Serotonin syndrome in patients with headache disorders

Managing Cluster Headache in Patients with Medical, Psychiatric, and Surgical Comorbidities

PURPOSE OF REVIEW

What should a provider know about medications and other treatments in patients with cluster headache who have medical, psychiatric, and surgical comorbidities? What conversations should providers have with patients about living with and managing cluster headache?

RECENT FINDINGS

While the number of treatments used in cluster headache is relatively small, numerous considerations were identified related to managing patients with comorbidities. Many of these touch on cardiac, cardiovascular, and cerebrovascular health, but full histories are needed to guide safe and effective treatment. Both older and newer treatments may be contraindicated in certain patients with cluster headache or should be considered carefully. In addition to incorporating medical, psychiatric, and surgical histories in the management plan, collaboration with other providers may be beneficial. Providers should also inquire about patient practices and discuss participation in clinical trials that might be a good fit for the individual.

Lithium inhibits tryptophan catabolism via the inflammation-induced kynurenine pathway in human microglia

Despite its decades' long therapeutic use in psychiatry, the biological mechanisms underlying lithium's mood-stabilizing effects have remained largely elusive. Here, we investigated the effect of lithium on tryptophan breakdown via the kynurenine pathway using immortalized human microglia cells, primary human microglia isolated from surgical specimens, and microglia-like cells differentiated from human induced pluripotent stem cells. Interferon (IFN)-γ, but not lipopolysaccharide, was able to activate immortalized human microglia, inducing a robust increase in indoleamine-2,3-dioxygenase (IDO1) mRNA transcription, IDO1 protein expression, and activity. Further, chromatin immunoprecipitation verified enriched binding of both STAT1 and STAT3 to the IDO1 promoter. Lithium counteracted these effects, increasing inhibitory GSK3β^S9 phosphorylation and reducing STAT1^S727 and STAT3^Y705 phosphorylation levels in IFN-γ treated cells. Studies in primary human microglia and hiPSC-derived microglia confirmed the anti-inflammatory effects of lithium, highlighting that IDO activity is reduced by GSK3 inhibitor SB-216763 and STAT inhibitor nifuroxazide via downregulation of P-STAT1^S727 and P-STAT3^Y705 . Primary human microglia differed from immortalized human microglia and hiPSC derived microglia-like cells in their strong sensitivity to LPS, resulting in robust upregulation of IDO1 and anti-inflammatory cytokine IL-10. While lithium again decreased IDO1 activity in primary cells, it further increased release of IL-10 in response to LPS. Taken together, our study demonstrates that lithium inhibits the inflammatory kynurenine pathway in the microglia compartment of the human brain.

Antiepileptic drugs and serotonin syndrome- A systematic review of case series and case reports

Serotonin syndrome (SS) is a drug‑induced, potentially fatal, clinical syndrome resulting from drugs that have serotonergic properties. Several antiepileptic drugs (AEDs) are known to have serotonergic properties and it can be hypothesized that such AEDs can cause SS. This study aims to review the literature on SS in patients receiving AEDs. We performed a systematic review of Scopus and MEDLINE/PUBMED for case reports and case series of SS where patients had received at least one AED at the onset of symptoms. The cases published in the English literature between 1 January 1991 and 1 April 2021 were included. Initial search identified 1263 articles of which 63 (76 patients) were included in the final analysis. Most of the included cases (53 cases, 70%) have been published in the last 10 years. The mean age of the 76 patients was 40.6 ± 17.8 years, and 51% of cases were females. These patients had been exposed to a total of 8 different types of AEDs. Valproic acid was the most common drug (29, 38%), followed by lamotrigine (22, 29%), gabapentin (16, 21%), pregabalin (seven, 9%), topiramate (five, 7%) and carbamazepine (two, 3%). There has been one case each with phenytoin and oxcarbazepine. Seven (9%) patients received more than one AEDs. Most patients (67, 88%) also received other serotoninergic agents. Only nine (12%) patients were on AEDs alone. The most common clinical condition for using AEDs was psychiatric disorders (36 patients, 47.3%), followed by migraine (17, 22.4%), other painful conditions (15, 19.7%), epilepsy (7, 9.2%), and perioperative conditions (8, 10.5%). Death was reported in two patients. We suggest that AEDs, because of their serotonergic properties, may induce SS, especially in patients who are on another serotonergic agent.

Clinical Relevance of Pharmacogenetics in Serotonin Syndrome

Serotonin syndrome is a predictable life-threatening condition that is caused by serotonergic stimulation of the central and peripheral nervous systems. A patient's genetic profile can amplify exposure risk as many serotonergic drugs are metabolized by CYP450 enzymes, and these enzymes may be altered in functionality. We report a case of an elderly man who presented with serotonin syndrome after a dose change in valproic acid 5 weeks prior. His medication list consisted of low-dose serotonergic agents, which is unusual as most cases of serotonin syndrome involve higher doses. A review of his pharmacogenetic profile is presented to retrospectively evaluate the additive risk for serotonin syndrome and implications on resuming serotonergic agents.

Refining the Clinical Features of Serotonin Syndrome: A Prospective Observational Study of 45 Patients

Introduction:

Serotonin syndrome (SS) is a drug-induced clinical syndrome that results from the excess intrasynaptic concentration of serotonin. Prospective observations are limited for SS.

Methods:

We prospectively recruited 45 consecutive adult patients (>18 years) fulfilling the Hunter's criteria for SS. All patients were subjected to a detailed clinical history and examinations. Patients were subjected to appropriate investigations to find out the other causes. The causation of SS to serotonergic drugs was assessed according to Naranjo adverse drug reaction probability scale.

Results:

The mean age was 37.3 years (range: 18–59 years). Sixty-two percent of patients were male. There were 15 different underlying clinical syndromes for which serotonergic drugs were started. Psychiatry conditions (36%) and cough/respiratory tract infection (16%) were the two most common clinical conditions for starting serotonergic drugs. We noted 49 different symptoms and physical signs. Overall, tremor (78%) and dizziness (47%) were the two most common symptoms. Headache (16%) and dizziness (16%) were the two most common initial (or first) symptoms. However, gait difficulty and febrile encephalopathy were the two most common reasons to visit the hospital. We noted 18 different drugs causing SS. Thirty-eight percent of patients received single serotonergic agent antidepressants, pain medicines and cough syrups were other important drugs causing SS.

Conclusions:

This study represents the largest clinic-based study on SS. SS is not rare in clinical practice. However, various aspects of this syndrome are still to be determined. All patients on serotonergic drugs should be physically examined for the presence of SS on the development of any new symptom.