Application of Color Doppler Ultrasound to Identify and Repair Postoperative Cerebrospinal Fluid Leak: A Technical Note.

BACKGROUND: Incidental durotomy is a known complication of spinal surgery. Persistent cerebrospinal fluid (CSF) leak after unrecognized durotomy may lead to prolonged hospitalization and significant morbidity. If initial bed rest fails, the surgeon must choose between nontargeted methods such as oversewing the wound and lumbar drain placement or return to the operating room. OBJECTIVE: To report the novel use of color flow doppler (CFD) in conjunction with ultrasound (US) to localize the point of CSF leak, assist with aspiration of the pseudomeningocele, and direct the application of fibrin sealant or epidural blood patch. METHODS: This article includes a description of the technique as a technical note. RESULTS: A 72-year-old man underwent L2-5 laminectomies for spinal stenosis. During the index operation, a durotomy occurred and was repaired primarily. The patient subsequently developed leg weakness, back pain, and bulging of the incision. Using CFD, the site of durotomy was determined. Under direct visualization, 34 mL of CSF was aspirated from the pseudomeningocele and 20 mL of fibrin sealant was placed opposing the durotomy. At 2-month follow-up, CFD confirmed absent flow and MRI demonstrated pseudomeningocele resolution. CONCLUSION: This article represents the first report highlighting the utility of CFD US to guide epidural patch placement for postsurgical CSF leaks. CFD allows localization of the durotomy and direct application of blood or fibrin sealant, potentially increasing the success rate of epidural blood patch in postoperative patients. This approach is less invasive than revision surgery and does not require the prolonged hospitalization of lumbar drainage or other nontargeted interventions.

What Is the Learning Curve for Lumbar Spine Surgery Under Spinal Anesthesia?

BACKGROUND: Spinal anesthesia (SA) is routinely used in obstetrics and orthopedic surgery but has not been widely adopted in lumbar spine surgery (LSS). One perceived barrier is the learning curve for the neurosurgical and anesthesia team associated with managing a patient in the prone position under SA. METHODS: A retrospective cohort of 34 LSS cases under SA at our institution was examined. Operative time, corrected operative time per level, and complications were analyzed. The learning curve was assessed using a curve-fit regression analysis. RESULTS: Of patients, 62% were female, with mean (SD) age and body mass index of 60.7 (10.8) years and 29.9 (4.6) kg/m2, respectively. The mean (SD) for each time segment was operating room arrival to incision 35.7 (8.1) minutes, total surgical time 100.4 (35.8) minutes, and procedure finish to operating room exit 3.4 (2.5) minutes. When the times were normalized to procedure type and analyzed sequentially, the mean (SD) slope of all trendlines was 0.003 (0.005) with correlation coefficients of R2 = 0.0002-0.01, indicating no appreciable learning curve. Normalized postanesthesia care unit time was significantly shorter for overnight stay versus same-day discharge (0.64 vs. 1.36, P = 0.0005). CONCLUSIONS: Our data demonstrate the lack of a learning curve when SA is implemented in LSS cases by an anesthetic team already familiar with SA techniques for other procedures. Importantly, the surgical team was already familiar with the minimally invasive surgery approaches used in conjunction with SA. This study highlights that the barriers to transitioning to SA for LSS may be fewer than perceived.

Spinal versus general anesthesia for minimally invasive transforaminal lumbar interbody fusion: implications on operating room time, pain, and ambulation.

OBJECTIVE: There has been increasing interest in the use of spinal anesthesia (SA) for spine surgery, especially within Enhanced Recovery After Surgery (ERAS) protocols. Despite the wide adoption of SA by the orthopedic practices, it has not gained wide acceptance in lumbar spine surgery. Studies investigating SA versus general anesthesia (GA) in lumbar laminectomy and discectomy have found that SA reduces perioperative costs and leads to a reduction in analgesic use, as well as to shorter anesthesia and surgery time. The aim of this retrospective, case-control study was to compare the perioperative outcomes of patients who underwent minimally invasive surgery (MIS)-transforaminal lumbar interbody fusion (TLIF) after administration of SA with those who underwent MIS-TLIF under GA. METHODS: Overall, 40 consecutive patients who underwent MIS-TLIF by a single surgeon were analyzed; 20 patients received SA and 20 patients received GA. Procedure time, intraoperative adverse events, postoperative adverse events, postoperative length of stay, 3-hour postanesthesia care unit (PACU) numeric rating scale (NRS) pain score, opioid medication, and time to first ambulation were collected for each patient. RESULTS: The two groups were homogeneous for clinical characteristics. A decrease in total operating room (OR) time was found for patients who underwent MIS-TLIF after administration of SA, with a mean OR time of 156.5 ± 18.9 minutes versus 213.6 ± 47.4 minutes for patients who underwent MIS-TLIF under GA (p < 0.0001), a reduction of 27%. A decrease in total procedure time was also observed for SA versus GA (122 ± 16.7 minutes vs 175.2 ± 10 minutes; p < 0.0001). No significant differences were found in intraoperative and postoperative adverse events. There was a difference in the mean maximum NRS pain score during the first 3 hours in the PACU as patients who received SA reported a lower pain score compared with those who received GA (4.8 ± 3.5 vs 7.3 ± 2.7; p = 0.018). No significant difference was observed in morphine equivalents received by the two groups. A difference was also observed in the mean overall NRS pain score, with 2.4 ± 2.1 for the SA group versus 4.9 ± 2.3 for the GA group (p = 0.001). Patients who received SA had a shorter time to first ambulation compared with those who received GA (385.8 ± 353.8 minutes vs 855.9 ± 337.4 minutes; p < 0.0001). CONCLUSIONS: The results of this study have pointed to some important observations in this patient population. SA offers unique advantages in comparison with GA for performing MIS-TLIF, including reduced OR time and postoperative pain, and faster postoperative mobilization.

Initial Results of Precision Treatment of Postoperative Cerebrospinal Fluid Leak with Ultrasound-Guided Epidural Blood Patch.

BACKGROUND: Incidental durotomy, a known complication of spinal surgery, can lead to persistent cerebrospinal fluid leak and pseudomeningocele if unrecognized or incompletely repaired. We describe the use of ultrasound to visualize the site of durotomy, observe the aspiration of the pseudomeningocele, and guide the precise application of an ultrasound-guided epidural blood patch (US-EBP), under direct visualization in real time. METHODS: A retrospective review was performed to determine demographic, procedural, and outcome characteristics for patients who underwent US-EBP for symptomatic postoperative pseudomeningocele. RESULTS: Overall, 48 patients who underwent 49 unique episodes of care were included. The average age and body mass index were 60.5 (±12.6) years and 27.8 (±4.50) kg/m2, respectively. The most frequent index operation was laminectomy (24.5%), and 36.7% of surgeries were revision operations. Durotomy was intended or recognized in 73.4% of cases, and the median time from surgery to symptom development was 7 (interquartile range 4-16) days. A total of 61 US-EBPs were performed, with 51.0% of patients experiencing resolution of their symptoms after the first US-EBP. An additional 20.4% were successful with multiple US-EBP attempts. Complications occurred in 14.3% of cases, and the median clinical follow-up was 4.3 (interquartile range 2.4-14.5) months. CONCLUSIONS: This manuscript represents the largest series in the literature describing US-EBP for the treatment of postoperative pseudomeningocele. The success rate suggests that routine utilization of US-guided EBP may allow for targeted treatment of pseudomeningoceles, without the prolonged hospitalization associated with lumbar drains or the risks of general anesthesia and impaired wound healing associated with surgical revision.

Attenuating hypoxia driven malignant behavior in glioblastoma with a novel hypoxia-inducible factor 2 alpha inhibitor.

Hypoxia inducible factor (HIFs) signaling contributes to malignant cell behavior in glioblastoma (GBM). We investigated a novel HIF2α inhibitor, PT2385, both in vitro, with low-passage patient-derived cell lines, and in vivo, using orthotopic models of glioblastoma. We focused on analysis of HIF2α expression in situ, cell survival/proliferation, and survival in brain tumor-bearing mice treated with PT2385 alone and in combination with standard of care chemoradiotherapy. HIF2α expression increased with glioma grade, with over half of GBM specimens HIF2α positive. Staining clustered in perivascular and perinecrotic tumor regions. Cellular phenotype including proliferation, viability, migration/invasion, and also gene expression were not altered after PT2385 treatment. In the animal model, PT2385 single-agent treatment did improve median overall survival compared to placebo (p = 0.04, n = 21) without a bioluminescence correlate (t = 0.67, p = 0.52). No difference in animal survival was seen in combination treatment with radiation (RT)/temozolomide (TMZ)/PT2385 (p = 0.44, n = 10) or mean tumor bioluminescence (t 1.13, p = 0.32). We conclude that HIF2α is a reasonable novel therapeutic target as expressed in the majority of glioblastomas in our cohort. PT2385 as a single-agent was efficacious in vivo, however, an increase in animal survival was not seen with PT2385 in combination with RT/TMZ. Further study for targeting HIF2α as a therapeutic approach in GBM is warranted.

Comparative metrics of neurosurgical scientific journals: What do they mean to readers?

BACKGROUND: In regard to scientific information, are we effectively reaching the universe of physicians in the 21st century, all of whom have different backgrounds, practice environments, educational experiences, and varying degrees of research knowledge? METHODS: A comparison of the top nine neurosurgery journals based on various popular citation indices and also on the digital metric, Readers (Users)/month, was compiled from available metrics and from internet sources. RESULTS: Major differences in the ranking of the Readers (Users)/month metrics compared to ranking of the various citation indices were found. It is obvious that the citation indices do not measure the number of readers of a publication. Which metric should be used in judging the value of a scientific paper? The answer to that question relates to what the interest of the reader has in the scientific information. It appears that the academic scientist may have a different reason for reading a scientific publication than a physician caring for a patient. CONCLUSIONS: There needs to be more than one type of metric that measures the value and "Impact" of a scientific paper based on how physicians learn.

External jugular venous sampling for Cushing's disease in a patient with hypoplastic inferior petrosal sinuses.

The authors report the case of a 30-year-old female patient with suspected Cushing's disease with an anatomical variation of hypoplastic inferior petrosal sinuses and nearly exclusive anterior drainage from the cavernous sinus, who underwent external jugular venous blood sampling with successful disease confirmation and microadenoma localization. The patient presented with signs and symptoms consistent with Cushing's syndrome, but with discordant preliminary diagnostic testing. She underwent attempted bilateral inferior petrosal sinus sampling; however, she had hypoplastic inferior petrosal sinuses bilaterally and predominantly anterior drainage from the cavernous sinus into the external jugular circulation. Given this finding, the decision was made to proceed with external jugular venous access and sampling in addition to internal jugular venous sampling. A positive adrenocorticotropic hormone (ACTH) response to corticotropin-releasing factor was obtained in the right external jugular vein alone, suggesting a right-sided pituitary microadenoma as the cause of her Cushing's disease. The patient subsequently underwent a transsphenoidal hypophysectomy that confirmed the presence of a right-sided ACTH-secreting microadenoma, which was successfully resected. She was hypocortisolemic on discharge and has had no signs of recurrence or relapse at 6 months postoperation.

Craniocervical Osteoradionecrosis Treated with Neoadjuvant and Adjuvant Hyperbaric Oxygen in Combination with Posterior Spinal Fusion.

BACKGROUND: Radiation therapy for malignant head and neck cancers includes a risk for off-target effects to bony structures, posing a risk for osteoradionecrosis (ORN). Patients in whom ORN develops can also harbor concomitant osteomyelitis and reduced healing capacity, making for a particularly challenging entity to treat. Hyperbaric oxygen therapy (HBO) has been shown to be effective in the treatment of mandibular ORN in the otolaryngology literature; yet, few reports exist detailing its utility when treating ORN of the craniocervical junction. Herein, we report 2 cases of ORN of the craniocervical junction who received both neoadjuvant and adjuvant HBO in combination with posterior spinal fusion. CASE DESCRIPTION: Two patients with craniocervical junction ORN were treated with HBO delivered over 20 sessions before and after surgery in 90-minute treatments to 2.5 atmospheres of pressure. The patients underwent posterior occipital-cervical fusions with an average operative time of 301 (±21.5) minutes with 250 (±150) mL of blood loss. Both patients stayed in the hospital for 5 days, with no periprocedural complications. Outcomes included a 30% improvement of global assessment of function on follow-up EuroQol 5-Dimension Questionnaire. Postoperative imaging demonstrated solid bony fusion, and both patients returned to full work duty. CONCLUSIONS: ORN is a difficult-to-treat radiation complication in head and neck cancers. Few reports exist detailing treatment options for ORN of the craniocervical junction in conjunction with surgical stabilization. We report 2 successful cases of HBO-assisted treatment of ORN and highlight the important role HBO can play in promoting bony fusion in these at-risk patients.

Successful application of stereotactic radiosurgery for multiply recurrent Rathke's cleft cysts.

OBJECTIVE: Rathke's cleft cysts (RCCs) are benign lesions of the sella turcica that usually come to neurosurgical attention due to compression of the optic apparatus (OA) and headaches. Treatment options for these lesions include observation, aspiration of cyst contents, or open resection of the cyst with the cyst wall. All of these options involve the potential for cyst recurrence or enlargement. In this study the authors report on a potential new therapeutic option for RCCs, i.e., stereotactic radiosurgery (SRS). METHODS: A retrospective review was conducted of 5 patients with histologically confirmed, multiply recurrent RCCs who were treated with single-fraction SRS at a tertiary referral academic medical center. RESULTS: The total cohort consisted of 5 female patients with an average age of 31.8 years. The most common presenting symptom was headache followed by blurry vision. The symptoms were present on average for 7 months before intervention. The median number of surgeries prior to radiosurgery was 2. The average volume of lesion treated was 0.34 cm3. The median SRS dose was 12.5 Gy prescribed to the 50% isodose line with an average prescription coverage of 96.6%. The median dose to the OA was 5 Gy. At last follow-up, 3 of 5 cysts had completely regressed, 1 had regressed by more than 50% but was still present, and 1 was stable, with an overall mean follow-up duration of 34.2 months. There were no neurological, endocrinological, or visual complications attributable to SRS during the follow-up period. CONCLUSIONS: RCCs can be a challenging clinical entity to treat, especially when they are multiply recurrent. In patients with an average of 2 previous surgeries for resection, a single SRS session prevented recurrence universally, with an average follow-up of almost 3 years. These results indicate that further investigation of the treatment of RCCs with SRS is indicated.

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.

A Comparison of the Existing Wellness Programs in Neurosurgery and Institution Champion's Perspectives.

Once the accepted norm during Harvey Cushing's time, the mantra of work to the exclusion of family and lifestyle is now recognized as deleterious to overall well-being. A number of neurosurgical residency training programs have implemented wellness programs to enhance the physical, mental, and emotional well-being of trainees and faculty. This manuscript highlights existing organized wellness education within neurosurgery residency programs in order to describe the motivations behind development, structure, and potential implementation strategies, cost of implementation, and identify successes and barriers in the integration process. This manuscript is designed to serve as a "how-to" guide for other programs who may identify a need in their own trainees and begins the discussion of how to develop wellness, leadership, grit, and resiliency within our future generation of neurosurgeons.

A review of Big Data analytics and potential for implementation in the delivery of global neurosurgery.

Global access to neurosurgical care is still a work in progress, with many patients in low-income countries not able to access potentially lifesaving neurosurgical procedures. "Big Data" is an increasingly popular data collection and analytical technique predicated on collecting large amounts of data across multiple data sources and types for future analysis. The potential applications of Big Data to global outreach neurosurgery are myriad: from assessing the overall burden of neurosurgical disease to planning cost-effective improvements in access to neurosurgical care, and collecting data on conditions which are rare in developed countries. Although some global neurosurgical outreach programs have intelligently implemented Big Data principles in their global neurosurgery initiatives already, there is still significant progress that remains to be made. Big Data has the potential to drive the efficient improvement of access to neurosurgical care across low- and medium-income countries.

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.

Incidental durotomy in the pediatric spine population.

OBJECTIVESpine surgery is less common in children than adults. These surgeries, like all others, are subject to complications such as bleeding, infection, and CSF leak. The rate of incidental durotomy in the pediatric population, and its associated complications, has scarcely been reported in the literature.METHODSThis is a retrospective chart review of all pediatric patients operated on at Wake Forest Baptist Health from 2012 to 2017 who underwent spine surgeries. The authors excluded any procedures with intended durotomy, such as tethered cord release or spinal cord tumor resection.RESULTSFrom 2012 to 2017, 318 pediatric patients underwent surgery for a variety of indications, including adolescent idiopathic scoliosis (51.9%), neuromuscular scoliosis (27.4%), thoracolumbar fracture (2.83%), and other non-fusion-related indications (3.77%). Of these patients, the average age was 14.1 years, and 71.0% were female. There were 6 total incidental durotomies, resulting in an overall incidence of 1.9%. The incidence was 18.5% in revision operations, compared to 0.34% for index surgeries. Comparison of the revision cohort to the durotomy cohort revealed a trend toward increased length of stay, operative time, and blood loss; however, the trends were not statistically significant. The pedicle probe was implicated in 3 cases and the exact cause was not ascertained in the remaining 3 cases. The 3 durotomies caused by pedicle probe were treated with bone wax; 1 was treated with dry Gelfoam application and 2 were treated with primary repair. Only 1 patient had a persistent leak postoperatively that eventually required wound revision.CONCLUSIONSIncidental durotomy is an uncommon occurrence in the pediatric spinal surgery population. The majority occurred during placement of pedicle screws, and they were easily treated with bone wax at the time of surgery. Awareness of the incidence, predisposing factors, and treatment options is important in preventing complications and disability.

Cerebral Abscess in Young Adult with Hypoplastic Left Heart Syndrome.

BACKGROUND: Cerebral abscesses are rare, potentially life-threatening entities that result from local spread or hematogenous dissemination to the brain. Prompt diagnosis and initiation of treatment is key in lowering morbidity and preventing mortality associated with cerebral abscesses. Congenital heart diseases with right-to-left intracardiac shunts can be complicated by brain abscesses via paradoxical embolism of infected microthrombi. Hypoplastic left heart syndrome (HLHS) is a rare congenital heart disease characterized by an underdeveloped left heart that uses intracardiac shunting to achieve adequate systemic circulation. We present the first reported case of a cerebral abscess in a patient with HLHS. The pathophysiology of HLHS and how it predisposes patients to development of cerebral abscesses is discussed. CASE DESCRIPTION: A 25-year-old male was transferred to our institution complaining of headache, nausea, and vomiting. The patient was not an intravenous (IV) drug user, and serologic testing was negative for human immunodeficiency virus. Magnetic resonance imaging revealed a 2.6-cm left occipital abscess, which was surgically resected without complication, and the patient was treated with IV antibiotics. CONCLUSION: HLHS is a rare congenital cardiac malformation. The long-term outcome of patients with this condition continues to improve as treatment paradigms evolve. As such, patients with HLHS are living longer, and their potential to develop cerebral abscesses secondary to their unique systemic circulation is increasing with improved life expectancy. Surgeons and physicians should maintain a high index of suspicion for cerebral abscess in the setting of HLHS.

Lifting the veil on stroke outcomes: revisiting stroke centers' transparency through public reporting of metrics.

Public reporting of healthcare metrics provides transparency that allows patients and emergency medical providers to make informed decisions about where patients should receive care. Most previous reports about public reporting of health metrics have demonstrated significant improvements in outcome metrics after implementation. However, no mechanism exists, voluntary or otherwise, for the public reporting of outcomes of stroke care. We review the components of public reporting of health outcomes data and its limited history in stroke outcomes. We summarize the literature on public reporting in cardiovascular interventions, particularly percutaneous coronary interventions, as a close corollary to mechanical neurothrombectomy. The benefits, limitations, and controversies associated with reporting of cardiovascular outcomes are reviewed with a focus on the development of risk-avoidant behaviors. This article serves as a primer for discussion of the potential benefits, limitations, and unintended consequences of public reporting of stroke data.

Occipital Condyle Fractures and Concomitant Cervical Spine Fractures: Implications for Management.

BACKGROUND: Occipital condyle fractures (OCFs) have traditionally been described based on anatomic characteristics; however, recent literature has proposed management based on biomechanical stability and neural element compression. The treatment of biomechanically stable fractures varies between observation and cervical immobilization. Before determining the best management approach, an understanding of concomitant cervical spine fractures in the presence of OCFs is important. The primary aim of this pilot study was to determine the rate of occurrence of biomechanically significant cervical spine fractures with OCFs. METHODS: A retrospective chart review was performed of 13,363 patients presenting to a level 1 trauma center between 2013 and 2017 with a diagnosis of OCF. RESULTS: Forty-six patients presented with OCFs, with an average Glasgow Coma Scale score of 12 on presentation and an average Injury Severity Score of 23. The average patient age was 42.1 years, and 4 patients had bilateral OCFs. Approximately 30% of these patients had associated intracranial injuries and 59% had an associated cervical spine injury. The overall rate of associated potentially biomechanically significant cervical spine fracture was 43.5%. Treatment of OCFs included collar immobilization (83%) and observation (17%). The average duration of follow-up was 3.37 months. CONCLUSIONS: This study characterizes cervical spine fractures that occur concomitantly with OCFs. The results indicate that more than one-half of patients with OCFs do not have biomechanically significant fractures elsewhere in the cervical spine. This subset of patients will be the cohort for a prospective study to assess whether collar immobilization is necessary.

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.