Serotonin syndrome associated with metaxalone overdose.

INTRODUCTION: Serotonin syndrome is a potentially life-threatening entity associated with pro-serotonergic medications in therapeutic use, in overdose, or when co-administered with other drugs. A broad range of drugs and drug combinations have been associated with serotonin syndrome. Metaxalone overdose associated with serotonin syndrome has not been previously reported. CASE REPORT: (Case 1) A 23-year-old female overdosed on tramadol and metaxalone. She developed dysautonomia, diaphoresis, lower extremity rigidity and spontaneous clonus, flaccid upper extremities, and hyperthermia 5 h after ingestion. Her course was complicated by status epilepticus. (Case 2) A 56-year-old female overdosed on metaxalone and was found unresponsive. She developed dysautonomia, lower extremity rigidity and spontaneous clonus, flaccid upper extremities, rhabdomyolysis, acute renal failure, and hyperthermia. Non-depolarizing neuromuscular blockade and cooling blankets were required to control hyperthermia in both cases. Serum metaxalone levels were markedly elevated in both cases. CONCLUSION: These are the first reported cases of metaxalone overdose associated with serotonin syndrome, which may be related to monoamine oxidase inhibition.

Hemodialysis treatment of monomorphic ventricular tachycardia associated with chronic lithium toxicity.

INTRODUCTION: A patient with chronic lithium toxicity developed a life-threatening ventricular arrhythmia that resolved during removal of lithium by hemodialysis. Chronic lithium toxicity commonly results from diminished elimination and can produce neurotoxicity. Cardiovascular complications have been reported and generally affect the sinoatrial node and produce bradyarrhythmias. The majority of these arrhythmias require no emergent intervention. Ventricular arrhythmias associated with lithium toxicity are occasionally mentioned in the literature, but actual cases are rarely reported. CASE REPORT: A 74-year-old man was brought into the emergency department with a 3-day history of progressive encephalopathy, tremor, and weakness. The lithium level was elevated at 2.2 mmol/L, with a normal serum potassium. Electrocardiography revealed nonsustained monomorphic ventricular tachycardia (120-130 beats/min) lasting up to 1 min, alternating with sinus bradycardia and wandering atrial pacemaker. Episodes of monomorphic ventricular tachycardia recurred >100 times. The patient required a norepinephrine infusion for hypotension. Emergent hemodialysis was initiated to remove lithium and to treat the monomorphic ventricular tachycardia, which was felt to be secondary to lithium toxicity. Episodes of monomorphic ventricular tachycardia abated as hemodialysis progressed. The episodes resolved completely within 4 h of initiating hemodialysis. The patient was discharged home in sinus rhythm on day 5. Lithium was not reinstated. CONCLUSION: Monomorphic ventricular tachycardia associated with chronic lithium toxicity is exceptionally rare. Hemodialysis is a treatment option.

A case of neurotoxicity following envenomation by the Sidewinder rattlesnake, Crotalus cerastes.

INTRODUCTION: North American rattlesnake envenomations typically result in local tissue injury and hematologic derangements. Neurotoxicity is uncommon but when present often manifests as fasciculations and paresthesias. Neurotoxicity following Sidewinder (Crotalus cerastes) envenomation has not been previously reported. CASE REPORT: A 56-year-old man bitten on the right foot developed painful paresthesias, weakness and fasciculations of the right lower extremity, and involuntary muscle contractions of the anterior thigh. Local tissue effects and hemotoxicity never developed. The patient was discharged 5 days after the bite with resolution of fasciculations but continued to have right-sided weakness. The snake was identified as a Sidewinder, C. cerastes, by the patient and two independent herpetologists. CONCLUSION: This is the first reported case of a Sidewinder rattlesnake envenomation resulting in neurotoxicity.