Visish M. Srinivasan

The history of external ventricular drainage

External ventricular drainage (EVD) is one of the most commonly performed neurosurgical procedures. It was first performed as early as 1744 by Claude-Nicholas Le Cat. Since then, there have been numerous changes in technique, materials used, indications for the procedure, and safety. The history of EVD is best appreciated in 4 eras of progress: development of the technique (1850-1908), technological advancements (1927-1950), expansion of indications (1960-1995), and accuracy, training, and infection control (1995-present). While EVD was first attempted in the 18th century, it was not until 1890 that the first thorough report of EVD technique and outcomes was published by William Williams Keen. He was followed by H. Tillmanns, who described the technique that would be used for many years. Following this, many improvements were made to the EVD apparatus itself, including the addition of manometry by Adson and Lillie in 1927, and continued experimentation in cannulation/drainage materials. Technological advancements allowed a great expansion of indications for EVD, sparked by Nils Lundberg, who published a thorough analysis of the use of intracranial pressure (ICP) monitoring in patients with brain tumors in 1960. This led to the application of EVD and ICP monitoring in subarachnoid hemorrhage, Reye syndrome, and traumatic brain injury. Recent research in EVD has focused on improving the overall safety of the procedure, which has included the development of guidance-based systems, virtual reality simulators for trainees, and antibiotic-impregnated catheters.

Vessel perforation during stent retriever thrombectomy for acute ischemic stroke: technical details and clinical outcomes

Background Vessel perforation during stent retriever thrombectomy is a rare complication; typically only single instances have been reported. Objective To report on a series of patients whose stent retriever thrombectomy was complicated by intraprocedural vessel perforation and discuss its potential mechanisms, rescue treatment strategies, and clinical significance. Methods Cases with intraprocedural vessel perforation, where a stent retriever was used either as a primary treatment approach or as a part of a direct aspiration first pass technique (ADAPT), were included in the final analysis. Clinical data, procedural details, radiographic and clinical outcomes were collected from nine participating centers. Results Intraprocedural vessel perforation during stent retriever thrombectomy occurred in 16 (1.0%) of 1599 cases. 63% of intraprocedural perforations occurred at distal locations. Endovascular rescue techniques (most commonly, intracranial balloon occlusion for tamponade) were attempted in 50% of cases. Procedure was aborted without any rescue attempts in 44% of cases. Mortality during hospitalization and at 3 months was 56% and 63%, respectively. 25% of patients achieved good functional outcome at 3 months after the procedure. Conclusions Intraprocedural perforations during stent retriever thrombectomy were rare, but when they occurred were associated with high mortality. Perforations most commonly occurred at distal occlusion sites and were often characterized by difficulty traversing the occlusion with a microcatheter or microwire, or while withdrawing the stent retriever. Nevertheless, 25% of patients had a favorable functional outcome, suggesting that in some patients with this complication good neurological recovery is achievable.

Aneurysms with persistent patency after treatment with the Pipeline Embolization Device

The Pipeline Embolization Device (PED) was approved for the treatment of intracranial aneurysms from the petrous to the superior hypophyseal segment of the internal carotid artery. However, since its approval, its use for treatment of intracranial aneurysms in other locations and non-sidewall aneurysms has grown tremendously. The authors report on a cohort of 15 patients with 16 cerebral aneurysms that incorporated an end vessel with no significant distal collaterals, which were treated with the PED. The cohort includes 7 posterior communicating artery aneurysms, 5 ophthalmic artery aneurysms, 1 superior cerebellar artery aneurysm, 1 anterior inferior cerebellar artery aneurysm, and 2 middle cerebral artery aneurysms. None of the aneurysms achieved significant occlusion at the last follow-up evaluation (mean 24 months). Based on these observations, the authors do not recommend the use of flow diverters for the treatment of this subset of cerebral aneurysms.

Tumor Vaccines for Malignant Gliomas

Despite continued research efforts, glioblastoma multiforme (GBM) remains the deadliest brain tumor. Immunotherapy offers a novel way to treat this disease, the genetic signature of which is not completely elucidated. Additionally, these tumors are known to induce immunosuppression in the surrounding tumor microenvironment via an array of mechanisms, making effective treatment all the more difficult. The immunotherapeutic strategy of using tumor vaccines offers a way to harness the activity of the host immune system to potentially control tumor progression. GBM vaccines can react to a variety of tumor-specific antigens, which can be harvested from the patient’s unique pathological condition using selected immunotherapy techniques. This article reviews the rationale behind and development of GBM vaccines, the relevant clinical trials, and the challenges involved in this treatment strategy.

Cone-beam CT angiography (Dyna CT) for intraoperative localization of cerebral arteriovenous malformations.

Background Arteriovenous malformations (AVMs) of the brain are commonly treated in multimodality fashion, with endovascular embolization followed by surgical extirpation being one of the most effective strategies. Modern endovascular suites enable rotational angiography, also known as cone-beam CT angiography (CBCT-A), using the full capability of modern C-arm digital angiography systems. This imaging modality offers a superior image quality to current options such as digital subtraction angiography, MRI, or CT angiography. Preoperative planning can be greatly aided by the resolution of angioarchitecture seen in CBCT-A images. Furthermore, these images can be used for intraoperative neuronavigation when integrated with widely used frameless stereotactic systems. The utility and outcome of the use of CBCT-A for preoperative planning and intraoperative localization of AVMs was evaluated. Methods A retrospective review was performed of 16 patients in which CBCT-A was performed, including radiological review and all clinical data. Results CBCT-A was successfully employed in all cases including those with (n=9) and without (n=7) rupture. Complete resection confirmed by postoperative angiography was achieved in all cases. Conclusions We present a novel application of CBCT-A in the treatment of AVMs, both for preoperative surgical planning and an intraoperative reference during neuronavigation.

Nuances in Localization and Surgical Treatment of Syringomyelia Associated with Fenestrated and Webbed Intradural Spinal Arachnoid Cyst: A Retrospective Analysis.

INTRODUCTION Intradural spinal arachnoid cysts (SACs) are among many etiologies for syringomyelia. Consequentially, neurologic symptoms arise such as pain, gait disturbance, and bladder dysfunction. Identification of SAC on magnetic resonance imaging (MRI) can be challenging, as SACs can be fenestrated or in the form of fine webs. METHODS Imaging and clinical data for 7 patients who underwent surgical treatment for SAC associated with syringomyelia were reviewed. All previous publications of this pathology were reviewed via MEDLINE search. RESULTS Seven patients with a mean age 59 years were found to have a SAC causing syringomyelia. Intraoperative exploration confirmed SAC appearances of fine webs or a fluid-filled loculation impinging on the spinal cord. Common presentations were back pain, gait disturbance, and bladder incontinence. Diagnosis was made by MRI, although in 3 cases, the SAC was not identified on the initial review. Computed tomography myelogram was performed in one case due to the enlarged syringomyelia and lack of obvious spinal cord compression. Thoracic laminectomy/laminoplasty was performed for all patients, centered at the level of a subtle indentation of the cord; the syringomyelia proper was not directly addressed. Postoperatively, all patients had complete resolution of their symptoms with MRI demonstrating resolution of the syringomyelia. CONCLUSIONS Careful evaluation of the MRI can demonstrate subtle indentation of the cord at the caudal or cephalad end of the syringomyelia and may obviate the need for additional imaging. Meticulous arachnoid dissection and establishment of good CSF flow is sufficient for resolution of the syringomyelia, averting the need for more aggressive procedures.

Pediatric National Surgical Quality Improvement Program: Useful for Quality Improvement in Craniosynostosis Surgery?

Abstract The American College of Surgeons and the American Pediatric Surgical Association collaborate to provide pediatric hospitals with multispeciality surgical outcomes data through the Pediatric National Surgical Quality Improvement Program (NSQIP Peds). The authors used this national multicenter database to describe 30-day outcomes from craniosynostosis surgery and identify associations with perioperative events and blood transfusion. Data from NSQIP Peds were used to describe children undergoing craniosynostosis surgery. The authors examined statistical association of clinical risk factors with the defined end point outcomes of perioperative complications and blood transfusion. Five hundred seventy-two surgeries were included. By Common Procedural Terminology codes, 93 identified as single suture synostosis, the remainder as multiple or unknown suture involvement. Location of the affected suture is not captured. Mean surgical time was 196.84 minutes (SD 113.46). Mean length of stay was 4.22 days (SD 5.04). Sixty-seven percent of patients received blood transfusions. 3.15% were other perioperative occurrences, including infection, wound disruption, unplanned reintubation, stroke/hemorrhage, cardiac arrest, seizures, thromboembolism. 2.8% were readmitted; 2.45% underwent reoperation within 30 days. Duration of surgery and length of hospital stay significantly differed in the presence of blood transfusion versus none. On multivariate analysis, duration from anesthesia start to surgery start, duration from surgery end to anesthesia end, and duration of operation were risk factors for blood transfusion. Pediatric NSQIP gives a national overview of 30-day outcome metrics in craniosynostosis surgery. Perioperative adverse event rate was 3.15%. Duration of surgery and duration of anesthesia were significantly associated with blood transfusion. The authors identified opportunities for pediatric NSQIP database improvement.

The burden of neurothrombectomy call: a multicenter prospective study

Introduction Neurothrombectomy frequency is increasing, and a better understanding of the neurothrombectomy call burden is needed. Methods Neurointerventional physicians at nine participating stroke centers prospectively recorded time requirements for all neurothrombectomy (NT) consultations over 30 consecutive 24 hour call periods. Results Data were collected from a total of 270 days of call. 214 NT consultations were reported (mean 0.79 per day), including 130 ‘false positive’ consultations that ultimately did not lead to thrombectomy (mean 0.48 per day). 84 NT procedures were performed at the nine centers (0.32 per day, or 1 every 3 days). Most (59.8%) consultations occurred between 5pm and 7am. 30% of thrombectomy procedures resulted in delays in scheduled cases; treating physicians had to emergently travel to the hospital for 51.2% of these cases. A median of 27 min was spent on each false positive consultation and 171 min on each thrombectomy. Overall, the median physician time spent on NT responsibilities per 24 hour call period was 69 min (mean 85 min; IQR 16–135 min). Conclusions NT consultations are frequent and often disrupt physician schedules, requiring physicians to commute in from home after hours in the majority of cases. As procedural and consultation volumes increase, it is crucial to understand the significant burden of call on neurointerventional physicians and develop strategies that reduce the potential for burnout. Importantly, this study was performed prior to the completion of the DAWN and DEFUSE3 trials; NT consultations are expected to continue to increase in the future.

Craniosynostosis surgery: the legacy of Paul Tessier

Paul Louis Tessier is recognized as the father of craniofacial surgery. While his story and pivotal contributions to the development of the multidisciplinary practice of craniofacial surgery are much highlighted in plastic surgery literature, they are seldom directly discussed in the context of neurosurgeons. His life and legacy to craniosynostosis and neurosurgery are explored in the present paper.

Flow diversion for the treatment of posterior inferior cerebellar artery aneurysms: a novel classification and strategies

Background The pipeline embolization device (PED) is frequently used in the treatment of anterior circulation aneurysms, especially around the carotid siphon, with generally excellent results. However, treatment of posterior inferior cerebellar artery (PICA) aneurysms with flow diversion (FD) has not been specifically described or discussed. While there are reports of treating PICA aneurysms using placement of FD stents in the vertebral artery, there are no reports of treating these lesions by placement of flow diverting stents in the PICA vessel itself. Due to the unique anatomy and morphology of these aneurysms, it requires special attention. We assessed our multi-institutional experience treating these lesions, including the first reported cases of the PED placed within the PICA. Methods Institutional databases of neuroendovascular procedures were reviewed for cases of intracranial aneurysms treated with the PED. Patient and aneurysm data as well as angiographic imaging were reviewed for all cases of PICA aneurysms treated with the PED. PICA aneurysms were defined as aneurysms that involved the PICA. Vertebral aneurysms without disease in the PICA were excluded from the study. Results 10 PICA aneurysms were treated during the study period. These were classified based on their morphology and location into two main types and five total subtypes for consideration of treatment with flow diversion. All aneurysms were successfully treated, with 8/10 completely obliterated and 2 with a partial reduction in size. Three patients had the PED placed entirely in the PICA and no patient suffered from a medullary or cerebellar stroke. All PEDs were patent and all patients were independent at the last follow-up. Conclusions The PED may be used successfully to treat select aneurysms of the PICA. We present the first described cases of successful PED treatment of PICA aneurysms with direct placement of the PED in the PICA vessel itself. The proposed classification system aids in that selection.