PRACTICE Neuroleptic malignant syndrome: case report and discussion Geethan J. Chandran, John R. Mikler, David L. Keegan Abstract tion and cardiac troponin levels. Other laboratory results, including electrolyte levels, were normal. WE REPORT A CASE INVOLVING AN 81-YEAR-OLD man with schizoaffec- The patient was observed for the night. The next morn- tive disorder who presented with neuroleptic malignant syndrome ing his Parkinsonian features and elevated temperature per- (NMS) after an increase in his neuroleptic dose. NMS, a rare but sisted, and he was found to have bilateral hyporeflexia. The potentially fatal complication of neuroleptic medications (e.g., loxapine therapy was stopped because neuroleptic malig- antipsychotics, sedatives and antinauseants), is characterized by nant syndrome (NMS) was suspected. That afternoon the hyperthermia, muscle rigidity, an elevated creatine kinase level CK level climbed to 2574 U/L. The next day, the patient and autonomic instability. The syndrome often develops after a had increased rigidity and his temperature rose to 39.3°C. sudden increase in dosage of the neuroleptic medication or in A septic workup yielded normal results, but the urine myo- states of dehydration. Treatment is mainly supportive and in- cludes withdrawal of the neuroleptic medication and, possibly, globin test result was positive. A firm diagnosis of NMS administration of drugs such as dantrolene and bromocriptine. was made, and therapy with dantrolene (70 mg intra- Complications of NMS include acute renal failure and acute res- venously) was started and about 24 hours later was changed piratory failure. Given the widespread prescription of neuroleptics to bromocriptine (2.5 mg 3 times daily). by physicians in a variety of fields, all physicians need to be able Within a few days, the patient’s NMS symptoms im- to recognize and appropriately manage NMS. proved and his CK level returned to normal. As his symp- toms resolved, the bromocriptine dose was tapered off. In order to control his ongoing psychotic symptoms, the pa- Case tient was prescribed olanzapine (2.5 mg once daily) because of its lower reported rate of NMS. He was also given ser- An 81-year-old man with a history of schizoaffective dis- traline (25 mg once daily) to control his depressive symp- order presented to hospital with increasing auditory hallu- toms. After 5 weeks, his depressive and psychotic symptoms cinations, persecutory delusions and depressive symptoms, improved considerably, and he was discharged from hospi- including suicidal ideation. He was admitted to hospital and tal without further complications. given loxapine (10mg every morning, 50 mg every evening) for his psychotic symptoms and methotrimeprazine (10 mg Comments once daily) for sleep disturbance. Two weeks earlier he had been prescribed venlafaxine by his family physician and had NMS is an uncommon but serious complication of been experiencing some symptomatic hypotensive episodes neuroleptic medications. It was first described in 1967 as as a result. He had also been taking levothyroxine (0.1 mg “akinetic hypertonic syndrome.” 1,2 The frequency of the syn- once daily) and procyclidine (2.5 mg once daily). drome ranges from 0.07% to 2.2% among patients receiving Within 3 days after admission, the methotrimeprazine neuroleptic medications.1 The mortality is 10%–30%.1 therapy was stopped because of somnolence and the loxa- NMS likely results from a complex interaction between pine dose increased to 65 mg/d at bedtime. Twelve hours the neuroleptic medication and a susceptible host. Two the- after this change, the patient had diaphoresis, tremulous- ories have been proposed to explain the syndrome: central ness, urinary incontinence and some cognitive impairment. dopamine receptor blockade and skeletal muscle defect. In His temperature was elevated (38.3°C), and although nor- the first theory, the dopaminergic receptor antagonism by motensive (blood pressure 124/84 mm Hg) he had tachy- neuroleptics may interfere with dopamine’s normal role in cardia (heart rate 128 beats/min) and exhibited Parkinson- central thermoregulation. Heat is produced from serotonin ian features, including tremor, rigidity and unsteady gait. stimulation in the hypothalamus, and dopamine inhibits this An electrocardiogram revealed no acute ischemic changes. process. Dopaminergic blockade therefore leads to less inhi- Laboratory investigation revealed mild leukocytosis (leuko- bition of serotonin stimulation and contributes to the hy- cyte count 11.7 × 109/L), with a shift to the left (neutrophil perthermia seen in NMS.3 To support this theory, there count 9.9 × 109/L). His aspartate aminotransferase level was have been reported cases of conditions resembling NMS in elevated (82 U/L), and his creatine kinase (CK) level was patients with Parkinson’s disease who had no history of the markedly elevated (1145 U/L), with normal CK MB frac- syndrome and in whom therapy with levodopa–carbidopa CMAJ • SEPT. 2, 2003; 169 (5) 439 © 2003 Canadian Medical Association or its licensors P RACTICE NMS.18 There seems to be no significant difference in the Box 1: Neuroleptic medications associated duration of clinical symptoms with long-acting neuroleptics 18 with neuroleptic malignant syndrome compared with short-acting ones. Psychomotor agitation (NMS)* preceding the onset of symptoms is a significant clinical manifestation in patients who are at risk of NMS.15,19 Dehy- Typical neuroleptics Atypical neuroleptics dration with the concomitant use of neuroleptics has been • Haloperidol (+++) Clozapine (+) implicated as a risk factor for the syndrome, because the de- • Chlorpromazine (++) Olanzapine (+) creased blood volume induces peripheral vasoconstriction and impairs heat dissipation. NMS can often be prevented • Fluphenazine, long Quetiapine (+) by ensuring that patients receiving neuroleptics are well hy- acting (++) Risperidone (+) drated. Other risk factors for NMS include stress, humidity • Fluphenazine (++) and concomitant use of lithium, anticholinergic agents or • Levomepromazine (+) some antidepressants.9 • Loxapine (+) Many diagnostic criteria have been proposed for NMS, but because of its variable presentation, no single set of cri- *+ = rarely associated with NMS, +++ = more commonly associated with NMS.1,8–14 teria is used universally. Some clinical manifestations are described in Box 2.1,9,20 The symptoms usually develop over 24 to 72 hours and can last from 1 to 44 days (about 10 days on average).13 There is no typical sequence of symp- and amantadine was abruptly stopped.4 Because central toms, but extrapyramidal symptoms usually occur before thermoregulation is mediated by noradrenergic, dopamin- autonomic ones.17 Hyperthermia, rigidity and recent initia- ergic, serotoninergic and cholinergic pathways, it is unlikely tion of drug therapy with one or more neuroleptics are that the syndrome is due to central dopaminergic blockade common features of NMS. alone.1 Furthermore, dopamine may directly inhibit skeletal The differential diagnosis of NMS is described in muscle contraction, and therefore dopamine blockade may Box 3.1,10,12,20,21 A thorough history taking, physical examina- result in increased skeletal muscle contraction.5 tion and laboratory investigations, including leukocyte In the second theory, NMS is believed to share a patho- count with differential, renal function tests, and measure- physiology with malignant hyperthermia.6 The symptoms ment of electrolyte, serum CK, urine myoglobin and serum of hyperthermia, rigidity and elevated CK levels are com- lithium concentrations, should be performed. An electro- mon to both conditions, as is the response to the peripheral encephalogram, CT scan of the head and lumbar puncture muscle relaxant, dantrolene. Furthermore, both conditions should also be considered to rule out other causes. produce abnormal in vitro contractility test results.1,7 As has For treatment, it is essential to recognize the symptoms been found in patients with malignant hyperthermia, in and to stop the neuroleptic therapy immediately. Support- vitro investigations of patients with NMS have revealed ive therapy, such as fever reduction, hydration and nutri- multiple defects in skeletal muscle, usually associated with increased calcium release from the sarcoplasmic reticulum.5 Box 2: Clinical manifestations of NMS Most neuroleptic medications have some risk of NMS associated with them Physical findings • Opisthotonos† 1,8–14 (Box 1). Even atypical neuroleptics • Abnormal blood pressure • Positive Babinski’s sign previously thought to have less risk, such (typically hypertension)* 13,14 8 • Tachycardia* as olanzapine and quetiapine, have • Altered level of consciousness* been associated with reported cases of • Tachypnea* • Chorea NMS. A rapid change in neuroleptic dose • Trismus‡ 15 • Diaphoresis* is a major risk factor for the syndrome, Laboratory findings especially if it occurs within 5 days before • Fever (temperature > 38.5°C)* ↑ the onset of symptoms,16 and the risk can • Generalized tonic-clonic • Creatine kinase level* persist for 20 days or more after discontin- seizures • Leukocytosis, with shift to the left* uing the neuroleptic therapy.1 NMS most • Muscle rigidity* • Myoglobinuria* often occurs after the initiation or increase • Mutism • ↑ Transaminase levels in dose of neuroleptics, but rarely it can occur after the sudden discontinuation of *Common finding. 17 †Extreme hyperextension of the body in which the head and heels are bent backward and the the drug therapy.