Brain multimodality monitoring in patients suffering from acute aneurysmal subarachnoid hemorrhage: clinical value and complications.

Brain multimodality monitoring measuring brain tissue oxygen pressure, cerebral blood flow, and cerebral near-infrared spectroscopy may help optimize the neurocritical care of patients with aneurysmal subarachnoid hemorrhage and delayed cerebral ischemia. We retrospectively looked for complications associated with the placement of the probes and checked the reliability of the different tools used for multimodality monitoring. In addition, we screened for therapeutic measures derived in cases of pathological values in multimodality monitoring in 26 patients with acute aneurysmal subarachnoid hemorrhage. Computed tomography scans showed minor hemorrhage along with the probes in 12 patients (46.2%). Missing transmission of values was observed in 34.1% of the intended time of measurement for cerebral blood flow probes and 15.5% and 16.2%, respectively, for the two kinds of probes measuring brain tissue oxygen pressure. We identified 744 cumulative alarming values transmitted from multimodality monitoring. The most frequent intervention was modifying minute ventilation (29%). Less frequent interventions were escalating the norepinephrine dosage (19.9%), elevating cerebral perfusion pressure (14.9%) or inspiratory fraction of inspired oxygen (7.5%), transfusing red blood cell concentrates (1.2%), initiating further diagnostics (2.3%) and neurosurgical interventions (1.9%). As well, 355 cases of pathological values had no therapeutic consequence. The reliability of the measuring tools for multimodality monitoring regarding a continuous transmission of values must be improved, particularly for cerebral blood flow monitoring. The overall high rate of missing therapeutic responses to pathological values derived from multimodality monitoring in patients with aneurysmal subarachnoid hemorrhage underlines the need for structured tiered algorithms. In addition, such algorithms are the basic requirement for prospective multicenter studies, which are urgently needed to evaluate the role of multimodality monitoring in treating these patients.

Intracranial Pressure and Intracranial Elastance Monitoring in Neurocritical Care.

Patients with acute brain injuries tend to be physiologically unstable and at risk of rapid and potentially life-threatening decompensation due to shifts in intracranial compartment volumes and consequent intracranial hypertension. Invasive intracranial pressure (ICP) monitoring therefore remains a cornerstone of modern neurocritical care, despite the attendant risks of infection and damage to brain tissue arising from the surgical placement of a catheter or pressure transducer into the cerebrospinal fluid or brain tissue compartments. In addition to ICP monitoring, tracking of the intracranial capacity to buffer shifts in compartment volumes would help in the assessment of patient state, inform clinical decision making, and guide therapeutic interventions. We review the anatomy, physiology, and current technology relevant to clinical management of patients with acute brain injury and outline unmet clinical needs to advance patient monitoring in neurocritical care.

Safety and Reliability of Bedside, Single Burr Hole Technique for Intracranial Multimodality Monitoring in Severe Traumatic Brain Injury.

BACKGROUND: We aimed to provide a systematic description of our 2-year experience using a standardized bedside, single burr hole approach to intracranial multimodality monitoring (MMM) in patients with severe traumatic brain injury (sTBI), focusing on safety and probe reliability. METHODS: We performed this observational cohort study at a university-affiliated, Level I trauma center with dedicated 20-bed neuroscience intensive care unit. We included 43 consecutive sTBI patients who required MMM to guide clinical care based on institutional protocol and had a four-lumen bolt placed to measure intracranial pressure, brain tissue oxygen, regional cerebral blood flow, brain temperature, and intracranial electroencephalography. RESULTS: sTBI patients were aged 41.6 ± 17.5 years (mean ± SD) and 84% were men. MMM devices were placed at a median of 12.5 h (interquartile range [IQR] 9.0-21.4 h) after injury and in non-dominant frontal lobe in 72.1% of cases. Monitoring was conducted for a median of 97.1 h (IQR 46.9-124.6 h) per patient. While minor hemorrhage, pneumocephalus, or small bone chips were common, only one (2.4%) patient experienced significant hemorrhage related to device placement. Radiographically, device malpositioning was noted in 13.9% of patients. Inadvertent device discontinuation occurred for at least one device in 58% of patients and was significantly associated with the frequency of travel for procedures or imaging. Devices remained in place for > 80% of the total monitoring period and generated usable data > 50% of that time. CONCLUSIONS: A standardized, bedside single burr hole approach to MMM was safe. Despite some probe-specific recording limitations, MMM provided real-time measurements of intracranial pressure, oxygenation, regional cerebral blood flow, brain temperature, and function.

Safety of Chemical DVT Prophylaxis in Severe Traumatic Brain Injury with Invasive Monitoring Devices.

BACKGROUND: Patients with traumatic brain injuries (TBIs) have an increased risk of developing a deep vein thrombosis (DVT), but the risk of hemorrhage expansion with intracranial monitoring devices remains unknown. We sought to determine the safety of chemical DVT prophylaxis in severe TBI patients with invasive intracranial pressure monitors. METHODS: We retrospectively reviewed all patients with severe TBI admitted to the neurosurgical intensive care unit of a large tertiary care center over a three-year period. RESULTS: 155 patients were included with an incidence of DVT of 12 %. The median length of time to a stable head CT was 2 days, and the median time to initiation of chemical DVT prophylaxis was 3.6 days. The odds of DVT increased with intraparenchymal hemorrhage [OR 7.21, 95 % CI (1.43-36.47), p = 0.0169], non-White ethnicity [OR 7.86, 95 % CI (1.23-50.35), p = 0.0295], female gender [OR 13.93, 95 % CI (2.47-78.73), p = 0.0029], smoking [OR 4.32, 95 % CI (1.07-17.51), p = 0.0405], no anticoagulation [OR 25.39, 95 % CI (4.26-151.48), p < 0.001], and an IVC filter [OR 15.82, 95 % CI (3.14-79.76), p < 0.001]. Twenty-eight (18 %) of these subjects experienced in-hospital mortality. The risk of in-hospital death was significantly increased among those who did not receive anticoagulation. This study found no association between DVT formation, hemorrhage expansion, or increased risk from invasive monitoring devices between various doses of unfractionated heparin (UH) and low-molecular-weight heparin (LMWH). CONCLUSION: We conclude that DVT prophylaxis with either LMWH or UH is safe with intracranial pressure monitors in place.

A spatiotemporal study of gliosis in relation to depth electrode tracks in drug-resistant epilepsy.

Key questions remain regarding the processes governing gliogenesis following central nervous system injury that are critical to understanding both beneficial brain repair mechanisms and any long-term detrimental effects, including increased risk of seizures. We have used cortical injury produced by intracranial electrodes (ICEs) to study the time-course and localization of gliosis and gliogenesis in surgically resected human brain tissue. Seventeen cases with ICE injuries of 4-301 days age were selected. Double-labelled immunolabelling using a proliferative cell marker (MCM2), markers of fate-specific transcriptional factors (PAX6, SOX2), a microglial marker (IBA1) and glial markers (nestin, GFAP) was quantified in three regions: zone 1 (immediate vicinity: 0-350 µm), zone 2 (350-700 µm) and zone 3 (remote ≥2000 µm) in relation to the ICE injury site. Microglial/macrophage cell densities peaked at 28-30 days post-injury (dpi) with a significant decline in proliferating microglia with dpi in all zones. Nestin-expressing cells (NECs) were concentrated in zones 1 and 2, showed the highest regenerative capacity (MCM2 and PAX6 co-expression) and were intimately associated with capillaries within the organizing injury cavity. There was a significant decline in nestin/MCM2 co-expressing cells with dpi in zones 1 and 2. Nestin-positive fibres remained in the chronic scar, and NECs with neuronal morphology were noted in older injuries. GFAP-expressing glia were more evenly distributed between zones, with no significant decline in density or proliferative capacity with dpi. Colocalization between nestin and GFAP in zone 1 glial cells decreased with increasing dpi. In conclusion, NECs at acute injury sites are a proliferative, transient cell population with capacity for maturation into astrocytes with possible neuronal differentiation observed in older injuries.

Review: pathophysiology of intracranial hypertension and noninvasive intracranial pressure monitoring.

Measurement of intracranial pressure (ICP) is crucial in the management of many neurological conditions. However, due to the invasiveness, high cost, and required expertise of available ICP monitoring techniques, many patients who could benefit from ICP monitoring do not receive it. As a result, there has been a substantial effort to explore and develop novel noninvasive ICP monitoring techniques to improve the overall clinical care of patients who may be suffering from ICP disorders. This review attempts to summarize the general pathophysiology of ICP, discuss the importance and current state of ICP monitoring, and describe the many methods that have been proposed for noninvasive ICP monitoring. These noninvasive methods can be broken down into four major categories: fluid dynamic, otic, ophthalmic, and electrophysiologic. Each category is discussed in detail along with its associated techniques and their advantages, disadvantages, and reported accuracy. A particular emphasis in this review will be dedicated to methods based on the use of transcranial Doppler ultrasound. At present, it appears that the available noninvasive methods are either not sufficiently accurate, reliable, or robust enough for widespread clinical adoption or require additional independent validation. However, several methods appear promising and through additional study and clinical validation, could eventually make their way into clinical practice.

Stereoelectroencephalography Versus Subdural Strip Electrode Implantations: Feasibility, Complications, and Outcomes in 500 Intracranial Monitoring Cases for Drug-Resistant Epilepsy.

BACKGROUND: Both stereoelectroencephalography (SEEG) and subdural strip electrodes (SSE) are used for intracranial electroencephalographic recordings in the invasive investigation of patients with drug-resistant epilepsy. OBJECTIVE: To compare SEEG and SSE with respect to feasibility, complications, and outcome in this single-center study. METHODS: Patient characteristics, periprocedural parameters, complications, and outcome were acquired from a pro- and retrospectively managed databank to compare SEEG and SSE cases. RESULTS: A total of 500 intracranial electroencephalographic monitoring cases in 450 patients were analyzed (145 SEEG and 355 SSE). Both groups were of similar age, gender distribution, and duration of epilepsy. Implantation of each SEEG electrode took 13.9 ± 7.6 min (20 ± 12 min for each SSE; P < .01). Radiation exposure to the patient was 4.3 ± 7.7 s to a dose area product of 14.6 ± 27.9 rad*cm2 for SEEG and 9.4 ± 8.9 s with 21 ± 22.4 rad*cm2 for SSE (P < .01). There was no difference in the length of stay (12.2 ± 7.2 and 12 ± 6.3 d). The complication rate was low in both groups. No infections were seen in SEEG cases (2.3% after SSE). The rate of hemorrhage was 2.8% for SEEG and 1.4% for SSE. Surgical outcome was similar. CONCLUSION: SEEG allows targeting deeply situated foci with a non-inferior safety profile to SSE and seizure outcome comparable to SSE.

Iatrogenic cerebral abscess leading to resolution of severe delusional disorder.

A cerebral abscess (focal infection of brain parenchyma) carries a high mortality and morbidity. Iatrogenic cerebral abscesses are less common and make up 10% of all cases. The presence of a cerebral abscess can rarely improve a patient's prognosis and quality of life, however this case illustrates an abscess and its treatment following a prolonged course of antibiotics leading to resolution of a severe psychotic disorder. This is a case report of a 32-year-old female inpatient at a psychiatric hospital with a long-standing history of congenital hydrocephalus, cerebral palsy and organic delusional disorder who developed an iatrogenic cerebral abscess after insertion of an implantable intracranial pressure monitoring device. After receiving treatment of 6 weeks of intravenous meropenem the patient's mental condition rapidly improved, she became stable and euthymic and was discharged home. The patient has since had no delusions or hallucinations and is living independently at home.

[Neurophysiological monitoring options in brain tumour resections. Consensus statement from the Spanish Society of Neurosurgery's (SENEC) Neuro-oncology Working Group and the Spanish Society of Clinical Neurophysiology (SENFC)]. / Opciones de monitorización neurofisiológica en la resección de tumoraciones cerebrales. Documento de consenso entre el Grupo de Trabajo de Neurooncología de la Sociedad Española de Neurocirugía (SENEC) y la Sociedad Española de Neurofisiología Clínica (SENFC).

Brain tumours located in or in proximity to eloquent areas are a significant neurosurgical challenge. Performing this kind of surgery with neurophysiological monitoring to improve resections with reduced permanent focal neurological deficit has become widely accepted in the literature. However, how to conduct this monitoring, the exact definition of an eloquent area and whether to perform this surgery with the patient awake or asleep are still subject to rigorous scientific debate. Members of the Neuro-oncology Working Group (GTNO) of the Spanish Society of Neurosurgery (SENEC) and members of the Spanish Society of Clinical Neurophysiology (SENFC) have published a consensus statement to explain the different neurophysiological monitoring options currently available in awake and asleep patients to obtain better surgical resection without neurological deficits. An exhaustive review of the literature has also been conducted.

Complications in Aneurysmal Subarachnoid Hemorrhage Patients With and Without Subdural Electrode Strip for Electrocorticography.

PURPOSE: Patients with aneurysmal subarachnoid hemorrhage (aSAH) frequently develop secondary noninfectious and infectious complications with an important impact on clinical course and outcome. In this study, we report on the rate of typical extracranial and intracranial complications in 30 prospectively enrolled patients with severe aSAH who received a linear subdural recording strip for continuous electrocorticography to detect ictal epileptiform events and spreading depolarizations. METHODS: The group was compared with 30 retrospectively included patients with aSAH who had not received a subdural recording strip, but were treated during the same period. The control group was matched according to an aSAH grading system, sex, and establishment of external ventricular drainage, but could not be matched according to aneurysm treatment and focal brain lesions such as initial intracerebral hemorrhages. RESULTS: No evidence was found that procedures of the electrocorticography study led to clinically relevant complications. In particular, the subdural strip did not lead to local damage of brain tissue or any increased rate of meningitis/ventriculitis. The median score on the modified Rankin Scale on day 15 was the same in both groups. Minor differences between both groups are explained by the limitations in the study design. CONCLUSIONS: Our study suggests that neuromonitoring with a subdural recording strip for up to 15 days can be safely performed in patients with aSAH.

Safety of staged epilepsy surgery in children.

BACKGROUND: Surgical resection of epileptic foci relies on accurate localization of the epileptogenic zone, often achieved by subdural and depth electrodes. Our epilepsy center has treated selected children with poorly localized medically refractory epilepsy with a staged surgical protocol, with at least 1 phase of invasive monitoring for localization and resection of epileptic foci. OBJECTIVE: To evaluate the safety of staged surgical treatments for refractory epilepsy among children. METHODS: Data were retrospectively collected, including surgical details and complications of all patients who underwent invasive monitoring. RESULTS: A total of 161 children underwent 200 admissions including staged procedures (>1 surgery during 1 hospital admission), and 496 total surgeries. Average age at surgery was 7 years (range, 8 months to 16.5 years). A total of 250 surgeries included resections (and invasive monitoring), and 189 involved electrode placement only. The cumulative total number of surgeries per patient ranged from 2 to 10 (average, 3). The average duration of monitoring was 10 days (range, 1-30). There were no deaths. Follow-up ranged from 1 month to 10 years. Major complications included unexpected new permanent mild neurological deficits (2%/admission), central nervous system or bone flap infections (1.5%/admission), intracranial hemorrhage, cerebrospinal fluid leak, and a retained strip (each 0.5%/admission). Minor complications included bone absorption (5%/admission), positive surveillance sub-/epidural cultures in asymptomatic patients (5.5%/admission), noninfectious fever (5%/admission), and wound complications (3%/admission). Thirty complications necessitated additional surgical treatment. CONCLUSION: Staged epilepsy surgery with invasive electrode monitoring is safe in children with poorly localized medically refractory epilepsy. The rate of major complications is low and appears comparable to that associated with other elective neurosurgical procedures.

Safety of hybrid electrodes for single-neuron recordings in humans.

BACKGROUND: Intracranial in vivo recordings of individual neurons in humans are increasingly performed for a better understanding of the mechanisms of epileptogenesis and of the neurobiological basis of cognition. So far, information about the safety of stereotactic implantations and of magnetic resonance imaging (MRI) with hybrid depth electrodes is scarce. OBJECTIVE: The aim of this study was to assess neurosurgical safety of implantations, recordings, and imaging using hybrid electrodes in humans. METHODS: Perioperative and long-term safety of implantation of a total of 88 hybrid depth electrodes with integrated microwires was assessed retrospectively in 25 consecutive epilepsy patients who underwent implantation of electrodes from 2007 to 2011 based on electronically stored charts. Safety aspects of MRI are reported from both in vitro and in vivo investigations. Precision of electrode implantation is evaluated based on intraoperative computed tomography and pre- and postoperative MRI. RESULTS: There was no clinically relevant morbidity associated with the use of hybrid electrodes in any of the patients. Precision of recordings from the targets aimed at was similar to that of standard depth electrodes. In vitro studies demonstrated the absence of relevant heating of hybrid electrodes with newly designed connectors with MRI at 1.5 T, corresponding to well-tolerated clinical MRI in patients. CONCLUSION: Given the technical approach described here, precise targeting and safe use are possible with hybrid electrodes containing microwires for in vivo recording of human neuronal units.