1. Meyer L, Stracke CP, Jungi N, et al. Thrombectomy for primary distal posterior cerebral artery occlusion stroke: the TOPMOST study. JAMA Neurol 2021;78:434–44

The objective of this study was to investigate the frequency as well as the clinical and safety outcomes of mechanical thrombectomy for isolated posterior circulation distal, medium vessel occlusion stroke and to compare them with the outcomes of standard medical treatment with or without intravenous thrombolysis (IVT) in daily clinical practice. This multicenter case-control study analyzed patients who were treated for primary distal occlusion of the posterior cerebral artery (PCA) of the P2 or P3 segment. These patients received mechanical thrombectomy or standard medical treatment (with or without IVT) at 1 of 23 comprehensive stroke centers in Europe, the United States, and Asia between January 1, 2010, and June 30, 2020. Of 243 patients from all participating centers who met the inclusion criteria, 184 patients were matched. Among these patients, the median age was 74 years and 51.6% were female individuals. Posterior circulation distal, medium vessel occlusions were located in the P2 segment of the PCA in 149 patients (81.0%) and in the P3 segment in 35 patients (19.0%). At discharge, the mean NIHSS score decrease was −2.4 points in the standard medical treatment cohort and −3.9 points in the mechanical thrombectomy cohort, with a mean difference of −1.5 points.  Significant treatment effects of mechanical thrombectomy were observed in the subgroup of patients who had higher NIHSS scores on admission of 10 points or higher and in the subgroup of patients without IVT.

The fragility of distal smaller-sized vessels has always been a major concern in endovascular stroke treatment because of its increased risk for complications that lead to intracerebral hemorrhage and are associated with poor outcomes, especially in patients who are eligible for IVT. The present multicenter analysis did not substantiate this concern. They observed similar rates of symptomatic bleeding events in both treatment cohorts (4.3%) that did not exceed the results of previous thrombectomy RCTs and large registry data on anterior LVO strokes.

Although rarely performed at comprehensive stroke centers, mechanical thrombectomy for posterior circulation DMVO is a safe, and technically feasible treatment option for occlusions of the P2 or P3 segment of the PCA compared with standard medical treatment with or without IVT.

2 tables, 3 figures, no imaging

2. Mandia D, Shor N, Benoist JF, et al. Adolescent-onset and adult-onset vitamin-responsive neurogenetic diseases: a review. JAMA Neurol 2021;78:483–90

This article reviews all articles reporting cases of patients with a genetically confirmed inherited vitamin-responsive neurological disease and neurological onset after the age of 10 years. On this basis, 24 different diseases are described, involving vitamins A, B1, B2, B3, B6, B8, B9, B12, E, and tetrahydrobiopterin (BH4). Information such as clinical symptoms, disease course, imaging studies, biochemical alterations, and response to treatment present an overall picture of these patients.

Wernicke encephalopathy is an acquired clinical condition caused by a thiamin (or vitamin B1) deficiency, often in a context of malnutrition and/or disordered alcohol use. The encephalopathy is usually associated with peculiar features, such as cerebellar syndrome, seizures, ophthalmoplegia, and/or ptosis. A close phenotype can be seen in adults in 2 thiamin-associated neurogenetic diseases: biotin-thiamin–responsive encephalopathy (BTRE) and E1-α pyruvate dehydrogenase deficiency (PDHAD). These 2 conditions are treatable causes of the genetically heterogeneous Leigh syndrome.

MR imaging typically shows T2 hyperintensities of caudate heads and putamen, as in Leigh syndrome, but also mesial thalami and periacqueductal gray matter, as in Wernicke encephalopathy. In biotin-thiamin–responsive encephalopathy, a cortical involvement with scattered foci of T2 hyperintensities has also been described in the acute phases of the disease.

Biotinidase is an enzyme responsible for the recycling of biotin (vitamin B8), the cofactor for human carboxylases. Biotinidase deficiency results therefore in biotin deficiency, reduction of carboxylases activity, and consequent impairment of several metabolic pathways, such as gluconeogenesis, fatty acids biosynthesis, and amino acids catabolism. As in other energetic defects (eg, biotin-thiamin–responsive encephalopathy), symptoms are often exacerbated by a stressful event, such as fever or trauma. From a clinical point of view, late forms present with bilateral optic neuropathy and longitudinally extensive myelopathy and therefore should be investigated in cases of seronegative or refractory neuromyelitis optica.

4 figures including MRI

3. Müller DMJ, Robe PA, Ardon H, et al. Quantifying eloquent locations for glioblastoma surgery using resection probability maps. J Neurosurg 2021;134:1091–101

Resectability has been expressed as percentage resectable volume of the preoperative tumor volume or as volume of residual tumor, and notable disagreement has been reported between expected and observed resectability. Reports have estimated a minimum threshold for extent of resection (EOR) between 78% and 98%, and a maximum residual volume between 1 and 5 ml to prolong survival of glioblastoma.

Brain regions to avoid during surgery are sometimes referred to as “eloquent,” i.e., functionally of critical importance, which will result in loss of brain functions if removed or damaged. Nowadays intraoperative stimulation mapping is the standard to identify these brain regions in individual patients. It helps, however, to have a measure of brain function prior to surgery to guide decisions on biopsies and whether and where in the brain to apply intraoperative stimulation mapping.

Another source of potentially useful information before surgery is resection probability maps based on a large number of prior resections. Resection probability maps of nonenhancing glioma have been previously used to estimate the resection result, to evaluate the potential for brain plasticity, and to compare resection results between surgical teams.

The authors determined the diagnostic accuracy of the “expected residual tumor volume” (eRV) and the “expected resectability index” (eRI) as preoperative measures to guide biopsy decisions, estimate resectability, and predict functional outcome and survival in comparison with eloquence grade (Sawaya et al).

Consecutive patients with first-time glioblastoma surgery in 2012–2013 were included from 12 hospitals. The expected residual tumor volume was calculated from the preoperative MR images of each patient using a resection probability map, and the expected resectability index was derived from the tumor volume. As reference, Sawaya’s tumor location eloquence grades (EGs) were classified. Resectability was measured as observed extent of resection (EOR) and residual volume, and functional outcome as change in Karnofsky Performance Scale score. Receiver operating characteristic curves and multivariable logistic regression were applied.

Of 915 patients, 674 (74%) underwent a resection with a median EOR of 97%, functional improvement in 71 (8%), functional decline in 78 (9%), and median survival of 12.8 months. The expected resectability index and expected residual tumor volume identified biopsies and EORs of at least 80%, 90%, or 98% better than EG.

They conclude that the expected residual tumor volume and expected resectability index predict biopsy decisions, resectability, and survival better than eloquence grading and may be useful preoperative indices to support surgical decisions.

6 figures with MRI

4. Dmytriw AA, Kapadia A, Enriquez-Marulanda A, et al. Vertebral artery aneurysms and the risk of cord infarction following spinal artery coverage during flow diversion. J Neurosurg 2020;1–10. Available from: https://thejns.org/view/journals/j-neurosurg/aop/article-10.3171-2020.1.JNS193293/article-10.3171-2020.1.JNS193293.xml

Coverage of the anterior spinal artery (ASA) ostia is a source of considerable consternation regarding flow diversion (FD) in vertebral artery (VA) aneurysms due to cord supply. The authors sought to assess the association between coverage of the ASA, posterior spinal artery (PSA), or lateral spinal artery (LSA) ostia when placing flow diverters in distal VAs and clinical outcomes, with emphasis on cord infarction.

Sixty patients with 63 VA and posterior inferior cerebellar artery aneurysms treated with FD were identified. The median aneurysm diameter was 7 mm and fusiform type was the commonest morphology (42.9%). During a procedure, 1 (61.7%) or 2 (33.3%) flow diverters were placed. Complete occlusion was achieved in 71.9%. Symptomatic thromboembolic complications occurred in 7.4% of cases and intracranial hemorrhage in 10.0% of cases. The ASA was identified in 51 (80.9%) and covered by the flow diverter in 29 (56.9%). Patency after flow diverter coverage on last follow-up was 89.2% for ASA and 100% for PSA/LSA, not significantly different between covered and noncovered groups (p = 0.5 and p > 0.99, respectively). No complications arose from coverage.

This multicenter study evaluated the association of ASA and PSA/LSA ostia coverage after FD with the risk for spinal infarction to assess whether this was relevant to flow diverter placement in the intracranial VA. The study showed no significant change in ASA or PSA/LSA patency after coverage with an FD stent.

4 tables, 3 figures

5. Przybylowski CJ, Zhao X, Baranoski JF, et al. Preoperative embolization versus no embolization for WHO grade I intracranial meningioma: a retrospective matched cohort study. J Neurosurg 2020;134(March):1–8

The authors reviewed the cases of all patients who underwent resection of a WHO grade I intracranial meningioma at their institution from 2008 to 2016. Propensity score matching was used to generate embolization and nonembolization cohorts of 52 patients each, and a retrospective review of clinical and radiological outcomes was performed.

52 consecutive patients who underwent embolization were compared to 52 patients who did not undergo embolization. Variables controlled for included patient age, tumor laterality, tumor location, tumor diameter, tumor invasion into a major dural sinus, and tumor encasement around the internal carotid artery or middle cerebral artery. The embolization and nonembolization cohorts did not differ in terms of estimated blood loss during surgery, Simpson grade IV resection, perioperative procedural complications, development of permanent new neurological deficits, or favorable modified Rankin Scale (mRS) score (a score of 0–2) at last follow-up, respectively. When comparing the final mRS score to the preoperative mRS score, patients in the embolization group were more likely than patients in the nonembolization group to have an improvement in mRS score.

After controlling for patient age, tumor size, tumor laterality, tumor location, tumor invasion into a major dural sinus, and tumor encasement of the ICA or MCA, preoperative tumor embolization intended to decrease tumor vascularity did not improve the surgical outcomes of patients with WHO grade I intracranial meningiomas, but it did lead to a greater chance of clinical improvement compared to patients not treated with embolization, but the likelihood of being functionally independent at last follow-up did not differ between groups.

5 tables, no imaging

6. Chiarini G, Cho S-M, Whitman G, et al. Brain injury in extracorporeal membrane oxygenation: a multidisciplinary approach. Semin Neurol 2021 Apr 13. Available from: http://www.thieme-connect.de/DOI/DOI?10.1055/s-0041-1726284

Extracorporeal membrane oxygenation (ECMO) represents an established technique to provide temporary cardiac and/or pulmonary support. ECMO, in veno-venous, venoarterial or in extracorporeal carbon dioxide removal modality, is associated with a high rate of brain injuries. These complications have been reported in 7-15% of adults and 20% of neonates, and are associated with poor survival. Thromboembolic events, loss of cerebral autoregulation, alteration of the blood–brain barrier, and hemorrhage related to anticoagulation represent the main causes of severe brain injury during ECMO. The most frequent forms of acute neurological injuries in ECMO patients are intracranial hemorrhage (2–21%), ischemic stroke (2–10%), seizures (2–6%), and hypoxic–ischemic brain injury. Brain death may also occur in this population. Neurosurgical evacuation of ICH is associated with a high morbidity and mortality rate, mainly due to anticoagulation and multiple-organ dysfunction, but can be an option in carefully selected patients.  Other frequent complications are infarction (1–8%) and cerebral edema (2–10%), as well as neuropsychological and psychiatric sequelae, including posttraumatic stress disorder. Cerebral air embolism is a serious complication of ECMO, associated with decreased venous return in the ECMO circuit, chest trauma due to CPR, or due to severe ventilator-induced lung injury.  In these patients, air bubbles, which can be found in the cerebral venous sinuses, brain parenchyma, or subarachnoid space, can cause acute focal neurologic signs, impairment of consciousness, seizures, and headache, usually mimicking stroke.

Of course, Covid 19 comes to mind when reading this paper, so here are some Covid numbers from Intensive Care Medicine volume 47, pages 344–348 (2021):

ECMO configuration used was VV in 91% of cases, VA in 5% and other in 4%. The mean PaO2 before ECMO implantation was 65 mmHg. The mean duration of ECMO support has been 18 days and the mean ICU length of stay of these patients was 33 days. As of the 14th September 2020, overall 841 patients have been weaned from ECMO support, 601 died during ECMO support, 71 died after withdrawal of ECMO, 79 are still receiving ECMO support.

180 references, 3 tables, 2 figures

7. Borg A, Hill CS, Nurboja B, et al. A randomized controlled trial of the X-Stop interspinous distractor device versus laminectomy for lumbar spinal stenosis with 2-year quality-of-life and cost-effectiveness outcomes. J Neurosurg Spine 2021;34:544–52. Available from: https://thejns.org/view/journals/j-neurosurg-spine/34/4/article-p544.xml

Interspinous distractor devices (IDDs) have been used in the management of LSS for over a decade. Their use is controversial due to mixed reports on their success rates, cost, and high failure rates. The X-Stop Interspinous Process Decompression System (Medtronic Spine LLC) was the first IDD to be approved by the US FDA for the treatment of LSS. This device is intended to provide relief of the symptoms of neurogenic claudication from LSS while being minimally invasive. The procedure time for insertion is short, with potentially fewer complications than a laminectomy, and the device can be removed if necessary. X-Stop use has become increasingly popular in the management of LSS. The safety of the device was confirmed by the FDA in the US and by the National Institute for Health and Care Excellence (NICE) in the United Kingdom (UK), and its clinical efficacy was found to be similar to that of laminectomy, with a reported 70% success rate for improvement in symptoms.

The objective of this study was to determine whether the device is cost effective when compared with the standard treatment of laminectomy and how the device influences QOL.

A multicenter, open-label randomized controlled trial of 47 patients with LSS was conducted; 21 patients underwent insertion of the X-Stop device and 26 underwent laminectomy. The primary outcomes were monetary cost and QOL measured using the EQ-5D questionnaire administered at 6-, 12-, and 24-month time points.

The mean monetary cost for the laminectomy group was £2712 ($3316 [USD]), and the mean cost for the X-Stop group was £5148 ($6295): £1799 ($2199) procedural cost plus £3349 mean device cost (£2605 additional cost per device). Using an intention-to-treat analysis, the authors found that the mean quality-adjusted life-year (QALY) gain for the laminectomy group was 0.92 and that for the X-Stop group was 0.81.

They conclude that laminectomy was more cost-effective than the X-Stop for the treatment of LSS, primarily due to device cost. The X-Stop device led to an improvement in QOL, but it was less than that in the laminectomy group. The use of the X-Stop IDD should be reserved for cases in which a less-invasive procedure is required.

5 figures, 3 tables

8. Ghaznawi R, Geerlings MI, Jaarsma-Coes M, et al. Association of white matter hyperintensity markers on MRI and long-term risk of mortality and ischemic stroke. Neurology 2021;96:e2172–83. Available from: http://www.neurology.org/lookup/doi/10.1212/WNL.0000000000011827

They included 999 consecutive patients with manifest arterial disease enrolled in the Second Manifestations of Arterial Disease–Magnetic Resonance (SMART-MR) study. They obtained WMH markers (volume, type, and shape) from brain MRI scans performed at baseline using an automated algorithm. During follow-up, occurrence of death and ischemic stroke was recorded. Using Cox regression, they investigated associations of WMH markers with risk of mortality and ischemic stroke, adjusting for demographics, cardiovascular risk factors, and cerebrovascular disease.

In this cohort of patients with manifest arterial disease, they observed that WMH volume, type, and shape were associated with long-term clinical outcomes. Specifically, they found that a greater volume and a more irregular shape of periventricular or confluent WMH were related to a higher risk of death and ischemic stroke. A confluent WMH type was also associated with a greater risk of death and ischemic stroke. These relationships were independent of demographics, cardiovascular risk factors, and cerebrovascular disease at baseline.

The finding that total WMH volume was related to risk of mortality and stroke is in line with previous studies. However, the associations of WMH volume subclassifications and WMH types with clinical outcomes presented in this study are novel. They found that the risk of mortality and ischemic stroke was predominantly determined by the volume of periventricular or confluent WMH, rather than the volume of deep WMH.

4 tables, 3 figures

The American Society of Neuroradiology is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians. Visit the ASNR Education Connection website to claim CME credit for this podcast.

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