Malignant hyperthermia susceptibility in neuroleptic malignant syndrome

Office-based General Anesthesia for a Patient With a History of Neuroleptic Malignant Syndrome

First described in 1956 subsequent to a reaction reported to the newly introduced antipsychotic drug chlorpromazine, neuroleptic malignant syndrome (NMS) is a rare, potentially life-threatening reaction to antipsychotic drugs characterized by high fever, muscle rigidity, altered mental status, and autonomic instability. All neuroleptics, including newer antipsychotics, have been linked to this condition. Due to similar symptoms, it is debatable if individuals with NMS can be susceptible to malignant hyperthermia (MH). This case report presents the anesthetic care of a 30-year-old male undergoing general anesthesia in the office-based dental environment. The rationale behind the selected total intravenous anesthesia technique without NMS or MH triggering agents is outlined as well as other agents that may still be questionable regarding their trigger effect for NMS.

Electroconvulsive Therapy for Neuroleptic Malignant Syndrome: A Case Series

OBJECTIVES

Neuroleptic malignant syndrome (NMS) is an uncommon condition associated with significant morbidity and mortality. Data on treatment interventions are limited. In this case series, we sought to describe all NMS cases requiring ECT from a large academic institution over a nearly 2-decade period.

METHODS

We retrospectively identified all patients with NMS who were treated with ECT over a 17-year period. Patients were included in the study based on chart review using the International Consensus Diagnostic Criteria for NMS. Data were collected related to clinical findings, treatment course, and response to ECT.

RESULTS

We identified 15 patients meeting the inclusion criteria. Most patients had neurocognitive or schizophrenia spectrum disorders and developed NMS after exposure to multiple antipsychotic drugs. All patients received bitemporal ECT after failed pharmacotherapy for NMS. Electroconvulsive therapy was well tolerated and resulted in a remission rate of 73.3% (n = 11). Patients showed early initial response to ECT (mean of 4.2 treatments), but an average of 17.7 treatments was necessary to minimize recurrence of catatonic signs. One patient died after interruption of the index course of ECT because of severe infection, and another was discharged to hospice care after limited response. These cases highlight the lethality of NMS and its complications despite aggressive treatment measures.

CONCLUSIONS

Bitemporal ECT was well tolerated and effective in treating NMS refractory to pharmacotherapy. We suggest that ECT be considered early in cases of NMS that are refractory to pharmacological interventions, especially if the underlying condition is also responsive to ECT.

Neuroleptic malignant syndrome: a concealed diagnosis with multitreatment approach

While neuroleptic malignant syndrome (NMS) is typically characterised by delirium, motor rigidity, fever and dysautonomia, the syndrome is not pathognomonic, and NMS remains a diagnosis of exclusion. Here, we describe the case of a 44-year-old woman, with no relevant psychiatric history, admitted to a nephrology unit due to acute renal failure. After administration of antipsychotics, she presented with mental status alteration, generalised tremor, rigidity and autonomic nervous system dysfunction. Fever and rhabdomyolysis, however, were not prominent, and NMS was not considered initially in the differential diagnosis. The resulting delay in diagnosis, with continued administration of antipsychotics, led to progressive clinical deterioration. Once NMS was considered, however, antipsychotics were withdrawn and the patient was treated with electroconvulsive therapy (ECT), followed by administration of a dopamine receptor agonist, with close to full remission of all symptoms. Importantly, during outpatient follow-up, sustained mild and asymmetric tremor and rigidity was noted, leading to a diagnosis of Parkinson's disease. While this raises questions regarding differential diagnosis between NMS in Parkinson's disease, versus worsening of Parkinson's disease due to antipsychotic treatment, the former is supported by the acute and rapidly progressive onset of exuberant autonomic dysfunction and clouded conscience, after administration of a neuroleptic. Ultimately, a definitive distinction between these two alternatives for diagnosis of the inaugural neurological presentation in this patient is not possible. Nevertheless, we believe this case illustrates that NMS can be easily missed, particularly in atypical cases, delaying appropriate treatment, and that a flexible multimodal treatment approach, involving ECT, should be considered for complex clinical cases. Furthermore, it also underlines the importance of post-NMS follow-up, to investigate underlying neurological or medical disorders, particularly in those patients who do not have a full recovery.

Neuroleptic Malignant Syndrome: No Longer Exclusively a “Neuroleptic” Phenomenon

Objective:

To review the literature concerning the incidence of neuroleptic malignant syndrome (NMS) associated with the use of atypical antipsychotics.

Data Sources:

Cases were identified through a search of MEDLINE (1986–March 2004) using the terms neuroleptic malignant syndrome, antipsychotic, clozapine, risperidone, olanzapine, quetiapine, ziprasidone, and aripiprazole.

Study Selection and Data Extraction:

Case reports of possible NMS secondary to second-generation antipsychotics were selected for review. Reports meeting the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, criteria for NMS were considered. Case reports in which 1 of the 2 major diagnostic criteria was met were also included in the analysis. Furthermore, at least one minor criterion was met. Case reports in which patients received traditional antipsychotics were excluded.

Data Synthesis:

NMS is a rare and sometimes fatal disease. Several theories exist as to how NMS develops, and an equally large amount of diagnostic criteria are available. However, the majority of available data are based on the first-generation neuroleptics and very few exist with regard to the second-generation antipsychotics.

Conclusions:

Although there are numerous case reports of NMS occurring secondary to the use of second-generation antipsychotics, the incidence has never been fully elucidated. While the reasons for this remain uncertain, not all cases of second-generation–induced NMS fulfill the diagnostic criteria established for traditional neuroleptics and therefore may not be reported as such.

Propofol-Remifentanil Combination for Management of Electroconvulsive Therapy in a Patient with Neuroleptic Malignant Syndrome

Electroconvulsive therapy can be effective in severe or treatment resistant neuroleptic malignant syndrome patients. Anesthesia and use of muscle relaxant agents for electroconvulsive therapy in such patients may encounter anesthesiologists with specific challenges. This case report describes successful management of anesthesia in 28-year-old male patient undergoing eight electroconvulsive therapy sessions for treatment of neuroleptic malignant syndrome.

Neuroleptic malignant syndrome associated with metoclopramide in a burn patient

Neuroleptic malignant syndrome (NMS) is an uncommon, potentially fatal syndrome that occurs with the use of neuroleptic medications. In view of the rarity of this syndrome and the overlap with the pathophysiologic manifestations of a burn, the burn surgeon may not readily recognize NMS on presentation. We describe the case of a 27-year-old man with 15% TBSA burns who developed NMS as a result of metoclopramide use. Recognition and treatment resulted in a prompt resolution of symptoms. Initial treatment should include immediate withdrawal of all neuroleptic agents, measures aimed at decreasing body temperature, supportive care, and restoration of dopamine balance. Various authors have advocated treatment with various medications, including benzodiazepines, dantrolene, and dopaminergic agents. It is important for burn unit personnel to be aware of this syndrome because the early institution of therapy can be life saving.

A noninvasive investigation of muscle energetics supports similarities between exertional heat stroke and malignant hyperthermia

Exertional heat stroke (EHS) is usually triggered by strenuous exercise performed under hot and humid environmental conditions. Although the pathogenesis of an EHS episode differs from that of a clinical malignant hyperthermia (MH) crisis, both conditions share some similarities in symptoms, such as the abnormal increase in core temperature. By use of (31)P magnetic resonance spectroscopy, we analyzed the muscle energetics of 26 post-EHS subjects for whom in vitro halothane/caffeine contracture tests were abnormal and investigated possible similarities with subjects susceptible to MH. An early decrease of pH was noted during the first minute of exercise in EHS subjects as compared with controls. EHS subjects were divided into two subgroups according to the diagnostic score previously developed for MH subjects. The 19 subjects (73%) with a score higher than 2 displayed significantly larger caffeine-induced and earlier ryanodine-induced contractures on muscle biopsies as compared with the rest of the group (7 subjects). The results demonstrate that muscle energetics are abnormal in subjects who have experienced EHS and suggest a possible link between MH and EH, although all EHS cannot be considered as MH.

[Malignant hyperthermia susceptibility in 3 patients with malignant neuroleptic syndrome]

Hyperthermia, skeletal muscle rigidity, rhabdomyolysis, acidosis and multiple system insufficiency characterize malignant hyperthermia. Anaesthetic malignant hyperthermia follows halogenated volatile agents and/or depolarizing muscle relaxants utilization. Diagnosis is based on in vitro muscle contracture in response to halothane and/or caffeine exposure. Neuroleptic malignant syndrome affects patients taking neuroleptic drugs; clinical findings include hyperthermia, extrapyramidal rigidity, acidosis, neurovegetative instability and neurological signs. We report three neuroleptic malignant syndrome patients with positive muscle contracture tests which shows that muscle from neuroleptic malignant syndrome patients may in some instances show alterations similar to those of anaesthetic malignant hyperthermia.

The use of clonidine in the management of autonomic overactivity in neuroleptic malignant syndrome

The aim of this study was to identify the effectiveness of clonidine in the recovery of patients with neuroleptic malignant syndrome and autonomic dysfunction, including blood pressure lability. Nine patients with neuroleptic malignant syndrome and autonomic dysfunction were treated with clonidine in the intensive care unit, according to a protocol, and the results were compared with those of seven patients with the same syndrome who were not treated with clonidine. Clonidine was administered until blood pressure stability was fully restored, and thereafter the dose was gradually reduced. There was a significant reduction in the duration of ventilation and stay in the intensive care unit in the clonidine group. Three patients from the nonclonidine group died. The data suggest that in the clonidine group, patients with neuroleptic malignant syndrome and autonomic dysfunction appear to have better and faster recovery, especially in blood pressure control, after intravenous clonidine treatment.

An analysis of 17 catatonic patients diagnosed with neuroleptic malignant syndrome

This study was conducted to show that catatonia is a predisposing factor for neuroleptic malignant syndrome (NMS) and to review the nosological relationship between catatonia and NMS. Seventeen consecutive cases of NMS were analyzed prospectively with reference to clinical and investigative findings before and after exposure to a neuroleptic. The series comprised eight males and nine females, ranging in age from 18 years to 65 years. Prior to neuroleptic exposure, all patients exhibited features compatible with criteria for catatonia (mutism/excitement) according to the Diagnostic and Statistical Manual of Mental Disorders, Third Edition-Revised, (DSM-III-R). Following neuroleptic administration (single dose in nine cases), patients deteriorated into a febrile, rigid, and obtunded state accompanied by autonomic dysfunction and raised creatine phosphokinase levels. These features were consistent with a diagnosis of NMS. Neuroleptics were discontinued and supportive medical treatment instituted. Benzodiazepines were beneficial in eight cases in relieving stupor, but bromocriptine and dantrolene were generally ineffective. In all patients diagnosed with NMS in the authors' series, catatonia was an invariable prodromal state. It appears that the administration of a neuroleptic intensified the preexisting catatonic state and precipitated a malignant variant of the disorder, which is currently recognized as NMS. The authors, therefore, challenge the separate nosological status of NMS and catatonia and suggest that these syndromes are part of a unitary pathophysiological disorder.

Electroconvulsive treatment of neuroleptic malignant syndrome: a review and report of cases

OBJECTIVE

Neuroleptic malignant syndrome (NMS) is a potentially lethal adverse effect of neuroleptic medication, with no satisfactory treatment currently available. Electroconvulsive therapy (ECT) has been anecdotally reported to be effective in its treatment. We review 45 published case reports of ECT for NMS and describe nine new cases, to examine its effectiveness, the likelihood of adverse reactions, and the theoretical implications of such treatment.

METHOD

The authors used Medline to identify reports in the English literature where ECT was used in cases of suspected NMS. In addition, the charts of patients referred to the second author for treatment of NMS were reviewed and cases in which ECT used were identified.

RESULTS

The case reports suggest that ECT is effective in many individuals with NMS, even when drug therapy has failed. The response is usually apparent after a few treatments, generally up to six. The response is not predictable on the basis of age, gender, psychiatric diagnosis or any particular feature of NMS including catatonia. Electroconvulsive therapy is a relatively safe treatment in NMS, although the risk of cardiovascular complications should be considered. Malignant hyperthermia due to the anaesthesia associated with ECT has not been reported in patients with NMS, and succinylcholine has been used safely with the exception of one report of fever and raised creatine kinase levels and another report of hyperkalemia.

CONCLUSIONS

Electroconvulsive therapy is the preferred treatment in severe NMS, cases where the underlying psychiatric diagnosis is psychotic depression or catatonia, and in cases where lethal catatonia cannot be ruled out. The effectiveness of ECT for the treatment of NMS has theoretical implications for the relationship between NMS and catatonia, and the possible pathophysiological mechanisms that underlie these disorders.

Repeated propofol anesthesia for a patient with a history of neuroleptic malignant syndrome

Neuroleptic malignant syndrome (NMS) is the most serious side effect produced by the administration of antipsychotic drugs. NMS shares many clinical similarities with malignant hyperthermia (MH), but the etiology of NMS and the relation between NMS and MH remain unknown. Anesthetic regimens for patients with NMS are not well established. We gave repeated anesthesia to a patient with a history of NMS undergoing electroconvulsive therapy for the treatment of depression. Propofol and vecuronium were used in twelve consecutive ECT sessions without complications. In this case report, we describe the safe and satisfactory repeated use of propofol in a patient with a history of NMS, and outline NMS and its questionable relation to MH.

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.

Neuroleptic malignant syndrome and mivacurium: a safe alternative to succinylcholine?

Neuroleptic malignant syndrome (NMS) and malignant hyperthermia (MH) may have a common pathogenic mechanism; therefore, it has been suggested that known triggering agents for MH (such as succinylcholine) should be avoided in patients with NMS. Electroconvulsive therapy (ECT) continues to play a major therapeutic role in contemporary psychiatry, and succinylcholine has been the muscle relaxant of choice in attenuating violent muscle contractions induced by ECT. Mivacurium is a non-depolarizing muscle relaxant with a relatively rapid onset and a short duration of action, and to date it has been proved safe in MH-susceptible patients. In this case report, following succinylcholine use during ECT, a patient with NMS developed an increase in temperature and serum creatine kinase (CK) level, possibly due to an MH reaction. Since the patient's mental status necessitated further ECT, mivacurium was administered during subsequent treatment and resulted in effective attenuation of muscle contractions without elevation of patient temperature or CK levels. In addition, there was no marked prolongation of the anaesthetic. Mivacurium is a suitable agent for patients with NMS undergoing ECT, as it has not been associated with precipitation of an MH response.

[Lack of sensitivity to per-anesthetic malignant hyperthermia in 32 patients who developed neuroleptic malignant syndrome]

The aim of this study was to verify whether a relationship exists between neuroleptic malignant syndrome (NMS) and anaesthetic-induced malignant hyperthermia (MH) or not. The in vitro halothane-caffeine tests were performed on muscle tissue obtained from 32 patients with documented NMS episodes. The diagnosis of NMS relied on Levenson's criteria. The results, expressed in accordance with the criteria of the European MH Group, defined 29 subjects as MH non-susceptible. Three patients were classified as MH equivocal. These findings demonstrate the lack of any link between NMS and MH. Therefore, patients with a history of NMS are not likely to be at risk of developing MH and special measures against MH are not required for anaesthesia in these patients.

Drug-induced hyperthermia

Drugs with antidopaminergic properties and those capable of stimulating serotonin release can be responsible for hyperthermia syndromes such as neuroleptic malignant syndrome and serotonin syndrome. Dopamine and serotonin are important neurotransmitters in temperature regulation and it is likely that these reactions result from drug-induced changes in neurotransmitter levels. We describe three cases of drug-induced hyperthermia, discuss their aetiology and management, with both general measures and therapies designed to redress neurotransmitter imbalance.

Malignant Hyperthermia

Malignant hyperthermia (MH) is a rare, genetically inherited hypermetabolic syndrome that remains dormant until triggered by exposure to certain conditions (emotional and physical stresses) or pharmacological agents (anesthetic gases and succinylcholine) in susceptible individuals. It is believed that MH is caused by a derangement in the control of intracellular calcium ions, which results in a hypermetabolic state from sustained muscle contractures. Without supportive measures and immediate treatment with the antidote, dantrolene, the mortality rate from MH can be as high as 70%. A complete personal and family medical history before surgery can show important clues that might alter the anesthetic regimen preoperatively and postoperatively (eg, the use of nontriggering agents) in MH-susceptible patients. Anesthesia personnel need to recognize the early signs of a MH crisis (eg, tachycardia, muscle stiffness, hypercapnia, and tachypnea), then monitor for other signs (eg, arrhythmias, blood pressure changes, fever, metabolic and respiratory acidosis, and mottling cyanosis), and initiate prompt treatment. Because immediate recognition and treatment of this potentially fatal hyperpyrexic episode increase a patient's chance of survival, other health care personnel (eg, nurses, pharmacists) play key roles in the emergency treatment of a MH crisis. A suspected episode of MH should be followed up with contracture testing to determine MH susceptibility (MHS). Reports of MH should be reported to the North American MH Registry.

Issues in the perioperative care of the patient with psychiatric illness

Several topics have been reviewed pertaining to psychiatric patients requiring either surgery or ECT. Most of the morbidity unique to this group of patients in the perioperative period results from drug side effects or interactions. Complications can be minimized by familiarity with the side effects of psychotropic medication and by the discontinuation of these medications when indicated.

Neuroleptic malignant syndrome and malignant hyperthermia. Important issues for the medical consultant

Neuroleptic malignant syndrome and malignant hyperthermia share two cardinal clinical features: hypothermia and rigidity. Both syndromes can result in rhabdomyolysis and have high mortality rates if left untreated. This article reviews each syndrome and its pathogenesis and treatment.

Neuroleptic malignant syndrome induced by domperidone

A 47-year-old woman with diabetic gastroparesis, on treatment with domperidone, a dopamine-receptor antagonist, was admitted to the hospital in coma, with high blood pressure and nonreactive pupils. She then developed high fever. Her condition progressively worsened for two days, when muscle rigidity was noted and creatine phosphokinase was greater than 2000 U/liter. A diagnosis of neuroleptic malignant syndrome was made, and the patient was given dantrolene with prompt and complete resolution of all signs and symptoms. Subsequent inquiry revealed a distant past history of positive muscle biopsy for malignant hyperthermia, obtained after the diagnosis had been made in a family member. This case suggests that domperidone may induce neuroleptic malignant syndrome and that patients with malignant hyperthermia are at increased risk for this complication.

Malignant hyperthermia and neuromuscular disease

Malignant hyperthermia (MH) is a rare clinical syndrome characterized by hypermetabolism and triggered by specific anesthetic agents. The mechanism of this abnormal reaction is due to uncontrolled calcium flux in the skeletal muscles resulting in a variable clinical syndrome of muscle rigidity, respiratory and metabolic acidosis, and elevation of temperature. The specific genetic defect underlying this condition has not been identified in humans, though in susceptible swine a mutation of the gene for the ryanodine receptor, a large protein which comprises the calcium channel in the sarcoplasmic reticulum, has been identified recently. Inheritance in humans appears to be autosomal dominant with variable penetrance. Patients with MH rarely have physical or laboratory signs of muscle disease. However, scattered case reports and investigations of individuals with known myopathies and other muscle related problems, such as acute rhabdomyolysis or idiopathic persistently elevated creatine kinase, suggest a possible association of MH with a variety of neuromuscular diseases and stress syndromes. This association is very strong in the case of central core disease (CCD) where it is supported by clinical and laboratory evidence, including the proximity of the CCD gene to the ryanodine receptor gene on chromosome 19. A variety of other diseases have been implicated and can be classified as possibly associated (King-Denborough syndrome, Duchenne muscular dystrophy) or unlikely to be associated (myotonia congenita, sudden infant death syndrome, limb girdle dystrophy, neuroleptic malignant syndrome, etc.).(ABSTRACT TRUNCATED AT 250 WORDS)

The muscle findings in the neuroleptic malignant syndrome associated with lysergic acid diethylamide

A detailed pathological description of the muscle findings in a case of the neuroleptic malignant syndrome (NMS) following ingestion of lysergic acid diethylamide (LSD) is given, including the first ultrastructural analysis. Focal necrosis, oedema, and hypercontraction of fibres with glycogen and lipid depletion, were identified, all of which had resolved completely a year later. The findings are compared with those in malignant hyperthermia. It is suggested that the results support the view that in NMS, the muscle rigidity is due to central mechanisms and, in both this disorder and malignant hyperthermia, it is responsible for the hyperpyrexia and its life-threatening complications.

Recurrent neuroleptic malignant syndrome associated with inv dup(15) and mental retardation

Neuroleptic malignant syndrome (NMS) is an uncommon but serious adverse reaction to neuroleptic drugs. Clinically, it resembles malignant hyperthermia, a pharmacogenetic disorder of anesthesiology. Inv dup(15) is a rare but underrecognized cause of mental retardation among institutionalized patients. NMS and inv dup(15) have not been previously reported together. Their association should encourage clinicians to search for genetic markers for NMS.

Anesthetic management of a patient with neuroleptic malignant syndrome

Neuroleptic malignant syndrome is an uncommon, idiosyncratic, and sometimes life-threatening disorder associated with the use of neuroleptic drugs. The pathogenesis of neuroleptic malignant syndrome is uncertain, but it may be similar to that of malignant hyperthermia (MH). Some of the symptoms of neuroleptic malignant syndrome are similar to those of MH. We anesthetized a 17-year-old man with this syndrome multiple times for electroconvulsive therapy (ECT) using a variety of anesthetic techniques. In this patient, dantrolene pretreatment and the use of nondepolarizing muscle relaxants did not relieve symptoms of the syndrome, including fever and creatine phosphokinase (CPK) increases.

A rapidly progressing lethal case of neuroleptic malignant syndrome

A fast progressing lethal case of neuroleptic malignant syndrome (NMS) complicated by disseminated intravascular coagulation (DIC) is presented. The fulminant course is infrequent and relates NMS to malignant hyperthermia. Muscular relaxation in combination with fluid load dramatically decreased the temperature, but the catastrophic course of this case was so advanced that the currently recommended treatment of NMS was impossible.

Anesthesia and mental illness

Although drug interaction probably remains the most potentially serious problem, current evidence suggests that psychiatric medication need not be discontinued prior to anesthesia and surgery, discontinuation of medication may constitute its own hazards. Most interactions can be predicted and appropriate precautions taken, the use of meperidine is now absolutely contraindicated for patients receiving MAOI's.

Pathogenesis and treatment of neuroleptic malignant syndrome

1. Neuroleptic drugs (antipsychotics) produce numerous side effects which include serious extrapyramidal symptoms consisting of akathisia, dystonia, neuroleptic malignant syndrome, parkinsonian reactions such as postural abnormality, tremor, akinesia or bradykinesia, rigidity, and tardive dyskinesia. 2. Among the complications of neuroleptic chemotherapy, the most serious and potentially fatal complication is malignant syndrome, which is characterized by extreme hyperthermia, "lead pipe" skeletal muscle rigidity causing dyspnea, dysphagia, and rhabdomyolysis, autonomic instability, fluctuating consciousness, leukocytosis, and elevated creatine phosphokinase. 3. Neuroleptic malignant syndrome should be differentiated from malignant hyperthermia, lethal catatonia, and other pathological states producing some of these same symptoms. 4. In addition to neuroleptics, malignant syndrome has been caused by thymoleptics (antidepressants), metoclopramide (antiemetic), metoclopramide combined with cimetidine, tetrabenazine, overdosage of benzodiazepine, phenelzine, dothiepin and alcohol, and amphetamine. 5. Factors leading to and/or facilitating the emergence of neuroleptic malignant syndromes are reportedly organic brain syndrome, dehydration, exhaustion, external heat load, excessive sympathetic discharge, use of long acting neuroleptics, high doses of neuroleptics, rapid dose titration with neuroleptics, abrupt discontinuation of antiparkinsonism agents, and concurrent lithium therapy. 6. Although, the pathogenesis of neuroleptic malignant syndrome is not understood completely, a blockade of dopaminergic receptors in the hypothalamus, spinal cord and striatum, an alteration of dopaminergic-serotonergic transmission in the body, an enhanced synthesis and action of prostaglandin E1 and E2, and a modification of calcium-mediated signal transduction in the body have been suggested. 7. The treatment of malignant syndrome includes immediate withdrawal of neuroleptic drugs, i.v. infusion of dantrolene, and oral administration of bromocriptine; or alternatively i.v. infusion of dantrolene and the combination of levodopa-carbidopa. 8. Other measures to enhance the therapeutic effectiveness of the aforementioned regimens are to include the use of anticholinergic drugs such as benztropine to enhance the effectiveness of bromocriptine, of lorazepam if catatonic symptoms persist, or of electroconvulsive therapy (ECT) if psychotic symptoms persist. 9. These treatments, however, must be "active" rather than "passive", in order to avert fatalities and/or unfortunate sequelae from this iatrogenic and incompletely understood disease.

The association between the neuroleptic malignant syndrome and malignant hyperthermia

The neuroleptic malignant syndrome (NMS) is an uncommon but dangerous complication of treatment with neuroleptic drugs. A primary defect in skeletal muscle has been suggested in view of similarities in the clinical presentations of NMS and anaesthetic-induced malignant hyperthermia (MH). The in vitro halothane-caffeine contracture tests are the most reliable method of identifying individuals susceptible to MH. The aim of this study was to define if a relationship exists between NMS and MH susceptibility. Hence, the in vitro halothane and caffeine contracture tests were performed on muscle tissue obtained from eight NMS, ten MH-susceptible and ten control patients. The results, which are expressed in accordance with the criteria of the European MH Group, defined the eight NMS subjects as MH non-susceptible. The response to halothane and caffeine exposure of skeletal muscle from NMS and control subjects was the same and significantly different from that of muscle from patients susceptible to MH. Furthermore, muscle from subjects in NMS and control group responded similarly to increasing concentrations of chlorpromazine. These results do not point towards an association between NMS and MH.

Sarcoplasmic ionic calcium concentration in neuroleptic malignant syndrome

The neuroleptic malignant syndrome (NMS) is an uncommon but serious adverse effect of antipsychotic medication. Similarities in the clinical picture, and muscle alterations, between NMS and susceptibility to malignant hyperthermia (MH) suggest common mechanisms underlying both disorders. Sarcoplasmic ionic calcium concentration ([Ca2+]i) was measured by means of Ca2+ selective microelectrodes in intact intercostal muscle fibers isolated from NMS patients and from subjects with no evidence of neuromuscular disease, who served as controls. The mean resting membrane potential and [Ca2+]i were -84 +/- 0.4 mV and 0.11 +/- 0.01 microM (mean +/- SEM) in the control subjects, while they were -84 +/- 0.6 mV and 0.51 +/- 0.02 microM in NMS muscle fibers. Only the difference in [Ca2+]i is significant (P less than 0.001). The incubation of control and NMS muscle bundles in dantrolene (10(-6) M) induced a reduction of [Ca2+]i to 0.06 +/- 0.01 microM and 0.20 +/- 0.04 microM respectively. These results show an alteration in sarcoplasmic ionic [Ca2+] in NMS muscle fibers, suggesting that a dysfunction in skeletal muscle plays some role in the pathogenesis of NMS.

Effects of droperidol, haloperidol and ketamine on halothane, succinylcholine and caffeine contractures: implications for malignant hyperthermia

The effects of two structurally similar butyrophenones (droperidol and haloperidol) and ketamine were evaluated in an in vitro system to determine their potential for eliciting or exacerbating an episode of malignant hyperthermia. Muscle strips from patients referred for diagnostic testing for malignant hyperthermia and muscle strips from the rat diaphragm were exposed to droperidol, haloperidol, or ketamine prior to challenge with halothane, succinylcholine or caffeine. If any agent augmented the contracture response to the malignant hyperthermia triggering or diagnostic agents, then the agent was considered unsafe for use in malignant hyperthermia susceptible patients. Droperidol 10 mumol/l and ketamine 100 mumol/l did not induce contractures in human or rat skeletal muscle when added alone, nor did they augment halothane, succinylcholine or caffeine contractures. These agents appear to be safe for use in patients susceptible to malignant hyperthermia. In contrast, haloperidol 10 mumol/l augmented the response to succinylcholine about 1.5-fold and may be contraindicated in MH susceptibles.

[Management of a patient with malignant hyperthermia susceptibility during anesthesia and daily living]

Death from malignant hyperthermia (MH) still occurs in France. However, anaesthesia of the MH susceptible (MhS) patient is quite possible without any more risk than for patients who are not MhS. Guidelines have been worked out: "trigger" drugs such as volatile anaesthetics (halothane, enflurane, isoflurane) and depolarizing muscle relaxants must be imperatively avoided; "non-trigger" drugs should be used, such as nitrous oxide, barbiturates, benzodiazepines, propofol, opiates, non-depolarizing muscle relaxants, amide or ester local anaesthetics at the usual doses without adrenaline. Moreover, dantrolene should be available in all hospitals, 12 bottles being a minimum at hand, or, better, 30 (about 10 mg.kg-1). In some cases, such as emergencies, an unprepared operating theatre, or an unprepared ventilator, the patient should be premedicated with 2.5 mg.kg-1 dantrolene intravenously. The ventilator, the circuit and the operating theatre should not contain any trace of halogenated vapour. The usual parameters, as well as temperature and expired CO2 concentration, should be closely monitored. MhS patients must also be given counselling. This includes explanations about MH, its genetic features, the main laboratory tests used to detect susceptibility, as well as advice about lifestyle, the use of drugs other than general and local anaesthetics, and a discussion concerning the association of MH with other diseases. This counselling is not always easy to provide, because many answers are not, as yet, definitive.

[Clinical features of malignant hyperthermia crisis]

Malignant hyperthermia (MH) is a pharmacogenetic disorder. It is classically described as a hypermetabolic state triggered by halogenated anaesthetics and/or depolarizing muscle relaxants. In fact, since Denborough and Lovel's case, it has been shown that MH has a great number of clinical forms. The overwhelming picture of muscular hypercatabolism with fulminating hyperthermia and generalized rigidity is becoming rare. A better knowledge of the first symptoms explains in part the better prognosis: masseter spasm after suxamethonium, an increase in expired CO2 concentration, unexplained tachycardia, ventricular arrhythmias. The use of dantrolene reduced the mortality of MH. The different types of clinical manifestations are due to genetic differences, the concentration of the anaesthetic agent, and the length of time of exposure to the drug. The severity of the episode is linked to environmental factors such as stress, physical exercise, ambient temperature, concomitant use of other drugs. Masseter spasm after suxamethonium is specific for MH, but not pathognomonic. It occurs in 1% of cases in children when using halothane with suxamethonium. However, in those patients who displayed such a spasm, more than 50% had a positive contracture test. Masseter spasm is often associated with severe rhabdomyolysis in patients with muscle dystrophy, especially Duchenne's dystrophy. In the latter case, major cardiac problems may occur at the time of anaesthetic induction. Even if there are no other signs of MH, all patients who have had a masseter spasm must be considered as open to doubt, and should be further explored. MH is often difficult to diagnose in medium severity types.(ABSTRACT TRUNCATED AT 250 WORDS)