Serotonin Syndrome

47 y.o. female who presents with 1 week of tremor, increased rigidity and trouble walking. Pt recently had effexor dose increased on 10/11 and abilify dose increased in September. Abruptly stopped abilify 2 weeks ago. For last week has had a new tremor in all 4 extremities. Has also had shuffling gate and felt unsteady on her feet. She states she’s never had these sx before. Finally she describes some rib pain and mild abd pain. No fevers, chills, headache, vision changes, leg swelling, bruising, hematuria, dysuria, si, hi, neck pain, gland swelling. Due to persistent tremor and worsening ability to walk went to osh. At osh had neg head ct, cxr, ua, cbc, chemistry. Transferred here for further eval.

Past Medical History
Anxiety
Depressive disorder, not elsewhere classified

Medications:
FEXOFENADINE
EFFEXOR

Physical Exam

VITAL SIGNS: BP134/69, P 125, T 98.7 degrees F, SpO2 93.00%.
General appearance: alert, cooperative, appears stated age
Eye: pupils equal, round, and briskly reactive to light; extraocular movements and vision intact; ; conjunctiva normal; no corneal abrasion; no tenderness, swelling, or ecchymosis; skin intact
Neck: supple, symmetrical, trachea midline and no adenopathy
Lungs: clear to auscultation bilaterally
Heart: regular rate and rhythm, S1, S2 normal, no murmur, click, rub or gallop
Abdomen: soft, non-tender. Bowel sounds normal. No masses, no organomegaly
Extremities: extremities normal, atraumatic, no cyanosis or edema
Pulses: 2+ and symmetric
Neurologic: Diffuse tremor in all 4 extremities. No inducible ocular clonus. Does have 4 beat clonus on dorsiflexion feet. Brisk patellar reflex. Mild rigidity. Strength/sensation intact

Serotonin Syndrome

The diagnosis of serotonin syndrome is made solely on clinical grounds. Serotonin syndrome encompasses a spectrum of disease where the intensity of clinical findings is thought to reflect the degree of serotonergic activity. Mental status changes can include anxiety, agitated delirium, restlessness, and disorientation. Patients may startle easily. Autonomic manifestations can include diaphoresis, tachycardia, hyperthermia, hypertension, vomiting, and diarrhea. Neuromuscular hyperactivity can manifest as tremor, muscle rigidity, myoclonus, hyperreflexia, and bilateral Babinski sign. Hyperreflexia and clonus are particularly common; these findings, as well as rigidity, are more often pronounced in the lower extremities

THE MAJORITY OF CASES OF SEROTONIN SYNDROME PRESENT WITHIN 24 HOURS, AND MOST WITHIN 6 HOURS, OF A CHANGE OR INITIATION OF A DRUG

The HUNTER CRITERIA for serotonin syndrome (SS) are fulfilled if the patient has taken a serotonergic agent and has one of the following:
-Spontaneous clonus
-Inducible clonus and agitation or diaphoresis
-Ocular clonus and agitation or diaphoresis
-Tremor and hyperreflexia
-Hypertonia
-Temperature above 38°C and ocular clonus or inducible clonus
(the patient in this case had 2 criteria- inducible clonus and agitation as well and tremor and hyperreflexia)

TREATMENT
Discontinue serotonergic agents
– Sedate using benzodiazepines (eg, lorazepam 1 to 2 mg IV per dose; 0.02 to 0.04 mg/kg/dose in children): goal is to eliminate agitation, neuromuscular abnormalities (eg, tremor, clonus), and elevations in heart rate and blood pressure; titrate dose to effect
-Anticipate complications; in severe SS vital signs can fluctuate widely and rapidly
-If benzodiazepines and supportive care fail to improve agitation and abnormal vital signs, give CYPROHEPTADINE (12 mg orally or by orogastric tube for initial adult dose; pediatric doses included in main text)
-Treat patients with temperature >41.1°C with immediate sedation, paralysis, and endotracheal intubation; treat hyperthermia with standard measures; avoid antipyretics such as acetaminophen

SUMMARY OF Graudins, Andis et al. Treatment of the Serotonin Syndrome With Cyproheptadine. The Journal of Emergency Medicine. Vol 16, No. 4, pp 615-619, 1998:

Cyproheptadine is a 1st generation histamine-1 receptor antagonist with non-specific antagonist properties at 5HT-1a and 5-HT2 receptros.
It has FDA approval as an anti-histamine.
typical dosing for serotonin syndrome is 8-12 mg orally.
In this case study all patients responded within 1-2 hr of Cyproheptadine administration.
In this case study and multiple others, the major side effect of cyproheptadine is drowsiness

AFTER RECEIVING CYPROPHEPTADINE OUR PATIENT CEASED TREMORING, HAD IMPROVED RIGIDITY, AND HAD HER HEART RATE DROP BY 25BPM WITHIN AN HOUR OF RECEIVING THE DRUG. SHE WAS ADMITTED TO NEURO FOR MONITORING

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