Recovery from disorders of consciousness: mechanisms, prognosis and emerging therapies.

Substantial progress has been made over the past two decades in detecting, predicting and promoting recovery of consciousness in patients with disorders of consciousness (DoC) caused by severe brain injuries. Advanced neuroimaging and electrophysiological techniques have revealed new insights into the biological mechanisms underlying recovery of consciousness and have enabled the identification of preserved brain networks in patients who seem unresponsive, thus raising hope for more accurate diagnosis and prognosis. Emerging evidence suggests that covert consciousness, or cognitive motor dissociation (CMD), is present in up to 15-20% of patients with DoC and that detection of CMD in the intensive care unit can predict functional recovery at 1 year post injury. Although fundamental questions remain about which patients with DoC have the potential for recovery, novel pharmacological and electrophysiological therapies have shown the potential to reactivate injured neural networks and promote re-emergence of consciousness. In this Review, we focus on mechanisms of recovery from DoC in the acute and subacute-to-chronic stages, and we discuss recent progress in detecting and predicting recovery of consciousness. We also describe the developments in pharmacological and electrophysiological therapies that are creating new opportunities to improve the lives of patients with DoC.

Subarachnoid hemorrhage guidance in the era of the COVID-19 pandemic - An opinion to mitigate exposure and conserve personal protective equipment.

Aneurysmal subarachnoid hemorrhage (SAH) patients require frequent neurological examinations, neuroradiographic diagnostic testing and lengthy intensive care unit stay. Previously established SAH treatment protocols are impractical to impossible to adhere to in the current COVID-19 crisis due to the need for infection containment and shortage of critical care resources, including personal protective equipment (PPE). Centers need to adopt modified protocols to optimize SAH care and outcomes during this crisis. In this opinion piece, we assembled a multidisciplinary, multicenter team to develop and propose a modified guidance algorithm that optimizes SAH care and workflow in the era of the COVID-19 pandemic. This guidance is to be adapted to the available resources of a local institution and does not replace clinical judgment when faced with an individual patient.

Current treatment of central retinal artery occlusion: a national survey.

BACKGROUND: Central retinal artery occlusion (CRAO) is an ophthalmological emergency, the retinal analog of a stroke. To date there is no consensus or national guidelines on how this disorder should be managed. As academic neurologists and ophthalmologists treat CRAO frequently, we set out to understand how these clinicians approach patients with CRAO with a national survey. METHODS: We identified university-associated teaching hospitals offering vascular neurology, neuro-ophthalmology and/or retina fellowships in the US and asked the directors of the programs to respond to questions in an open response format to profile the acute management of CRAO at their institution. RESULTS: We found remarkable heterogeneity in the approach to acute treatment of patients with CRAO among the 45 institutions that responded to the survey. Only 20% had a formal policy, guideline or white paper to standardize the approach to treatment. The primary treating physician was an ophthalmologist, neurologist, or neuro-ophthalmologist 44, 27, and 4% of the time, respectively; 24% were co-managed acutely by neurology and ophthalmology. Intravenous fibrinolysis was offered to selected patients in 53% of institutions, and was the preferred initial treatment in 36%. When the acute treatment team involved a vascular neurologist, fibrinolysis was more likely to be considered a first-line treatment (p < 0.05). Anterior chamber paracentesis, ocular massage and hyperbaric oxygen therapy were offered 42, 66 and 7% of the time, respectively, while 9% of institutions offered no treatment. Anterior chamber paracentesis was more likely to be offered at programs where neurologists were not involved in treating CRAOs (p < 0.001). At 35% of institutions, patients with acute CRAO were not routinely referred to a general emergency room for initial evaluation and treatment. Carotid imaging was routinely obtained by 89% of programs, magnetic resonance imaging of the brain by 69%, echocardiogram by 62%, laboratory screening for an inflammatory state by 27% and retinal angiography by 30%. The thoroughness of vascular risk factors' screening was greater in programs that routinely referred acute CRAO cases to the emergency department. CONCLUSIONS: This survey shows that there is significant variability in treatment practices for acute CRAO in the US. Because of the high cerebrovascular and cardiovascular risk reported in this population of patients, it is notable that the approach to risk factor screening is also highly variable and many programs do not routinely refer patients to an emergency department for urgent evaluation. Finally, there appears to be equipoise among treatment teams regarding the efficacy of systemic fibrinolysis, as 53% of programs report a willingness to treat at least some patients with this modality.

Neuroanatomic connectivity of the human ascending arousal system critical to consciousness and its disorders.

The ascending reticular activating system (ARAS) mediates arousal, an essential component of human consciousness. Lesions of the ARAS cause coma, the most severe disorder of consciousness. Because of current methodological limitations, including of postmortem tissue analysis, the neuroanatomic connectivity of the human ARAS is poorly understood. We applied the advanced imaging technique of high angular resolution diffusion imaging (HARDI) to elucidate the structural connectivity of the ARAS in 3 adult human brains, 2 of which were imaged postmortem. High angular resolution diffusion imaging tractography identified the ARAS connectivity previously described in animals and also revealed novel human pathways connecting the brainstem to the thalamus, the hypothalamus, and the basal forebrain. Each pathway contained different distributions of fiber tracts from known neurotransmitter-specific ARAS nuclei in the brainstem. The histologically guided tractography findings reported here provide initial evidence for human-specific pathways of the ARAS. The unique composition of neurotransmitter-specific fiber tracts within each ARAS pathway suggests structural specializations that subserve the different functional characteristics of human arousal. This ARAS connectivity analysis provides proof of principle that HARDI tractography may affect the study of human consciousness and its disorders, including in neuropathologic studies of patients dying in coma and the persistent vegetative state.