Background: ACMT's ToxIC group developed a registry of bedside consultations in January of 2010. Over five thousand cases seen by toxicologists nationwide have been entered into this database. This constitutes a database that can be used to help understand and advance the practice of clinical toxicology.
Objective: With the increased use of serotonergic medications, the diagnosis of serotonin syndrome (SS) has continued to increase. Our objective is to describe the characteristics surrounding the diagnosis and treatment of cases entered into the "Toxic Registry" as SS.
Methods: The ToxIC Case Registry was searched from January 1, 2010 through April 4, 2011. All cases entered as SS were further classified based upon demographics, agents involved, signs and treatments.
Results: A total of 105 cases were identified as having SS. Forty-six cases (43.8%) were males and 59 (56.2%) female. Twenty nine cases (27.6%) involved a single agent, 72 (68.6%) had multiple drug ingestions and 4 cases (4%) had no agents documented. The pharmacological classes most commonly associated with SS were antidepressants (70%), antipsychotics (15%) and anticonvulsants (13%). The top serotonergic drugs involved were citalopram (n 22; 21%), dextromethorphan (n 12; 11.4%), bupropion (n 12; 11.4%), lithium (n 11; 10.5%), sertraline (n 9; 8.6%), venlafaxine (n 9; 8.6%) and tramadol (n 8; 7.6%). Medications not commonly thought to cause SS that were reported as single drug ingestions included fentanyl (n 4), sufentanyl (n 1), mephedrone (n 2), and valproate (n 1). Diphenhydramine was involved in 3 multi-drug ingestions, one involving only co-ingestions of acetaminophen and clonazepam. The most common sign reported was hyperreflexia (n 56; 53.3%) followed by tachycardia (n 51; 48.6%), delirium (n 47; 44.8%) and agitation (n 43; 41%). Hyperthermia was reported in 16 (15.2%) cases. The data collection sheet of the online registry does not have a checkbox for ocular clonus/nystagmus or clonus. A text box is available for documentation, but no cases had these symptoms manually entered. Given the lack of documentation of ocular clonus/nystamus or clonus, we were unable to compare how many patients met Sternbach's or Hunters Criteria for diagnosis. Pharmacological treatments consisted of benzodiazepines in 51 (48.6%) cases and cyproheptidine in 7 (6.7%) cases.
Conclusions: The ToxIC Registry was a useful tool for review of SS and allowed identification of medications not commonly thought to cause SS. Future iterations of the ToxIC Registry may wish to include some data fields currently not collected.