1. Shah P, Bassett DS, Wisse LEM, et al. Structural and functional asymmetry of medial temporal subregions in unilateral temporal lobe epilepsy: A 7T MRI study. Hum Brain Mapp. 2019;(November 2018):2390-2398. doi:10.1002/hbm.24530
Mesial temporal lobe epilepsy (TLE) is the most common type of localization-related epilepsy, affecting approximately one in 1,000 people worldwide. Approximately 30% of TLE patients do not respond to medical therapy and are candidates for surgical removal of the seizure-generating area. Accurate seizure localization prior to surgery is crucial in order to maximize chances of seizure freedom and minimize post-surgical cognitive deficits. While approximately two-thirds of TLE patients have mesial temporal sclerosis (MTS) identified on structural MRI (TLE-MTS), the remaining one-third have normal-appearing (“nonlesional”) clinical MRI scans (TLE-NL).
In this study, the authors used 7 Tesla (7T) MRI to probe fine-grained structure and function within the MTL. Since the first 7T MRI scanner was approved by the U.S. Food and Drug Administration in late 2017, there is a need to develop tools maximizing the clinical utility of 7T data as they become more readily available. Building on their previous analyses of intra-MTL subregional connectivity in healthy adults, the authors employed an automated multi-atlas pipeline on submillimeter 7T T2-weighted MRI to segment MTL subregions in TLE patients and healthy controls. In addition to subject-specific subregional volumetric analyses, they applied graph theoretical methods to 7T resting-state BOLD-fMRI data to characterize subject-specific functional MTL subregional networks. The authors focused on asymmetry-based metrics, as structural and functional asymmetry indices have previously been used to aid in seizure lateralization.
They utilized high-resolution 7T T2-weighted magnetic resonance imaging (MRI) and resting-state BOLD-fMRI to characterize volumetric asymmetry and functional network asymmetry of MTL subregions in unilateral medically refractory TLE patients and healthy controls. They subdivided the TLE group into mesial temporal sclerosis patients (TLE-MTS) and MRI-negative nonlesional patients (TLE-NL). Using an automated multi-atlas segmentation pipeline, they delineated 10 MTL subregions per hemisphere for each subject. They found significantly different patterns of volumetric asymmetry between the two groups, with TLE-MTS exhibiting volumetric asymmetry corresponding to decreased volumes ipsilaterally in all hippocampal subfields, and TLE-NL exhibiting no significant volumetric asymmetries other than a mild decrease in whole-hippocampal volume ipsilaterally. They also found significantly different patterns of functional network asymmetry in the CA1 subfield and whole hippocampus, with TLE-NL patients exhibiting asymmetry corresponding to increased connectivity ipsilaterally and TLE-MTS patients exhibiting asymmetry corresponding to decreased connectivity ipsilaterally. Their findings provide initial evidence that functional neuroimaging-based network properties within the MTL can distinguish between TLE subtypes.
4 Figures, 1 table.
2. Nesvick CL, Oushy S, Rinaldo L, Wijdicks EF, Lanzino G, Rabinstein AA. Clinical complications and outcomes of angiographically negative subarachnoid hemorrhage. Neurology. 2019;92(20):e2385-e2394. doi:10.1212/WNL.0000000000007501
Approximately 10-15% of patients with nontraumatic subarachnoid hemorrhage (SAH) who undergo digital subtraction angiography (DSA) have no identifiable source of hemorrhage. Patients with nontraumatic SAH and a normal angiogram are said to have angiographically negative SAH. Angiographically negative hemorrhage encompasses 2 radiographic patterns of bleeding. Perimesencephalic-pattern is confined to the perimesencephalic cisterns with limited extension into the medial Sylvian fissures. Patients with perimesencephalic pattern have a well-described, distinctly benign clinical course with very low rates of hydrocephalus, delayed cerebral ischemia, and an overall excellent clinical outcome relative to patients with aneurysmal SAH. Aneurysmal-pattern angiographically negative SAH is characterized by hemorrhage extension into the lateral Sylvian and interhemispheric fissures in a fashion that resembles bleeding from a ruptured cerebral aneurysm. Multiple studies have suggested that patients with aneurysmal pattern angio negative SAH may have similar rates of delayed cerebral ischemia and poor functional outcome to those with aneurysmal SAH when taking into account pertinent risk factors.
This was a retrospective cohort study of patients with aneurysmal subarachnoid hemorrhage (aSAH), aneurysmal-pattern angiographically negative subarachnoid hemorrhage, and perimesencephalic-pattern angiographically negative subarachnoid hemorrhage (panSAH) treated at a single tertiary referral center between January 2006 and April 2018. Ninety-nine patients with angiographically negative subarachnoid hemorrhage (33 aneurysmal-pattern angiographically negative subarachnoid hemorrhage and 66 perimesencephalic-pattern angiographically negative subarachnoid hemorrhage) and 464 patients with aSAH were included in this study. Outcomes included symptomatic hydrocephalus requiring CSF drainage, need for ventriculoperitoneal shunt, radiographic vasospasm, delayed cerebral ischemia (DCI), radiographic infarction, disability level within 1 year of ictus, and at last clinical follow-up as defined by the modified Rankin Scale.
Patients with aneurysmal-pattern angiographically negative subarachnoid hemorrhage and perimesencephalic-pattern angiographically negative subarachnoid hemorrhage had similar rates of delayed cerebral ischemia and radiologic infarction, and patients with aneurysmal -pattern angiographically negative subarachnoid hemorrhage had significantly lower rates compared to aSAH. Patients with aneurysmal-pattern angiographically negative subarachnoid hemorrhage were more likely than those with perimesencephalic pattern angiographically negative subarachnoid hemorrhage to require temporary CSF diversion and ventriculoperitoneal shunt, with similar rates to those seen in aSAH. Only one patient with angiographic negative SAH died in the hospital. Compared to those with aSAH, patients with aneurysmal pattern angiographically negative subarachnoid hemorrhage were significantly less likely to have a poor functional outcome within 1 year of ictus.
Delayed cerebral ischemia is very uncommon in angiography negative SAH, but patients with aneurysmal pattern angio negative SAH have a similar need for short- and long-term CSF diversion to patients with aSAH. Nevertheless, patients with aneurysmal pattern angio negative SAH have significantly better short- and long-term outcomes.
5 figures, 2 tables with CT and Kaplan-Meier plots.
3. Vogel J, Carmona R, Ainsley CG, Lustig RA. The Promise of Proton Therapy for Central Nervous System Malignancies. Neurosurgery. 2019;84(5):1000-1010. doi:10.1093/neuros/nyy454
Proton, or charged particle therapy is characterized by a Bragg peak, in which most of the dose is deposited at the end of the particle’s range within the tissue. This results in significantly decreased exit dose and may improve the therapeutic ratio by sparing normal tissues from the relatively high doses used to control intracranial tumors without compromising dose delivered to the target. In 1946 that Robert R. Wilson proposed that accelerated protons could be used for localized cancer therapy based on their favorable depth-dose distribution. The first publication describing clinical use of proton therapy for pituitary irradiation was reported in 1957.
For a given proton beam energy, the Bragg peak is very narrow. In order to cover a tumor volume, the beams of different energies must be combined to produce a spread-out Bragg peak (SOBP). Using current technologies, a SOBP may be produced using double-scattering proton therapy (DS-PT, or passive modulation) or pencil beam scanning proton therapy (PBS-PT, or active modulation).
This nice review discusses the outcomes in several tumors using proton beam treatment, including low and high grade gliomas, meningiomas, pituitary tumors and vestibular schwannomas. They also discuss the differences in outcome between conventional fractionated and stereotactic proton treatments and future directions.
2 Figures
4. Madhavan K, Chieng LO, Armstrong VL, Wang MY. Spondylodiscitis in end-stage renal disease: a systematic review. J Neurosurg Spine. 2019;30(5):674-682. doi:10.3171/2018.9.SPINE18824
In this systematic review, a total of 30 articles met the inclusion criteria. Including the 4 patients from the authors’ patient population, 212 patients with spine infections and maintenance dialysis were identified. The patients’ ages ranged from 38 to 78 years. The duration of dialysis ranged from a few days to 16 years. The time from onset of back pain to diagnosis ranged from 3 days to 6 months. The most common causative organism was Staphylococcus aureus, followed by Staphylococcus epidermidis and gram-negative bacteria. Most of the patients were treated with antibiotics alone (76.8%), although surgery was indicated when patients presented with neurological deficits (p < 0.011). Approximately one-quarter of the patients developed neurological deficits, with devastating consequences. Fever and neurological deficits at presentation, culture positive for methicillin-resistant S. aureus, and age > 65 years were highly correlated with mortality in this analysis.
Back pain (83.3%) was manifested in a majority of patients; fever (65.3%) was a less common presentation, but it was still among the most common presenting features. The location of pain varied: cervical area in 24.5% of cases, thoracic in 31.8%, lumbar in 42.7%, and more than 1 region in 0.9%. The time to diagnosis from the onset of back pain ranged from 3 days to 6 months.
Blood cultures were only carried out in 62.5% to establish diagnosis. However, among these, only 63% of the total blood cultures returned positive. Other methods used to identify pathogens involved cultures of needle aspiration and tissue from wound debridement.
In the pooled multivariate analysis, there were several factors that were associated with mortality, although none of them reached statistical significance. Old age had the highest predictive risk. Back pain does not seem to link with mortality, as it was present in almost all patients. Neurological deficit at presentation and identification of methicillin-resistant S. aureus do contribute as positive predictors of mortality, although the relationship was not statistically significant.
Several risk factors lead to failure of antibiotics and progression of disease in patients with ESRD. Challenges to diagnosis include vague presenting symptoms, co-existing destructive spondyloarthropathy, poor immune response, chronic elevations of inflammatory markers, and recurrent bacteremia. Infectious processes are more likely to cause permanent neurological deficits than transient deficits. The authors recommend close observation and serial imaging of these patients for early signs of neurological deficits.
1 Figure, 4 tables, no imaging
5. Lawton MT, Lang MJ. The future of open vascular neurosurgery: perspectives on cavernous malformations, AVMs, and bypasses for complex aneurysms. J Neurosurg. 2019;130(5):1409-1425. doi:10.3171/2019.1.JNS182156
This is a wide ranging view of the current status of open vascular neurosurgery, and focusses on cavernous malformations, aneurysms and bypass techniques….a lot of bypass techniques.
Dr. Lawton believes that today a thriving microvascular practice requires subspecialization, a collaborative team of endovascular surgeons and vascular neurologists, supportive neurosurgical partners, an academic medical center, regional prominence, and a large catchment population. Microvascular neurosurgeons will also need a health system that funnels patients from a network of hospitals outside the region. The high-volume hospitals (top 20% by case volume) perform 60% of neurosurgical cases. After adjustments for patient morbidity and case complexity, these centers were 4.3% less expensive, and transferring 10% of patients from low-volume hospitals to high-volume hospitals would have saved about $192 million annually. These economic attributes will drive the future regionalization of microsurgery. Ironically, the future is moving back to the days of Charles Drake when patients with a lesion like a vertebrobasilar aneurysm were referred to a designated center of excellence where committed neurosurgeons gained expertise and made therapeutic advancements. Consolidation of health systems, bundled services, published outcome metrics, advancing technology, political reform, and mass marketing will likely stimulate this reformulation of neurosurgical care. Attracting patients and securing case volume has become so challenging that it is no longer possible to rely on neurosurgical prowess and reputation.
8 Figures, 1 table
6. Orlando A, Levy AS, Rubin BA, et al. Isolated subdural hematomas in mild traumatic brain injury. Part 1: the association between radiographic characteristics and neurosurgical intervention. J Neurosurg. 2019;130(5):1616-1625. doi:10.3171/2018.1.JNS171884
This was a 3.5-year, retrospective observational cohort study at a Level I trauma center. All adult trauma patients with mild traumatic brain injury and isolated subdural hematomas were included in the study. Maximum length and thickness (in mm) of acute SDHs, the presence of acute-on-chronic SDH, mass effect, and other hemorrhage-related variables were double–data entered; discrepant results were adjudicated after a maximum of 4 reviews. Patients with coagulopathy, skull fractures, no acute hemorrhage, a non-SDH ICH, or who did not undergo imaging on admission were excluded. The primary outcome was neurosurgical intervention (craniotomy, burr hole, catheter drainage of SDH, placement of intracranial pressure monitor, shunt, or ventriculostomy).
A total of 176 patients were included: 28 patients did, and 148 patients did not receive a neurosurgical intervention. Increasing head Abbreviated Injury Scale score was significantly associated with neurosurgical interventions. There was a strong correlation between the first 3 reviews on maximum hemorrhage length and maximum hemorrhage thickness. The neurosurgical intervention group had a mean maximum SDH length and thickness that were 61 mm longer and 13 mm thicker than those of the nonneurosurgical intervention group. After adjusting for the presence of an acute-on-chronic hemorrhage, for every 1-mm increase in the thickness of an isolated subdural hematoma, the odds of a neurosurgical intervention increase by 32%. There were no interventions for any SDH with a maximum thickness ≤ 5 mm on initial presenting scan.
The authors note that special attention was paid to not obtain thickness measurements too high on the skull, due to artificially larger thickness measurements secondary to the increasingly tangential nature of axial slices at higher levels. Additionally, tentorial SDHs were not measured, because coronal imaging was not available for all patients. So this is a definite limitation of the study, given that sagittal and coronal reformats were not available and utilized for measurement.
5 Tables, 1 figure
7. Hasan D, Zanaty M, Starke RM, et al. Feasibility, safety, and changes in systolic blood pressure associated with endovascular revascularization of symptomatic and chronically occluded cervical internal carotid artery using a newly suggested radiographic classification of chronically occluded. J Neurosurg. 2019;130(5):1468-1477. doi:10.3171/2018.1.JNS172858
The radiographic images of 100 consecutive subjects with chronically occluded internal carotid artery were analyzed. A new classification of chronically occluded internal carotid artery was proposed based on the morphology, location of occlusion, and presence or absence of reconstitution of the distal ICA. The classification was used to predict successful revascularization in 32 symptomatic chronically occluded internal carotid arteries in 31 patients, five of whom were female.
Four types (A–D) of radiographic chronically occluded internal carotid artery were identified:
Type A category is defined by occlusion of the cervical ICA is tapered with proximal ICA lumen patency. In addition, the cavernous and/or petrous segments are reconstituted by collateral vessels from the external carotid artery (ECA) and/or retrograde filling from the supraclinoid segment.
For type B occlusion of the cervical ICA is not tapered; instead, a stump is present, and the immediate proximal portion of the cervical ICA lumen is patent. In addition, the cavernous and/or petrous segments are reconstituted by collateral vessels from the ECA and/ or retrograde filling from the supraclinoid segment.
For type C, the occlusion of the cervical ICA is at the common carotid artery bifurcation (the cervical ICA appears completely amputated at the bifurcation), and no ICA lumen is observed. The common carotid artery continues as the ECA. However, the cavernous and/or petrous segment is reconstituted by either collateral vessels from the ECA and/or retrograde filling from the supraclinoid segment. Type D is the same as type C, except that there is no reconstitution of the cavernous and/ or petrous segments.
Types A and B (stump) were more amenable to safe revascularization than types C and D (no stump). Recanalization was successful at a rate of 68.75% (22/32 COICAs; type A: 8/8; type B: 8/8; type C: 4/8; type D: 2/8). The perioperative complication rate was 18.75% (6/32; type A: 0/8 [0%]; type B: 1/8 [12.50%]; type C: 3/8 [37.50%], type D: 2/8 [25.00%]). None of these complications led to permanent morbidity or death. Twenty (64.52%) of 31 subjects had improvement in their symptoms at the 2–6 months’ follow-up. A statistically significant decrease in systolic blood pressure (SBP) was noted in 17/21 (80.95%) patients who had successful revascularization, which persisted on follow-up.
The authors conclude that this classification of chronically occluded internal carotid artery can be used by the interventionist for guidance on the feasibility and potential success of revascularization for symptomatic COICA. The complication rate indicates less morbidity than the natural history of the disease.
Technique: They probe the interface of the occlusion using a microwire. In type A occlusions, they aim for the most tapered portion of the occlusion. In types B and C, they explore the entire surface to find a weak spot to cross the occlusion. If unsuccessful, they use an exchange 035 or 038 Glidewire to perform the same maneuvers. In some instances, when the occlusion is calcified and difficult to cross, they use the back end of the Glidewire. Once they cross the proximal occlusion, the microcatheter/catheter is advanced until they reach the patent lumen of the ICA. Once it is confirmed, the exchange Glidewire is removed and an exchange microwire is advanced through a 5-Fr Berenstein catheter. The distal tip of the exchange microwire is positioned in the distal MCA vessel. They then use the microwire as a railroad for delivering different devices to reconstruct the occluded segment from distal to proximal. A distal protection device is used unless it cannot be delivered because of technical difficulties. The carotid reconstruction is performed from distal to proximal, with coronary stents distally (Rebel, Boston Scientific; Vision, Abbott Vascular) and carotid stents proximally (Acculink and Xcat, Abbott Vascular).
4 Figures, 3 tables including the very necessary figure showing the types of carotid occlusion
8. Agam MS, Wedemeyer MA, Wrobel B, Weiss MH, Carmichael JD, Zada G. Complications associated with microscopic and endoscopic transsphenoidal pituitary surgery: experience of 1153 consecutive cases treated at a single tertiary care pituitary center. J Neurosurg. 2019;130(5):1576-1583. doi:10.3171/2017.12.JNS172318
This is a retrospective analysis of 1153 consecutive transsphenoidal pituitary adenoma resections performed at the Keck Hospital of USC between November 1992 and March 2017 was conducted. Microscopic transsphenoidal resection was performed in 85.3% of cases, and endoscopic transsphenoidal resection was performed in 14.7%. Analysis of perioperative complications and patient and tumor risk factors was conducted.
The overall median hospital stay was 3 days. There was 1 perioperative death (0.1%).
Surgical complications included:
postoperative cerebrospinal fluid leak (2.6%),
epistaxis (1.1%),
postoperative hematoma (1.1%),
meningitis (1.0%),
cranial nerve paresis (0.8%),
hydrocephalus (0.8%),
vision loss (0.6%),
stroke (0.3%),
abdominal hematoma or infection (0.2%),
carotid artery injury (0.1%),
vegetative state (0.2%).
Perioperative medical complications included:
bacteremia/sepsis (0.5%),
pneumonia (0.3%),
myocardial infarction (0.3%),
deep venous thrombosis/pulmonary embolism (0.1%).
Endocrine complications were the most frequent, including transient diabetes insipidus (4.3%), symptomatic hyponatremia (4.2%), new hypopituitarism (any axis) (3.6%), permanent diabetes insipidus (0.3%), and adrenal insufficiency (0.2%). There were no significant differences between microscopic and endoscopic approaches with regard to surgical complications (6.4% vs 8.8%) or endocrine complications (11.4 vs 11.8%). Risk factors for surgical complications included prior transsphenoidal surgery (11.4% vs 6.8%), preoperative vision loss (10.3% vs 6.8%), and presence of adenoma invasion on MRI. In one of the largest studies assessing medical and surgical complications associated with microscopic and endoscopic transsphenoidal PA resections, the rate of death or major disability was 0.26%. Risk factors for complications included prior surgical or radiation-based treatment, endocrinopathies, and invasive pituitary adenoma.
6 Tables
