Neuroleptic Malignant Syndrome (NMS) Flashcards
What is the pathophysiology of NMS?
The underlying pathology is thought to be central D2 receptor blockade or dopamine depletion in the hypothalamus and nigrostriatal/spinal pathways. This leads to an elevated temperature set-point and so there is impairment of normal homeostasis and rigidity in extrapyramidally induced muscle.
However, doesn’t explain why you can get with low potency neuroleptics, so thought other mechanisms may be involved e.g. skeletal muscle calcium metabolism or sympathoadrenal hyperactivity.
which cohort of patients have the highest incidence of NMS?
• Incidence higher in males under the age of 40 (potentially reflecting use of antipsychotics)
When does NMS most commonly occur?
• NMS is most common after ignition or increase of dose of antipsychotics, and in 90% of cases occurs within 10 days but can occur at any time
Risk factors for NMS?
- Use of antipsychotics
- Genetic/metabolic susceptibility
- Withdrawal from anti-Parkinsonian medication
- Patient agitation or catatonia
- High ambient temp. and dehydration
- Previous episode of NMS
- Less commonly – use of other agents with central D2 receptor antagonist activity e.g. anticholinergic medications, lithium…
Symptoms of NMS?
- Dyspnoea (due to hypoventilation caused by muscle rigidity)
- Increasing tremor or involuntary movements
- Oculogyric crises (prolonged involuntary upward deviation of the eyes)
- Opisthotonos (spasm of muscles causing backward arching of head, neck and spine)
- Seizures
- Chorea (a neurological disorder characterised by jerky involuntary movements affecting especially the shoulders, hips, and face)
How long can symptoms persist after discontinuation of offending agent?
5-10 days
Signsof NMS?
- Hyperthermia, temp. above 38oC
- Muscular rigidity
- Alteration In mental state due to confusion or agitation and altered consciousness
- Autonomic instability: pallor, tachycardia, fluctuating blood pressure, excessive salivation/sweating, tremor, incontinence
Diagnostic criteria for NMS?
• Antipsychotics within 1-4 weeks • Hyperthermia (>38oC) • Muscle rigidity • Five of the following: o Changed mental status o Tachycardia o Hypo-/Hypertension o Tremor o Incontinence o Diaphoresis (excessive sweating) or Sialorrhoea (excessive salivation) o Increased creatinine phosphokinase (CPK) or urinary myoglobin o Metabolic acidosis o Leukocytosis o Exclusion of other illnesses
DDx for NMS?
- Simple dystonic/akathisia reaction to antipsychotics
- Serotonin Syndrome
- Malignant hyperpyrexia
- Recreational drug toxicity
Ix for NMS?
• Bloods o FBC shows leukocytosis o U&Es metabolic disturbance (due to acidosis or AKI) o Hypocalcaemia is frequently associated o LFTs show elevated transaminases and lactate dehydrogenase o CK usually elevated o Coagulation studies (to detect coagulopathy) • Urine o Urine Myoglobin check o Urinary drug screen • BUFALO if sepsis suspected • Imaging o CXR if sepsis suspected o CT head to exclude other diagnoses • LP exclude other diagnoses
Mx of NMS?
- ABCDE
- Airway and breathing need to be secured and protected
- IV benzodiazepines in those who are agitated (avoid physical restraint as can worsen hyperthermia)
- DISCONTINUE offending drug
- IV fluids for dehydration
- Cooling device and antipyretics to treat hyperthermia
- Haemodialysis may be required
- ECT can be used if medication fails to improve condition
What is given if cause was overdose with antipsychotic?
activated charcoal
What is mortality rate and why?
Has a very high mortality rate (5-11.6%) due to the cardiovascular collapse, respiratory failure, myoglobinuric AKI, arrhythmias or DIC.
What is morbidity caused by?
respiratory failure, AKI, Seizures and arrhythmia
complications of NMS?
- Cardiac arrest
- Rhabdomyolysis
- AKI
- Seizures
- Respiratory failure
- DIC (Disseminated intravascular coagulation)
- Aspiration pneumonitis
- Deterioration in psychiatric condition due to withdrawal of drug
- Infection
- Heart failure
- PE
