Acute Febrile Encephalopathy with Rigidity

Febrile encephalopathy with rigidity can be the presenting feature of several life-threatening neurological emergencies such as neuroleptic malignant syndrome (NMS) and serotonin syndrome. Although the pathogenesis of these conditions is poorly understood, we review advances in our understanding of underlying genetic and other biological mechanisms. We also discuss the complex and expanding differential diagnoses which include other drug-induced hyperpyrexia or rigidity syndromes (eg malignant hyperthermia, parkinsonism-hyperpyrexia syndrome, malignant catatonia) as well as autoimmune syndromes. Finally, we consider potential predictive and preventative approaches along with best practice management strategies.

Postoperative Serotonin Syndrome: A Case Report Highlighting Dexmedetomidine for Refractory Symptoms

Serotonin syndrome (SS) is a life-threatening condition caused by excessive serotonin, typically due to drugs such as selective serotonin reuptake inhibitors (SSRIs), monoamine oxidase inhibitors (MAOIs), and certain opioids. It often results from combining two serotonin-affecting drugs or excessive use of one. SS is diagnosed clinically, presenting with neuromuscular hyperactivity, autonomic instability, and altered mental status, with clonus as a key distinguishing feature. The Hunter Criteria aids diagnosis but should not be used to rule out SS. Treatment starts with discontinuing the offending agent, followed by supportive care, including airway management and stabilization of vital signs. Benzodiazepines can help control seizures and agitation, while cyproheptadine may be used in moderate to severe cases. Benzodiazepines have many side effects and cyproheptadine is only available in oral formulations, which adds complexity to effective treatment. In rare instances, SS can be refractory and may require intubation and neuromuscular paralytics. In this case, we present a case of a 42-year-old female who developed confusion, tachycardia, muscle rigidity, and hypertension after outpatient ankle surgery, where she received midazolam, fentanyl, propofol, toradol, ondansetron, meperidine, and dexamethasone perioperatively. Her daily medication also included fluoxetine, dextroamphetamine-amphetamine, and trazodone. The patient required intubation for continued diazepam administration and was admitted to the ICU. Despite improving vital signs, she remained altered with diffuse muscle rigidity. After three days of refractory SS, dexmedetomidine, an alpha-2 antagonist, was administered. The patient showed clinical improvement over the next four days and was stable enough for extubation and discontinuation of dexmedetomidine. The patient made significant clinical progress and was discharged to follow up with her primary care provider. This case highlights the importance of early detection through clinical context and not relying solely on the Hunter criteria and the potential use of dexmedetomidine as an adjuvant to benzodiazepine therapy.

Dexmedetomidine in the treatment of toxicologic conditions: a systematic review and review of the toxicology investigators consortium database

INTRODUCTION

Dexmedetomidine is an alpha-2 adrenoceptor agonist which is widely used for sedation. Dexmedetomidine does not suppress the respiratory drive and produces a state of cooperative sedation; it may be associated with beneficial outcomes in the general critical care population. The role of dexmedetomidine in the treatment of toxicologic conditions (excluding alcohol withdrawal) is unclear.

OBJECTIVES

To critically assess and summarize the literature regarding the use of dexmedetomidine in toxicologic conditions other than alcohol withdrawal.

METHODS

We performed a systematic review of the medical literature to identify all existing evidence regarding the use of dexmedetomidine for toxicologic conditions. We excluded reviews and commentary, studies reporting exclusively on alcohol withdrawal, and studies reporting the use of dexmedetomidine to treat iatrogenic sedative withdrawal in the intensive care unit. We also performed a review of the Toxicology Investigators Consortium (ToxIC) database for patients treated with dexmedetomidine.

RESULTS

We identified 98 studies meeting inclusion criteria; 87 of these were case reports or case series, representing 99 unique cases. Eleven articles with other designs were identified, which included 138 patients treated with dexmedetomidine for toxicologic conditions. Ninety-three cases from the ToxIC registry met inclusion criteria. Common indications for dexmedetomidine included stimulant intoxication, sedative withdrawal, serotonin syndrome, antimuscarinic toxidrome, opioid withdrawal, and cannabinoid intoxication. Dexmedetomidine was usually administered by continuous infusion; bolus administration was reported in a minority of cases. Adverse effects were uncommon. The quality of evidence was generally low, given the preponderance of case reports, the rate of missing or poorly reported data, and the near-universal co-administration of other sedatives.

TREATMENT OF STIMULANT POISONING

Fifty-nine patients with stimulant poisoning were treated with dexmedetomidine. There was reasonably good evidence that dexmedetomidine was helpful in the treatment of stimulant poisoning.

TREATMENT OF SEDATIVE WITHDRAWAL

Twenty-two patients with sedative withdrawal were treated with dexmedetomidine. Several case reports of very high-quality suggested efficacy of dexmedetomidine for this indication, particularly for baclofen withdrawal.

TREATMENT OF SEROTONIN SYNDROME

Twenty-six patients with serotonin syndrome were treated with dexmedetomidine. This evidence was of lower quality due to missing clinical details, potential overdiagnosis of serotonin syndrome, and near-universal concomitant treatment with other sedatives.

TREATMENT OF ANTIMUSCARINIC POISONING

Forty-two patients with antimuscarinic poisoning were treated with dexmedetomidine. This evidence was of low quality and was limited by infrequent use of the preferred antidote, physostigmine.

TREATMENT OF OPIOID WITHDRAWAL

Forty-four patients with opioid withdrawal were treated with dexmedetomidine. This evidence was of low quality due to missing clinical details and near-universal concomitant treatment with other agents. The one high-quality trial reported the use of dexmedetomidine in ultra-rapid opioid detoxification, which is not indicated in modern practice.

TREATMENT OF CANNABINOID INTOXICATION

Five patients with cannabinoid intoxication were treated with dexmedetomidine. No definite conclusion can be drawn from the limited available evidence.

DISCUSSION

It is important to distinguish between the use of dexmedetomidine as a general sedative, which is likely to increase as the overall utilization of dexmedetomidine in critical care settings increases, and the use of dexmedetomidine as a specific pharmacologic treatment for a toxicologic condition. Well-established pharmacologic data from animal and human studies suggest dexmedetomidine counteracts stimulant-induced norepinephrine release. The mechanism by which dexmedetomidine treats sedative withdrawal is unclear. Some animal data show that dexmedetomidine may indirectly suppress serotonin release, which may suggest a role for dexmedetomidine in this condition.

CONCLUSIONS

There is a small and generally low-quality body of evidence which suggests that dexmedetomidine may be helpful in the treatment of certain toxicologic conditions, particularly stimulant intoxication and sedative withdrawal. Further high-quality research is needed to clarify the role of dexmedetomidine in patients with toxicologic conditions.

High risk and low prevalence diseases: Serotonin syndrome

INTRODUCTION

Serotonin syndrome is a rare, frequently misdiagnosed, serious condition with high morbidity.

OBJECTIVE

This review highlights the pearls and pitfalls of serotonin syndrome, including diagnosis, initial resuscitation, and management in the emergency department (ED) based on current evidence.

DISCUSSION

Serotonin syndrome is a potentially deadly toxidrome marked by excess serotonin receptor activity or neurotransmission. Features of serotonin syndrome include 1) neuromuscular excitation such as tremor, hyperreflexia, and clonus; 2) autonomic dysfunction such as tachycardia, hypertension/hypotension, and hyperthermia; and 3) altered mental status such as agitation, delirium, and coma. Although serotonin syndrome may be more obvious in patients who have overdosed on serotonergic agents such as serotonin reuptake inhibitors (SSRIs), multiple other medications may also cause serotonin syndrome. Alternative diagnoses such as sepsis, neuroleptic malignant syndrome, and decompensated hyperthyroidism should be considered. The primary components of therapy include stopping the offending agent and supportive care, which focuses on agitation control, monitoring for and treating hyperthermia, and managing autonomic instability.

CONCLUSIONS

An understanding of serotonin syndrome can assist emergency clinicians in diagnosing and managing this disease.

Serotonin Toxicity in Children and Adolescents: A Systematic Review and Meta-Analysis of Cases

Objectives: Serotonin toxicity is a state of central nervous system (CNS) excitation classically featuring altered mental status, neuromuscular excitation, and autonomic instability. While retrospective studies and reviews have characterized serotonin toxicity in adults, there have been no systematic reviews of serotonin toxicity in pediatric populations. The goal of this review was to use published case reports to describe serotonin toxicity in pediatric patients and to consider the impact of age on clinical presentation. Methods: A search for case reports of serotonin toxicity in patients younger than 18 years was conducted. Cases were systematically screened for inclusion using serotonin toxicity diagnostic tools, and a meta-analysis of case characteristics was conducted. Results: Sixty-six cases of serotonin toxicity in pediatric patients were reviewed. Only 56.1% met diagnostic criteria for serotonin toxicity on all three of the most commonly used diagnostic tools. Antidepressants were found to be the most common trigger of toxicity, implicated in 78.8% of cases. While onset of toxicity was rapid following overdose, toxicity was more likely to be delayed in the setting of medication titration (71.8% vs. 0%, p < 0.0001). Signs of neuromuscular excitation were prevalent, occurring in 92.4% of cases with 81.8% showing the full triad of neuromuscular symptoms, altered mental status, and autonomic instability. The only age-related differences occurred in relation to activation symptoms (more likely to be reported in children than in adolescents) and seizures (less likely to be reported in children than in adolescents or toddlers). Treatment was primarily supportive in nature, although 25.8% of patients received cyproheptadine. In all but one reviewed case, the patient survived. Conclusions: The presentation of serotonin toxicity in the pediatric population is similar to that seen in adults. Treatment is supportive with most patients achieving full recovery. Further exploration of the age-related differences in serotonin activity within the CNS is needed.

Serotonin Syndrome Associated With Vilazodone Overdose in a 22-Month-Old Treated With Dexmedetomidine

BACKGROUND

Vilazodone was approved by the U.S. Food and Drug Administration in 2011 as a treatment for major depression disorder. Vilazodone is a selective serotonin reuptake inhibitor and 5-HT1A agonist used in the treatment of depression in adults. Vilazodone increases the availability and activity of serotonin and its neural pathways. Vilazodone blocks the serotonin reuptake pump and desensitizes serotonin receptors (especially 5HT1A autoreceptors), therefore increasing serotonergic neurotransmission. Its partial agonist actions at presynaptic somatodendritic 5HT1A autoreceptors theoretically enhance serotonergic activity, contributing to antidepressant actions. There are limited reports exploring its effects in children after unintentional ingestion. Typical adult dosing is titrated from an initial dose of 10 mg up to a maximum dose of 40 mg daily. Serotonin syndrome classically manifests with restlessness, hyperthermia, tachycardia, mydriasis, and increased tone, and is typically treated with benzodiazepines, cyproheptadine, and supportive care. Dexmedetomidine has also been used in case reports to treat serotonin syndrome.

CASE REPORT

We report the case of a toddler with a laboratory-confirmed vilazodone overdose exhibiting symptoms of serotonin syndrome, including restlessness, hyperthermia, mydriasis, dystonia, agitation, seizure-like activity, roving eye movement, tachycardia, and elevated creatine kinase. The patient was admitted and initially treated with supportive care and lorazepam per recommendations of the poison center, which did not recommend cyproheptadine use. On decompensation with suspected serotonin syndrome, the patient was treated with dexmedetomidine. In addition, urine toxicology screening (Amphetamines II assay; Roche, Indianapolis, IN) was positive for amphetamines; however, confirmatory testing (gas chromatography-mass spectrometry) was negative. The patient improved and was discharged after returning to her baseline status at 74 h post ingestion. Importantly, this patient did not require intubation and mechanical intubation, in spite of the large amount of vilazodone ingested. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: With increasing prescription of vilazodone, emergency physicians should have a high level of suspicion so as not to miss this toxidrome. The possibility of false-positive amphetamine screenings when an overdose of vilazodone is suspected should be investigated. Finally, systematic evaluation of the use of dexmedetomidine as treatment for serotonin syndrome or vilazodone ingestion should be done to confirm efficacy.

Effects of dexmedetomidine on stress hormones in patients undergoing cardiac valve replacement: a randomized controlled trial

Background

Stress response always occurs in cardiac valve replacement patients undergoing cardiopulmonary bypass (CPB).

Methods

60 patients undergoing cardiac valve replacement were recruited and randomized into control and Dex groups. Dex group received 1.0 μg·kg-1 of Dex for 10 min intravenously before anesthesia, followed by 0.5 μg·kg-1·h-1 of Dex, steadily administered throughout the procedure. And controlled group received the identical velocity of saline as Dex group. Plasma level of cortisol (Cor), epinephrine (E), norepinephrine (NE), and serotonin (5-HT) were evaluated at four timepoints: Before administration (T0), sawn sternum (T1), end of extracorporeal circulation (T2), and 24 h post operation (T3). General data of operation and recovery such as heart rate (HR), mean arterial pressure (MAP), intraoperative bispectral index (BIS), and hospitalization time in the intensive care unit (ICU) were also compared.

Results

Increase of Cor, E, NE, and 5-HT for the Dex group was significant lesser than that in the control group (P < 0.05), and ICU hospitalization time and ventilator support time was significantly shorter in the Dex group. The proportion of patients discharged from the hospital with better prognosis was significantly higher than that in the control group, while there were no significant differences in hospitalization costs and vasoactive drugs use between the two groups.

Conclusions

Dex reduces plasma Cor, E and NE elevations in patients after CPB, alleviates the stress reaction of the body, shortens the hospitalization time and ventilator support time in ICU, and plays a positive role in the rehabilitation of patients undergoing cardiac valve replacement.

Trial registration

China Clinical Trial Registry (No. ChiCTR-IPR-17010954) March 22rd, 2017.

[The serotonin syndrome: An updated literature review]

The serotonin syndrome is a potentially deadly complication resulting from drug adverse effect, drug-drug interaction or overdose involving one or more serotonergic molecules, e.g., antidepressants, psychostimulants and sometimes an "ignored" serotonergic compound. The serotonin syndrome typically consists of a clinical triad including cognitive/behavioral, neurovegetative and neuromuscular features. However, this syndrome is characterized by major clinical heterogeneity, making the diagnosis difficult in practice. Moreover, many practitioners are quite unaware of this syndrome. Available scores and classifications can help physicians in their diagnosis approach. Knowing the responsible molecules, their potential interactions and mechanisms of action can help preventing this complication allowing therapeutic education among patients. This updated article reviews the clinical presentation, prevention, management, and pathophysiology of the serotonin syndrome, and addresses the most recent advances in pharmacogenetics regarding this syndrome.

Drug-Induced Serotonin Syndrome

Serotonin syndrome is a potentially fatal condition caused by drugs that affect serotonin metabolism or act as serotonin receptor agonists. Monoamine oxidase inhibitors, selective serotonin reuptake inhibitors, and serotonin-norepinephrine reuptake inhibitors are the medications most commonly associated with serotonin syndrome. Serotonin syndrome can be mild and of short duration, but a prolonged course, life-threatening complications, and death are possible. Detection of serotonin syndrome is not difficult if the diagnostic criteria are understood and properly used, but the syndrome has no confirmatory tests and other drug-induced syndromes can, to a degree, mimic serotonin syndrome. The treatment is symptomatic and supportive. Antidotal therapies are available, but the evidence for their effectiveness is limited. If serotonin syndrome is promptly identified and aggressively treated, the patient should fully recover.

A comparison of midazolam and dexmedetomidine for the recovery of serotonin syndrome in rats

Serotonin syndrome is a drug-related toxicity caused by excess serotonin within the central nervous system. We recently encountered a case of serotonin syndrome that developed in the early postoperative period that was successfully treated with intravenous dexmedetomidine. Although the prescriptive literature has commonly recommended sedation with benzodiazepines for controlling agitation in serotonin syndrome, the effectiveness of dexmedetomidine has also been reported in several clinical conditions. In the present study, we conducted a reverse translational experiment to compare the efficacy of dexmedetomidine and midazolam, at equi-sedative doses, on serotonergic toxicity-like responses in rats. Animals were subcutaneously injected with 0.75 mg/kg 8-OH-DPAT, a full 5-HT1A agonist. 8-OH-DPAT-treated rats showed serotonin syndrome-like behaviors (low body posture, forepaw treading), hyperlocomotion, and decreased body temperature, which were completely inhibited by pretreatment with WAY 100635, a selective 5-HT1A antagonist (n = 8). Intramuscular injection of midazolam (1.0 mg/kg) or dexmedetomidine (0.01 mg/kg), which comparably induced observable signs of sedation, was tested in the present study. Concomitant treatment with midazolam significantly attenuated the hyperlocomotion, but failed to affect traditional serotonin syndrome behaviors and body temperature in 8-OH-DPAT-treated rats (n = 8). On the other hand, concomitant treatment with dexmedetomidine significantly attenuated all of these parameters (n = 8). The present case and related reverse translational experiment demonstrate that dexmedetomidine may be more beneficial for the treatment of serotonin syndrome compared to the current recommended treatment with benzodiazepines.