Remote magnetic navigation enables precision telesurgery.

Medical devices actuated by external magnetic fields can create opportunities for clinical adoption of precision telesurgery.

Microsurgical Treatment of Pineal Tumors: Anatomy and Techniques.

Pineal region tumors are challenging lesions in terms of surgical accessibility and removal.1 The complexity is compounded by the infrequency and heterogeneity of pineal neoplasms.2,3 In Video 1, we present the case of a 39-year-old woman who presented with progressive headaches and vision impairment. She underwent microsurgical resection for a pineal parenchymal tumor of intermediate differentiation. We discuss the rationale, risks, and benefits of treatment for this patient, as well as provide a detailed overview of the alternative approaches that may be considered. Additionally, we discuss the unique anatomic considerations for each approach and include a virtual reality-compatible 3-dimensional fly-through to highlight the relationship between the tumor and relevant venous anatomy. The patient tolerated the procedure well with excellent neurologic outcome, and her follow-up imaging showed no evidence of tumor recurrence.

Predictive Model Evaluating Risk of Hemorrhage in Intracranial Aneurysms: Analysis from Prospectively Collected HEAT Trial Database.

OBJECTIVE: We analyzed the data of patients enrolled in the Hydrogel Endovascular Aneurysm Treatment (HEAT) trial to develop and validate a model to predict the risk of aneurysmal hemorrhage. METHODS: Analysis included data from 600 patients enrolled for the HEAT trial and included single saccular aneurysms of 3-14 mm size. Baseline characteristics were compared between patients with ruptured and unruptured aneurysms. Regression analysis was performed in the training set to identify significant risk factors and was validated in the validation dataset. The complete dataset was used to formulate a scoring model in which positive and negative predictors were assigned 1 and -1 points, respectively. RESULTS: Data from 593 patients were analyzed in which 169 (28.5%) patients had ruptured aneurysms. The training (n = 297) and validation dataset (n = 296) had a comparable proportion of ruptured aneurysms (29.3% and 27.7%). Dome-to-neck ratio >2.5 (odds ratio [OR] 3.66), irregular shape (OR 3.79), daughter sac (OR 5.89), and anterior and posterior communicating artery locations (OR 3.32 and 3.56, respectively) had a higher rupture rate. Use of aspirin was associated with lower risk of hemorrhage (OR 0.16). The area under the curve from the receiver operating curve analysis was 0.88, 0.87, and 0.87 in the training, validation, and combined data set, respectively. The scoring model created a score of -1 to 2, yielding an of aneurysmal hemorrhage probability from 1.5% (score -1) to 70% (score 2). CONCLUSIONS: This prospective study identifies dome-to-neck ratio >2.5, irregular shape, presence of daughter sac, absence of aspirin use, and aneurysm location at anterior communicating and posterior communicating artery as factors associated with increased risk of hemorrhagic presentation in small- to medium-sized intracranial aneurysms. Our model provides an estimate of rupture risk based on the presence or absence of these factors.

Cerebrospinal Venous Fistula Presenting with Cognitive Decline: Systematic Literature Review and Report of Two Cases.

OBJECTIVE: A cerebrospinal fluid (CSF) venous fistula (CVF) is an aberrant connection between the subarachnoid space and a vein resulting in CSF loss. The presentation and management of CVF with cognitive decline is incompletely understood. METHODS: A systematic review was completed following the PRISMA guidelines. Articles that included at least 1 case of imaging-confirmed CVF with details on patient treatment were included. A separate review of cases of patients with spontaneous intracranial hypotension (SIH) with frontotemporal dementia (FTD) or dementia symptoms was also completed. RESULTS: Ten CVF articles (69 patients; average age, 51.5 years) and 5 SIH with FTD or dementia articles (n = 41; average age, 55.9 years) were identified. Only 1 patients with CVF with cognitive abnormalities was identified. The most common symptom was headache in both reviews. Brain sag was identified in all patients, whereas CSF leak was identified in only 2 patients with SIH with FTD or dementia (4.9%). An epidural blood or fibrin glue patch was used in all patients with CVF and in 33 patients with SIH with FTD or dementia. Fifty-five patients with CVF (79.7%) and 27 patients with SIH with FTD or dementia (65.9%) had surgery. CONCLUSIONS: The 2 cases and literature reviews show the difficulty in diagnosis and treatment of CVF with cognitive decline. Novel imaging techniques should be used in patients with cognitive decline in whom a CSF leak is suspected. Transvenous embolization or surgery should be considered before patching for treatment of CVF-induced brain sag and resulting dementia.

Microsurgical Technique for Resection of a Cerebellopontine Angle Epidermoid Tumor.

Epidermoid tumors are slow-growing, benign, congenital lesions.1 They commonly arise in the cerebellopontine angle, fourth ventricle, suprasellar region, or spinal cord.2 Symptoms may include hearing loss, facial pain, and headaches. The management options include observation or surgical resection. If the patient has symptoms, surgical resection is the treatment option of choice with the goal of gross total resection. In Video 1, we discuss the microsurgical technique for the resection of a right cerebellopontine angle epidermoid tumor. A 22-year-old male patient presented with chronic headache, decreased right-sided hearing, right facial pain, and right facial twitching. Magnetic resonance imaging revealed the characteristic finding of an epidermoid tumor, which appeared as isointense on T1 and hyperintense on T2 with diffusion-weighted imaging. The patient was taken to the operating room, and a retrosigmoid craniotomy was performed on the basis of the transverse and sigmoid sinuses. The tumor capsule was opened, and the tumor was decompressed by removing the internal components consisting of epithelial keratin and cholesterol crystals, allowing for a gross total resection to be achieved. The patient's postoperative computed tomography scan showed no residual tumor, and the patient was discharged on postoperative day 1 in stable condition.

Clinical outcomes of first- and second-generation hydrogel coils compared with bare platinum coils: a systematic literature review.

Endovascular coiling has revolutionized intracranial aneurysm treatment; however, recurrence continues to represent a major limitation. The hydrogel coil was developed to increase packing density and improve neck healing and therefore decrease recurrence rates. In this paper, we review treatment outcomes of first- (1HCs) and second-generation (2HCs) hydrogel coils and compare them to those of bare platinum coils (BPC). A query of multiple databases was performed. Articles with at least 10 aneurysms treated with either 1HC or 2HC were selected for analysis. Collected data included aneurysm size, rupture status, initial occlusion, initial residual neck/aneurysm, packing density, mortality, morbidity, recurrence, and retreatment rates. The primary endpoint was recurrence at final follow-up. Secondary endpoints included residual neck and dome rates as well as procedure-related complications and functional dependence at final follow-up. Studies that compared 1HC to BPC showed significant lower recurrence (24% vs. 30.8%, p = 0.02) and higher packing density (58.5% vs. 24.1%, p < 0.001) in 1HC but no significant difference in initial occlusion rate (p = 0.08). Studies that compared 2HC to BPC showed lower recurrence (6.3% vs. 14.3%, p = 0.007) and retreatment rates (3.4% vs. 7.7%, p = 0.010) as well as higher packing density (36.4% vs. 29.2%, p = 0.002) in 2HC, with similar initial occlusion rate (p = 0.86). The rate of complications was not statistically different between HC (25.5%) and BPC (22.6%, p = 0.06). Based on our review, the 1HC and 2HC achieved higher packing density and lower recurrence rates compared to BPC. The safety profile was similar between both groups.

Real-Time MRI-Guided Stereotactic Aspiration of Spontaneous Intracerebral Hematoma: A Preclinical Feasibility Study.

BACKGROUND: Minimally invasive surgical techniques have reinvigorated the role of surgical options for spontaneous intracranial hematomas; however, they are limited by the lack of real-time feedback on the extent of hematoma evacuation. OBJECTIVE: To describe the development of a MRI-guided catheter-based aspiration system, the ClearPoint Pursuit Neuroaspiration Device (ClearPoint Neuro) and validation in phantom models. METHODS: In this preclinical experimental trial, 8 phantom brains with skull models were created to simulate an intracranial hematoma with 2 clot sizes, 30 cc (small clot) and 60 cc (large clot). After registration, the aspiration catheter (Pursuit device) was aligned to the desired planned trajectory. The aspiration of the clot was performed under real-time MRI scan in 3 orthogonal views. The primary end point was reduction of the clot volume to less than 15 cc or 70% of the original clot volume. RESULTS: Successful completion of clot evacuation was achieved in all models. The average postaspiration clot volume was 9.5 cc (8.7 cc for small clots and 10.2 cc for large clots). The average percentage reduction of clot volume was 76.3% (range 58.7%-85.2%). The average total procedure time (from frame registration to final postaspiration clot assessment) was 50 min. The average aspiration time was 6.9 min. CONCLUSION: This preclinical trial confirms the feasibility and efficacy of MRI-guided aspiration under real-time image guidance in simulation models for intracranial hematoma. Clinical use of the system in patients would further validate its efficacy and safety.

Awake Resection of an Arteriovenous Malformation.

Arteriovenous malformations (AVMs) are a highly complex array of abnormal arteries and veins that directly fistulize without intervening capillary beds.1 As AVMs can differ in size, location, and morphology, specific clinical management is determined for each individual patient, in conjunction with their specific goals and needs.2 This Video demonstrates the resection of an AVM located in the language area of eloquent cortex of a 38-year-old opera singer. The patient presented to the emergency department with a new-onset seizure. Magnetic resonance imaging including task-based functional imaging demonstrated a left post temporal AVM with associated hemosiderin-stained white matter and language activation just posterior to the lesion. Awake microsurgical resection was recommended given her career as an opera singer and the high-risk location of the AVM in proximity to eloquent language cortex, with additional goals of preventing further risk of hemorrhage and reduction in the risk of epilepsy. The patient underwent a left temporoparietal craniotomy with direct electrical stimulation-based language mapping and monitoring along with microsurgical resection of the AVM with image guidance, confirmed with intraoperative indocyanine green angiography. Postoperative angiography demonstrated no residual AVM with preservation of normal arterial and venous anatomy. At follow-up, the patient was clinically intact, seizure free, and off all antiepileptic medications. At 3 months, she resumed her career as an opera singer. Awake resection with intraoperative functional mapping can be used for select small AVMs to avoid injury to functional tissue and allow more aggressive resection of potentially epileptogenic tissue.

Microsurgical Clipping of a Postcoiling, Residual or Recurrent, Ruptured Anterior Communicating Artery Aneurysm.

Endovascular treatment modalities for intracranial aneurysms have seen a significant increase in popularity since the initial advent of the Guglielmi detachable coils in the early nineties.1 The publication of the International Subarachnoid Aneurysm Trial (ISAT) in addition to significant improvement in catheter and coil technology further cemented the endovascular-first approach, specifically for ruptured aneurysms.2 However, the increase in aneurysm coiling also led to a heightened awareness of its shortcomings, namely a significantly greater rate of recurrence and need for retreatment.3 The Cerebral Aneurysm Rerupture After Treatment (CARAT) study revealed that even though the rate of rerupture is low with both microsurgical and endovascular treatment modalities, the rate of rerupture is greater with incomplete versus complete aneurysm occlusion.4 Previously coiled aneurysms can be challenging to treat. While in some cases further endovascular therapies can be performed, microsurgical clipping remains a compelling alternative, specifically for small recurrent or residual ruptured aneurysms. However, microsurgical clipping of previously coiled aneurysms presents its own set of unique challenges. The presence of coils in the aneurysms increases the complexity of clip reconstruction. In addition, coil extrusion, which is often misdiagnosed as coil compaction on diagnostic imaging and therefore underreported, can further increase the risk of microsurgical dissection. In this operative video, we present a case of a postcoiling, residual or recurrent, ruptured anterior communicating artery aneurysm successfully treated through microsurgical clipping. The patient consented to the procedure as shown in this operative video (Video 1) and gave informed written consent for use of her images in publication.

A comparison of treating physician versus independent core lab assessments of post-aneurysm treatment imaging outcomes: an analysis of prospectively collected data from a randomized trial.

OBJECTIVE: Aneurysm occlusion has been used as surrogate marker of aneurysm treatment efficacy. Aneurysm occlusion scales are used to evaluate the outcome of endovascular aneurysm treatment and to monitor recurrence. These scales, however, require subjective interpretation of imaging data, which can reduce the utility and reliability of these scales and the validity of clinical studies regarding aneurysm occlusion rates. Use of a core lab with independent blinded reviewers has been implemented to enhance the validity of occlusion rate assessments in clinical trials. The degree of agreement between core labs and treating physicians has not been well studied with prospectively collected data. METHODS: In this study, the authors analyzed data from the Hydrogel Endovascular Aneurysm Treatment (HEAT) trial to assess the interrater agreement between the treating physician and the blinded core lab. The HEAT trial included 600 patients across 46 sites with intracranial aneurysms treated with coiling. The treating site and the core lab independently reviewed immediate postoperative and follow-up imaging (3-12 and 18-24 months, respectively) using the Raymond-Roy occlusion classification (RROC) scale, Meyer scale, and recanalization survey. A post hoc analysis was performed to calculate interrater reliability using Cohen's kappa. Further analysis was performed to assess whether degree of agreement varied on the basis of various factors, including scale used, timing of imaging, size of the aneurysm, imaging modality, location of the aneurysm, dome-to-neck ratio, and rupture status. RESULTS: Minimal interrater agreement was noted between the core lab reviewers and the treating physicians for assessing aneurysm occlusion using the RROC grading scale (k = 0.39, 95% CI 0.38-0.40) and Meyer scale (k = 0.23, 95% CI 0.14-0.38). The degree of agreement between groups was slightly better but still weak for assessing recanalization (k = 0.45, 95% CI 0.38-0.52). Factors that significantly improved degree of agreement were scales with fewer variables, greater time to follow-up, imaging modality (digital subtraction angiography), and wide-neck aneurysms. CONCLUSIONS: Assessment of aneurysm treatment outcome with commonly used aneurysm occlusion scales suffers from risk of poor interrater agreement. This supports the use of independent core labs for validation of outcome data to minimize reporting bias. Use of outcome tools with fewer point categories is likely to provide better interrater reliability. Therefore, the outcome assessment tools are ideal for clinical outcome assessment provided that they are sensitive enough to detect a clinically significant change.

Normalization of Peri-Arteriovenous Malformation Hemodynamics Prior to Direct Microsurgery: 2-Dimensional Operative Video.

Arteriovenous malformations (AVMs) are highly complex vascular lesions characterized by abnormal connections between arteries and an intervening nidus. Definitive and safe treatment of AVMs may require the combination of multiple treatment modalities to address the various complex features of the AVM.1 Endovascular embolization can be used as an adjuvant to surgery in order to control deep feeders, reduce flow, and address high-risk features such as aneurysms. In addition, by progressively reducing the AVM flow, staged embolization can lead to normalization of peri-AVM hemodynamics and therefore may decrease the risk of postresection hemorrhage.2,3 In this operative video, we present a case of a 41-yr-old female who presented with progressively worsening left-sided hemiparesis. Magnetic resonance imaging (MRI) and angiography revealed a complex right fronto-parietal AVM with significant associated edema, likely due to the vascular steal phenomenon. The area of edema, which included the motor cortex, was thought to be at high risk for postoperative hemorrhage from normal perfusion pressure breakthrough. We therefore decided to proceed with staged presurgical embolization to gradually normalize the perilesional hemodynamics, and therefore possibly reduce the risk of postoperative morbidity. The patient underwent 3 embolization sessions at 6-wk intervals. An MRI after the last embolization showed near-complete resolution of the fluid-attenuated inversion-recovery (FLAIR) signal around the AVM. Microsurgical resection was performed on the day after the last embolization. The patient tolerated the procedure well and was discharged at her neurological baseline with mild contralateral hemiparesis, which has continued to improve at follow-up. Postoperative angiography showed complete resection of the AVM. The patient consented to the procedure as shown in this operative video and gave informed written consent for use of her images in publication.

Microvascular Decompression Technique for Trigeminal Neuralgia Using a Vascular Clip.

Microvascular decompression (MVD) surgery is a well-established, effective treatment option for trigeminal neuralgia1 and hemifacial spasm.2 In 1967, Janetta et al3 introduced the concept of MVD surgery and pioneered the Janetta technique in which Teflon felt implants are placed between the trigeminal nerve and offending vessel. Though many cases are successfully managed with Teflon interposition, alternative techniques have been developed with the objective to alleviate vascular compression symptoms indefinitely, including transposition using biological glue,4 vascular clips,5,6 and a variety of "sling" techniques.7 In Video 1, we demonstrate a fenestrated clip transposition technique in the treatment of trigeminal neuralgia. We present the case of a 72-year-old female who presented with classic trigeminal neuralgia pain along the V2 and V3 distributions. Magnetic resonance imaging revealed evident compression of the trigeminal nerve by the superior cerebellar artery (SCA). A retrosigmoid craniotomy was performed, and the vascular loop of the SCA was visualized compressing the root entry zone with significant indentation of the trigeminal nerve. Wide arachnoid dissection along the SCA was carried out in order to mobilize the SCA away from the nerve. A small slit was created in the undersurface of the tentorium, and then the SCA loop was transposed to the tentorium using a fenestrated aneurysm clip. The postoperative course was uneventful, and the patient had complete resolution of her facial pain at 6-month follow-up. This method is likely an effective and durable method of decompression for trigeminal neuralgia.