiguous in the United States. Patients with back pain may turn to adjunctive use of cannabis to manage their pain. However, the implications of cannabis use on the achievement of bony fusion are not well-characterized. METHODS: Patients who underwent 1 to 3 level TLIF for degenerative disc disease or degenerative spondylolisthesis between 2010 and 2022 were identified using the PearlDiver Mariner all-claims insurance database. Cannabis users were identified with ICD 10 code F12.90. Patients undergoing surgery for nondegenerative pathologies such as tumors, trauma, or infection were excluded. 1:1 exact matching was performed using demographic factors, medical comorbidities, and surgical factors which were significantly associated with pseudarthrosis in a linear regression model. The primary outcome measure was development of pseudarthrosis within 24 months after 1 to 3 level TLIF. The secondary outcomes were the development of all-cause surgical complications as well as all-cause medical complications. RESULTS: A 1:1 exact matching resulted in two equal groups of 1593 patients who did or did not use cannabis and underwent 1 to 3 level TLIF. Patients who used cannabis were 80% more likely to experience pseudarthrosis compared with patients who do not [relative risk (RR): 1.816, 95% CI: 1.291-2.556, P <0.001]. Similarly, cannabis use was associated with significantly higher rates of all-cause surgical complications (RR: 2.350, 95% CI: 1.399-3.947, P =0.001) and all-cause medical complications (RR: 1.934, 95% CI: 1.516-2.467, P <0.001). CONCLUSION: After 1:1 exact matching to control for confounding variables, the findings of this study suggest that cannabis use is associated with higher rates of pseudarthrosis, as well as higher rates of all-cause surgical and all-cause medical complications. Further studies are needed to corroborate our findings.

Ehlers-Danlos Syndrome is Associated with Increased Rates of Adjacent Segment Disease Following TLIF: A Propensity Matched Study.

BACKGROUND: Ehlers-Danlos syndrome (EDS) is a collection of connective tissue disorders which are often associated with tissue laxity and disc degeneration. However, the implications of EDS on the risk of adjacent segment disease (ASD) after transforaminal lumbar interbody fusion (TLIF) are not well described. The objective of this study is to compare the rates of ASD among patients with EDS and those without EDS. METHODS: Patients who underwent 1-3 level TLIF for degenerative disc disease between 2010-2022 were identified using the PearlDiver Mariner all-claims insurance database. Patients with all types of EDS were included. Patients undergoing surgery for tumors, trauma, or infection were excluded. 1:1 propensity matching was performed using demographic factors, medical comorbidities, and surgical factors which were significantly associated with ASD in a linear regression model. The primary outcome measure was the development of ASD. The secondary outcomes were the development of pseudoarthrosis, medical complications, and surgical complications. RESULTS: Propensity matching resulted in 2 equal groups of 85 patients who did or did not have EDS and underwent 1-3 level TLIF. Patients without EDS were less likely to experience ASD (RR 0.18, 95% CI 0.09-0.35, P < 0.001). There was no significant difference between the 2 patient groups with regards to a diagnosis of pseudoarthrosis, and there was no significant difference for all-cause medical and surgical complications between the 2 patient groups. CONCLUSIONS: After propensity matching to control for confounding variables, the findings of this study suggest that EDS may be associated with an increased risk of ASD following TLIF. Future studies are needed to corroborate these findings.

Synthetic Interbody Devices and Traditional Bone Graft Are Associated With a Similar Rate of Surgical Complications After 1-2 Level Anterior Cervical Discectomy and Fusions.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: To compare the rates of all-cause surgical complications of synthetic interbody devices versus allograft or autograft in patients undergoing 1-2 levels anterior cervical discectomy and fusion (ACDF) procedures. SUMMARY OF BACKGROUND DATA: Cervical degenerative disorders affect up to 60% of older adults in the United States. Both traditional allograft or autograft and synthetic interbody devices (polyetheretherketone or titanium) are used for decompression and arthrodesis, with increasing utilization of the latter. However, the differences in their postsurgical complication profiles are not well-characterized. PATIENTS AND METHODS: Patients who underwent 1-2 level ACDFs for cervical radiculopathy or myelopathy between 2010 and 2022 were identified using the PearlDiver Mariner all-claims insurance database. Patients undergoing surgery for nondegenerative pathologies, such as tumors, trauma, or infection, were excluded. 1:1 exact matching was performed based on factors that were significant predictors of all-cause surgical complications in a linear regression model. The primary outcome measure was the development of all-cause surgical complications after 1-2 level ACDFs. The secondary outcome was all-cause medical complications. RESULTS: 1:1 exact matching resulted in two equal groups of 11,430 patients who received treatment with synthetic interbody devices or allograft/autograft. No statistically significant difference in all-cause surgical complications was found between the synthetic cohort and the allograft or autograft cohort after 1-2 level ACDFs (Relative Risk: 0.86, 95% confidence interval: 0.730-1.014, P = 0.079). No significant differences were observed regarding any specific surgical complications except for pseudoarthrosis (Relative Risk: 0.73, 95% confidence interval: 0.554-0.974, P = 0.037), which was higher in the allograft/autograft cohort. CONCLUSION: After 1:1 exact matching to control for confounding variables, the findings of this study suggest that all-cause surgical complications are similar in patients undergoing ACDFs with synthetic interbody devices or allograft/autographs. However, the rate of pseudarthrosis appears to be higher in patients with allograft/autographs. Future prospective studies are needed to corroborate these findings.

Surgeon Experience Matters: An Exact Matched Analysis of TLIF Outcomes Demonstrates No Difference in Surgical Outcomes Between Experienced Neurosurgeons and Orthopedic Surgeons.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To compare surgical and medical complications profile between neurosurgeons and orthopedic surgeons after transforaminal lumbar interbody fusion (TLIF) procedures. BACKGROUND: Studies comparing the impact of spine surgeon specialty (neurosurgery vs. orthopedic spine) on TLIF outcomes have been inconclusive and failed to control for operative learning curves and surgical maturity. Orthopedic spine surgeons perform fewer spine procedures in residency, although these differences may be attenuated by mandatory fellowship before starting practice. Any observed differences are likely attenuated with increasing surgeon experience. MATERIALS AND METHODS: Using an all-payer claims database, PearlDiver Mariner, 120 million patient records were analyzed between 2010 and 2022, to identify individuals with lumbar stenosis or spondylolisthesis who underwent index one- to three-level TLIF procedures. International Classification of Diseases-Ninth Edition (ICD-9), International Classification of Diseases-10th Edition (ICD-10) and Current Procedural Terminology (CPT) codes were used to query the database. Only Neurosurgeons and Orthopedic spine surgeons who had performed at least 250 procedures were included in the study. Patients undergoing surgery for tumor, trauma, or infection were excluded. 1:1 exact matching was performed using demographic factors, medical comorbidities, and surgical factors which were significantly associated with all-cause surgical or medical complications in a linear regression model. RESULTS: 1:1 exact matching created two equal groups of 18,195 patients without baseline differences who underwent TLIF procedures by neurosurgeons or orthopedic surgeons. There was no difference in all-cause surgical complications between neurosurgeons and orthopedic spine surgeons (relative risk=1.008, 95% CI: 0.850-1.195, P =0.965). All-cause medical complication rate was higher in the neurosurgery cohort (relative risk=1.144, 95% CI: 1.042-1.258, P =0.005). CONCLUSION: The results of this study suggest that after accounting for surgical maturity, neurosurgeons and orthopedic spine surgeons have similar surgical outcomes. However, neurosurgeons have higher all-cause medical complication rates compared with orthopedic spine surgeons. Further research is warranted to validate this relationship in other spine procedures and for other outcomes.

TLIF is Associated With Lower Rates of Adjacent Segment Disease and Complications Compared to ALIF: A Matched-Cohort Analysis.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: To compare the rate of adjacent segment disease (ASD) in patients undergoing anterior lumbar interbody fusion (ALIF) versus transforaminal lumbar interbody fusion (TLIF) for the treatment of degenerative stenosis and spondylolisthesis. SUMMARY OF BACKGROUND DATA: ALIF and TLIF are frequently used to treat Lumbar stenosis and spondylolisthesis. While both approaches have distinct advantages, it is unclear whether there are any differences in rates of ASD and postoperative complications. METHODS: A retrospective cohort study of patients who underwent index 1-3 levels ALIF or TLIF between 2010 and 2022, using the PearlDiver Mariner Database, an all-claims insurance database (120 million patients). Patients with a history of prior lumbar surgery and those undergoing surgery for cancer, trauma, or infection were excluded. Exact 1:1 matching was performed using demographic factors, medical comorbidities, and surgical factors found to be significantly associated with ASD in a linear regression model. The primary outcome was a new diagnosis of ASD within 36 months of index surgery, and secondary outcomes were all-cause medical and surgical complications. RESULTS: Exact 1:1 matching resulted in 2 equal groups of 106,451 patients undergoing TLIF and ALIF. The TLIF approach was associated with a lower risk of ASD (RR 0.58, 95% CI 0.56-0.59, P < 0.001) and all-cause medical complications (RR 0.94, 95% CI 0.91-0.98, P =0.002). All-cause surgical complications were not significantly different between both groups. CONCLUSION: After 1:1 exact matching to control for confounding variables, this study suggests that for patients with symptomatic degenerative stenosis and spondylolisthesis, a TLIF procedure (compared to ALIF) is associated with a decreased risk of developing ASD within 36 months of index surgery. Future prospective studies are needed to corroborate these findings. LEVEL OF EVIDENCE: Level-3.

Lumbar Arthroplasty Is Associated With a Lower Incidence of Adjacent Segment Disease Compared With ALIF: A Propensity-matched Analysis.

STUDY DESIGN: Retrospective Cohort Study. OBJECTIVE: The objective of this study was to compare the rate of adjacent segment disease (ASD) between lumbar disk arthroplasty (LDA) and anterior lumbar interbody fusion (ALIF). SUMMARY OF BACKGROUND DATA: LDA and ALIF are alternative surgical approaches used to treat lumbar degenerative disk disease. However, there is a paucity of studies comparing the risk of ASD after these procedures. METHODS: Patients who underwent 1- to 2-level LDA or ALIF between 2010 and 2022 were identified in the PearlDiver Mariner insurance all-claims database. Exclusion criteria included the history of prior lumbar spine surgery or surgery for tumors, trauma, or infection. 1:1 propensity matching was performed using demographic factors, medical comorbidities, and surgical factors, which were significantly associated with ASD. RESULTS: 1:1 propensity matching created two equal groups of 1625 patients without baseline differences who underwent LDA or ALIF. LDA was significantly associated with a lower risk of ASD (relative risk: 0.932, 95% CI, 0.899-0.967, P <0.001) and need for revision within 30 days (relative risk: 0.235, 95% CI, 0.079-0.698, P =0.007). There were no differences in all-cause surgical and medical complications between both groups. CONCLUSIONS: After risk adjustment for demographic and clinical characteristics, the results suggest that LDA is associated with a lower risk of ASD compared with ALIF. LDA was also associated with lower hospital cost and shorter length of stay.

Angiographic cerebral venous sinus calibers and drainage patterns in patients with normal intracranial pressure and idiopathic intracranial hypertension.

BACKGROUND: Normative venous sinus diameters are not well established. This study seeks to compare two-dimensional digital subtraction cerebral angiographic (DSA) venous sinus calibers for patients with normal intracranial pressure (ICP) and with idiopathic intracranial hypertension (IIH). METHODS: Patients who underwent diagnostic cerebral angiography from 2016 to 2020 were retrospectively identified. Two independent reviewers measured venous sinus calibers from anteroposterior (AP) and lateral carotid injection delayed venous phase in patients from two groups (group 1: patients with normal ICP; group 2: patients with IIH) after receiving training in a standardized measurement protocol, with measurements obtained from the superior sagittal sinus (SSS) through the sigmoid sinuses (SS). RESULTS: 97 patients from group 1 and 30 patients from group 2 were included. Interrater reliability was greater than 0.75 for all measured sites. Both groups had similar anatomical subtypes with most being right transverse sinus (TS) dominant or codominant. In group 1, men had significantly larger SSS on lateral view (p<0.001) and dominant TS calibers on AP view (p=0.02) compared with women. Both dominant TS measurements and SSS measurements (lateral plane) were significantly smaller among group 2 compared with group 1 (p<0.001 and 0.02, respectively). Patients with IIH had significantly larger dominant SS measurements (p=0.01). Bifid SSS anatomy was present in 9% of patients with mean caudal width 31 mm (range 19-49 mm). CONCLUSIONS: This study is the first to provide two-dimensional DSA dural venous sinus calibers in patients with and without IIH and to compare anatomical drainage types and calibers among groups.

Quality of life, need for retreatment, and the re-equilibration phenomenon after venous sinus stenting for idiopathic intracranial hypertension.

BACKGROUND: Long term failure rates after venous sinus stenting (VSS) for idiopathic intracranial hypertension (IIH) are poorly understood. METHODS: Retrospective analysis was performed on a prospectively-maintained single center database to identify patients with medically refractory IIH who underwent VSS. Patients with persistent or severe recurrent symptoms after VSS undergo lumbar puncture (LP), therefore LP serves as a marker for treatment failure. RESULTS: 81 patients underwent VSS with a mean follow-up of 10 months; 44 (54.3%) patients underwent LP after VSS due to persistent or recurrent symptoms at a mean of 12 months (median 7, range 2-43). There was a mean decrease in opening pressure (OP) on LP from pre- to post-VSS of 9.1 cm H2O (median 9.5). Overall, a total of 21 (25.9%) patients underwent further surgical intervention following VSS, including five who underwent repeat VSS (6.2% of total) and 18 who underwent cerebrospinal fluid shunting (22.2% of total). There was a non-significant (p=0.18) but overall increase in quality of life scores from pre-stenting (61.2) to last follow-up (71.2), and a significant decrease in Headache Impact Test-6 (HIT-6) scores (p=0.03) with mean pre-stenting and last follow-up scores of 62.7 and 55.8, respectively. CONCLUSIONS: VSS is an effective treatment for venous sinus stenosis in IIH; however, this study found higher rates of symptomatic recurrence and need for further surgical intervention (26%) than previously reported in the literature. Recurrence of symptoms occurred at a median of 7 months, even though OP remained lower at follow-up LP, suggestive of a re-equilibration phenomenon.

Changes in mean arterial pressure and end-tidal carbon dioxide content affect venous sinus pressures in patients with idiopathic intracranial hypertension: a randomized study.

INTRODUCTION: Little is known about how changes in physiologic parameters affect venous sinus pressure measurements, waveforms, or gradients associated with sinus stenosis. OBJECTIVE: To evaluate the effect of changes in cardiovascular and respiratory physiologic parameters on venous sinus pressure and caliber measurements in patients with idiopathic intracranial hypertension (IIH) undergoing venous sinus stenting. METHODS: In a prospective, randomized pilot study, eight patients with IIH undergoing venous sinus stenting were randomized to one of two groups. Under general anesthesia, patients underwent venous manometry and waveform recordings twice in succession based on assigned physiologic groups immediately before stenting. The mean arterial pressure (MAP) group maintained normocapnia but modified MAPs in two arms to control for temporal confounding: group A1 (MAP 60-80 mm Hg then 100-110 mm Hg) and group A2 (MAP 100-110 mm Hg then 60-80 mm Hg). The end-tidal carbon dioxide (EtCO2) group maintained a high-normal MAP similar to standard neuroanesthesia goals and modified EtCO2: group B1 (EtCO2 24-26 mm Hg then 38-40 mm Hg) and B2 (EtCO2 28-40 mm Hg then 24-26 mm Hg). RESULTS: In group A, superior sagittal sinus (SSS) pressures (ranging from 8 to 76 mm Hg) and trans-stenotic pressure gradients (TSPGs) (ranging from 2 to 67 mm Hg) were seen at MAP of 100-110 mm Hg compared with SSS pressures (4-38 mm Hg) and TSPGs (3-31 mm Hg) at 60-80 mm Hg. In group B, SSS pressures and TSPGs were considerably higher at EtCO2 levels of 38-40 mm Hg (15-57 mm Hg and 3-44 mm Hg, respectively) than at 24-26 mm Hg (8-26 mm Hg and 1-8 mm Hg, respectively). CONCLUSIONS: Despite the small sample size, this pilot study demonstrates a dramatic effect of both MAP and EtCO2 on venous sinus pressures obtained during venography. These findings underscore the importance of maintaining normal physiologic cardiovascular and respiratory parameters during venous sinus manometry.

Endovascular management of acute postprocedural flow diverting stent thrombosis.

INTRODUCTION: Postprocedural thrombosis is a rare complication after flow diverting stent (FD) implantation for aneurysm treatment with few reported cases in the literature. Management strategies and outcomes associated with this complication have not been reported. METHODS: A multicenter retrospective series of cases of acute postprocedural FD thrombosis were compiled and prevalence was calculated based on procedural volumes over a 7 year period. Acute postprocedural FD thrombosis was defined as the development of neurologic deficit with angiographic imaging demonstrating acute thrombus within the index FD stent at least 2 hours following completion of the implantation procedure. RESULTS: A total of 10 cases of postprocedural thrombosis were identified at five participating centers among a total of 768 patients treated (prevalence 1.3%). Thrombosis occurred a median of 5.5 days after implantation (range 0-83 days). 9/10 patients underwent emergent angiography with intent to perform endovascular reperfusion. A variety of different endovascular treatments were used, including aspiration thrombectomy, retrievable stent thrombectomy, balloon angioplasty, and intra-arterial thrombolytic infusion, without any procedural complications. There were no instances of FD migration, stent kinking, or aneurysm rupture. 90% of patients achieved Thrombolysis in Cerebral Infarction 2B or greater revascularization. Favorable clinical outcomes (modified Rankin Scale score of 0-2) at 3 months were achieved in 88% of patients. CONCLUSION: Acute postprocedural thrombosis of an FD is a rare complication that occurs in approximately 1-2% of patients after aneurysm treatment. Patients presenting with acute postprocedural FD thrombosis should be aggressively managed using large vessel occlusion thrombectomy techniques, as good angiographic and clinical outcomes are possible.

A descriptive study of venous sinus pressures and gradients in patients with idiopathic intracranial hypertension.

OBJECTIVE: To determine the relationship between normal physiologic and pathologic venous sinus pressures in patients with idiopathic intracranial hypertension (IIH), which is poorly understood. METHODS: Retrospective analysis was performed to identify patients with medically refractory IIH who were evaluated by angiography and retrograde venography with venous manometry. Patients were further subdivided into groups based on anatomic factors. RESULTS: 104 patients met inclusion criteria for the study. In the absence of non-invasive venographic screening, 58% of patients in this series were found to have pressure gradients of ≥8 mm Hg; 93% were located near the transverse-sigmoid sinus junction. Opening pressure (OP) is strongly predictive of superior sagittal sinus (SSS) pressures (p<0.001) and also of the presence of a pressure gradient ≥8 mm Hg (p<0.001). Twenty-three percent of patients with an OP <25 had a pressure gradient ≥8 mm Hg compared with 77% of patients with an OP ≥35. Analysis of patients with OP ≤20 suggests that SSS pressures in patients without IIH should be less than 16-18 mm Hg with total cranial gradients <5 mm Hg. Across all patients, a pressure decrement of approximately 1 mm Hg occurs with progressively more caudal transition across anatomic points of measurement. CONCLUSIONS: This study describes intracranial and extracranial venous pressure measurements and gradients in different subgroups of patients with IIH. OP is highly predictive of intracranial venous pressures and significant venous pressure gradients.

Metabolic networks of the human gut microbiota.

The human gut microbiota controls factors that relate to human metabolism with a reach far greater than originally expected. Microbial communities and human (or animal) hosts entertain reciprocal exchanges between various inputs that are largely controlled by the host via its genetic make-up, nutrition and lifestyle. The composition of these microbial communities is fundamental to supply metabolic capabilities beyond those encoded in the host genome, and contributes to hormone and cellular signalling that support the dynamic adaptation to changes in food availability, environment and organismal development. Poor functional exchange between the microbial communities and their human host is associated with dysbiosis, metabolic dysfunction and disease. This review examines the biology of the dynamic relationship between the reciprocal metabolic state of the microbiota-host entity in balance with its environment (i.e. in healthy states), the enzymatic and metabolic changes associated with its imbalance in three well-studied diseases states such as obesity, diabetes and atherosclerosis, and the effects of bariatric surgery and exercise.

A survey of burnout and professional satisfaction among United States neurointerventionalists.

BACKGROUND: The toll of burnout on healthcare is significant and associated with physician depression and medical errors. OBJECTIVE: To assess the prevalence and risk factors for burnout among neurointerventionalists. METHODS: A 39-question online survey containing questions about neurointerventional practice and the Maslach Burnout Inventory-Human Services Survey for medical personnel was distributed to members of major US neurointerventional physician societies. RESULTS: 320 responses were received. Median (interquartile range) composite scores for emotional exhaustion were 25 (16-35), depersonalization 7 (4-12), and personal accomplishment 39 (35-44). 164/293 respondents (56%) met established criteria for burnout. There was no significant relationship between training background, practice setting, call frequency, or presence of a senior partner on burnout prevalence. Multiple logistic regression analysis showed that feeling underappreciated by hospital leadership (OR=3.71; p<0.001) and covering more than one hospital on call (OR=1.96; p=0.01) were strongly associated with burnout. Receiving additional compensation for a call was independently protective against burnout (OR= 0.70; p=0.005). CONCLUSIONS: This survey of United States neurointerventional physicians demonstrated a self-reported burnout prevalence of 56%, which is similar to the national average among physicians across other specialties. Additional compensation for a call was a significant protective factor against burnout. In addition, feeling underappreciated by departmental or hospital leadership and covering more than one hospital while on call were associated with greater odds of burnout.

Correlation between angiographic stenosis and physiologic venous sinus outflow obstruction in idiopathic intracranial hypertension.

INTRODUCTION: The relationship between degree of angiographic venous sinus stenosis and the trans-stenosis pressure gradient magnitude in idiopathic intracranial hypertension (IIH) is poorly understood. The present study aimed to assess the utility of angiography, venography, and non-invasive imaging (MRV or CTV) for the diagnosis and characterization of clinically significant VSS. METHODS: Retrospective analysis of a prospectively collected database was performed to identify patients with medically refractory IIH who were evaluated by angiography and venous manometry for the presence of VSS with associated clinically significant pressure gradient. Angiographic stenosis was measured by two independent raters using novel methodology. RESULTS: Thirty-seven patients met inclusion criteria for the study. In total, 70% of patients had clinically significant pressure gradients and were selected for stenting. The optimal percentage stenosis for detection of a significant pressure gradient was 34% stenosis on venous phase arteriography (sensitivity 0.81 and specificity 0.91) and 31% stenosis on venography (0.92 and 0.73). For every 10% increase in stenosis, an approximate increase in pressure gradient of 3.5 mmHg is seen. MRV/CTV had a calculated sensitivity of 0.42, and a negative predictive value of 22%. CONCLUSION: The degree of stenosis predictive of a clinically significant pressure gradient (30-35%) in the venous sinuses is considerably lower than the arterial stenosis at which pathologic hemodynamic alterations occur. While highly predictive of a venous pressure gradient when a stenosis is identified, non-invasive imaging does not appear to be a suitable diagnostic evaluation for the purpose of ruling out clinically significant cerebral VSS.

Changes in End-Tidal Carbon Dioxide Partial Pressure Alter Venous Sinus Pressure Measurements in Idiopathic Intracranial Hypertension.

BACKGROUND: In the diagnosis of venous stenosis associated with idiopathic intracranial hypertension, previous studies have identified significant differences when venous pressures are measured under conscious sedation versus general anesthesia. No previous reports have investigated the effect that respiratory parameters may have on cerebral venous sinus pressure and the associated trans-stenosis pressure gradient. CASE DESCRIPTION: Two patients with idiopathic intracranial hypertension were retrospectively identified from a prospective database wherein venous manometry was performed as part of a venous stenting procedure with waveform recording during changes in end-tidal carbon dioxide level (EtCO2). Upon microcatheterization of the superior sagittal sinus after induction of general anesthesia, both patients were noted to have an EtCO2 of 29 mm Hg. After EtCO2 was corrected to 40 mm Hg, repeat venous manometry was conducted, which demonstrated increased SSS venous pressures from 12.6 to 21.1 mm Hg and 18.4 to 30.3 mm Hg in patients 1 and 2, respectively. In addition, the waveform amplitude increased in both patients after EtCO2 correction. CONCLUSIONS: This series demonstrates that EtCO2 changes have an immediate and pronounced effect on venous sinus pressure measurements with waveform changes that may correlate to increased intracranial pressure. These findings underscore the need to perform measurements of venous sinus pressure gradients under normal awake conditions.

Recommendations for the selection and treatment of patients with idiopathic intracranial hypertension for venous sinus stenting.

INTRODUCTION: Although venous sinus stenting (VSS) has emerged as a promising treatment option for patients with idiopathic intracranial hypertension (IIH) and associated venous sinus stenosis, there is considerable ambiguity regarding patient selection criteria, treatment protocols, and management strategies. METHODS: An extensive literature review was performed to identify all reports of VSS in patients with IIH using PubMed. Recommendations for the selection and treatment of patients with IIH with VSS are outlined as determined based on author opinion from supporting studies. Due to the lack of randomized trials and few published prospective studies, standard grading scales for recommendations and level of evidence are not fully applicable and therefore a revised grading scale has been provided for recommendations. RESULTS: The literature review identified a total of eight systematic reviews or meta-analyses and 29 published patient series on VSS. Recommendations for patient selection for diagnostic catheter angiography, angiography procedural considerations, stenting procedural considerations, and retreatment are provided based on the literature. Recommendations that were considered strong included: performance of venous sinus manometry to assess candidacy for treatment prior to stenting; administration of antiplatelet agents prior to stenting and for a follow-up period of at least 3-6 months; performance of post-stenting manometry to confirm resolution of pressure gradient; and performance of repeat angiography and manometry on patients with recurrence of symptoms after resolution with stenting to evaluate for recurrent stenosis. CONCLUSION: VSS for patients with IIH with venous sinus stenosis is now an established and effective treatment option. These recommendations have been provided, based on a summative review of the available published literature, to assist in standardizing care for patients with IIH undergoing VSS.

Venous waveform morphological changes associated with treatment of symptomatic venous sinus stenosis.

INTRODUCTION: Venous outflow obstruction is recognized as a contributing factor in a subset of patients with idiopathic intracranial hypertension (IIH). Little is known about venous sinus waveform morphology or how it changes after stenting. METHODS: Fifteen patients with IIH underwent waveform recording during catheter venography and manometry. Ten patients (Group A) with venous sinus stenosis and pressure gradient ≥7 mm Hg underwent waveform recording during awake venography and during stenting under general anesthesia. Five control IIH patients (Group B) without a gradient underwent awake recording only. RESULTS: Group A patients underwent successful stenting with reduction of their gradient from 15.1±6.19 mm Hg to 1.2±0.60 mm Hg. This resulted in an amplitude reduction from 8.3 mm Hg to 2.8 mm Hg (P=0.02). Qualitative evaluation of the waveform yielded a number of novel findings. In Group A before stenting, the observed waveform progressed from an intracranial pressure (ICP)-dominated to central venous pressure (CVP)-dominated waveform. Stenting abolished the high amplitude waveform and smoothed the transition from the intracranial to central venous measurement points. Group B displayed primarily CVP-influenced waveforms distal and proximal to the transverse-sigmoid junction along with respiratory variability of the waveform, absent in 8/10 Group A patients. General anesthesia appeared to blunt the waveform in 5/10 Group A patients. CONCLUSION: The cerebral venous waveform appears to be influenced by both the ICP and CVP waveforms. As measurement moves proximally, the waveform progressively changes to mirror the CVP waveform. Venous sinus stenosis results in a high amplitude waveform which improves with treatment of the stenosis.

Bibliometric indices: defining academic productivity and citation rates of researchers, departments and journals.

There has been an increasing focus on academic productivity for the purposes of promotion and funding within departments and institutions but also for comparison of individuals, institutions, specialties, and journals. A number of quantitative indices are used to investigate and compare academic productivity. These include various calculations attempting to analyze the number and citations of publications in order to capture both the quality and quantity of publications, such as the h index, the e index, impact factor, and Eigenfactor score. The indices have varying advantages and limitations and thus a basic knowledge is required in order to understand their potential utility within academic medicine. This article describes the various bibliometric indices and discusses recent applications of these metrics within the neurological sciences.