Neuroleptic malignant syndrome

Neuroleptic malignant syndrome induced by haloperidol following traumatic brain injury

The use of neuroleptics in the acute management of traumatic brain injury (TBI) is controversial and may be detrimental to recovery. The following case report describes a patient developing neuroleptic malignant syndrome (NMS) secondary to the use of haloperidol given to control the patient's agitation. The patient began to exhibit symptoms consistent with NMS (high fever, dystonia, diaphoresis, tachycardia, and decerebrate posturing) shortly after administration of the haloperidol. Upon transfer to a rehabilitation hospital, the symptoms persisted. When NMS is suspected, the first intervention is to remove the offending agent; thus, the administration of haloperidol was suspended, and the patient was placed on Amantadine and propranolol. Amantadine was used to increase the availability of dopamine to the mid-brain region, and the propranolol was used to control the fever, which was believed to be central in origin. The patient was able to complete his rehabilitation with no further incidence of fever or agitation. The patient met or exceeded all short-term physical therapy goals and was able to complete most of the neuropsychological tasks presented. The patient returned home 38 days after admission to the rehabilitation hospital and was able to perform most activities of daily living. At the 6-months follow-up visit, the patient was considering entrance into an adult vocational school.

Neuroleptic Malignant Syndrome Spectrum: A Case Report

Objective:

To report a suspected case of subclinical neuroleptic malignant syndrome (NMS) that possibly responded to electroconvulsive therapy.

Case Summary:

A 51-year-old white woman with a history of schizoaffective disorder, depressed type, was admitted to our inpatient unit after presenting with all features of NMS except fever. The patient's symptoms were markedly improved after eight courses of electroconvulsive therapy.

Discussion:

The “spectrum concept” of NMS is increasingly being recognized. More controlled studies are required to understand the components of this syndrome.

Olanzapine overdose with serum concentrations

Olanzapine, a new atypical antipsychotic drug, has been prescribed in the treatment of schizophrenia and psychotic mood disorders for approximately 2.3 million patients worldwide. Considering the increase in olanzapine prescriptions and the increased risk of suicide in this patient population, the number of reported cases of olanzapine overdose may be expected to increase. This report describes the clinical course and serum concentrations in a patient who consumed an olanzapine overdose (800 mg). Profound central nervous system depression and tachycardia without arrhythmia occurred within 2 hours after the ingestion. Additional clinical findings (ie, fever, mutism, agitation, dystonia, akathisia, elevated creatine kinase, and increased leukocyte count) were similar to those of neuroleptic malignant syndrome. After intubation, gut decontamination, and supportive care, the patient recovered and was discharged.

Marked elevation of serum creatine kinase associated with olanzapine therapy

OBJECTIVE

To report a case of marked elevation of serum creatine kinase (CK) associated with olanzapine therapy.

CASE SUMMARY

A 39-year-old white Jewish schizophrenic man treated with olanzapine developed an elevated serum CK concentration with a peak concentration of 4000 IU/L (normal < 230). No other diagnostic criteria for neuroleptic malignant syndrome (NMS) were present. On discontinuation of the drug, serum CK concentrations returned to normal within eight days.

DISCUSSION

Olanzapine, like other atypical antipsychotic drugs, may cause muscle injury with concomitant elevations of serum CK of muscle origin. We suggest that in patients treated with olanzapine, CK concentrations should be checked on initiation of therapy, within the first 48 hours, and weekly thereafter for at least one month. In addition, patients with clinical signs suggestive of NMS should be monitored more carefully. For those patients with a history of NMS, or even of isolated serum CK elevation during antipsychotic therapy, follow-up should be stricter.

CONCLUSIONS

Marked elevation of serum CK may be a possible complication of olanzapine therapy.

Clozapine-associated neuroleptic malignant syndrome: two new cases and a review of the literature

BACKGROUND

Clozapine has recently been found to be associated with neuroleptic malignant syndrome (NMS). Our objective is to determine if clozapine causes NMS, if the presentation of clozapine-induced NMS differs from that of traditional agents, and which set of diagnostic criteria will most readily allow diagnosis of NMS associated with clozapine.

METHODS

Two new cases of clozapine-associated NMS are presented, along with previously reported cases from the literature, identified by using a MEDLINE search (1966-August 1998). From all cases, concomitant medications and washout periods were examined (if available) to assess clozapine as the likely cause of NMS. Characteristics of clozapine and traditional antipsychotic-induced NMS were compared. Different diagnostic criteria for NMS were applied to the cases to determine which were more likely to diagnose the syndrome.

RESULTS

Clozapine was deemed a highly probable cause of NMS in 14 cases, a medium probability cause in five cases, and a low probability cause in eight cases. The most commonly reported clinical features were tachycardia, mental status changes, and diaphoresis. Fever, rigidity, and elevated creatine kinase were less prominent than in NMS associated with classical neuroleptics.

CONCLUSIONS

Clozapine appears to cause NMS, although the presentation may be different than that of traditional antipsychotics. Levenson's original and Addonizio's modified criteria were more likely to diagnose NMS than were other criteria. Clozapine-associated NMS may present with fewer clinical features. Limitations are the lack of detailed information provided by many of the case reports and the use of "modified" diagnostic criteria for retrospective diagnosis.

Sympathoadrenal hyperactivity and the etiology of neuroleptic malignant syndrome

OBJECTIVE

The author's goal was to develop a pathophysiological model for neuroleptic malignant syndrome with greater explanatory power than the alternative hypotheses of hypothalamic dopamine antagonism (elevated set point) and direct myotoxicity (malignant hyperthermia variant).

METHOD

Published clinical findings on neuroleptic malignant syndrome were integrated with data from human and animal studies of muscle physiology, thermoregulation, and autonomic nervous system function.

RESULTS

The data show that the sympathetic nervous system's latent capacity for autonomous activity is expressed when tonic inhibitory inputs from higher central nervous system centers are disrupted. These tonic inhibitory inputs are relayed to preganglionic sympathetic neurons by way of dopaminergic hypothalamospinal tracts. The sympathetic nervous system mediates hypothalamic coordination of thermoregulatory activity and is a primary regulator of muscle tone and thermogenesis, augmenting both of these when stimulated. In addition, the sympathetic nervous system modulates all of the other end-organs that function abnormally in neuroleptic malignant syndrome.

CONCLUSIONS

There is substantial evidence to support the hypothesis that dysregulated sympathetic nervous system hyperactivity is responsible for most, if not all, features of neuroleptic malignant syndrome. A predisposition to more extreme sympathetic nervous system activation and/or dysfunction in response to emotional or psychological stress may constitute a trait vulnerability for neuroleptic malignant syndrome, which, when coupled with state variables such as acute psychic distress or dopamine receptor antagonism, produces the clinical syndrome of neuroleptic malignant syndrome. This hypothesis provides a more comprehensive explanation for existing clinical data than do the current alternatives.

The neuroleptic malignant syndrome: an Indian experience

A study was performed to investigate the clinical presentation and outcome of the neuroleptic malignant syndrome (NMS) in a large teaching psychiatric hospital in India. Thirteen cases were identified after a thorough search of intensive care unit (ICU) records during the 4-year period between 1990 and 1993. Information collected from these cases was then compared against data from a representative control group of 252 inpatients who received neuroleptics, drawn randomly from each of the 4 years of the study. Statistical comparisons were made using Student's t test, the chi-square test, and Fisher's exact test. The incidence of NMS was 1.41 per 1,000 cases treated with neuroleptics (95% confidence interval, 0.71 to 2.14 per 1,000) and the mortality from NMS was 38%. Patients who developed NMS had a significantly higher incidence of coexisting physical or neurological illness and received a higher mean neuroleptic dose. Neuroleptic loading rates were not different in the NMS and control samples. Fluphenazine decanoate was implicated as a causative factor of NMS in a significantly higher proportion of these patients. The group with a fatal outcome was significantly older and received a higher neuroleptic dose than the control group, but not compared with the group that recovered.

Propofol infusion syndrome in children

The use of propofol infusions to sedate children in intensive care units has decreased after reports of deaths from myocardial failure. More recently it has been suggested that propofol might have been prematurely condemned. Information about 18 children who had received propofol infusions and suffered serious unwanted effects was used to define their common features. Three of the deaths occurred in one intensive care unit where propofol infusions had been used between 1987 and 1993. During this period 44 children with respiratory tract infections had been admitted to this unit and sedated for at least 48 h. Nine had received long-term (> 48 h), high-dose (> 4 mg.kg-1.h-1) propofol infusions and three had developed progressive myocardial failure and died. There was a significant association between receiving a long-term, high-dose propofol infusion and developing progressive myocardial failure (Fisher's Exact Test, two-tailed hypothesis, P = 0.0128) although a causative relationship could not be proved.

Addition of carbamazepine to long-term treatment with neuroleptics may induce neuroleptic malignant syndrome

BACKGROUND

Carbamazepine is an anticonvulsant, but also has an anti-manic effect, and recently it has been increasingly used in combination with neuroleptics. Nevertheless, there have been very few reports on the involvement of carbamazepine in the occurrence of neuroleptic malignant syndrome (NMS).

METHODS

A case of NMS occurring after addition of carbamazepine to long-term neuroleptic administration is described.

RESULTS

The patient had been treated with neuroleptics for about 30 years, and NMS developed when carbamazepine (400 mg/day) was added.

CONCLUSIONS

This case suggests that clinicians should consider the risk of NMS when carbamazepine is administered to patients undergoing long-term treatment with neuroleptics.

Clinical and pharmacologic risk factors for neuroleptic malignant syndrome: a case-control study

BACKGROUND

Pharmacologic and clinical risk factors for neuroleptic malignant syndrome have been suggested. High neuroleptic dose, rapid dosage increase, and parenteral administration were identified as risk factors in a case-control study; however, there are limited data regarding potential clinical risk factors.

METHODS

To examine potential clinical risk factors, we conducted a case-control study, comparing 12 cases to 24 controls, all treated with neuroleptics at our center. In addition to examining previously postulated pharmacologic risk factors, we also assessed for presence of psychomotor agitation, confusion, disorganization, and catatonia.

RESULTS

Significant differences were found between cases and controls for psychomotor agitation, confusion, disorganization, catatonia, mean and maximum neuroleptic dose, parenteral neuroleptic injections, neuroleptic dose increase within 5 days of the episode, magnitude of neuroleptic dose increase from initial dose, and extrapyramidal signs.

CONCLUSIONS

This study demonstrated that psychopathological features such as psychomotor agitation, confusion, disorganized behavior, and catatonia may be risk factors for the neuroleptic malignant syndrome, in addition to pharmacologic risk factors and extrapyramidal signs, including akathisia. In clinical practice, careful monitoring for prodromal signs of neuroleptic malignant syndrome is required during neuroleptic treatment of patients with psychomotor agitation, confusion, and/or disorganization, while in the presence of catatonia these drugs should be avoided.

Neuroleptic malignant syndrome. Recognition, prevention and management

Neuroleptic malignant syndrome (NMS) is a rare but potentially lethal form of drug-induced hyperthermia characterised by mental status changes, muscle rigidity, hyperthermia and autonomic dysfunction. Increased awareness and early recognition will lead to prompt management. The diagnosis of NMS presents a challenge because several medical conditions generate similar symptoms. The presentation and course of NMS can be quite variable ranging from a stormy and potentially fatal course to a relatively benign and self-limiting course. The most important aspect of treatment is prevention. This includes reducing risk factors (e.g. dehydration, agitation and exhaustion), early recognition of suspected cases and prompt discontinuation of the offending agent. All patients with psychosis should be monitored daily for dehydration and elevated temperature, have vital signs checked and agitation should be watched for. Antipsychotics should be used conservatively with gradual titration of doses. The management of NMS should be based on a hierarchy of symptom severity. Following an episode of NMS, the patient should be reassessed for further treatment with antipsychotics and rechallenge should not be attempted at least 2 weeks following resolution of symptoms of NMS. The patient and family should be educated about the episode and consent for further medication use obtained after a clear explanation of the risk-benefit analysis.

Hyperthermia, rhabdomyolysis, and disseminated intravascular coagulation associated with baclofen pump catheter failure

A 29-year-old man with C6 tetraplegia (ASIA A) using an implanted baclofen pump and intrathecal catheter infusion system for spasticity control developed severe spasticity, hyperthermia, hypotension, rhabdomyolysis, and disseminated intravascular coagulation after catheter disconnection. Tracheal intubation and mechanical ventilation were necessary. Extensive workup for a concurrent infection was negative except for urine cultures. The patient remained febrile for 10 days despite empirical antibiotic trials. Administration of high-dose benzodiazepines was inadequate for spasticity control. Spasticity control and his clinical condition, including body temperature, did not improve until his catheter was surgically replaced and intrathecal baclofen administration was resumed. The pharmacopathology of abrupt baclofen withdrawal and the similarities between this presentation, sepsis, neuroleptic malignant syndrome, and malignant hyperthermia are discussed. High-dose dantrolene was not used; however, based on similarities between this patient's presentation and neuroleptic malignant syndrome, it may have been the drug of choice.

Effect of dantrolene on KCl- or NMDA-induced intracellular Ca2+ changes and spontaneous Ca2+ oscillation in cultured rat frontal cortical neurons

Dantrolene has been known to affect intracellular Ca2+ concentration ([Ca2+]i) by inhibiting Ca2+ release from intracellular stores in cultured neurons. We were interested in examining this property of dantrolene in influencing the [Ca2+]i affected by the NMDA receptor ligands, KCl, L-type Ca2+ channel blocker nifedipine, and two other intracellular Ca2(+)-mobilizing agents caffeine and bradykinin. Effect of dantrolene on the spontaneous oscillation of [Ca2+]i was also examined. Dantrolene in microM concentrations dose-dependently inhibited the increase in [Ca2+]i elicited by NMDA and KCl. AP-5, MK-801 (NMDA antagonists), and nifedipine respectively reduced the NMDA and KCl-induced increase in [Ca2+]i. Dantrolene, added to the buffer solution together with the antagonists or nifedipine, caused a further reduction in [Ca2+]i to a degree similar to that seen with dantrolene alone inhibiting the increase in [Ca2+]i caused by NMDA or KCl. At 30 microM, dantrolene partially inhibited caffeine-induced increase in [Ca2+]i whereas it has no effect on the bradykinin-induced change in [Ca2+]i. The spontaneous oscillation of [Ca2+]i in frontal cortical neurons was reduced both in amplitude and in base line concentration in the presence of 10 microM dantrolene. Our results indicate that dantrolene's mobilizing effects on intracellular Ca2+ stores operate independently from the influxed Ca2+ and that a component of the apparent increase in [Ca2+]i elicited by NMDA or KCl represents a dantrolene-sensitive Ca2+ release from intracellular stores. Results also suggest that dantrolene does not affect the IP3-gated release of intracellular Ca2+ and that the spontaneous Ca2+ oscillation is, at least partially, under the control of Ca2+ mobilization from internal stores.

The neuroleptic malignant syndrome: a logical approach to the patient with temperature and rigidity

The neuroleptic malignant syndrome is a rare, potentially fatal, adverse reaction to neuroleptic drugs characterised by severe rigidity, high temperature and autonomic dysfunction. In the light of the hypothesized pathophysiology of this condition, a rational approach to the management of patients presenting with temperature and rigidity is provided. The aims of this approach are three-fold: to reduce the incidence of the condition, to be able to recognise it early so as to treat before life-threatening complications arise, and to be able to recognise early those conditions which mimic neuroleptic malignant syndrome, so as not to delay their specific treatment.

Neuroleptic malignant syndrome in the acquired immunodeficiency syndrome

Patients infected by the human immunodeficiency virus are predisposed to many infectious and noninfectious complications and often receive a variety of drugs. Furthermore, they seem to have a particular susceptibility to idiosyncratic adverse drug reactions. It is therefore surprising that only a few cases of the neuroleptic malignant syndrome have been described in patients with the acquired immunodeficiency syndrome. A high index of suspicion is required to diagnose the neuroleptic malignant syndrome in these patients, as its usual manifestations, including fever and altered consciousness, are frequently attributed to an underlying infection.

Molecular cloning and characterization of a human brain ryanodine receptor

We have cloned and sequenced the cDNA of the human brain ryanodine receptor (RyR3), which is composed of 4866 amino acids and shares characteristic structural features with the rabbit RyR3. Northern blot analysis shows that the human RyR3 mRNA is abundantly expressed in hippocampus, caudate nucleus and amygdala as well as in skeletal muscle. The human RyR3 mRNA is also detected in several cell lines derived from human brain tumors. Functional expression of RyR3 and a chimeric RyR suggests that RyR3 forms a calcium-release channel with a very low Ca2+ sensitivity.

Drug-induced hyperthermia

Drug-related causes of hyperthermia can often be overlooked in the setting of elevated body temperature. This article reviews the pathophysiology, presentation, and treatment of several drug-induced hyperthermia syndromes: malignant hyperthermia, neuroleptic malignant syndrome, sympathomimetic poisoning, and anticholinergic toxicity. Although the general approach is similar, specific management strategies may be required for each syndrome.

Catastrophic Consequences Secondary to Psychotropic Drugs, Part 1

The use of psychotropic drugs has dramatically changed the lives of many; yet as often occurs with technological advances, negative outcomes can be encountered. Potentially fatal reactions to neuroleptic drugs and serotonin-enhancing agents (e.g., antidepressants) have been presented in Part 1, with the intent of alerting and informing psychiatric nurses. Part 2 will complete this series on catastrophic consequences of psychotropic drugs with a discussion of agranulocytosis and lithium toxicity.

Heat intolerance induced by antidepressants

A case in which prescription medications induced heat intolerance which led to heat stroke is presented. A subject who suffered from depression and was treated with fluoxetine HCL (prozac) and lithium carbonate was engaged in mild intermittent work for 4 hours under hot/dry climatic conditions (Ta = 37 degrees C, rh = 15%). The subject lost consciousness, was hyperthermic and suffered from disseminated intravascular coagulation. A year later residual cerebellar symptoms were still evident and severe atrophy of the cerebellar tissue was demonstrated in a CT scan. It is suggested that drug-induced heat intolerance was the predisposing factor that reduced the patient ability to sustain exercise-heat stress, and under the favorable environmental circumstances led to excessive heat accumulation which ultimately caused heat stroke. This is the first description, to our knowledge, of heat intolerance of a patient treated by a combination of fluoxetine and lithium carbonate.

Development of an animal model for neuroleptic malignant syndrome: heat-exposed rabbits with haloperidol and atropine administration exhibit increased muscle activity, hyperthermia, and high serum creatine phosphokinase level

The neuroleptic malignant syndrome (NMS) is a life-threatening complication of neuroleptic treatment. To elucidate the pathogenesis of NMS, an animal model has been developed. Experimental rabbits treated with haloperidol (1 mg/kg) by intramuscular injection, were studied for the diagnostic symptoms of increased muscle rigidity, elevated body temperature, and high serum creatine phosphokinase (CPK) level. Administration of haloperiodol (1 mg/kg) and atropine (0.4 mg/kg), and exposure to high ambient temperature (35 degrees C) induced a significant increase in electromyographic activity with muscle rigidity similar to that observed in patients with NMS. Such rabbits also showed elevated body temperature and serum CPK value. In addition to the similarity of the signs and symptoms, all parameters measured (muscle rigidity, body temperature, and serum CPK level) were normalized by dantrolene treatment. The effectiveness of dantrolene in the experimental animal partially confirms the validity of this animal model for NMS. This experimental animal model for NMS may be useful to elucidate the pathogenesis of NMS.

No association between the neuroleptic malignant syndrome and mutations in the RYR1 gene associated malignant hyperthermia

The neuroleptic malignant syndrome (NMS) is a drug-induced disease caused by neuroleptics, but the pathogenesis of NMS is unknown. Since NMS is similar to malignant hyperthermia (MH) in clinical features and treatment, 6 mutations in the skeletal muscle ryanodine receptor (RYR1) gene, which were associated with MH, were investigated in unrelated NMS patients by single-strand conformation polymorphism analysis (SSCP). As a result, MH-susceptible RYR1 mutations were not detected in our NMS patients. A single base substitution, C7278T, was detected in one patient whose serum CPK level was repetitively elevated, but his other major symptoms did not fulfil the clinical criteria for NMS. Our results do not support the association between the neuroleptic malignant syndrome and mutations in the RYR1 gene associated with malignant hyperthermia.

Case study: neuroleptic malignant syndrome without pyrexia

Fever is generally considered to be an essential feature of neuroleptic malignant syndrome (NMS). The authors present the case of a 12-year-old boy who had many features of NMS but did not have fever. This case emphasizes the importance of assessing the total clinical situation. It also supports the concept of neuroleptic-induced catatonia (NIC) and NMS as disorders on the same spectrum. A scoring system is offered as a guide to severity of NIC-NMS.

Neuroleptic malignant syndrome in a patient with head injury

Neuroleptic malignant syndrome is an idiosyncratic reaction associated with the use of neuroleptic drugs. We report a case of this rare syndrome in a head injury patient associated with some unusual features: rhabdomyolysis with a high level of creatine kinase, the development of acute renal failure, the early use of continuous venovenous haemofiltration in treatment and rigidity that was refractory to conventional treatment with dantrolene and bromocriptine. The diagnosis in patients with multiple injuries must be based on a high index of suspicion.

Suspected neuroleptic malignant syndrome in a patient receiving clozapine

OBJECTIVE

To report a case of suspected neuroleptic malignant syndrome (NMS) associated with clozapine therapy.

CASE SUMMARY

A 42-year-old schizophrenic man treated with clozapine developed a temperature of 39.5 degrees C, diaphoresis, tachycardia, rigidity, and leukocytosis. His serum creatine kinase concentration was 25 000 U/L. A diagnosis of NMS was made. He was treated with bromocriptine and supportive therapy, and recovered within a week.

DISCUSSION

Despite earlier expectations that clozapine, with a pharmacologic profile differing from that of other antipsychotic medications, might not cause NMS, NMS remains the most likely diagnosis in this case.

CONCLUSIONS

NMS may be a possible complication of clozapine therapy.

Oxybutynin-induced heatstroke in an elderly patient

OBJECTIVE

To report an elderly patient with oxybutynin-induced heatstroke and to remind clinicians of the possibility of drugs as an etiology of hyperthermia.

CASE SUMMARY

An elderly man was admitted to the emergency department in a confused state. The day of admission was the hottest of the summer months in the San Francisco area. Because his rectal temperature was 40 degrees C and his skin was hot and dry, he was immediately packed in ice, given intravenous NaCl 0.9%, and a cooling fan was used to aid in external cooling. The patient was taking oxybutynin chloride, a drug with anticholinergic properties. The previous summer he had been admitted with a rectal temperature of 41.1 degrees C. No infectious etiology could be found. He was discharged in an improved state after a 48-hour observation period. The drug was discontinued.

DISCUSSION

It is important to recognize heatstroke and institute prompt management because of the high mortality associated with this thermoregulatory disorder. Prompt treatment should consist of rapid cooling and vigorous cardiopulmonary support.

CONCLUSIONS

The possibility of drug-induced heatstroke should be investigated in all patients admitted during the summer months with unexplained hyperthermia, especially the elderly. To our knowledge this is the first reported case of heatstroke associated with the use of oxybutynin.

Hyponatremia, convulsions and neuroleptic malignant syndrome in a male with schizoaffective disorder

OBJECTIVE

The aim of the study was to highlight the diagnostic difficulties occurring when hyponatremia presents concurrently with neuroleptic malignant syndrome (NMS). Diagnostic issues in the differentiation between hyponatremia and NMS are discussed.

CLINICAL PICTURE

A case of dilutional hyponatremia (DH) secondary to psychogenic polydipsia (PP) associated with NMS occurring in a male with schizoaffective disorder is described. The clinical picture was complicated by convulsions, perhaps due to clonazepam withdrawal and possible lithium toxicity.

TREATMENT

The patient was treated with supportive medical measures.

OUTCOME

The patient made a full recovery.

CONCLUSIONS

Hyponatremia and NMS have been found to be associated. This association may be due to an undefined common pathogenesis, or may be coincidental. Hyponatremia may also hinder the diagnosis of NMS.

Management of suspected neuroleptic malignant syndrome

OBJECTIVE

Neuroleptic Malignant Syndrome (NMS) is a rare but potentially lethal form of drug-induced hyperthermia. The objective of this paper is to provide data regarding early and suspected cases as well as offer guidelines for managing this condition. Knowledge of suspected cases will lead to early recognition and prompt management of this condition in the future.

METHOD

To address the gap in knowledge, we present 2 case reports of patients with early NMS-like symptoms. The case reports are followed by a brief review of the literature on differential diagnoses, risk factors, early signs and treatment data.

CONCLUSIONS

The most rational approach to treating NMS entails a hierarchy of interventions determined by the severity and progression of symptoms.

Structural change in dopamine D2 receptor gene in a patient with neuroleptic malignant syndrome

Dysfunction of the dopaminergic system has been suggested as a pathogenic mechanism in neuroleptic malignant syndrome. Therefore, we examined the complete coding sequences of the dopamine D2 receptor (DRD2) gene for structural abnormalities in 12 patients with a history of NMS, including two cases of familial NMS. Mutational analysis was performed by denaturing gradient gel electrophoresis (DGGE), a highly sensitive technique for detecting sequences differences. We found in one patient with a history of NMS a nucleotide substitution at codon 310 (CCG-->TCG) of exon 7 of the DRD2 gene which predicts the replacement of proline to serine in the third cytoplasmic loop of the receptor, a part of the receptor that interacts with G-proteins. A larger series of patients with NMS needs to be investigated to establish whether this allele is associated with an increased susceptibility to NMS.

Cerebrospinal fluid levels of monoamine metabolites and gamma-aminobutyric acid in neuroleptic malignant syndrome

To investigate the pathophysiology of neuroleptic malignant syndrome (NMS), we measured various cerebrospinal fluid (CSF) parameters in 11 patients and compared them with 8 age-matched normal controls. Concentrations of homovanillic acid (HVA) were significantly decreased during the active phase of NMS. This finding indicates that the dopaminergic nervous system of the patients was in a state of hypofunction in this phase and supports the central dopamine blockade theory of NMS. Reduced CSF HVA levels were also found after recovery from NMS, suggesting that hypofunction of the dopaminergic system may continue subclinically. The levels of 5-HIAA were decreased in the active phase, but the change was not significant. Therefore, a relationship between the development of NMS and disturbances of serotonin metabolism remains unclear. The levels of noradrenaline and its major metabolite, 3-methoxy-4-hydroxyphenylethyleneglycol increased significantly during the active phase, but returned to normal after recovery. These results show the existence of sympathetic nervous system hyperactivity during the active phase of NMS. The levels of gamma-aminobutyric acid (GABA) were significantly lower in the patients than in the controls. These findings suggest that there is a GABAergic deficiency in NMS. Thus, our study indicates that, in addition to dopamine hypoactivity, disturbances in various neurotransmitter systems are involved in the pathophysiology of NMS.

Hyperpyrexia associated with sustained muscle contractions: an alternative diagnosis to central fever

Muscle activity is the principal source of body heat production, and elevated core body temperatures may occur in healthy exercising persons. Hyperpyrexia from sustained tonic muscle contractions can also occur in a number of pathological conditions. The present case of hyperpyrexia associated with dystonic posturing and sustained muscle contraction in a child with encephalopathy illustrates the importance of recognizing muscular activity in the generation of fever of unknown origin following central nervous system injury. The pathophysiology, clinical features, and management of this uncommon cause of fever are discussed.

Hyperthermia and heatstroke

Occurring chiefly in epidemics during hot, humid summer weather, heatstroke dramatically demonstrates the consequences of uncontrolled body temperature elevation. It also illuminates the mechanism and management of unusual hyperthermic disorders associated, for example, with neuroleptic and anesthetic drugs.