Real-time trajectory guide tracking for intraoperative MRI-guided neurosurgery.

PURPOSE: In current intraoperative MRI (IMRI) methods, an iterative approach is used to aim trajectory guides at intracerebral targets: image MR-visible features, determine current aim by fitting model to image, manipulate device, repeat. Infrequent updates are produced by such methods, compared to rapid optically tracked stereotaxy used in the operating room. Our goal was to develop a real-time interactive IMRI method for aiming. METHODS: The current trajectory was computed from two points along the guide's central axis, rather than by imaging the entire device. These points were determined by correlating one-dimensional spokes from a radial sequence with the known cross-sectional projection of the guide. The real-time platform RTHawk was utilized to control MR sequences and data acquisition. On-screen updates were viewed by the operator while simultaneously manipulating the guide to align it with the planned trajectory. Accuracy was quantitated in a phantom, and in vivo validation was demonstrated in nonhuman primates undergoing preclinical gene ( n = 5 $$ n=5 $$ ) and cell ( n = 4 $$ n=4 $$ ) delivery surgeries. RESULTS: Updates were produced at 5 Hz In 10 phantom experiments at a depth of 48 mm, the cannula tip was placed with radial error of (min, mean, max) = (0.16, 0.29, 0.68) mm. Successful in vivo delivery of payloads to all 14 targets was demonstrated across nine surgeries with depths of (min, mean, max) = (33.3, 37.9, 42.5) mm. CONCLUSION: A real-time interactive update rate was achieved, reducing operator fatigue without compromising accuracy. Qualitative interpretation of images during aiming was rendered unnecessary by objectively computing device alignment.

Academics versus the Internet: Evaluating the readability of patient education materials for cerebrovascular conditions from major academic centers.

Background: Health literacy profoundly impacts patient outcomes as patients with decreased health literacy are less likely to understand their illness and adhere to treatment regimens. Patient education materials supplement in-person patient education, especially in cerebrovascular diseases that may require a multidisciplinary care team. This study aims to assess the readability of online patient education materials related to cerebrovascular diseases and to contrast the readability of those materials produced by academic institutions with those of non-academic sources. Methods: The readability of online patient education materials was analyzed using Flesch-Kincaid Grade Level (FKGL) and Flesch Reading Ease (FRE) assessments. Readability of academic-based online patient education materials was compared to nonacademic online patient education materials. Online patient education materials from 20 academic institutions and five sources from the web were included in the analysis. Results: Overall median FKGL for neurovascular-related patient online education documents was 11.9 (95% CI: 10.8-13.1), reflecting that they are written at a 12th grade level, while the median FRE was 40.6 (95% CI: 34.1-47.1), indicating a rating as "difficult" to read. When comparing academic-based online patient education materials to other internet sources, there was no significant difference in FRE and FKGL scores (P = 0.63 and P = 0.26 for FKGL and FRE, respectively). Conclusion: This study demonstrates that online patient education materials pertaining to cerebrovascular diseases from major academic centers and other nonacademic internet sites are difficult to understand and written at levels significantly higher than that recommended by national agencies. Both academic and nonacademic sources reflect this finding equally. Further study and implementation are warranted to investigate how improvements can be made.

Candida Shunt Infection Causing Arachnoiditis and Hydrocephalus: A Case Report.

Arachnoiditis is a relatively rare condition and can result in long-term chronic and debilitating complications if not diagnosed early and treated properly. However, diagnosis of arachnoiditis is rare and knowledge of potential causes of this condition is still sparse. Current known causes of arachnoiditis include infections, trauma, spinal tumors, and iatrogenic causes induced via neurological interventions. Here, we present a case of a 65-year-old female who presented with arachnoiditis caused by Candida albicans infection from a contaminated ventriculoperitoneal (VP) shunt, placed following the development of hydrocephalus from subarachnoid hemorrhage. During her initial assessment, the possibility of arachnoiditis was raised after spinal magnetic resonance imaging (MRI) due to leg weakness and spasms with bladder dysfunction. However, further workup was not pursued after a normal spinal angiogram and lack of constitutional symptoms. She presented six months later with symptoms of fever and lower abdominal pain. She was diagnosed with fungal arachnoiditis after a computerized tomography (CT) of the abdomen showed thickening of the fascia around the shunt catheter and fluid collections near the tip of the shunt in the abdominal cavity after hospitalization. The diagnosis was made after an ultrasound-guided tap of the same area revealed budding yeast and cerebrospinal fluid (CSF) showed growths of Candida albicans. Her shunt was removed, and she received intravenous (IV) antifungals and recovered. MRI should be considered with clinical presentations that are characteristic of arachnoiditis. Symptoms from fungal infections are usually dramatic; however, in some instances as in this case, they may follow a more progressive course. The patient should be extensively evaluated for infection, especially fungal, in interventions involving device placement even when minimally, but persistently, symptomatic.

Surgical Indications and Options for Hypertensive Hemorrhages.

The morbidity and mortality associated with spontaneous intracerebral haemorrhage high, with 40% reported mortality at 1 month and fewer than 40% of patients regaining functional independence. Despite advances made in the treatment of ischemic stroke, similar improvements have not been seen with intracerebral hemorrhage. Medical control of blood pressure and intracranial pressure, among other factors, are key to management. The impact of surgical intervention is less clear. This article reviews the data surrounding the surgical management of intracerebral hemorrhage, including open and minimally invasive techniques and discusses the controversies and future directions surrounding surgical management.

Delayed spinal epidural hematoma following T1 chance fracture: An illustrative case and review of the literature.

Background: A Chance fracture is a traumatic fracture of the thoracic or lumbar spine that occurs secondary to a flexion-distraction injury. Although patients with chance fractures rarely present with neurologic deficits, a subset may become symptomatic from spinal epidural hematomas (SEH) warranting emergent decompressive surgery. Case Description: An 87-year-old female on anticoagulation presented with a T1 Chance fracture after a fall. She was originally neurologically intact, but became paraplegic over the next 10 h. When the cervical/thoracic magnetic resonance revealed a SEH markedly compressing the cord between the C7-T1 levels, she underwent an emergent decompression; she also had a C5-T4 instrumented fusion. Postoperatively, she regained lower limb function, but expired on postoperative day 5 due to respiratory complications likely attributed to the prolonged surgery for the spinal instrumentation. Conclusion: Delayed SEH rarely occur following spinal Chance fractures. Here, an 87-year-old female on anticoagulation developed the 10-h delayed onset of a SEH with paraplegia attributed to a T1 Chance fracture at the C7-T1 level. Although she regained neurological function following the emergent decompression, she expired 5 days later likely due to the extended operative time/blood loss from the C5-T4 fusion that could have been avoided.

Atypical Teratoid/Rhabdoid Tumor of the Cerebellum in an Adult: Case Report and Literature Review.

BACKGROUND: Atypical teratoid/rhabdoid tumor (AT/RT) is a rare tumor that is most frequently encountered in the pediatric patient population. AT/RT accounts for approximately 1%-2% of all pediatric central nervous system tumors and roughly 10%-20% of tumors in patients younger than 3 years of age. While AT/RT has been encountered in the adult population, the vast majority of the cases reported occur in the supratentorial space. In the existing literature, only 3 adult cases that arise from the cerebellum have ever been reported. CASE DESCRIPTION: A 38-year-old female presented with 6 months of worsening nausea, emesis, vertigo, diplopia, and coordination difficulty. Magnetic resonance imaging revealed a T1 avidly contrast-enhancing mass, composed of both cystic and solid areas, extending from the cerebellum into the fourth ventricle. Following a gross total resection, surgical pathology was consistent with AT/RT, with tumor cell loss of integrase interactor-1 (INI-1) observed via immunohistochemical staining. CONCLUSIONS: This case represents just the fourth ever reported case of AT/RT arising from the cerebellum in an adult and the oldest reported age to date of a cerebellar AT/RT occurring in a female. Due to the paucity of reported adult AT/RT cases, little is known about adults with AT/RT. Further reports will function to improve the general understanding of AT/RT in the adult population.

Intraoperative Shortening of Aneurysm Clips: Revisiting an Old Technique in a New Era.

BACKGROUND: It can sometimes be challenging to find a suitable clip to treat an unusual aneurysm, or when the surrounding anatomy is unusual, especially in resource-limited environments. We describe a method to modify aneurysm clips based on the method originated by Sugita et al in 1985. Herein clip modification (Clip-Mod) is used to treat anatomically difficult anterior communicating artery aneurysms. METHODS: The Department of Neurological Surgery database was reviewed to find aneurysm patients treated using modified aneurysm clips. Clip-Mod was performed during surgery by shortening the tines of titanium aneurysm clips by abrasion applied from the side of a standard 3-mm surgical diamond drill bit under constant irrigation. Note that the thickness of the tines and the clip spring were not modified or contacted by the drill. RESULTS: Four cases used modified aneurysm clips, from 648 total clip-treated aneurysms (0.6%) by 2 surgeons over a 14-year period. Three patients presented with subarachnoid hemorrhages that were determined to be due to anterior communicating artery aneurysms. One patient presented with an incidental unruptured anterior communicating artery aneurysm. All 4 patients were treated with 3-mm titanium clips shortened intraoperatively to 1- to 2-mm lengths, to achieve aneurysm obliteration without stenosing parent or perforating vessels. CONCLUSIONS: All 4 patients have done well clinically with no reoccurrences after 2-6 years' follow-up, which included angiographic evaluation. The use of this "Clip-Mod" technique thus appears useful for anterior communicating artery aneurysms. Clip-Mod could also be considered for treating other aneurysms when the "perfect" length clip is not available.

A novel, low-cost, reusable, high-fidelity neurosurgical training simulator for cerebrovascular bypass surgery.

OBJECTIVECerebrovascular bypass surgery is a challenging yet important neurosurgical procedure that is performed to restore circulation in the treatment of carotid occlusive diseases, giant/complex aneurysms, and skull base tumors. It requires advanced microsurgical skills and dedicated training in microsurgical techniques. Most available training tools, however, either lack the realism of the actual bypass surgery (e.g., artificial vessel, chicken wing models) or require special facilities and regulations (e.g., cadaver, live animal, placenta models). The aim of the present study was to design a readily accessible, realistic, easy-to-build, reusable, and high-fidelity simulator to train neurosurgeons or trainees on vascular anastomosis techniques even in the operating room.METHODSThe authors used an anatomical skull and brain model, artificial vessels, and a water pump to simulate both extracranial and intracranial circulations. They demonstrated the step-by-step preparation of the bypass simulator using readily available and affordable equipment and consumables.RESULTSAll necessary steps of a superficial temporal artery-middle cerebral artery bypass surgery (from skin opening to skin closure) were performed on the simulator under a surgical microscope. The simulator was used by both experienced neurosurgeons and trainees. Feedback survey results from the participants of the microsurgery course suggested that the model is superior to existing microanastomosis training kits in simulating real surgery conditions (e.g., depth, blood flow, anatomical constraints) and holds promise for widespread use in neurosurgical training.CONCLUSIONSWith no requirement for specialized laboratory facilities and regulations, this novel, low-cost, reusable, high-fidelity simulator can be readily constructed and used for neurosurgical training with various scenarios and modifications.

Minimizing Retraction by Pia-Arachnoidal 10-0 Sutures in Intrasulcal Dissection.

BACKGROUND: In contemporary microneurosurgery reducing retraction-induced injury to the brain is essential. Self-retaining retractor systems are commonly used to improve visualization and decrease the repetitive microtrauma, but sometimes self-retaining retractor systems can be cumbersome and the force applied can cause focal ischemia or contusions. This may increase the morbidity and mortality. Here, we describe a technique of retraction using 10-0 sutures in the arachnoid. OBJECTIVE: To evaluate the imaging and clinical results in patients where 10-0 suture retraction was used to aid the surgical procedure. METHODS: Adjacent cortex was retracted by placing 10-0 nylon suture in the arachnoid of the bank or banks of the sulcus. The suture was secured to the adjacent dural edge by using aneurysm clips, allowing for easy adjustability of the amount of retraction. We retrospectively analyzed the neurological outcome, signal changes in postoperative imaging, and ease of performing surgery in 31 patients with various intracranial lesions including intracranial aneurysms, intra- and extra-axial tumors, and cerebral ischemia requiring arterial bypass. RESULTS: Clinically, there were no injuries, vascular events, or neurological deficits referable to the relevant cortex. Postoperative imaging did not show changes consistent with ischemia or contusion due to the retraction. This technique improved the visualization and illumination of the surgical field in all cases. CONCLUSION: Retraction of the arachnoid can be used safely in cases where trans-sulcal dissection is required. This technique may improve initial visualization and decrease the need for dynamic or static retraction.

Classification and Extraction of Resting State Networks Using Healthy and Epilepsy fMRI Data.

Functional magnetic resonance imaging studies have significantly expanded the field's understanding of functional brain activity of healthy and patient populations. Resting state (rs-) fMRI, which does not require subjects to perform a task, eliminating confounds of task difficulty, allows examination of neural activity and offers valuable functional mapping information. The purpose of this work was to develop an automatic resting state network (RSN) labeling method which offers value in clinical workflow during rs-fMRI mapping by organizing and quickly labeling spatial maps into functional networks. Here independent component analysis (ICA) and machine learning were applied to rs-fMRI data with the goal of developing a method for the clinically oriented task of extracting and classifying spatial maps into auditory, visual, default-mode, sensorimotor, and executive control RSNs from 23 epilepsy patients (and for general comparison, separately for 30 healthy subjects). ICA revealed distinct and consistent functional network components across patients and healthy subjects. Network classification was successful, achieving 88% accuracy for epilepsy patients with a naïve Bayes algorithm (and 90% accuracy for healthy subjects with a perceptron). The method's utility to researchers and clinicians is the provided RSN spatial maps and their functional labeling which offer complementary functional information to clinicians' expert interpretation.

Mask free Intravenous 3D Digital Subtraction Angiography (IV 3D-DSA) from a single C-arm acquisition.

Currently, clinical acquisition of IV 3D-DSA requires two separate scans: one mask scan without contrast medium and a filled scan with contrast injection. Having two separate scans adds radiation dose to the patient and increases the likelihood of suffering inadvertent patient motion induced mis-registration and the associated mis-registraion artifacts in IV 3D-DSA images. In this paper, a new technique, SMART-RECON is introduced to generate IV 3D-DSA images from a single Cone Beam CT (CBCT) acquisition to eliminate the mask scan. Potential benefits of eliminating mask scan would be: (1) both radiation dose and scan time can be reduced by a factor of 2; (2) intra-sweep motion can be eliminated; (3) inter-sweep motion can be mitigated. Numerical simulations were used to validate the algorithm in terms of contrast recoverability and the ability to mitigate limited view artifacts.

The myth of restenosis after carotid angioplasty and stenting.

BACKGROUND AND PURPOSE: Reported rates of in-stent restenosis after carotid artery stenting (CAS) vary, and restenosis risk factors are poorly understood. We evaluated restenosis rates and risk factors, and compared patients with 'hostile-neck' carotids (a history of ipsilateral neck surgery or irradiation) and atherosclerotic lesions. METHODS: Demographic, clinical, and radiological characteristics of patients undergoing cervical CAS between 1995 and 2010 with at least 1 month of follow-up were reviewed. Patients with substantial (≥50%) radiographic restenosis were compared with those without significant restenosis to identify restenosis risk factors. RESULTS: The analysis included 121 patients with 133 stented vessels; 91 (68.4%) lesions were symptomatic. Indications for stent placement included hostile-neck lesions, substantial surgical comorbidities, inclusion in a randomized carotid stenting trial, acute carotid occlusion, tandem stenosis, large pseudoaneurysm, high carotid bifurcation, and contralateral laryngeal nerve palsy. Procedures were technically successful in all but one lesion (99.2%). Perioperative stroke occurred in four cases (3.0%). Mean follow-up was 38 months (range 1-204 months), during which 23 vessels (17.3%) developed restenosis. Hostile-neck carotids (n=57) comprised 42.9% of all vessels treated and were responsible for 15 of 23 restenosis cases, resulting in a significantly higher restenosis rate than that of primary atherosclerotic lesions (26.3% vs 10.5%, p=0.017). By univariate analysis, the presence of calcified plaque was significantly associated with the incidence of in-stent restenosis (p=0.02). CONCLUSIONS: Restenosis rates after carotid angioplasty and stenting are low. Patients with a history of ipsilateral neck surgery or irradiation are at higher risk for substantial radiographic and symptomatic restenosis.

Surgical and endovascular treatment of pediatric spinal arteriovenous malformations.

OBJECTIVE: Pediatric spinal arteriovenous malformations (AVMs) are rare and complex lesions to treat. There are few reports of the endovascular and microsurgical treatment of these lesions in the pediatric population, and the treatment outcomes of these patients are not well described. The aim of this study was the clinical and radiographic outcomes of spinal AVMs in pediatric patients treated via endovascular and microsurgical modalities. METHODS: We identified nine children (5 boys, 4 girls; average age 11 years, range 3-17 years) treated for spinal AVMs between 1998 and 2010. Their charts were reviewed. RESULTS: Spinal AVMs most frequently involved the thoracic spinal cord. Four patients had associated Klippel-Trènaunay-Weber syndrome and one had hereditary hemorrhagic telangiectasia. There were two intramedullary, four conus medullaris, and three mixed extradural-intradural lesions. The most common presenting signs and symptoms were subarachnoid hemorrhage (n = 3) and paraparesis (n = 5). Endovascular intervention was used exclusively in two patients, and combined endovascular and microsurgical intervention was used in four patients. Surgery was the sole treatment in three patients with excellent results. There were two treatment-related complications: one case of subarachnoid hemorrhage and one case of scrotal swelling. The mean follow-up was 28.5 months and the median was 8 months (range, 1-65 months). The mean pretreatment World Health Organization (WHO)/Zubrod score was 2.4 (range, 1-4), and the mean post-treatment score was 1.4 (range, 0-4). One patient (11%) had a recurrence. CONCLUSIONS: Pediatric spinal AVMs require complex combined microsurgical and endovascular techniques to achieve favorable outcomes.

A micro-electrocorticography platform and deployment strategies for chronic BCI applications.

Over the past decade, electrocorticography (ECoG) has been used for a wide set of clinical and experimental applications. Recently, there have been efforts in the clinic to adapt traditional ECoG arrays to include smaller recording contacts and spacing. These devices, which may be collectively called "micro-ECoG" arrays, are loosely defined as intercranial devices that record brain electrical activity on the sub-millimeter scale. An extensible 3D-platform of thin film flexible micro-scale ECoG arrays appropriate for Brain-Computer Interface (BCI) application, as well as monitoring epileptic activity, is presented. The designs utilize flexible film electrodes to keep the array in place without applying significant pressure to the brain and to enable radial subcranial deployment of multiple electrodes from a single craniotomy. Deployment techniques were tested in non-human primates, and stimulus-evoked activity and spontaneous epileptic activity were recorded. Further tests in BCI and epilepsy applications will make the electrode platform ready for initial human testing.

Flexible thin film electrode arrays for minimally-invasive neurological monitoring.

We present approaches for using thin film polymeric electrode arrays for use in applications of minimally invasive neurological monitoring. The flexibility and unique surface properties of the thin-film polyimide substrate in combination with a compact device platform make them amenable to a variety of surgical implantation procedures. Using a rapid-prototyping and fabrication technique, arrays of various geometries can be fabricated within a week. In this paper we test two different approaches for deploying electrode arrays through small cranial openings.

Surgical treatment of blood blister-like aneurysms of the supraclinoid internal carotid artery with extracranial-intracranial bypass and trapping.

OBJECT: Blood blister-like aneurysms (BBAs) arise from the supraclinoid internal carotid artery (ICA) at non-branching sites. These aneurysms are challenging to treat primarily with either surgical clip placement or endovascular therapy. The authors describe a series of 4 patients who presented with high-grade subarachnoid hemorrhage (SAH) due to a BBA, which was treated with an extracranial-intracranial (EC-IC) bypass followed by trapping of the aneurysm. METHODS: Four patients presented with SAH due to a BBA of the ICA. Three of these patients were treated with an endovascular procedure; following the vasospasm period, definitive treatment with EC-IC bypass followed by trapping of the aneurysmal parent vessel was performed. RESULTS: Two of the patients who were treated endovascularly suffered rebleeding prior to bypass and trapping. Three of the 4 patients had a good outcome (modified Rankin Scale Score 1 or 2), and 1 patient who suffered 2 episodes of rebleeding died. CONCLUSIONS: Treatment of BBAs of the ICA remains difficult, particularly in the setting of high-grade SAH. Patients with this challenging condition often require multiple procedures and have a high incidence of rebleeding. Definitive treatment of these aneurysms consists of EC-IC bypass and surgical or endovascular trapping.

Alternative vascular graft for extracranial-intracranial bypass surgery: descending branch of the lateral circumflex femoral artery.

OBJECT: Arterial bypass is an important method of treating intracranial disease requiring sacrifice of the parent vessel. The conduits for extracranial-intracranial (EC-IC) bypass surgery include the superficial temporal artery, occipital artery, superior thyroid artery, radial artery, and saphenous vein (long or short). In an aging population with an increased prevalence of vascular disease, conduits for EC-IC bypass may be in short supply in some patients. Herein, the authors describe a case in which the descending branch of the lateral circumflex femoral artery (DLCFA) was utilized as a high-flow conduit for an EC-IC bypass. METHODS: This 22-year-old woman presented with irregular menstrual periods, secondary amenorrhea, and hypothyroidism. A giant intrasellar and suprasellar mass was found. Angiography confirmed a 3.5 x 2.1-cm fusiform aneurysm involving the cavernous and supraclinoid segments of the right internal carotid artery. A suitable radial artery conduit was not available. The DLCFA was harvested and anastomosed between the M(2) segment of the middle cerebral artery and the external carotid artery. RESULTS: Durable clinical and angiographic results were apparent at the 2-month follow-up. CONCLUSIONS: The DLCFA's diameter and length were used successfully in a high-flow EC-IC bypass surgery. The DLCFA may be a good alternative to radial artery and saphenous vein grafts for an EC-IC bypass requiring high flow.

The occipital artery for posterior circulation bypass: microsurgical anatomy.

OBJECT: The microsurgical anatomy of the occipital artery (OA) was studied to describe the diameter, length, and course of this vessel as it pertains to revascularization procedures of the posterior cerebral circulation. METHODS: The authors studied 12 OAs in 6 cadaveric heads that had been injected with colored latex. They evaluated the OA's ability to serve as a conduit for extracranial-intracranial (EC-IC) bypass in the posterior circulation. They measured the length of the OA and its diameter at common sites of anastomosis and compared these values with the diameters of the recipient vessels (V(3) and V(4) segments of the vertebral artery, caudal loop of the posterior inferior cerebellar artery [PICA], and anterior inferior cerebellar artery [AICA]). RESULTS: The mean thickness of the suboccipital segment of the OA was found to be 1.9 mm. The mean distance of the OA from the external occipital protuberance was found to be 45 mm. The mean length of the suboccipital segment of the OA was 79.3 mm. The mean thickness of the largest trunk of the V(3) segment, the V(4) segment, the caudal loop of the PICA, and the AICA were 3.3 mm, 3.1 mm, 1.2 mm, and 1 mm, respectively. CONCLUSIONS: The length, diameter, and flow accomodated by the OA make it an ideal choice as a conduit for posterior circulation bypass. The bypass from the OA to the caudal loop of the PICA demonstrates the least difference in vessel diameter, and is therefore best suited for EC-IC bypass procedures in the posterior circulation.