Neuroleptic malignant syndrome

Neuroleptic malignant syndrome
ICD-10	G21.0
ICD-9	333.92
DiseasesDB	8968

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Jesus Rosario Hernandez, M.D. [2]

Keywords and synonyms: NMS

Overview

The neuroleptic malignant syndrome is an uncommon adverse reaction to medications with dopamine receptor-antagonist properties or the rapid withdrawal of dopaminergic medications. The syndrome is characterized by severe rigidity, fever, tremor, autonomic dysfunction, altered mental status, and elevated serum creatinine phosphokinase. This is a life-threatening condition, with difficulties in diagnosis and treatment. This syndrome can further complicates psychiatric treatment.

Historical Perspective

NLM was known about as early as 1956, shortly after the introduction of the first phenothiazines, and is derived from the French syndrome malin des neuroleptiques.

Pathophysiology

The mechanism of NMS is thought to depend on decreased levels of dopamine due to:

• Dopamine receptor blockade
• Genetically reduced function of dopamine receptor D2

Causes

NMS is caused almost exclusively by antipsychotics, including all types of neuroleptic medicines along with newer antipsychotic drugs. The higher the dosage, the more common the occurrence. Rapid and large increases in dosage can also trigger the development of NMS. Other drugs, environmental or psychological factors, hereditary conditions, and specific demographics may cause greater risk, but to date no conclusive evidence has been found to support this. The disorder typically develops within two weeks of the initial treatment with the drug, but may develop at any time the drug is being taken. NMS may also occur in people taking a class of drugs known as dopaminergics when the dosage is reduced (i.e Levodopa).

Drug Causes

• Asenapine maleate
• Clozapine,
• Fluphenazine,
• Haloperidol,
• Iloperidone,
• Lorcaserin
• Loxapine
• Perphenazine
• Prochlorperazine
• Risperidone
• Rotigotine
• Thiothixene,
• Trifluoperazine

Differential Diagnosis

• Infection (sepsis, SIRS)
• Serotonin syndrome
• Delirium tremens
• Heat Stroke
• Malignant hyperthermia

NMS and Serotonin Syndrome

The clinical features of NMS and serotonergic syndrome are very similar. This can make differentiating them very difficult.

Features, classically present in NMS, that are useful for differentiating the two syndromes are:

• Fever
• Muscle rigidity
• Laboratory values (WBC and CK)

One the basis of stiffness and fever it can be differentiated from:

• Tetanus
• Stiff man syndrome
• Meningitis
• Tardive dyskinesia
• Parkinsonism

Differential Diagnosis of Fever and Stiffness

Disease	Diagnosis			Treatment
	Symptoms	Signs	Laboratory Findings
Tetanus	Tonic contraction of muscles between the spasmodic episodes Trismus or lockjaw Neck stiffness Swallowing difficulty Stiffening of the calf and pectoral muscle groups	Opisthotonos Leg extension with arm flexion Risus sardonicus respiratory distress	Not significant	Diazepam Magnesium  Human TIG
Neuroleptic Malignant Syndrome	History of intake of offending drugs e.g neuroleptics like: Fluphenazine Haloperidol Olanzapine Risperidone Autonomic instability Rigidity Disorientation Fever	Dysphagia Pallor Dyspnea Shuffling gait Agitation	Myoglobinemia Elevated LDH Elevated creatine kinase Hyperkalemia Elevated AST and ALT Hyperphosphatemia Elevated alkaline phosphatase Hyperuricemia	Supportive therapy Stop the offending agent Medical Therapy Dantrolene Amantadine Bromocriptine
Viral Meningitis	Fever Irritability Lack of appetite Lethargy Disoriented High grade fever Severe headache Stiff neck Sensitivity to bright light Nausea Vomiting	Headache Photophobia Phonophopia Pharyngitis in case of enterovirus infeciton Orchitis (In mumps) Vesicular or macular skin rash Petichiae Nuchal rigidity Signs of meningeal irritation: Kernig's sign Brudzinski's sign Altered mental status Hypotonia	CSF / plasma glucose ratio (>0.6) Lactate (mmols/l) (<2.1) Lymphocytes > granulocytes	Supportive Analgesics for pain. Acetaminophen for fever. Anti-viral therapy: Acyclovir Pleconaril
Stiff man syndrome	Marked rigidity Spasms Intermittent Painful Absent during sleep	Diaphoresis Arterial hypertension Tachypnea Cyanosis Apnea, tachypnea Respiratory arrest Dilatation of the pupils Tachycardia	CSF has Elevated IgG Oligoclonal bands Positive anti-GAD antibodies Elevated creatine kinase Normal CBC & ESR	Benzodiazepines Baclofen Vigabatrin  Valproic Acid, Neurontin Injected botulinum toxin  Prednisone, plasmapheresis, IVIG ( some success)
Drug induced (Tardive dyskinesia)	History of intake of the offending drug for at least one month Neuroleptics (antipsychotics) Metoclopramide Eye deviation Head and neck jerky movements No tonic contraction of the muscles between the spasms	Dyskinesia of the tongue and lips Dyskinesia of the limbs Dyskinesia of the neck	It is a clinical diagnosis depending on Dyskinetic movements Hx of > 1 month of antipsychotic use Labs may be done to rule out other differentials	Stop the offending agent Benztropine Benzodiazepines Injection of botulinum toxin Valbenzine Tetrabenazine
Strychnine poisoning	Hx of up to date tetanus immunizations History of intentional or accidental intake Strychnos nux vomica seeds Rodenticide	Hypervigilance Anxiety Mydriasis Hypereflexia Clonus Facial and neck stiffness	Blood assay Tissue assay Urine assay	Initial stabilization High dose Benzodiazepines Intubation and airway securing
Hypocalcaemia	Muscle twitching and cramping Circumoral and extremity paresthesia or tingling Altered mental status Irritability Depression Psychosis Seizure	Tetany (carpopedal spasm) Latent tetany Trousseau sign of latent tetany  Chvostek's sign  Hyperactive tendon reflexes	Decreased blood calcium levels	Two ampules of intravenous calcium gluconate 10% is given slowly in a period of 10 minutes, or If hypocalcemia is severe, calcium chloride is given instead Maintenance doses of both calcium and vitamin-D
Parkinson's disease	Stiffness Inability to write Jerky movements at rest Constipation Sleeping difficulty Walking difficulty	Tremor Rigidity Bradykinesia Postural instability Shuffling gait	Clinical diagnosis Improvement with dopaminergic therapy confirms diagnosis	Symptomatic therapy Dopamine agonists Levodopa Amantadine MAO inhibitors COMT inhibitors Anticholinergics

Risk Factors

• Antipsychotic drug administration
• Agitation
• Dehydration
• Iron deficiency
• ExhaustionDiagnostic and statistical manual of mental disorders : DSM-5. Washington, D.C: American Psychiatric Association. 2013. ISBN 0890425558.

Natural History, Complication and Prognosis

As with most illnesses, the prognosis is best when identified early and treated aggressively. In these cases NMS is usually not fatal, although there is currently no agreement on the exact mortality rate for the disorder. Studies have given the disorder a mortality rate as low as 5% and as high as 76%, although most studies agree that the correct percentage is in the lower spectrum, perhaps between 10% - 15%. Re-introduction to the drug that originally caused NMS to develop may also trigger a recurrence, although in most cases it does not.

Poor prognostic factors include:

• Administration of dopamine antagonists
• Administration of new atypical antipsychotics

Diagnosis

Diagnosis Criteria

DSM-V Diagnostic Criteria for Neuroleptic Malignant Syndrome

“

Patients have generally been exposed to a dopamine antagonist within 72 hours prior to symptom development. Hyperthermia (>100.4°F or >38.0°C on at least two occasions, measured orally), associated with profuse diaphoresis, is a distinguishing feature of neuroleptic malignant syndrome, setting it apart from other neurological side effects of anti psychotic medications. Extreme elevations in temperature, reflecting a breakdown in central thermoregulation, are more likely to support the diagnosis of neuroleptic malignant syndrome. Generalized rigidity, described as "lead pipe" in its most severe form and usually unresponsive to antiparkinsonian agents, is a cardinal feature of the disorder and may be associated with other neurological symptoms (e.g., tremor, sialorrhea, akinesia, dystonia, trismus, myoclonus, dysarthria, dysphagia, rhabdomyolysis). Creatine kinase elevation of at least four times the upper limit of normal is commonly seen. Changes in mental status, characterized by delirium or altered consciousness ranging from stupor to coma, are often an early sign. Affected individuals may appear alert but dazed and unresponsive, consistent with catatonic stupor. Autonomic activation and instability manifested by tachycardia (rate >25% above baseline), diaphoresis, blood pressure elevation (systolic or diastolic >25% above baseline) or fluctuation (>20 mmHg diastolic change or >25 mmHg systolic change within 24 hours), urinary incontinence, and pallor—may be seen at any time but provide an early clue to the diagnosis. Tachypnea (rate >50% above baseline) is common, and respiratory distress—resulting from metabolic acidosis, hyper metabolism, chest wall restriction, aspiration pneumonia, or pulmonary emboli can occur and lead to sudden respiratory arrest. A workup, including laboratory investigation, to exclude other infectious, toxic, metabolic, and neuropsychiatric etiologies or complications is essential. Although several laboratory abnormalities are associated with neuroleptic malignant syndrome, no single abnormality is specific to the diagnosis. Individuals with neuroleptic malignant syndrome may have leukocytosis, metabolic acidosis, hypoxia, decreased serum iron concentrations, and elevations serum muscle enzymes and catecholamines. Findings from cerebrospinal fluid analysis and neuroimaging studies are generally normal, whereas electroencephalography shows generalized slowing. Autopsy findings in fatal cases have been nonspecific and variable, depending on complications.

”

Symptoms

The first symptom to develop is usually muscular rigidity, followed by high fever and changes in cognitive functions. Other symptoms can vary, but may be unstable blood pressure, confusion, coma, delirium, muscle tremors, etc. Once symptoms do appear, they rapidly progress and can reach peak intensity in as little as three days. These symptoms can last anywhere from eight hours to forty days.

Laboratory Studies

A raised creatine phosphokinase (CPK) plasma concentration will be reported due to increased muscular activity. The patient may be hypertensive and suffering from a metabolic acidosis.

EEG Studies

A non-generalised slowing on an EEG is reported in around 50% of cases.

Unfortunately, symptoms of NMS are sometimes misinterpreted by doctors as symptoms of mental illness, delaying treatment.

Mnemonic

A mnemonic used to remember the features of NMS is: FEVER.

• F - Fever
• E - Encephalopathy
• V - Vitals unstable
• E - Elevated enzymes (elevated CPK)
• R - Rigidity of muscles

Treatment

Although treatment is not always necessary, it will help to cure the disease and prevent fatal developments from occurring. The first step in treatment is generally to remove the patient from any neuroleptic or antipsychotic drugs being taken and to treat fever aggressively. Many cases require intensive care, or some kind of supportive care at the minimum. Depending on the severity of the case, patients may require other treatments to contend with specific effects of the disorder. These include circulatory and ventilatory support, the drugs dantrolene sodium, bromocriptine, apomorphine and electroconvulsive therapy (ECT) if medication fails.