Brain death--think twice before labeling a patient

Peripheral nervous system and neuromuscular disorders in the emergency department: A review

INTRODUCTION

Acute presentations and emergencies in neuromuscular disorders (NMDs) often challenge clinical acumen. The objective of this review is to refine the reader's approach to history taking, clinical localization and early diagnosis, as well as emergency management of neuromuscular emergencies.

METHODS

An extensive literature search was performed to identify relevant studies. We prioritized meta-analysis, systematic reviews, and position statements where possible to inform any recommendations.

SUMMARY

The spectrum of clinical presentations and etiologies ranges from neurotoxic envenomation or infection to autoimmune disease such as Guillain-Barré Syndrome (GBS) and myasthenia gravis (MG). Delayed diagnosis is not uncommon when presentations occur "de novo," respiratory failure is dominant or isolated, or in the case of atypical scenarios such as GBS variants, severe autonomic dysfunction, or rhabdomyolysis. Diseases of the central nervous system, systemic and musculoskeletal disorders can mimic presentations in neuromuscular disorders.

CONCLUSIONS

Fortunately, early diagnosis and management can improve prognosis. This article provides a comprehensive review of acute presentations in neuromuscular disorders relevant for the emergency physician.

Successful Liver Transplantation from a Deceased Donor After Ethylene Glycol Ingestion: A Case Report and Review of the Literature of Organ Donation from Poisoned Donors

Despite the increase in deceased organ donation over the past ten years, the gap between patients awaiting transplant and available organs continues to widen. Deceased donors secondary to acute fatal poisonings represent less than 1% of all organ donors. Organs from poisoned donors have largely been discarded due to concerns of toxin transmission and poor organ function as well as the paucity of data that exists regarding this donor population. Here, we report a case of a 40-year-old male who underwent successful liver re-transplantation from a donor who died following ethylene glycol ingestion. To our knowledge this case report is the first to describe successful re-transplantation from an ethylene glycol-poisoned donor. We also provide a comprehensive review of the literature describing organ donation from poisoned donors.

Cobra snakebite mimicking brain death treated with a novel combination of polyvalent snake antivenom and anticholinesterase

In toxicology literature, snake bites were the second toxicology-relevant cause mimicking brain death. A 57-year-old woman with history of cobra snake bite. On examination, the brain stem reflexes were absent with Glasgow coma score of 3. The patient accomplished full neurological recovery after using a novel combination of Polyvalent Snake Antivenom (PSA) and anticholinesterases. This case highlights a unique presentation of cobra bite induced brain death mimicking. Thus, intensivist should exclude neuroparalytic effect of snakebite before considering withdrawal of ventilatory support or organ donation. Also, the life-threatening presentation of cobra envenomation mandates the use of higher doses of PSA to reverse the neuroparalytic toxicity. We should consider the rule of anticholinesterase as an adjunctive therapy to PSA in severe cobra envenomation.

Toxicologic Confounders of Brain Death Determination: A Narrative Review

The aim of this narrative review is to describe the toxicologic confounders of brain death currently reported in the literature to offer guidance for physicians assessing brain death after a toxic exposure. We established an a priori definition of a “brain death mimic” as an unresponsive, intubated patient missing some, but not all brainstem reflexes. We completed a review of the literature utilizing MEDLINE and EMBASE to find case reports of patients of all ages in English, French, and Spanish meeting the criteria and hand searched the references of the results. We recorded xenobiotic dose, duration of physical exam suggesting brain death, and how the cases failed to meet full brain death criteria, when available. Fifty-six cases representing 19 different substances met the a priori definition of brain death mimic. Xenobiotic toxicities included: snake envenomation (13), baclofen (11), tricyclic antidepressants (8), bupropion (7), alcohols (4), antiepileptic agents (3), barbiturates (2), antidysrhythmics (2), organophosphates (2), and one case each of magnesium, succinylcholine, tetrodotoxin, and zolpidem. All patients except one survived to discharge and the majority at their baseline physical health. The most common means by which the cases failed brain death examination prerequisites was via normal neuroimaging. The xenobiotics in this review should be considered in cases of poisoning resulting in loss of brainstem reflexes and addressed before brain death determination. Brain death diagnosis should not be pursued in the setting of normal cerebral imaging or incomplete evaluation of brain death prerequisites.

Liver Procurement from Poisoned Donors: A Survival Study

OBJECTIVES

Although transplant teams understand the effects of donor characteristics on liver transplant outcomes, few studies have investigated the quality of livers obtained from poisoned donors. The aim of this study was to compare livers procured from poisoned donors with a matched control group.

MATERIALS AND METHODS

Liver transplant outcomes from poisoned donors and from donors with trauma-induced death (as the control group) were compared using data of an Organ Procurement Unit from 2000 to 2013. Procured livers were evaluated via histology findings before transplant. Recipient characteristics were assessed in both groups, and immediate and medium-term (up to 5 years after transplant) survival rates were compared with the use of Kaplan-Meier analyses and log-rank tests.

RESULTS

Over a 13-year organ donation program, 1485 livers from brain dead patients were donated. Among them, 115 poisoned donors were evaluated for liver grafts; of these, 74 successful liver transplants were performed. In the poisoned donors, the incidence of reversed cardiac arrest was 54.1%. Likewise, acute kidney injury was detected in 14.9% of the patients, and 16.2% needed urgent dialysis either for clearance of the toxic agents or for treatment of acute kidney injury. No significant differences were observed in 1- to 5-year survival rates, and log-rank test also showed a significance level of 0.83.

CONCLUSIONS

Proper case selection strategies can be implemented to expand the donor pool, including use of poisoned donors. Hence, poisoning is not a contra-indication for a referral, which could lead to decreased mortality for patients requiring a liver transplant.

Antivenom for Neuromuscular Paralysis Resulting From Snake Envenoming

Antivenom therapy is currently the standard practice for treating neuromuscular dysfunction in snake envenoming. We reviewed the clinical and experimental evidence-base for the efficacy and effectiveness of antivenom in snakebite neurotoxicity. The main site of snake neurotoxins is the neuromuscular junction, and the majority are either: (1) pre-synaptic neurotoxins irreversibly damaging the presynaptic terminal; or (2) post-synaptic neurotoxins that bind to the nicotinic acetylcholine receptor. Pre-clinical tests of antivenom efficacy for neurotoxicity include rodent lethality tests, which are problematic, and in vitro pharmacological tests such as nerve-muscle preparation studies, that appear to provide more clinically meaningful information. We searched MEDLINE (from 1946) and EMBASE (from 1947) until March 2017 for clinical studies. The search yielded no randomised placebo-controlled trials of antivenom for neuromuscular dysfunction. There were several randomised and non-randomised comparative trials that compared two or more doses of the same or different antivenom, and numerous cohort studies and case reports. The majority of studies available had deficiencies including poor case definition, poor study design, small sample size or no objective measures of paralysis. A number of studies demonstrated the efficacy of antivenom in human envenoming by clearing circulating venom. Studies of snakes with primarily pre-synaptic neurotoxins, such as kraits (Bungarus spp.) and taipans (Oxyuranus spp.) suggest that antivenom does not reverse established neurotoxicity, but early administration may be associated with decreased severity or prevent neurotoxicity. Small studies of snakes with mainly post-synaptic neurotoxins, including some cobra species (Naja spp.), provide preliminary evidence that neurotoxicity may be reversed with antivenom, but placebo controlled studies with objective outcome measures are required to confirm this.

Diagnosis of reversible causes of coma

Because coma has many causes, physicians must develop a structured, algorithmic approach to diagnose and treat reversible causes rapidly. The three main mechanisms of coma are structural brain lesions, diffuse neuronal dysfunction, and, rarely, psychiatric causes. The first priority is to stabilise the patient by treatment of life-threatening conditions, then to use the history, physical examination, and laboratory findings to identify structural causes and diagnose treatable disorders. Some patients have a clear diagnosis. In those who do not, the first decision is whether brain imaging is needed. Imaging should be done in post-traumatic coma or when structural brain lesions are probable or possible causes. Patients who do not undergo imaging should be reassessed regularly. If CT is non-diagnostic, a checklist should be used use to indicate whether advanced imaging is needed or evidence is present of a treatable poisoning or infection, seizures including non-convulsive status epilepticus, endocrinopathy, or thiamine deficiency.