Jan Claassen

• Columbia University

Brain tissue hypoxia and metabolic dysfunction are common in patients with subarachnoid hemorrhage (SAH) and may worsen prognosis. We aimed to assess the impact of episodes of low brain tissue partial pressure of oxygen (PbtO2) and metabolic dysfunction (elevated lactate pyruvate ratio—LPR measured by cerebral microdialysis, CMD) on neurological ou...

Cognitive motor dissociation (CMD) can improve the accuracy to predict recovery of behaviorally unresponsive patients with acute brain injury, but acquisition and analysis of task-based electroencephalography (EEG) are technically challenging. N2 sleep patterns, such as sleep spindles on EEG, have been associated with good outcomes, rely on similar...

Acute ischemic lesions seen on brain magnetic resonance imaging (MRI) are associated with poor intracerebral hemorrhage (ICH) outcomes, but drivers for these lesions are unknown. Rapid hemoglobin decrements occur in the initial days after ICH and may impair brain oxygen delivery. We investigated whether acute hemoglobin decrements after ICH are ass...

Prognostication of patients with acute disorders of consciousness is imprecise but more accurate technology-supported predictions, such as cognitive motor dissociation (CMD), are emerging. CMD refers to the detection of willful brain activation following motor commands using functional magnetic resonance imaging or machine learning–supported analys...

Background: Patients with brain injury who are unresponsive to commands may perform cognitive tasks that are detected on functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). This phenomenon, known as cognitive motor dissociation, has not been systematically studied in a large cohort of persons with disorders of consciousn...

Clinical management of persons with disorders of consciousness (DoC) is dedicated largely to optimizing recovery. However, selecting a measure to evaluate the extent of recovery is challenging because few measures are designed to precisely assess the full range of potential outcomes, from prolonged DoC to return of preinjury functioning. Measures t...

Brain activation to motor commands is seen in 15% of clinically unresponsive patients with acute brain injury. This state called cognitive motor dissociation (CMD) is detectable by electroencephalogram (EEG) or functional magnetic resonance imaging, predicts long-term recovery, and is recommended by recent guidelines to support prognostication. How...

BACKGROUND This study proposes a modification to the traditional Hunt and Hess (tHH) grading scale for prognostication in aneurysmal subarachnoid hemorrhage (aSAH), which differentiates the most severe‐grade patients based on the presence or absence of brainstem dysfunction [determined by Glasgow Coma Scale (GCS) scores 3‐5]. METHODS Weighted aSAH...

Background Baseline anemia is associated with poor intracerebral hemorrhage (ICH) outcomes. However, underlying drivers for anemia and whether anemia development after ICH impacts clinical outcomes are unknown. We hypothesized that inflammation drives anemia development after ICH and assessed their relationship to outcomes. Methods and Results Pat...

Viscoelastic hemostatic assays (VHAs) provide more comprehensive assessments of coagulation compared with conventional coagulation assays. Although VHAs have enabled guided hemorrhage control therapies, improving clinical outcomes in life-threatening hemorrhage, the role of VHAs in intracerebral hemorrhage (ICH) is unclear. If VHAs can identify coa...

Resting-state electroencephalography (rsEEG) is usually obtained to assess seizures in comatose patients with traumatic brain injury (TBI). We aim to investigate rsEEG measures and their prediction of early recovery of consciousness in patients with TBI. This is a retrospective study of comatose patients with TBI who were admitted to a trauma cente...

Aneurysmal subarachnoid haemorrhage (aSAH) is a rare yet profoundly debilitating condition associated with high global case fatality and morbidity rates. The key determinants of functional outcome include early brain injury, rebleeding of the ruptured aneurysm and delayed cerebral ischaemia. The only effective way to reduce the risk of rebleeding i...

Background Intracerebral hemorrhage (ICH) is a major cause of maternal morbidity, but its pathophysiology is poorly characterized. We investigated characteristics of pregnancy‐associated ICH (P‐ICH), compared with ICH in similar aged nonpregnant adults of both sexes. Methods and Results We performed a retrospective analysis of 134 adults aged 18 t...

Background Viscoelastic hemostatic assays (VHA) provide more comprehensive assessments of coagulation compared to conventional coagulation assays. While VHAs have enabled guided hemorrhage control therapies, improving clinical outcomes in life-threatening hemorrhage, the role of VHAs in intracerebral hemorrhage (ICH) is unclear. If VHAs can identif...

Background: Ischemia on diffusion weighted imaging (DWI) after intracerebral hemorrhage (ICH) increases the risk of future ischemic stroke. Radiographic markers of small vessel disease, including cerebral microbleeds (CMB), are associated with DWI lesions. Though cortical superficial siderosis (cSS) is also a hemorrhagic small vessel disease subtyp...

Background: Ischemic lesions on diffusion weighted imaging (DWI) occur in one-third of intracerebral hemorrhage (ICH). Due to conflicting prior studies, it is uncertain if the degree of systolic blood pressure reduction increases the risk. Patients with severe, chronic hypertension may be more vulnerable to the development of ischemia after ICH due...

Background: We have previously identified that hemoglobin decrements and new-onset anemia during an intracerebral hemorrhage (ICH) hospitalization is frequent, rapid, and associates with poor outcome. Though this association may be related to impaired cerebral oxygen delivery, it is unclear whether these changes relate to cerebral ischemia. We inve...

Background: We identified that major ABO incompatible platelet transfusions are associated with poor intracerebral hemorrhage (ICH) outcomes, yet the driver for this relationship is unknown and does not appear to be related to impaired hemostasis. Conversely, acute ICH patients are known to develop remote ischemic lesions on brain MRI. These ischem...

Introduction: Intracerebral hemorrhage (ICH) is a major cause of maternal morbidity and mortality. While sex differences exist in clinical outcomes of ICH in young adults, it is not known if outcomes differ between pregnancy-associated ICH (PICH) and non-pregnancy-associated ICH (NPICH). Methods: We performed a cross-sectional analysis of 134 adult...

Introduction: Intracerebral hemorrhage (ICH) is a major cause of maternal mortality, but its pathophysiology is not well characterized. We investigated characteristics of pregnancy-associated ICH (PICH), compared with ICH in non-pregnant young adults of both sexes. Methods: We performed a cross-sectional analysis of 134 adults aged 18-44 years admi...

Introduction: Remote ischemic lesions identified on MRI neuroimaging after intracerebral hemorrhage (ICH) may be related to microthrombosis. We sought to evaluate whether hypercoagulability identified on viscoelastic hemostatic assay relates to these ischemic lesions. Methods: Spontaneous ICH patients enrolled in a single-center prospective observa...

Introduction: Intracerebral hemorrhage (ICH) accounts for 10-20% of strokes and is associated with severe disability and high mortality. While males are reported to have worse outcomes in older patients with ICH, data are limited regarding sex differences in mortality risk after ICH for younger patients. Methods: We conducted a cross-sectional stud...

Disorders of consciousness are neurological conditions characterized by impaired arousal and awareness of self and environment. Behavioral responses are absent or are present but fluctuating. Disorders of consciousness are commonly encountered in consequence of both acute and chronic brain injuries, yet reliable epidemiological estimates would requ...

Background Resting-state electroencephalogram (rsEEG) is usually obtained to assess seizures in comatose patients with traumatic brain injury (TBI) patients. We aim to investigate rsEEG measures and their prediction of early recovery of consciousness in comatose TBI patients. Methods This is a retrospective study of comatose TBI patients who were...

Purpose To investigate the effects of ketamine on patients with refractory status epilepticus after cardiac arrest. Methods In this retrospective cohort, selected EEG segments from patients after cardiac arrest were classified into different EEG patterns (based on background continuity and burden of epileptiform discharges) and spectral profiles (...

Background: We have identified that major ABO-incompatible platelet transfusions are associated with poor intracerebral hemorrhage (ICH) outcomes. The underlying drivers for the relationship of these incompatible platelet units on outcome are unknown, yet do not appear to be related to impaired hemostasis. Conversely, ICH patients are known to enco...

Remote ischemic lesions on diffusion-weighted imaging (DWI) occur in one third of patients with intracerebral hemorrhage (ICH) and are associated with worse outcomes. The etiology is unclear and not solely due to blood pressure reduction. We hypothesized that impaired cerebrovascular autoregulation and hypoperfusion below individualized lower limit...

Objectives: Low hemoglobin concentration impairs clinical hemostasis across several diseases. It is unclear whether hemoglobin impacts laboratory functional coagulation assessments. We evaluated the relationship of hemoglobin concentration on viscoelastic hemostatic assays in intracerebral hemorrhage (ICH) and perioperative patients admitted to an...

Background Electroencephalography (EEG) has long been recognized as an important tool in the investigation of disorders of consciousness (DoC). From inspection of the raw EEG to the implementation of quantitative EEG, and more recently in the use of perturbed EEG, it is paramount to providing accurate diagnostic and prognostic information in the ca...

In unconscious appearing patients with acute brain injury, wilful brain activation to motor commands without behavioural signs of command following, known as cognitive motor dissociation (CMD), is associated with functional recovery. CMD can be detected by applying machine learning to EEG recorded during motor command presentation in behaviourally...

Background and Purpose Non-O blood types are known to be associated with thromboembolic complications (TECs) in population-based studies. TECs are known drivers of morbidity and mortality in intracerebral hemorrhage (ICH) patients, yet the relationships of blood type on TECs in this patient population are unknown. We sought to explore the relations...

Unlabelled: Temporal trends and factors associated with the withdrawal of life-sustaining therapy (WLST) after acute stroke are not well determined. Design: Observational study (2008-2021). Setting: Florida Stroke Registry (152 hospitals). Patients: Acute ischemic stroke (AIS), intracerebral hemorrhage (ICH), and subarachnoid hemorrhage (SAH...

Background: Patients with disorders of consciousness who are behaviorally unresponsive may demonstrate volitional brain responses to motor imagery or motor commands detectable on functional magnetic resonance imaging or electroencephalography. This state of cognitive motor dissociation (CMD) may have prognostic significance. Methods: The Neurocr...

Objective: The objective of this study is to develop and validate a method for automatically identifying segments of intracranial pressure (ICP) waveform data from external ventricular drainage (EVD) recordings during intermittent drainage and closure. Methods: The proposed method uses time-frequency analysis through wavelets to distinguish periods...

Increased intracranial pressure (ICP) causes disability and mortality in the neuro-intensive care population. Current methods for monitoring ICP are invasive. We designed a deep learning framework using a domain adversarial neural network to estimate noninvasive ICP, from blood pressure, electrocardiogram, and cerebral blood flow velocity. Our mode...

Background Laboratory monitoring is not recommended when subcutaneous unfractionated heparin (SQ-UFH) is administered at prophylactic doses. However, aPTT prolongation and associated hemorrhage has been reported in the neurocritically ill. At our institution, Neuroscience Intensive Care Unit (Neuro-ICU) patients with prolonged aPTT are further eval...

Objectives This study investigated video eye tracking (VET) in comatose patients with traumatic brain injury (TBI). Methods We recruited healthy participants and unresponsive patients with TBI. We surveyed the patients' clinicians on whether the patient was tracking and performed the Coma Recovery Scale–Revised (CRS-R). We recorded eye movements i...

Background Somatosensory evoked potentials (SSEPs) help prognostication, particularly in patients with diffuse brain injury. However, use of SSEP is limited in critical care. We propose a novel, low-cost approach allowing acquisition of screening SSEP using widely available intensive care unit (ICU) equipment, specifically a peripheral “train-of-fo...

Interest in disorders of consciousness (DoC) has grown substantially over the past decade and has illuminated the importance of improving understanding of DoC biology; care needs (use of monitoring, performance of interventions, and provision of emotional support); treatment options to promote recovery; and outcome prediction. Exploration of these...

Introduction: Biological sex is known to impact cerebrovascular disease characteristics and clinical outcomes. While in intracerebral hemorrhage (ICH) it is known that biological sex impacts ICH incidence, it is less clear whether biological sex impacts ICH outcomes. Hypothesis: Female sex will be associated with ICH characteristics and clinical ou...

Introduction: There are described differences in coagulation between females and males. Specifically, female sex is associated with greater platelet activation and stronger clotting characteristics. It is unclear whether there are relevant coagulation differences identifiable between female and male patients suffering from intracerebral hemorrhage...

Introduction: The decision to withhold or withdraw life-sustaining therapy (WLST) is common after acute stroke. Factors that may influence the decision are not well determined. We aimed to investigate factors associated with WLST in hospitalized acute stroke patients. Methods: Patients with acute ischemic stroke (AIS), intracerebral hemorrhage (ICH...

Background: Little is known about the natural history of comatose patients with brain injury, as in many countries most of these patients die in the context of withdrawal of life-sustaining therapies (WLSTs). The accuracy of predicting recovery that is used to guide goals-of-care decisions is uncertain. We examined long-term outcomes of patients w...

Introduction: Cardiac arrest (CA) survivors have significant impairments and poor functional outcomes at hospital discharge. We assessed if discharge disposition to acute inpatient rehabilitation after CA-related hospitalization is associated with improved functional recovery at 12 months relative to alternative acute care hospital discharge dispos...

Background: Targeting a cerebral perfusion pressure optimal for cerebral autoregulation (CPPopt) has been gaining more attention to prevent secondary damage after acute neurological injury. Brain tissue oxygenation (PbtO2) can identify insufficient cerebral blood flow and secondary brain injury. Defining the relationship between CPPopt and PbtO2 a...

Background Impaired consciousness is common in intensive care unit (ICU) patients, and an individual’s degree of consciousness is crucial to determining their care and prognosis. However, there are no methods that continuously monitor consciousness and alert clinicians to changes. We investigated the use of physiological signals collected in the IC...

Over the past decades, electroencephalography (EEG) has become a widely applied and highly sophisticated brain monitoring tool in a variety of intensive care unit (ICU) settings. The most common indication for EEG monitoring currently is the management of refractory status epilepticus. In addition, a number of studies have associated frequent seizu...

Background and Objectives Status epilepticus that continues after the initial benzodiazepine and a second anticonvulsant medication is known as refractory status epilepticus (RSE). Management is highly variable as adequately powered clinical trials are missing. We aimed to determine if propofol and midazolam were equally effective in controlling RS...

Background Recovery trajectories of clinically unresponsive patients with acute brain injury are largely uncertain. Brain activation in the absence of a behavioural response to spoken motor commands can be detected by EEG, also known as cognitive-motor dissociation. We aimed to explore the role of cognitive-motor dissociation in predicting time to...

Subarachnoid haemorrhage (SAH) is the third most common subtype of stroke. Incidence has decreased over past decades, possibly in part related to lifestyle changes such as smoking cessation and management of hypertension. Approximately a quarter of patients with SAH die before hospital admission; overall outcomes are improved in those admitted to h...

Background The use of processed electroencephalography (pEEG) for depth of sedation (DOS) monitoring is increasing in anesthesia; however, how to use of this type of monitoring for critical care adult patients within the intensive care unit (ICU) remains unclear. Methods A multidisciplinary panel of international experts consisting of 21 clinician...

Background Hematoma and perihematomal edema volumes are important radiographic markers in spontaneous intracerebral hemorrhage. Accurate, reliable, and efficient quantification of these volumes will be paramount to their utility as measures of treatment effect in future clinical studies. Both manual and semi-automated quantification methods of hema...

Background/Objective: There have been numerous reports of neurological manifestations identified in hospitalized patients infected with SARS-CoV-2, the virus that causes COVID-19. Here, we identify the spectrum of associated neurological symptoms and diagnoses, define the time course of their development, examine readmission rates and mortality ris...

Background: Prolonged external ventricular drainage (EVD) in patients with subarachnoid hemorrhage (SAH) leads to morbidity, whereas early removal can have untoward effects related to recurrent hydrocephalus. A metric to help determine the optimal time for EVD removal or ventriculoperitoneal shunt (VPS) placement would be beneficial in preventing...

This proceedings article presents actionable research targets on the basis of the presentations and discussions at the 2nd Curing Coma National Institutes of Health (NIH) symposium held from May 3 to May 5, 2021. Here, we summarize the background, research priorities, panel discussions, and deliverables discussed during the symposium across six maj...

Background: Dysfunctional cerebral autoregulation often precedes delayed cerebral ischemia (DCI). Currently, there are no data-driven techniques that leverage this information to predict DCI in real time. Our hypothesis is that information using continuous updated analyses of multimodal neuromonitoring and cerebral autoregulation can be deployed t...

Objective: Estimate time to recovery of command-following and associations between hypoxemia with time to recovery of command-following METHODS: In this multi-center, retrospective, cohort study during the initial surge of the United States' pandemic (March-July 2020) we estimate the time from intubation to recovery of command-following, using Kap...

Objectives: Early consciousness disorder (ECD) after acute ischemic stroke (AIS) is understudied. ECD may influence outcomes and the decision to withdraw life-sustaining treatment (WOLST). Methods: We studied patients with AIS from 2010-2019 across 122 Florida Hospitals participating in the Florida Stroke Registry. We studied the effect of ECD o...

Background The objective of this study was to evaluate the accuracy of seizure burden in patients with super-refractory status epilepticus (SRSE) by using quantitative electroencephalography (qEEG).MethodsEEG recordings from 69 patients with SRSE (2009–2019) were reviewed and annotated for seizures by three groups of reviewers: two board-certified...

Background: Characterization of coronavirus disease 2019 (COVID-19) endotypes may help explain variable clinical presentations and response to treatments. While risk factors for COVID-19 have been described, COVID-19 endotypes have not been elucidated. Objectives: We sought to identify and describe COVID-19 endotypes of hospitalized patients. Metho...

Background The literature related to the use of processed EEG (pEEG) for depth of sedation (DOS) monitoring is increasing, however it is unclear how to use this type of monitoring for critical care patients within the intensive care unit (ICU). Methods We performed a systematic review of the literature according to the Grade of Recommendation asses...

Background and Purpose Impaired level of consciousness (LOC) on presentation at hospital admission in patients with intracerebral hemorrhage (ICH) may affect outcomes and the decision to withhold or withdraw life-sustaining treatment (WOLST). Methods Patients with ICH were included across 121 Florida hospitals participating in the Florida Stroke R...

Background Consciousness in patients with brain injury is traditionally assessed based on semiological evaluation at the bedside. This classification is limited because of low granularity, ill-defined and rigid nomenclatures incompatible with the highly fluctuating nature of consciousness, failure to identify specific brain states like cognitive mo...

Coma and disorders of consciousness (DoC) are highly prevalent and constitute a burden for patients, families, and society worldwide. As part of the Curing Coma Campaign, the Neurocritical Care Society partnered with the National Institutes of Health to organize a symposium bringing together experts from all over the world to develop research targe...

Background The current state of the science regarding the care and prognosis of patients with disorders of consciousness is limited. Scientific advances are needed to improve the accuracy, relevance, and approach to prognostication, thereby providing the foundation to develop meaningful and effective interventions.Methods To address this need, an i...

Background: Intracranial pressure waveform morphology reflects compliance, which can be decreased by ventriculitis. We investigated whether morphologic analysis of intracranial pressure dynamics predicts the onset of ventriculitis. Methods: Ventriculitis was defined as culture or Gram stain positive cerebrospinal fluid, warranting treatment. We...

Background Prevalence and etiology of unconsciousness are uncertain in hospitalized patients with coronavirus disease 2019 (COVID-19). We tested the hypothesis that increased inflammation in COVID-19 precedes coma, independent of medications, hypotension, and hypoxia.Methods We retrospectively assessed 3203 hospitalized patients with COVID-19 from...

Background Electroencephalography (EEG) findings following cardiovascular collapse in death are uncertain. We aimed to characterize EEG changes immediately preceding and following cardiac death.Methods We retrospectively analyzed EEGs of patients who died from cardiac arrest while undergoing standard EEG monitoring in an intensive care unit. Patien...

Background Vaccine induced immune medicated thrombocytopenia or VITT, is a recent and rare phenomenon of thrombosis with thrombocytopenia, frequently including cerebral venous thromboses (CVT), that has been described following vaccination with adenovirus vaccines ChAdOx1 nCOV-19 (AstraZeneca) and Ad26.COV2·S Johnson and Johnson (Janssen/J&J). The...

Objective To determine the ability of quantitative electroencephalography (QEEG) to improve the accuracy of predicting recovery of consciousness by post-cardiac arrest day 10. Methods Unconscious survivors of cardiac arrest undergoing daily clinical and EEG assessments through post-cardiac arrest day 10 were studied in a prospective observational...

Many patients with SARS-CoV-2 infection develop neurological signs and symptoms, though, to date, little evidence exists that primary infection of the brain is a significant contributing factor. We present the clinical, neuropathological, and molecular findings of 41 consecutive patients with SARS-CoV-2 infections who died and underwent autopsy in...