The serotonin syndrome

Adverse drug reactions resulting in hyperthermia in the intensive care unit

Hyperthermia is frequently seen in the intensive care setting and is associated with significant morbidity and mortality. It is often initially misdiagnosed as fever associated with infection. Atypical presentations of classic syndromes are common. Clinical suspicion is the key to diagnosis. Adverse drug reactions are a frequent culprit. Syndromes include adrenergic "fever," anticholinergic "fever," antidopaminergic "fever," serotonin syndrome, malignant hyperthermia, uncoupling of oxidative phosphorylation, and withdrawal from baclofen. This review describes the pathophysiology of hyperthermia, as distinct from fever, and the physiology, diagnosis, and treatment of serotonin syndrome, neuroleptic malignant syndrome, malignant hyperthermia, and baclofen withdrawal. Much of the available evidence regarding the treatment of these disorders is based on single case reports, case series, or animal models. Therapeutic modalities consist of identification/withdrawal of possible offending agent(s), support directed at lowering temperature and preventing/treating complications, as well as targeted pharmacologic therapy directed at the specific cause. Early recognition and treatment using a multidisciplinary approach are essential to achieve the best possible outcome.

Movement disorder emergencies

Movement disorder emergencies include any movement disorder which evolves over hours to days, in which failure to appropriately diagnose and manage can result in patient morbidity or mortality. It is crucial that doctors recognize these emergencies with accuracy and speed by obtaining the proper history and by being familiar with the phenomenology of frequently encountered movements. These disorders will be discussed based on the most common associated involuntary movement, either parkinsonism, dystonia, chorea, tics or myoclonus, and, when available, review the workup and treatment options based on the current literature.

Use of antidepressants in nursing home residents. A joint statement of the members of the Long Term Care Professional Leadership Council (LTCPLC)

The Long Term Care Professional Leadership Council (LTCPLC) wishes to provide information and comment regarding the appropriate use of antidepressants in nursing home residents. There are many appropriate indications for prescribing antidepressants. As with all other medications, antidepressants have both benefits and risks. It is reasonable to promote the careful use and periodic reconsideration of the need for antidepressants. The F329 Unnecessary Drug guidance encourages judicious decision making for all medication categories, including antidepressants.

Choreoathetosis, an unusual presentation of serotonin syndrome

We describe a 63 year old male with serotonin syndrome, presenting with choreoathetosis. Differentiating this syndrome from neuroleptic malignant syndrome remains a challenge. It is important to be aware of drugs that can potentially precipitate this syndrome.

Systematic overview of drug interactions with antidepressant medications

OBJECTIVE

Antidepressants are commonly used drugs with potential for numerous drug interactions. This study aims to systematically review the literature on drug interactions with antidepressants.

METHODS

We searched MEDLINE (1966 to November 2003) and EMBASE (1980 to 2003), using the heading drug interactions combined with individual antidepressant names. We restricted searches to English-language articles and human studies. We screened drug interaction texts and review articles for relevant studies. We included articles reporting original human data on drug interactions with antidepressants commonly used in North America. Articles were independently evaluated by 2 reviewers on clinical effect, clinical significance, and quality of evidence. Discrepancies were resolved by consensus.

RESULTS

There were 904 eligible interactions, involving 9509 patients, for a total of 598 summary interactions. Of these, 439 (73%) demonstrated an interaction, 148 (25%) had no effect, and 11 (2%) had conflicting evidence. For 510 interactions (85%), the quality of evidence was poor. It was fair for 67 (11%) interactions and good for 10 (2%) interactions. There were no interactions with excellent quality of evidence. There were 145 (24%) interactions of major clinical significance. These were predominantly hypertensive emergencies and serotonin syndrome. Most interacting drugs had central nervous system (CNS) activity. As expected, monoamine oxidase inhibitors (MAOIs) appear to be the most problematic family in terms of potential for serious drug interactions.

CONCLUSIONS

Drug interactions with antidepressants are an important cause for concern, but this concern is based primarily on poor evidence. We recommend caution when combining antidepressants with other CNS drugs, particularly when coadministering MAOIs with other substances.

Interaction of serotonergic antidepressants and opioid analgesics: Is serotonin syndrome going undetected?

OBJECTIVES

To describe the potential for interaction between opioids and serotonergic antidepressants leading to the development of serotonin syndrome (SS), mechanism of the interaction, and the spectrum of SS in elderly residents of a long-term care facility.

DESIGN

Case series.

SETTING

Long-term care facility (LTCF) in California.

PARTICIPANTS

Four elderly LTCF residents treated with serotonergic antidepressants including selective serotonin reuptake inhibitor (SSRI) or mirtazapine and opioids.

MEASUREMENTS

Signs and symptoms suggestive of SS.

RESULTS

We describe 4 cases of probable SS among elderly residents of a LTCF. The spectrum of serotonin toxicity ranged from visual hallucinations, muscle rigidity, myoclonus, or hypertension in patients taking an opiate with an SSRI to lethargy, hypotension, and hypoxia in a patient taking tramadol and mirtazapine.

CONCLUSION

While many can benefit from coadministration of serotonergic antidepressants and opioids, it appears that some individuals are at increased risk for SS. Since SS is a clinical diagnosis, heightened clinician awareness of the possibility of SS among patients receiving SSRI or mirtazapine in combination with opioids may lead to earlier detection and avoidance of potentially lethal consequences.

Movement disorder emergencies

For the past 4 years, Dr. Stanley Fahn and I have given a course at the American Academy of Neurology annual meeting on the topic of movement disorder emergencies. The purpose of this review article is to summarize the topic and to present it to readers of this journal. The text of this article has appeared in nearly the same form as the Academy syllabus accompanying our course. It is being presented here so that readers of the journal may review the material.

Movement disorder emergencies in the perioperative period

Movement disorder emergencies are uncommon in the perioperative period; however, when they occur, then carry significant morbidity. By paying attention to the phenomenology of the movement disorder, the effects of medications administered in the operating room, and unusual sequelae of surgery, neurologists can have a positive impact on the outcome of these patients.

[Rhabdomyolysis and myoglobinuria]

Rhabdomyolysis is a disorder characterized by acute damage of the sarcolemma of the skeletal muscle leading to release of potentially toxic muscle cell components into the circulation, most notably creatine phosphokinase (CK) and myoglobin, and is frequently accompanied by myoglobinuria. Therefore, the term myoglobinuria is often used interchangeably with the term rhabdomyolysis. This disorder may result in potential life-threatening complications such as acute myoglobinuric renal failure, hyperkalemia and cardiac arrest, disseminated intravascular coagulation, and compartment syndrome. The condition is etiologically heterogeneous and may result from a large variety of diseases affecting muscle membranes, membrane ion channels, and muscle energy supply including acquired causes (e.g., exertion, crush injury and trauma, alcoholism, drugs, and toxins) and hereditary causes (e.g., disorders of carbohydrate metabolism, disorders of lipid metabolism, or diseases of the muscle associated with malignant hyperthermia). In many patients with idiopathic recurrent rhabdomyolysis, specific inherited metabolic defects have not been recognized up to now.

Serotonin syndrome and other serotonergic disorders

Serotonin syndrome is an iatrogenic disorder induced by pharmacologic treatment with serotonergic agents that increases serotonin activity. In addition, there is a wide variety of clinical disorders associated with serotonin excess. The frequent concurrent use of serotonergic and neuroleptic drugs and similarities between serotonin syndrome and neuroleptic malignant syndrome can present the clinician with a diagnostic challenge. In this article, we review the pathophysiology, diagnosis, and treatment of serotonin syndrome as well as other serotonergic disorders.

Rhabdomyolysis: a review

Rhabdomyolysis, a syndrome of skeletal muscle breakdown with leakage of muscle contents, is frequently accompanied by myoglobinuria, and if sufficiently severe, acute renal failure with potentially life-threatening metabolic derangements may ensue. A diverse spectrum of inherited and acquired disorders affecting muscle membranes, membrane ion channels, and muscle energy supply causes rhabdomyolysis. Common final pathophysiological mechanisms among these causes of rhabdomyolysis include an uncontrolled rise in free intracellular calcium and activation of calcium-dependent proteases, which lead to destruction of myofibrils and lysosomal digestion of muscle fiber contents. Recent advances in molecular genetics and muscle enzyme histochemistry may enable a specific metabolic diagnosis in many patients with idiopathic recurrent rhabdomyolysis.

Serotonin syndrome presenting as hypotonic coma and apnea: potentially fatal complications of selective serotonin receptor inhibitor therapy

OBJECTIVE

To describe a patient who developed serotonin syndrome on four separate occasions as a result of monotherapy with two different selective serotonin receptor inhibitors (fluoxetine and cetalopram).

DESIGN

Case report.

SETTING

Community hospital.

PATIENTS

Single patient with four episodes of serotonin syndrome.

MEASUREMENTS AND MAIN RESULTS

The syndrome was characterized by coma/unresponsiveness (four episodes), dilated pupils (four episodes), salivation (two episodes), dryness of mouth (two episodes), myoclonus like activity of eyelids (four episodes), oculogyric crisis (four episodes), flaccid paralysis of all extremities (four episodes), tremors (two episodes), apnea (two episodes), restlessness (one episode). Recovery occurred within 24 hrs, although muscle pain and weakness persisted for 2 months after stopping fluoxetine. Apnea occurred in both episodes associated with fluoxetine therapy.

CONCLUSION

Apnea and coma may occur in serotonin syndrome.

Serotonin syndrome: early management with cyproheptadine

OBJECTIVE

To report a psychiatric patient who developed serotonin syndrome after a medication overdose and whose marked mydriasis was quickly reversed by administration of cyproheptadine. This phenomenon was confirmed when other cases of serotonin syndrome were studied.

METHOD

In the index patient as well as in three subsequent cases of serotonin syndrome, pupil diameter, muscle tone, mental status, and vital signs were monitored before and after a test dose of cyproheptadine as medications were discontinued and antiserotonergic therapy begun.

RESULTS

In each patient, cyproheptadine produced rapid reversal of mydriasis within one hour of the initial dose. Other signs of serotonin syndrome remitted more slowly. As the signs and symptoms of serotonin syndrome remitted and pupils returned to normal size and reactiveness, cyproheptadine therapy seemed to produce mydriasis after each dose. Cessation of therapy after this point did not result in recurrence of symptoms. One patient developed serotonin syndrome twice. Two patients developed serotonin syndrome during treatment with medications that are partial serotonin antagonists (mirtazapine and nefazodone).

CONCLUSIONS

Rapid reversal of mydriasis in serotonin syndrome by cyproheptadine may serve as a specific suppressive test for the condition, and possibly may add to our understanding of the syndrome. Treatment with cyproheptadine is not thought to abbreviate the illness, but provides symptomatic relief while symptoms persist.

Massive sertraline overdose

Selective serotonin reuptake inhibitor medications are considered relatively safe even in overdose. We report a massive overdose of sertraline with the highest serum sertraline concentration reported to date. Clinical features of this patient were confusion, agitation, myoclonus, hyperreflexia, fever, and creatine kinase elevation. This case may represent serotonin syndrome caused by sertraline overdose alone.

Serotonin syndrome. Presentation of 2 cases and review of the literature

Serotonin syndrome is an underreported complication of pharmacotherapy that has been relatively ignored in the medical literature. We discuss 2 recent cases seen at our institution and 39 cases described in the English-language literature since 1995. We found that patients with serotonin syndrome most often (74.3%) presented within 24 hours of medication initiation, overdose, or change in dosage. The most common presenting symptoms and signs were confusion, agitation, diaphoresis, tachycardia, myoclonus, and hyperreflexia. The prevalences of hypertension, coma/unresponsiveness, seizures, and death were not as prominent in our study as previously reported, perhaps reflecting earlier recognition and intervention. The most common therapeutic intervention was supportive care alone (48% of patients). The use of 5-hydroxytryptamine (5-HT) antagonists such as cyproheptadine, however, has become more common and might reduce the duration of symptoms. Only 1 death occurred, and most patients (57.5%) had complete resolution of their symptoms within 24 hours of presentation. The increased use of serotonergic agents (alone and in combination) across multiple medical disciplines presents the possibility that the prevalence and clinical significance of this condition will rise in the future. Internists will need to be increasingly aware of and prepared for this pharmacologic complication. Prevention, early recognition of the clinical presentation, identification and removal of the offending agents, supportive care, and specific pharmacologic therapy are all important to the successful management of serotonin syndrome.

Elderly patients with altered mental status

Mental status changes in the elderly are a source of concern and a challenge for the emergency physician. A variety of medical conditions and psychiatric disturbances are potential causes of those symptoms. Acute changes must be differentiated from mental status alterations occurring as a result of chronic conditions. This article focuses on the emergency evaluation, treatment, and differential diagnosis of this symptom complex.

Serotonin syndrome due to venlafaxine overdose

A case is presented of serotonin syndrome after deliberate overdose of the antidepressant venlafaxine. The mechanism, diagnosis, and management of this disorder is discussed.