Juergen Beck

Occurrence of Vasospasm and Infarction in Relation to a Focal Monitoring Sensor in Patients after SAH: Placing a Bet when Placing a Probe?

Introduction Vasospastic brain infarction is a devastating complication of aneurysmal subarachnoid hemorrhage (SAH). Using a probe for invasive monitoring of brain tissue oxygenation or blood flow is highly focal and may miss the site of cerebral vasospasm (CVS). Probe placement is based on the assumption that the spasm will occur either at the dependent vessel territory of the parent artery of the ruptured aneurysm or at the artery exposed to the focal thick blood clot. We investigated the likelihood of a focal monitoring sensor being placed in vasospasm or infarction territory on a hypothetical basis. Methods From our database we retrospectively selected consecutive SAH patients with angiographically proven (day 7–14) severe CVS (narrowing of vessel lumen >50%). Depending on the aneurysm location we applied a standard protocol of probe placement to detect the most probable site of severe CVS or infarction. We analyzed whether the placement was congruent with existing CVS/infarction. Results We analyzed 100 patients after SAH caused by aneurysms located in the following locations: MCA (n = 14), ICA (n = 30), A1CA (n = 4), AcoA or A2CA (n = 33), and VBA (n = 19). Sensor location corresponded with CVS territory in 93% of MCA, 87% of ICA, 76% of AcoA or A2CA, but only 50% of A1CA and 42% of VBA aneurysms. The focal probe was located inside the infarction territory in 95% of ICA, 89% of MCA, 78% of ACoA or A2CA, 50% of A1CA and 23% of VBA aneurysms. Conclusion The probability that a single focal probe will be situated in the territory of severe CVS and infarction varies. It seems to be reasonably accurate for MCA and ICA aneurysms, but not for ACA or VBA aneurysms.

Clazosentan: prevention of cerebral vasospasm and the potential to overcome infarction

Cerebral vasospasm is a common complication occurring after aneurysmal subarachnoid hemorrhage (SAH). It is recognized as a leading preventable cause of morbidity and mortality in this patient group, but its management is challenging, and new treatments are needed. Clazosentan is an endothelin receptor antagonist designed to prevent endothelin-mediated cerebral vasospasm. Vajkoczy et al. (Neurosurg 103:9-17, 2005) initially demonstrated that clazosentan reduced moderate/severe angiographically proven vasospasm by 55% relative to placebo. These findings led to the initiation of the CONSCIOUS trial program to further examine the efficacy and safety of clazosentan in reducing angiographic vasospasm and improving clinical outcome after aneurysmal SAH. In the first of these studies, CONSCIOUS-1, 413 patients were randomized to placebo or clazosentan 1, 5 or 15 mg/h. Clazosentan reduced angiographic vasospasm dose-dependently relative to placebo with a maximum risk reduction of 65% with the highest dose. Despite this, there was no benefit of clazosentan on the secondary protocol-defined morbidity/mortality endpoint; however, additional post-hoc and modified endpoint analyses provided some evidence for a potential clinical benefit. Two additional large-scale studies (CONSCIOUS-2 and CONSCIOUS-3) are now underway to further investigate the potential of clazosentan to improve long-term clinical outcome.

Quantitative magnetic resonance angiography as a potential predictor for cerebral hyperperfusion syndrome: a preliminary study

OBJECTIVE Cerebral hyperperfusion syndrome (CHS) is a rare but devastating complication of carotid endarterectomy (CEA). This study sought to determine whether quantitative hemodynamic assessment using MR angiography can stratify CHS risk. METHODS In this prospective trial, patients with internal carotid artery (ICA) stenosis were randomly selected for pre- and postoperative quantitative phase-contrast MR angiography (QMRA). Assessment was standardized according to a protocol and included Doppler/duplex sonography, MRI, and/or CT angiography and QMRA of the intra- and extracranial supplying arteries of the brain. Clinical and radiological data were analyzed to identify CHS risk factors. RESULTS Twenty-five of 153 patients who underwent CEA for ICA stenosis were randomly selected for pre- and postoperative QMRA. QMRA data showed a 2.2-fold postoperative increase in blood flow in the operated ICA (p < 0.001) and a 1.3-fold increase in the ipsilateral middle cerebral artery (MCA) (p = 0.01). Four patients had clinically manifested CHS. The mean flow increases in the patients with CHS were significantly higher than in the patients without CHS, both in the ICA and MCA (p < 0.001). Female sex and a low preoperative diastolic blood pressure were the clearest clinical risk factors for CHS, whereas the flow differences and absolute postoperative flow values in the ipsilateral ICA and MCA were identified as potential radiological predictors for CHS. CONCLUSIONS Cerebral blood flow in the ipsilateral ICA and MCA as assessed by QMRA significantly increased after CEA. Higher mean flow differences in ICA and MCA were associated with the development of CHS. QMRA might have the potential to become a noninvasive, operator-independent screening tool for identifying patients at risk for CHS.

Intraoperative identification of the corticospinal tract and dorsal column of the spinal cord by electrical stimulation

Objectives Anatomical identification of the corticospinal tract (CT) and the dorsal column (DC) of the exposed spinal cord is difficult when anatomical landmarks are distorted by tumour growth. Neurophysiological identification is complicated by the fact that direct stimulation of the DC may result in muscle motor responses due to the centrally activated H-reflex. This study aims to provide a technique for intraoperative neurophysiological differentiation between CT and DC in the exposed spinal cord. Methods Recordings were obtained from 32 consecutive patients undergoing spinal cord tumour surgery from July 2015 to March 2017. A double train stimulation paradigm with an intertrain interval of 60 ms was devised with recording of responses from limb muscles. Results In non-spastic patients (55% of cohort) an identical second response was noted following the first CT response, but the second response was absent after DC stimulation. In patients with pre-existing spasticity (45%), CT stimulation again resulted in two identical responses, whereas DC stimulation generated a second response that differed substantially from the first one. The recovery times of interneurons in the spinal cord grey matter were much shorter for the CT than those for the DC. Therefore, when a second stimulus train was applied 60 ms after the first, the CT-fibre interneurons had already recovered ready to generate a second response, whereas the DC interneurons were still in the refractory period. Conclusions Mapping of the spinal cord using double train stimulation allows neurophysiological distinction of CT from DC pathways during spinal cord surgery in patients with and without pre-existing spasticity.

S122. Intraoperative electrical stimulation to identify the corticospinal tract and dorsal column during spinal cord tumor surgery

Introduction Anatomical identification of the corticospinal tract (CT) and the dorsal column (DC) of the exposed spinal cord is difficult when anatomical landmarks are distorted by tumour growth. Intraoperative neurophysiological identification is complicated by the fact that direct stimulation of the DC may result in muscle motor responses due to the centrally activated H-reflex. This study aimed to provide a technique for intraoperative neurophysiological differentiation between CT and DC in the surgical exposed spinal cord. Methods Recordings were obtained from 32 consecutive patients undergoing intramedullary or intradural-extramedullary spinal cord tumour surgery from 07/2015 to 03/2017. A double train stimulation paradigm with an intertrain interval of 60 ms was devised by a hand held probe with simultaneous recording of responses from limb muscles. Results In non spastic patients (55% of cohort) an identical second response was noted following the first response after CT stimulation, but the second response was absent after DC stimulation. In patients with preexisting spasticity (45%), CT stimulation again resulted in two identical responses, whereas DC stimulation generated a second response that differed substantially from the first one. The recovery times of interneurons in the spinal cord grey matter for the CT were much shorter than those for the DC. Therefore, when a second stimulus train was applied 60 ms after the first, the CT-fibre interneurons had already recovered ready to generate a second response, whereas the DC interneurons were still in the refractory period. Conclusion Intraoperative mapping of the surgical exposed spinal cord using double-train stimulation paradigm allows neurophysiological distinction of CT from DC pathways during spinal cord surgery in patients with and without preexisting spasticity.

Gender-related differences in aneurysmal subarachnoid hemorrhage: A hospital based study.

OBJECTIVES Aneurysmal subarachnoid hemorrhage (aSAH) is more common in women than in men. Despite its clinical relevance, knowledge about the potential gender differences in the clinical course and outcome of aSAH is sparse - we aimed at elucidating such differences. PATIENTS AND METHODS Retrospective cohort study including patients ≥18years of age with aSAH admitted to an interdisciplinary intensive-care center at the University Hospital of Bern (Switzerland). RESULTS The study included 120 patients with aSAH. Sixty-nine percent of the enrolled patients were women. The women were older than men (mean [standard deviation] age 58±13years vs. 51±12years, P=0.006), and were increasingly overrepresented across increasing age-strata. Global disease severity at admission, measured by the APACHE II score, was higher in women than in men (median score 18 points [IQR 12-26] vs. 14 points [IQR 10-19], P=0.006). Men and women had similar medical histories and severity of aSAH. We found no evidence for major differences in the adopted aneurysm-securing strategy and intensive care interventions. At 6 months from aSAH, mortality was higher in women than men (28% vs. 16%), but this did not reach statistical significance (P=0.25). APACHE II, but not gender, was associated with unfavorable outcome at 6 months. CONCLUSION Women outnumbered men among aSAH patients, especially along increasing age strata, and had increased global disease severity on admission. No other significant differences between genders were found.

Stent-assisted coiling of a ruptured vertebrobasilar junction aneurysm via direct vertebral artery puncture

A 78-year-old patient was admitted with subarachnoid hemorrhage caused by rupture of a broad-based vertebrobasilar junction aneurysm. Direct endovascular access to the vertebrobasilar circulation was not possible due to chronic occlusion of the proximal dominant left vertebral artery (VA), hypoplastic right VA and posterior communicating arteries. The distal cervical left VA was reconstituted by muscular branches of the ascending cervical artery. Therefore, endovascular access was gained by direct percutaneous VA puncture guided by a roadmap-controlled anterior approach at the level of C5 proximally to the main reconstituting collateral feeders. Successful endovascular treatment of the aneurysm was performed by stent-assisted coiling. Closure of the puncture site at the cervical VA level was achieved by occluding the proximal part of the VA with coils. The post-interventional clinical course was uneventful; early post-interventional CT showed no evidence of cervical hematoma.