Chronic serotonin syndrome: A retrospective study

Serotonin syndrome controversies: A need for consensus

Serotonin syndrome (SS) is a drug-induced clinical syndrome resulting from increased serotonergic activity in the central nervous system. Although more than seven decades have passed since the first description of SS, it is still an enigma in terms of terminology, clinical features, etiology, pathophysiology, diagnostic criteria, and therapeutic measures. The majority of SS cases have previously been reported by toxicology or psychiatry centers, particularly in people with mental illness. However, serotonergic medications are used for a variety of conditions other than mental illness. Serotonergic properties have been discovered in several new drugs, including over-the-counter medications. These days, cases are reported in non-toxicology centers, such as perioperative settings, neurology clinics, cardiology settings, gynecology settings, and pediatric clinics. Overdoses or poisonings of serotonergic agents constituted the majority of the cases observed in toxicology or psychiatry centers. Overdose or poisoning of serotonergic drugs is uncommon in other clinical settings. Patients may develop SS at therapeutic dosages. Moreover, these patients may continue to use serotonergic medications even if they develop mild to moderate SS due to several reasons. Thus, the clinical presentation (onset, severity, and clinical features) in such instances may not exactly match what toxicologists or psychiatrists observe in their respective settings. They produce considerable diversity in many aspects of SS. However, other experts discount these new developments in SS. Since SS is a potentially lethal illness, consensus is required on several concerns related to SS.

Medication-overuse headache overlapping with serotonin syndrome

Serotonin syndrome (SS) is an iatrogenic, drug-induced clinical syndrome caused by an increase in the intrasynaptic concentration of serotonin. Serotonin plays a significant role in the pathophysiology of migraines. Upregulation of 5-HT2A receptors is found in medication-overuse headache (MOH). Several migraine medications, both preventative and abortive drugs, act on serotonin receptors. We report two patients with chronic migraine who developed MOH. Besides headache, patients had frequent attacks of dizziness, restlessness, irritability, insomnia, excessive sweating, abdominal discomforts and tremors. These symptoms were suggestive of withdrawal headache. However, on physical examinations, we elicited hyperreflexia, hypertonia, clonus, tachycardia, hypertension, mydriasis and hyperactive bowel sound. Both patients also met the criteria for SS. Cyproheptadine was started. All features, including headaches, got better after cyproheptadine administration within 24 hours. In 7 days, there was practically total improvement. Both patients continued to take cyproheptadine as a preventative medicine, and migraine frequency was under control.

A Case Series of 11 Patients With Subacute Serotonin Syndrome

BACKGROUND

Serotonin syndrome is an acute, life-threatening illness characterized by mental status changes, neuromuscular symptoms, and autonomic instability. Some patients taking serotonergic antidepressants have been noted to have unexplained mental status changes and/or neuromuscular changes without autonomic instability raising the possibility of a more chronic or attenuated form of serotonin syndrome.

OBJECTIVE

Assessment of antidepressant blood levels to support the diagnosis of a subacute serotonin syndrome.

METHODS

At a tertiary psychiatric outpatient clinic, patients with unexplained mental status and/or neuromuscular changes without autonomic instability had antidepressant blood levels assessed.

RESULTS

Eleven patients were identified with signs and symptoms partially consistent with serotonin syndrome. Nine patients had cognitive changes, while four patients had motor changes, and three patients had psychosis. All patients had elevated blood levels of a single serotonergic antidepressant. Limited follow-up suggests that symptoms improve with reduction of antidepressant medication.

CONCLUSIONS

These cases suggest that a more chronic, attenuated form of serotonin syndrome exists. Diagnostic criteria are proposed for a distinct clinical entity: subacute serotonin syndrome (SSS). Further research is required to validate these criteria. Clinicians should consider drawing antidepressant levels for patients with symptoms and signs suggestive of SSS-especially those at increased vulnerability for excessive serotonergic agonism. Given the high prevalence of antidepressant medication use, the awareness of SSS could lead to improved patient outcomes and public health.

Serotonin Syndrome Precipitated by Amantadine in a Patient With Persistent Post Concussive Symptoms - A Case Report

Symptoms after mild traumatic brain injury (MTBI) can persist for greater than 1 month in up to 20% of individuals, yet there are no current medications approved by the Food and Drug Administration for treatment of specific concussion related sequelae. Amantadine, a dopamine agonist and N-Methyl-D-aspartate antagonist, is increasingly being used as a treatment option for individuals with traumatic brain injury across the spectrum of injury severity. This case report describes a 22-year-old individual who sustained an MTBI without loss of consciousness or post-traumatic amnesia after striking their head against a metal cabinet. The individual was referred to an interdisciplinary outpatient brain rehabilitation program secondary to persistent symptoms after MTBI, was prescribed amantadine for post-traumatic headache 97 days after injury, and subsequently developed symptoms of serotonin syndrome (SS) within 10 days of medication initiation. While SS caused by amantadine has been described in individuals with renal failure, this case report is the first to describe amantadine precipitating SS - confirmed by a validated diagnostic criterion and successfully treated with lorazepam and cyproheptadine - in a patient with normal renal function already on duloxetine, bupropion, and gabapentin. This case report is important in elucidating potential contributions of amantadine to the development of SS and highlighting the important role clinicians have in assessing for polypharmacy when prescribing amantadine for individuals with traumatic and acquired brain injuries.

Retrospective identification of new psychoactive substances in patient samples submitted for clinical drug analysis

New psychoactive substances (NPS) are life-threatening through unpredictable toxicity and limited analytical options for clinicians. We present the retrospective identification of NPS in raw data from a liquid chromatography-high resolution mass spectrometry (LC-HRMS) based multidrug panel analysis on 14,367 clinical oral fluid samples requested during 2019 mainly by psychiatric and addiction care clinics. Retrospectively analysed NPS included 48 notified originally in 2019 by the European Union Early Warning System (EU-EWS) and 28 frequently reported in Sweden. Of 88 included NPS, 34 (mitragynine, flualprazolam, 3F/4F-α-P(i)HP, etizolam, 4F-MDMB-BINACA, cyproheptadine, 5F-MDMB-PICA, isotonitazene, isohexedrone, MDPEP, N-ethylpentedrone, tianeptine, flubromazolam, 4'-methylhexedrone, α-P(i)HP, eutylone, mephedrone, N-ethylhexedrone, 5F-MDMB-PINACA, ADB-BUTINACA, 3-methoxy PCP, 4F-furanylfentanyl, 4F-isobuturylfentanyl, acrylfentanyl, furanylfentanyl, clonazolam, norfludiazepam, 3F-phenmetrazine, 3-MMC, 4-methylpentedrone, BMDP, ethylphenidate, methylone, α-PVP) were identified as 219 findings in 84 patients. Eight NPS notified in 2019 were identified, five before EWS release. NPS occurred in 1.20% of all samples and 1.53% of samples containing traditional drugs, and in 1.87% of all patients and 2.88% of patients using traditional drugs. NPS use was more common in men and polydrug users. Legal (not scheduled) NPS were more used than comparable illegal ones. Retrospective identification could be useful when prioritizing NPS for clinical routine analysis and when studying NPS epidemiology.