Intravenous Ganaxolone: Pharmacokinetics, Pharmacodynamics, Safety, and Tolerability in Healthy Adults

Ganaxolone, a neuroactive steroid anticonvulsant that modulates both synaptic and extrasynaptic γ-aminobutyric acid type A (GABAA ) receptors, is in development for treatment of status epilepticus (SE) and rare epileptic disorders, and has been approved in the United States for treatment of seizures associated with cyclin-dependent kinase-like 5 deficiency disorder in patients ≥2 years old. This phase 1 study in 36 healthy volunteers evaluated the pharmacokinetics, pharmacodynamics, and safety of intravenous ganaxolone administered as a (i) single bolus, (ii) infusion, and (iii) bolus followed by continuous infusion. After a single bolus over 2 minutes (20 mg) or 5 minutes (10 or 30 mg), ganaxolone was detected in plasma with a median Tmax of 5 minutes, whereas a 60-minute infusion (10 or 30 mg) or a bolus (6 mg over 5 minutes) followed by infusion (20 mg/h) for 4 hours achieved a median Tmax of approximately 1 and 3 hours, respectively. Cmax was dose and administration-time dependent, ranging from 73.8 ng/mL (10 mg over 5 minutes) to 1240 ng/mL (30 mg over 5 minutes). Bolus doses above 10 mg of ganaxolone markedly influenced the bispectral index score with a rapid decline; smaller changes occurred on the Modified Observer's Assessment of Alertness/Sedation scale and in quantitative electroencephalogram. Most adverse events were of mild severity, with 2 events of moderate severity; none were reported as serious. No effects on systemic hemodynamics or respiratory functions were reported. Overall, ganaxolone was generally well tolerated at the doses studied and demonstrated pharmacokinetic and pharmacodynamic properties suitable to treat SE.

Multidisciplinary Approach to Sedation and Early Mobility of Intubated Critically Ill Neurologic Patients Improves Mobility at Discharge

Background and Purpose

Over-sedation may confound neurologic assessment in critically ill neurologic patients and prolong duration of mechanical ventilation (MV). Decreased sedative use may facilitate early functional independence when combined with early mobility. The objective of this study was to evaluate the impact of a stepwise, multidisciplinary analgesia-first sedation pathway and early mobility protocol on medication use and mobility in the neuroscience intensive care unit (ICU).

Methods

We performed a single-center prospective cohort study with adult patients admitted to a neuroscience ICU between March and June 2016-2018 who required MV for greater than 48 hours. Patients were included from three separate phases of the study: Phase I - historical controls (2016); Phase II - analgesia-first pathway (2017); Phase III - early mobility protocol (2018). Primary outcomes included propofol requirements during MV, total rehabilitation therapy provided, and functional mobility during ICU admission.

Results

156 patients were included in the analysis. Decreasing propofol exposure was observed during Phase I, II, and III (median 2243.7 mg/day vs 2065.6 mg/day vs 1360.8 mg/day, respectively; P = .04 between Phase I and III). Early mobility was provided in 59.7%, 40%, and 81.6% of patients while admitted to the ICU in Phase I, II, and III, respectively (P < .01). An increased proportion of patients in Phase III were walking or ambulating at ICU discharge (26.7%; 8/30) compared to Phase I (7.9%, 3/38, P = .05).

Conclusions

An interdisciplinary approach with an analgesia-first sedation pathway with early mobility protocol was associated with less sedative use, increased rehabilitation therapy, and improved functional mobility status at ICU discharge.

Disparities in Decompressive Cranial Surgery Utilization in Severe Traumatic Brain Injury Patients without a Primary Extra-Axial Hematoma: A U.S. Nationwide Study

OBJECTIVE

Decompressive craniectomy is recommended to reduce mortality in severe traumatic brain injury (TBI). Disparities exist in TBI treatment outcomes; however, data on disparities pertaining to decompressive craniectomy utilization is lacking. We investigated these disparities, focusing on race, insurance, sex, and age.

METHODS

Hospitalizations (2004-2014) were retrospectively extracted from the Nationwide Inpatient Sample. The criteria included are as follows: age ≥18 years and indicators of severe TBI diagnosis. Poor outcomes were defined as discharge to institutional care and death. Multivariable logistic regression models were used to assess the effects of race, insurance, age, and sex, on craniectomy utilization and outcomes.

RESULTS

Of 349,164 hospitalized patients, 6.8% (n = 23,743) underwent craniectomy. White (odds ratio [OR] = 0.50, 95% confidence interval [CI] = 0.44-0.57; P < 0.001) and Black (OR = 0.45, 95% CI = 0.32-0.64; P = 0.003) Medicare beneficiaries were less likely to undergo craniectomy. Medicare (P < 0.0001) and Medicaid beneficiaries (P < 0.0001) of all race categories had poorer outcomes than privately insured White patients. Black (OR = 1.2, 95% CI = 1.08-2.34; P = 0.001) patients with private insurance and Black (OR = 1.39, 95% CI = 1.22-1.58; P < 0.0001) Medicaid beneficiaries had poorer outcomes than privately insured White patients (P < 0.0001). Older patients (OR = 0.74, 95%, CI = 0.71-0.76; P < 0.001) were less likely to undergo craniectomy and were more likely to have poorer outcomes. Females (OR = 0.82, 95% CI = 0.76-0.88; P < 0.001) were less likely to undergo craniectomy.

CONCLUSIONS

There are disparities in race, insurance status, sex, and age in craniectomy utilization and outcome. This data highlights the necessity to appropriately address these disparities, especially race and sex, and actively incorporate these factors in clinical trial design and enrollment.

Intravenous ganaxolone for the treatment of refractory status epilepticus: Results from an open-label, dose-finding, phase 2 trial

OBJECTIVE

Patients with refractory status epilepticus (RSE) have failed treatment with benzodiazepines and ≥1 second-line intravenous (IV) antiseizure medication (ASM). Guidelines recommend IV anesthesia when second-line ASMs have failed, but potential harms can outweigh the benefits. Novel treatments are needed to stop and durably control RSE without escalation to IV anesthetics. Ganaxolone is an investigational neuroactive steroid in development for RSE treatment. This study's objective was to determine the appropriate dosing for IV ganaxolone in RSE and obtain a preliminary assessment of efficacy and safety.

METHODS

This was an open-label, phase 2 trial conducted from February 19, 2018 to September 18, 2019, at three sites in the United States. Patients were aged ≥12 years, had convulsive or nonconvulsive SE, and failed to respond to ≥1 second-line IV ASM. Twenty-one patients were screened; 17 were enrolled. Patients received IV ganaxolone added to standard-of-care ASMs. Ganaxolone infusion was initiated as an IV bolus (over 3 min) with continuous infusion of decreasing infusion rates for 48-96 h followed by an 18-h taper. There were three ganaxolone dosing cohorts: low, 500 mg/day; medium, 650 mg/day; and high, 713 mg/day. The primary end point was the number of patients not requiring escalation to IV anesthetic treatment within 24 h of ganaxolone initiation.

RESULTS

Most of the 17 enrolled patients (65%) had nonconvulsive SE, and had failed a median of three prior ASMs, including first-line benzodiazepine and second-line IV ASM therapy. Median time to SE cessation following ganaxolone initiation was 5 min. No patient required escalation to third-line IV anesthetics during the 24-h period following ganaxolone initiation. Two treatment-related serious adverse events (sedation) were reported. Of the three deaths, none was considered related to ganaxolone; all occurred 9-22 days after completing ganaxolone.

SIGNIFICANCE

IV ganaxolone achieved rapid and durable seizure control in patients with RSE, and showed acceptable safety and tolerability.

Multiple high-grade and rare immune-related adverse events in a colon cancer patient with genomic and cytokine profiling

We report a case of multiple high-grade and rare immune-related adverse events (irAEs) in a patient with microsatellite instability-high (MSI-H) metastatic colorectal cancer (mCRC). A middle-aged MSI-H mCRC patient with metastases to the lungs and lymph nodes received several lines of chemotherapy and immunotherapy and developed five different high-grade irAEs during immunotherapy, including lymphadenitis, pneumonitis, hypophysitis, thyroiditis and transverse myelitis. Genomic profiling revealed high tumor mutational burden of 43 Muts/Mb. Cytokine profiling showed a threefold increase in MMP-9 shortly prior to the onset of lymphadenitis and a fourfold increase of Ang-1 1 week after the resolution of lymphadenitis. Further studies are warranted to investigate the association of MSI-H mCRC with irAEs and the role of cytokines in predicting irAEs.

Use of Transcranial Doppler as a Biomarker of CAR T Cell-Related Neurotoxicity

Background and Objectives

To examine the relationship between transcranial Doppler (TCD) mean flow velocity (MFV) and the severity and temporal onset of neurotoxicity after chimeric antigen receptor (CAR) T-cell therapy in patients with relapsed lymphoma.

Methods

We identified a cohort of 165 patients with relapsed or refractory B-cell lymphoma who received CAR T-cell therapy. TCDs were performed at baseline, treatment day 5, and throughout hospitalization based on development of neurologic symptoms. We assessed the percent change in velocity from baseline in each of the 6 major supratentorial arteries and the relationship of these values to development and timing of neurotoxicity.

Results

Our cohort was 30% female with an average age of 60 years. Of patients with TCDs performed, 63% developed neurotoxicity, and 32% had severe neurotoxicity. The median time of neurotoxicity onset was day 7. Higher maximum percent change in MFV across all vessels was significantly associated with likelihood of developing neurotoxicity (p = 0.0002) and associated with severe neurotoxicity (p = 0.0421). We found that with increased percent change in MFV, the strength of correlation between day of TCD velocity change and day of neurotoxicity onset increased. There was no single vessel in which increase in MFV was associated with neurotoxicity.

Discussion

Our study demonstrates an association between increase in TCD MFV and the development of neurotoxicity, as well as timing of neurotoxicity onset. We believe that TCD ultrasound may be used as a bedside functional biomarker in CAR T-cell patients and may guide immunologic interventions to manage toxicity in this complex patient group.

Neurologic Complications in Patients with Cancer

Neurologic symptoms are commonly seen in patients with cancer and can be among the most challenging to diagnose and manage. It is often difficult to determine if new neurologic symptoms are secondary to direct effects of a malignant lesion, systemic complications of disease, paraneoplastic disorders, or side effects of cancer treatment itself. However, early diagnosis and treatment of each of these conditions can improve patients' quality of life and long-term functional outcomes. In this review, we describe a systematic approach to the diagnosis of new neurologic symptoms in patients with known malignancy. We have categorized the neurologic complications of cancer through a mechanistic approach, with an emphasis on ascertaining underlying pathophysiology to guide treatment choice. This review focuses on the acute neurologic complications of cancer that require hospital admission.

EEG findings in CART T associated neurotoxicity: clinical and radiological correlations

BACKGROUND

While EEG is frequently reported as abnormal after CAR T cell therapy, its clinical significance remains unclear. We aim to systematically describe EEG features in a large single-center cohort and correlate them with clinical and radiological findings.

METHODS

We retrospectively identified patients undergoing CAR T cell therapy who had continuous EEG. Neurotoxicity grades, detailed neurological symptoms, and brain MRI or FDG-PET were obtained. Correlation between clinical and radiological findings and EEG features was assessed.

RESULTS

In 81 patients with median neurotoxicity grade 3 (IQR 2-3), diffuse EEG background slowing was the most common finding and correlated with neurotoxicity severity (p <0.001). A total of 42 patients had rhythmic or periodic patterns, 16 of them within the ictal-interictal-continuum (IIC), 5 with clinical seizures, and 3 with only electrographic seizures. Focal EEG abnormalities, consisting of lateralized periodic discharges (LPD, n=1), lateralized rhythmic delta activity (LRDA, n=6), or focal slowing (n=19), were found in 22 patients. All patients with LRDA, LPD, and 10/19 patients with focal slowing had focal clinical symptoms concordant with these EEG abnormalities. In addition, these focal EEG changes often correlated with PET hypometabolism or MRI hypoperfusion, in absence of a structural lesion.

CONCLUSION

In adult patients experiencing neurotoxicity after CAR T cell infusion, EEG degree of background disorganization correlated with neurotoxicity severity. IIC patterns and focal EEG abnormalities are frequent and often correlate with focal clinical symptoms and with PET-hypometabolism/MRI-hypoperfusion, without structural lesion. The etiology of these findings remains to be elucidated.

Clinical Predictors of Neurotoxicity After Chimeric Antigen Receptor T-Cell Therapy

Importance

Chimeric antigen receptor (CAR) T-cell therapy for relapsed or refractory hematologic malignant neoplasm causes severe neurologic adverse events ranging from encephalopathy and aphasia to cerebral edema and death. The cause of neurotoxicity is incompletely understood, and its unpredictability is a reason for prolonged hospitalization after CAR T-cell infusion.

Objective

To identify clinical and laboratory parameters predictive of neurotoxicity and to develop a prognostic score associated with its risk.

Design, Setting, and Participants

This single-center diagnostic/prognostic accuracy study was conducted at Brigham and Women's Hospital/Dana Farber Cancer Institute from April 2015 to February 2020. A consecutive sample of all patients undergoing CAR T-cell therapy with axicabtagene ciloleucel for relapsed or refractory lymphoma were assessed for inclusion (n = 213). Patients who had previously received CAR T cells or who were treated for mantle cell lymphoma were excluded (n = 9). Patients were followed up for a minimum of 30 days from the date of CAR T-cell infusion.

Main Outcomes and Measures

The primary outcomes were measures of performance (accuracy, sensitivity, specificity, area under the curve) of a diagnostic tool to predict the occurrence of CAR-associated neurotoxicity, as graded by the Common Terminology Criteria for Adverse Events criteria.

Results

Two hundred four patients (127 men [62.2%]; mean [SD] age, 60.0 [12.1] years) were included in the analysis, of which 126 (61.8%) comprised a derivation cohort and 78 (38.2%), an internal validation cohort. Seventy-three patients (57.9%) in the derivation cohort and 45 patients (57.7%) in the validation cohort experienced neurotoxicity. Clinical and laboratory values obtained early in admission were used to develop a multivariable score that can predict the subsequent development of neurotoxicity; when tested on an internal validation cohort, this score had an area under the curve of 74%, an accuracy of 77%, a sensitivity of 82%, and a specificity of 70% (positive:negative likelihood ratio, 2.71:0.26).

Conclusions and Relevance

The score developed in this study may help predict which patients are likely to experience CAR T-cell-associated neurotoxicity. The score can be used for triaging and resource allocation and may allow a large proportion of patients to be discharged from the hospital early.

Myelopathy Due to CAR-T Related Neurotoxicity Treated with Siltuximab

Chimeric antigen receptor T (CART) cell therapy is highly effective for relapsed/refractory hematologic malignancy [1,2]; however, cytokine release syndrome (CRS) and neurotoxicity are observed in up to 77% of patients [3]. In large case series, the most common presentations of neurotoxicity were encephalopathy (57%), headache (42%), tremor (38%) and aphasia (35%). CART mediated spinal cord toxicity is not well characterized. Structural neurologic damage (stroke and intracranial hemorrhage) was only observed in 1-2% and seizures were seen in 1%-8% of cases [3, 4]. Neuroimaging findings in patients with neurotoxicity are rare and not specific.

Neurological complications of cancer immunotherapy (CAR T cells)

Chimeric antigen receptor (CAR) T cell therapy has become an indispensable tool in the treatment of advanced malignancy, however, it is associated with significant neurologic toxicity. The pathophysiology of CAR T-cell associated neurotoxicity is incompletely understood, and the specific risk factors have only recently begun to be characterized. Despite a growing clinical experience with CAR T cell therapy, the unpredictability of neurologic symptoms remains a source of great anxiety for patients and practitioners alike, and a major limitation for more widespread adoption of this important treatment modality. The purpose of this review is to familiarize clinicians with the typical clinical manifestations and salient features of CAR T cell associated neurotoxicity. We place an emphasis on highlighting the clinical and laboratory markers that may be helpful for predicting clinical course, allowing teams to anticipate necessary supportive measures. We will also review the appropriate diagnostic workup for CAR T cell neurotoxicity and current treatment recommendations.

Validation of diffuse correlation spectroscopy measures of critical closing pressure against transcranial Doppler ultrasound in stroke patients

SIGNIFICANCE

Intracranial pressure (ICP), variability in perfusion, and resulting ischemia are leading causes of secondary brain injury in patients treated in the neurointensive care unit. Continuous, accurate monitoring of cerebral blood flow (CBF) and ICP guide intervention and ultimately reduce morbidity and mortality. Currently, only invasive tools are used to monitor patients at high risk for intracranial hypertension.

AIM

Diffuse correlation spectroscopy (DCS), a noninvasive near-infrared optical technique, is emerging as a possible method for continuous monitoring of CBF and critical closing pressure (CrCP or zero-flow pressure), a parameter directly related to ICP.

APPROACH

We optimized DCS hardware and algorithms for the quantification of CrCP. Toward its clinical translation, we validated the DCS estimates of cerebral blood flow index (CBFi) and CrCP in ischemic stroke patients with respect to simultaneously acquired transcranial Doppler ultrasound (TCD) cerebral blood flow velocity (CBFV) and CrCP.

RESULTS

We found CrCP derived from DCS and TCD were highly linearly correlated (ipsilateral R2  =  0.77, p  =  9  ×  10  -  7; contralateral R2  =  0.83, p  =  7  ×  10  -  8). We found weaker correlations between CBFi and CBFV (ipsilateral R2  =  0.25, p  =  0.03; contralateral R2  =  0.48, p  =  1  ×  10  -  3) probably due to the different vasculature measured.

CONCLUSION

Our results suggest DCS is a valid alternative to TCD for continuous monitoring of CrCP.

Diffuse Cerebral Edema After Moyamoya Disease-Related Intracerebral Hemorrhage: A Case Report

Moyamoya disease (MMD) is a rare, progressive occlusive disease characterized by bilateral internal carotid artery hypoplasia that often presents with ischemic stroke and intracerebral hemorrhage (ICH). Although MMD-related ICH is generally managed similarly to spontaneous ICH, we present a case in which standard management strategies may have led to an unprecedented devastating outcome. A 37-year-old female without any previous medical history presented with headache and right-sided weakness. A computed tomography (CT) scan revealed a large left basal ganglia ICH. Vessel imaging revealed diffuse narrowing of the entire anterior circulation with prominent leptomeningeal collaterals consistent with MMD. The patient's systolic blood pressure was kept under 140 mmHg. During the hospitalization, she became hypocarbic while being trialed on pressure support ventilation. Several hours later, she developed fixed and dilated pupils. Repeat CT head showed new diffuse cerebral edema with tonsillar herniation. Despite hyperosmolar therapy, paralytics, pentobarbital, and cerebrospinal fluid diversion, no improvement was noted. Unfortunately, brain MRI revealed multifocal brainstem infarcts with superimposed Duret hemorrhages. Herein, we report diffuse cerebral edema as a complication of MMD-related ICH. We hypothesize that disruptions of delicate cerebral autoregulatory mechanisms led to extensive hypoxic-ischemic injury. In the setting of ICH, aggressive blood pressure management coupled with relative hypocapnia may have likely caused vasoconstriction of poorly compliant arteries leading to worsened cerebral blood flow and ischemia. Therefore, because of its complex pathophysiology, strict adherence to eucapnia should be maintained in MMD-related ICH.

Microembolic Signals Detected by Transcranial Doppler Predict Future Stroke and Poor Outcomes

BACKGROUND AND PURPOSE

Although transcranial Doppler detects microembolic signals (MES) in numerous settings, the practical significance of such findings remains unclear.

METHODS

Clinical information from ischemic stroke or transient ischemic attack patients (n = 248) who underwent embolic monitoring from January 2015 to December 2018 was obtained.

RESULTS

MES were found in 15% of studies and ischemic recurrence was seen in 11% of patients (over 7 ± 6 days). Patients with MES had more lacunes than those without MES (1 ± 3 vs. 1 ± 2, P = .016), were more likely to have ischemic recurrence (37% vs. 6%, P < .001), undergo a future revascularization procedure (26% vs. 10%, P = .005), have a longer length of stay (9 vs. 4 days, P = .043), and have worse functional disability at discharge (modified Rankin Scale 3-6, 66% vs. 34%, P < .001). After controlling for several relevant cofactors, patients with MES were more likely to have ischemic recurrence (HR 4.90, 95% CI 2.16-11.09, P < .001), worse functional disability (OR 3.31, 95% CI 1.22-8.99, P = .019), and longer length of stays (β = .202, P < .001).

CONCLUSIONS

MES may help to risk stratify patients as their presence is associated with ischemic recurrence and worse outcomes.

Chromatic fading following complete adaptation to unique hues

Profound vision loss occurs after prolonged exposure to an unchanging featureless visual environment. The effect is sometimes called visual fade. Here we investigate this phenomenon in the color domain using two different experiments. In the first experiment we determine the time needed for a colored background to appear achromatic. Four backgrounds were tested. Each represented the observers’ four unique hues. This adaptation time was compared with time to recover after adaptation Hue shifts at the end of the adaptation period were also measured. There were wide individual differences in adaptation times and recovery times. Overall recovery was faster than adaptation (p < 0.02). There were minimal shifts in hue. In the second experiment the changes in saturation (Munsell chroma) and lightness (Munsell value) of the background were monitored at six time intervals during the adapting process. Again asymmetric matching with Munsell samples was used. There were two distinct components to both the adaptation and recovery phases; one fast with time constant <1s, the other slow with time constant between 40 and 160s.

The experiments show that the special case of visual fade involving color represents the sensory basis for many color-related effects involving adaptation.

Successful Wean Despite Emergence of Ictal-Interictal EEG Patterns During the Weaning of Prolonged Burst-Suppression Therapy for Super-Refractory Status Epilepticus

BACKGROUND

Management of refractory status epilepticus (SE) commonly involves the induction of burst suppression using intravenous anesthetic agents. However, the endpoints of these therapies are not well defined. Weaning anesthetic agents are complicated by the emergence of electroencephalogram (EEG) patterns along the ictal-interictal continuum (IIC), which have uncertain significance given that IIC patterns may worsen cerebral metabolism and oxygenation, have a dissociation between scalp and depth EEG recordings, or may indicate a late stage of SE itself. Determining the significance of IIC patterns in the unique context of anesthetic weaning is important to prevent the potential for unnecessarily prolonging anesthetic coma.

METHODS

Among 118 individuals with SE, we retrospectively identified a series of patients who underwent at least 24 h of burst-suppression therapy, experienced two or more weaning trials, and developed IIC patterns during anesthetic weaning. Anesthetic titration strategies during the emergence of these patterns were examined.

RESULTS

Each of the six individuals who met inclusion criteria experienced aggressive weaning despite the emergence of IIC patterns. The IIC patterns that were encountered during anesthetic weaning (including generalized and lateralized periodic discharges) are described in detail. Favorable outcomes were reported in each subject.

CONCLUSION

IIC patterns encountered during anesthetic weaning may be transitional and warrant observation, allowing for the emergence of more definitive clinical or electrographic results. The metabolic impact of these IIC patterns on brain activity is uncertain, but weaning strategies that treat IIC as a surrogate of recurrent SE risk further prolonging anesthetic management and its known toxicity. We speculate that these patterns may have a context-specific association with SE relapse, with less-risk conferred when these patterns are observed during the weaning of anesthetic agents after prolonged burst-suppression therapy. Other electrographic features aside from this clinical context may discriminate the risk of SE relapse, such as EEG background activity.

Neuropathology of a Case With Fatal CAR T-Cell-Associated Cerebral Edema

Chimeric antigen receptor (CAR) T cells are a new and powerful class of cancer immunotherapeutics that have shown potential for the treatment of hematopoietic malignancies. The tremendous promise of this approach is tempered by safety concerns, including potentially fatal neurotoxicity, sometimes but not universally associated with cytokine release syndrome. We describe the postmortem examination of a brain from a 21-year-old patient with relapsed pre-B cell acute lymphoblastic leukemia (ALL) who died from fulminant cerebral edema following CAR T-cell infusion. We found a range of changes that included activation of microglia, expansion of perivascular spaces by proteinaceous exudate, and clasmatodendrosis-a beading of glial fibrillary acidic protein consistent with astrocyte injury. Notably, within the brain parenchyma, we identified only infrequent T cells and did not identify ALL cells or CAR T cells. The overall findings are nonspecific but raise the possibility of astrocyte and blood-brain barrier dysfunction as a potential etiology of fatal CAR T-cell neurotoxicity in this patient.

Fatal Powassan Encephalitis (Deer Tick Virus, Lineage II) in a Patient With Fever and Orchitis Receiving Rituximab

Importance

Powassan virus is a rare but increasingly recognized cause of severe neurological disease.

Objective

To highlight the diagnostic challenges and neuropathological findings in a fatal case of Powassan encephalitis caused by deer tick virus (lineage II) in a patient with follicular lymphoma receiving rituximab, with nonspecific anti-GAD65 antibodies, who was initially seen with fever and orchiepididymitis.

Design, Setting, and Participants

Comparison of clinical, radiological, histological, and laboratory findings, including immunohistochemistry, real-time polymerase chain reaction, antibody detection, and unbiased sequencing assays, in a single case report (first seen in December 2016) at an academic medical center.

Exposure

Infection with Powassan virus.

Main Outcomes and Measures

Results of individual assays compared retrospectively.

Results

In a 63-year-old man with fatal Powassan encephalitis, serum and cerebrospinal fluid IgM antibodies were not detected via standard methods, likely because of rituximab exposure. Neuropathological findings were extensive, including diffuse leptomeningeal and parenchymal lymphohistiocytic infiltration, microglial proliferation, marked neuronal loss, and white matter microinfarctions most severely involving the cerebellum, thalamus, and basal ganglia. Diagnosis was made after death by 3 independent methods, including demonstration of Powassan virus antigen in brain biopsy and autopsy tissue, detection of viral RNA in serum and cerebrospinal fluid by targeted real-time polymerase chain reaction, and detection of viral RNA in cerebrospinal fluid by unbiased sequencing. Extensive testing for other etiologies yielded negative results, including mumps virus owing to prodromal orchiepididymitis. Low-titer anti-GAD65 antibodies identified in serum, suggestive of limbic encephalitis, were not detected in cerebrospinal fluid.

Conclusions and Relevance

Owing to the rarity of Powassan encephalitis, a high degree of suspicion is required to make the diagnosis, particularly in an immunocompromised patient, in whom antibody-based assays may be falsely negative. Unbiased sequencing assays have the potential to detect uncommon infectious agents and may prove useful in similar scenarios.

Correction to: Ventral striatal and septal area hypermetabolism on FDG-PET in herpes simplex viral encephalitis

The word "hypermetabolism" needs to be replaced by "hypometabolism" at only ONE place and NOT throughout the article.So the correction could be stated as:"In the case description section, the sentence "A repeat dedicatedbrain FDG-PET scan performed on day 9, under burst suppression,showed diffuse hypermetabolism with persistent relativehypermetabolism in the left ventral striatum and septalarea (Fig. 1b)."should read as"A repeat dedicatedbrain FDG-PET scan performed on day 9, under burst suppression,showed diffuse hypometabolism with persistent relativehypermetabolism in the left ventral striatum and septalarea (Fig. 1b)." At all other places, the word hypermetabolism is appropriate.

Ventral striatal and septal area hypermetabolism on FDG-PET in herpes simplex viral encephalitis

A 71-year-old man presented with sudden onset, generalized tonic-clonic seizures and altered mental status. Initial brain magnetic resonance imaging was normal but a brain FDG-PET scan showed hypermetabolism in the left ventral striatum and septal area. Initial cerebrospinal fluid (CSF) examination showed mildly elevated protein but herpes simplex virus (HSV) polymerase chain reaction (PCR) was negative. A repeat CSF examination performed 9 days later showed a positive HSV PCR. Histopathological and immunohistochemical examination of autopsy specimen confirmed the presence of CD45+ lymphocytes and HSV antigen, suggesting the presence of both inflammation and viral infection corresponding to PET abnormality.

Fast cyclic stimulus flashing modulates perception of bi-stable figure

Many experiments have demonstrated that the rhythms in the brain influence the initial perceptual information processing. We investigated whether the alternation rate of the perception of a Necker cube depends on the frequency and duration of a flashing Necker cube. We hypothesize that synchronization between the external rhythm of a flashing stimulus and the internal rhythm of neuronal processing should change the alternation rate of a Necker cube. Knowing how a flickering stimulus with a given frequency and duration affects the alternation rate of bistable perception, we could estimate the frequency of the internal neuronal processing. Our results show that the perception time of the dominant stimulus depends on the frequency or duration of the flashing stimuli. The duration of the stimuli, at which the duration of the perceived image was maximal, was repeated periodically at 4 ms intervals. We suppose that such results could be explained by the existence of an internal rhythm of 125 cycles/s for bistable visual perception. We can also suppose that it is not the stimulus duration but the precise timing of the moments of switching on of external stimuli to match the internal stimuli which explains our experimental results. Similarity between the effects of flashing frequency on alternation rate of stimuli perception in present and previously performed experiment on binocular rivalry support the existence of a common mechanism for binocular rivalry and monocular perception of ambiguous figures.

Inflammation and Demyelination

Autoimmune disease affecting the central nervous system is a common cause for admission to the neurointensive care unit. Although well-described clinical syndromes exist, patients more commonly present with progressive neurologic dysfunction and some combination of laboratory and radiographic evidence of central nervous system inflammation. The urgency to intervene to prevent permanent damage to the nervous system often conflicts with diagnostic uncertainty. This chapter outlines some of the basic diagnostic and therapeutic principles of autoimmune diseases of the central nervous system. The chapter characterizes disorders not as a list of individual disease entities but rather as clusters of syndromes based on common underlying mechanisms of immune dysfunction. This approach focuses on early interventions rather than precise diagnosis. As our understanding of the immune system continues to grow, this framework will allow for a more sophisticated approach to the management of patients with these complex, often devastating but frequently reversible, neurologic illnesses.

Autoimmune Encephalitis in Critical Care: Optimizing Immunosuppression

Autoimmune diseases affecting the nervous systems are a common cause of admission to the intensive care unit (ICU). Although there exist several well-described clinical syndromes, patients more commonly present with progressive neurologic dysfunction and laboratory and radiographic evidence of central nervous system (CNS) inflammation. In the critical care setting, the urgency to intervene to prevent permanent damage to the nervous system and secondary injury from the systemic manifestations of these syndromes often conflicts with diagnostic uncertainty. Furthermore, treatment is limited by current therapeutic agents that remain non-specific for individual diseases, especially for those whose pathophysiology remains unclear. Primary autoimmune, paraneoplastic, parainfectious, and iatrogenic neurologic disorders all share the common underlying pathophysiology of an adaptive immune response directed against an antigen within the nervous system. Several different mechanisms of immune dysfunction are responsible for pathogenesis within each of these categories of disease, and it is at this level of pathophysiology that the most effective and appropriate therapeutic decisions are made. In this review, we outline the basic diagnostic and therapeutic principles in the management of autoimmune diseases of the nervous system in the ICU. We approach these disorders not as lists of distinct clinical syndromes or molecular targets of autoimmunity but rather as clusters of syndromes based on these common underlying mechanisms of immune dysfunction. This approach emphasizes early intervention over precise diagnosis. As our understanding of the immune system continues to grow, this framework will allow for a more sophisticated approach to the management of patients with these complex, often devastating but frequently reversible, neurologic illnesses.

Brexanolone as adjunctive therapy in super-refractory status epilepticus

Objective

Super‐refractory status epilepticus (SRSE) is a life‐threatening form of status epilepticus that continues or recurs despite 24 hours or more of anesthetic treatment. We conducted a multicenter, phase 1/2 study in SRSE patients to evaluate the safety and tolerability of brexanolone (USAN; formerly SAGE‐547 Injection), a proprietary, aqueous formulation of the neuroactive steroid, allopregnanolone. Secondary objectives included pharmacokinetic assessment and open‐label evaluation of brexanolone response during and after anesthetic third‐line agent (TLA) weaning.

Methods

Patients receiving TLAs for SRSE control were eligible for open‐label, 1‐hour brexanolone loading infusions, followed by maintenance infusion. After 48 hours of brexanolone infusion, TLAs were weaned during brexanolone maintenance. After 4 days, the brexanolone dose was tapered. Safety and functional status were assessed over 3 weeks of follow‐up.

Results

Twenty‐five patients received open‐label study drug. No serious adverse events (SAEs) were attributable to study drug, as determined by the Safety Review Committee. Sixteen patients (64%) experienced ≥1 SAE. Six patient deaths occurred, all deemed related to underlying medical conditions. Twenty‐two patients underwent ≥1 TLA wean attempt. Seventeen (77%) met the response endpoint of weaning successfully off TLAs before tapering brexanolone. Sixteen (73%) were successfully weaned off TLAs within 5 days of initiating brexanolone infusion without anesthetic agent reinstatement in the following 24 hours.

Interpretation

In an open‐label cohort of limited size, brexanolone demonstrated tolerability among SRSE patients of heterogeneous etiologies and was associated with a high rate of successful TLA weaning. The results suggest the possible development of brexanolone as an adjunctive therapy for SRSE requiring pharmacological coma for seizure control. Ann Neurol 2017;82:342–352

First-in-man allopregnanolone use in super-refractory status epilepticus

Super‐refractory status epilepticus (SRSE) is associated with high morbidity and mortality. Treatment of SRSE is complicated by progressive cortical hyperexcitability believed to result in part from synaptic GABA receptor internalization and desensitization. Allopregnanolone, a neurosteroid that positively modulates synaptic and extrasynaptic GABA_A receptors, has been proposed as a novel treatment. We describe the first two patients with SRSE who were each successfully treated with a 120‐h continuous infusion of allopregnanolone. Both patients recovered from prolonged SRSE with good cognitive outcomes.

Timing of Decompressive Hemicraniectomy for Stroke

Background and Purpose—

Previous clinical trials were not designed to discern the optimal timing of decompressive craniectomy for stroke, and the ideal surgical timing in patients with space-occupying infarction who do not exhibit deterioration within 48 hours is debated.

Methods—

Patients undergoing decompressive craniectomy for stroke were extracted from the Nationwide Inpatient Sample (2002–2011). Multivariable logistic regression evaluated the association of surgical timing with mortality, discharge to institutional care, and poor outcome (a composite end point including death, tracheostomy and gastrostomy, or discharge to institutional care). Covariates included patient demographics, comorbidities, year of admission, and hospital characteristics. However, standard stroke severity scales and infarct volume were not available.

Results—

Among 1301 admissions, 55.8% (n=726) underwent surgery within 48 hours. Teaching hospital admission was associated with earlier surgery ( P =0.02). The timing of intervention was not associated with in-hospital mortality. However, when evaluated continuously, later surgery was associated with increased odds of discharge to institutional care (odds ratio, 1.17; 95% confidence interval, 1.05–1.31, P =0.005) and of a poor outcome (odds ratio, 1.12; 95% confidence interval, 1.02–1.23; P =0.02). When evaluated dichotomously, the odds of discharge to institutional care and of a poor outcome did not differ at 48 hours after hospital admission, but increased when surgery was pursued after 72 hours. Subgroup analyses found no association of surgical timing with outcomes among patients who had not sustained herniation.

Conclusion

s—In this nationwide analysis, early decompressive craniectomy was associated with superior outcomes. However, performing decompression before herniation may be the most important temporal consideration.

Colour Matching of Isoluminant Samples and Backgrounds: A Model

A cone-opponent-based vector model is used to derive the activity in the red-green, yellow-blue, and achromatic channels during a sequential asymmetric colour-matching experiment. Forty Munsell samples, simulated under illuminant C, were matched with their appearance under eight test illuminants. The test samples and backgrounds were photometrically isoluminant with each other. According to the model, the orthogonality of the channels is revealed when test illuminants lie along either red-green or yellow-blue cardinal axes. The red-green and yellow-blue outputs of the channels are described in terms of the hue of the sample. The fact that the three-channel model explains the data in a colour-matching experiment indicates that an early form of colour processing is mediated at a site where the three channels converge, probably the input layer of V1.

Abstract WMP77: Neurovascular Complications During Long-term Left Ventricular Assist Device (LVAD) Support: Single Center Experience

Introduction: Left ventricular assist devices (LVAD) have emerged as the standard of care for treating patients with advanced heart failure refractory to maximal medical therapy. Postoperative cerebrovascular complications are an important cause of morbidity and decreased quality of life. However, the literature contains little data on the incidence, predictors, and outcome of stroke.

Hypothesis: We aimed to determine the incidence of cerebrovascular complications, their type, and association with stroke risk factors and anticoagulation therapy.

Methods: Data were collected prospectively on all patients with LVADs implanted at BWH. Categorical variables were tested by Chi-square.

Results: From 2007 to 2015, 151 patients (123 male; median age 57) underwent implantation of HeartMate II LVAD: 79 bridge to transplant, 62 destination therapy, and 10 bridge to candidacy.

Strokes occurred in 31 patients (21%). Risk of stroke did not correlate with sex (25 male, 6 female) or age (median at stroke onset 57). Seventeen acute ischemic strokes (AIS) occurred in 16 patients and 17 intracerebral hemorrhages (ICH) occurred in 15 patients. Four of the AIS were complicated by secondary hemorrhage. Events occurred at a mean of 362 days from implantation (range 5 days-6 years 8 months).

All patients except one were on warfarin at time of stroke (goal INR 2-3.5). Mean INR at AIS onset was 2.3 compared to 3.0 for ICH. Of the 15 ICH patients, 3 had supratherapeutic INR > 3.5. Eleven of the 16 AIS patients were also receiving ASA, 1 ASA + dipyridamole, 1 ASA + dipyridamole + bivalirudin. One received ASA only. All ICH patients and all those with AIS with secondary hemorrhage were on ASA.

Patients with COPD were more likely to have a stroke (p = 0.0006); 30 of the 151 patients had COPD and 13 of them (43%) had strokes. Risk of stroke did not correlate with DM, HTN, hyperlipidemia, CKD, PAD, AF, or prior stroke.

Nineteen of 31 patients with stroke versus 22 of 120 without stroke died (mortality 61 v 18 %; p << 0.001).

Conclusions: Stroke is an important cause of major morbidity and mortality in patients on LVAD support. Patients with COPD are at an increased risk of stroke. Further studies addressing post-LVAD stroke risk, prevention, and treatment are warranted.

Brainstem and limbic encephalitis with paraneoplastic neuromyelitis optica

The spectrum of disorders associated with anti-neuromyelitis optica (NMO) antibody is being extended to include infrequent instances associated with cancer. We describe a patient with brainstem and limbic encephalitis from NMO-immunoglobulin G in serum and cerebrospinal fluid in the context of newly diagnosed breast cancer. The neurological features markedly improved with excision of her breast cancer and immune suppressive therapy. This case further broadens the NMO spectrum disorders (NMOSD) by an association between NMOSD and cancer and raises the question of coincidental occurrence and the appropriate circumstances to search for a tumor in certain instances of NMO.

Ataxia induced by a thymic neuroblastoma in the elderly patient

Thymic neuroblastoma is a rare tumor with only few reports in modern literature. Whereas most data is taken from childhood neuroblastoma, little is known about the characteristics of the disease in the adult and elderly population.

There are significant differences between adult and childhood neuroblastoma which are reviewed below.

We report a case of a 62-year-old male who presented with neurological symptoms of ataxia and opsoclonus and an anterior mediastinal mass. Ultimately, the patient underwent a resection of the mass and pathologic review identified a thymic neuroblastoma. This is the first case of thymic neuroblastoma associated with symptomatic central nervous system disease; it is presented with an up-to-date review of the previous cases in the field as well with a review of the literature of post adolescent neuroblastoma.

Fatal hyperammonemic brain injury from valproic Acid exposure

Background

Hyperammonemia is known to cause neuronal injury, and can result from valproic acid exposure. Prompt reduction of elevated ammonia levels may prevent permanent neurological injury. We report a case of fatal hyperammonemic brain injury in a woman exposed to valproic acid.

Case

A 38-year-old woman with schizoaffective disorder and recent increase in valproic acid dosage presented with somnolence and confusion and rapidly progressed to obtundation. Brain MRI showed diffuse bilateral restricted diffusion in nearly the entire cerebral cortex. She had normal liver function tests but serum ammonia level was severely elevated at 288 μmol/l. Genetic testing showed no mutation in urea cycle enzymes. Despite successful elimination of ammonia with hemodialysis she developed fatal cerebral edema.

Conclusion

Cerebral edema secondary to hyperammonemia is potentially reversible if recognized early. Ammonia excretion can be facilitated by initiation of hemodialysis and administration of scavenging agents (sodium phenylacetate and sodium benzoate). Severe hyperammonemia can result from valproic acid exposure even in the absence of hepatotoxicity or inborn errors of metabolism. It is important to check serum ammonia in any patient with encephalopathy who has had recent valproic acid exposure.

Systematic violations of von Kries rule reveal its limitations for explaining color and lightness constancy

Cone contrast remains constant, when the same object/background is seen under different illuminations-the von Kries rule [Shevell, Vis. Res. 18, 1649 (1978)]. Here we explore this idea using asymmetric color matching. We find that von Kries adaptation holds, regardless of whether chromatic constancy index is low or high. When illumination changes the stimulus luminance (reflectance), lightness constancy is weak and matching is dictated by object/background luminance contrast. When this contrast is masked or disrupted, lightness constancy mechanisms are more prominent. Thus von Kries adaptation is incompatible with lightness constancy, suggesting that cortical mechanisms must underlie color constancy, as expected from neurophysiological studies [Zeki, Nature 284, 412 (1980); Wild, Nature 313, 133 (1985)].

Influences of prolonged viewing of tilted lines on perceived line orientation: the normalization and tilt after-effect

Gibson [J. Exp. Psychol. 16, 1 (1993)] observed that during prolonged viewing, a line perceptually rotates toward the nearest vertical or horizontal meridian (the normalization effect), and moreover, the perceived orientation of a subsequently presented line depends on the orientation of the adapting one (the tilt after-effect). The mechanisms of both phenomena remain poorly understood. According to our experimental results, the adapting line perceptually rotates to the nearest of three orientations: vertical, horizontal, and diagonal. We propose a simple neuronal model of orientation detectors whose responses are determined by the cardinal detectors. It is shown that both normalization and tilt after-effect may be explained by adaptation of these cardinal detectors.