Malignant hyperthermia

The clinical outlook is variable, and reflects the variable penetrance of this condition. The patient may require months to recover muscle strength and obtain relief from symptoms such as muscle pain.[102]Werneid K, Brandom B. Survey of long-term sequelae in survivors of a malignant hyperthermia reaction. Open J Anesthesiol. 2016 Jan:6(1);1-7. http://www.scirp.org/journal/PaperInformation.aspx?paperID=62896

Abortive MH

Removal of the trigger agent alone may result in resolution of symptoms, but this is unusual. It might occur if a patient susceptible to MH received succinylcholine with no potent inhalation anesthetic, or if the exposure to inhalation anesthetic was only for minutes rather than hours and the elimination of inhalation anesthetic occurred rapidly. In this situation the symptoms of MH may resolve very quickly with no systemic complications. Blood gases may reveal a transient mixed acidosis. Rhabdomyolysis may produce decreased renal function postoperatively.

Acute MH

In this situation acidosis will not resolve with elimination of trigger agents. Administration of dantrolene is necessary to prevent extreme acidosis and critical elevation of temperature. Other symptomatic treatments may also be required (aggressive cooling and treatment of hyperkalemia).[1]Hopkins PM, Girard T, Dalay S, et al. Malignant hyperthermia 2020: guideline from the Association of Anaesthetists. Anaesthesia. 2021 May;76(5):655-64. https://www.doi.org/10.1111/anae.15317 http://www.ncbi.nlm.nih.gov/pubmed/33399225?tool=bestpractice.com If symptoms resolve before temperature elevation is critical, full recovery may occur over the course of hours (for metabolic abnormalities) and days to months (for weakness and muscle pain). Symptoms of increased metabolism may occur again either before or more than 12 hours after the initial treatment, and prophylactic dantrolene is administered in the ICU for at least 24 hours after the initial acute episode to prevent this.[95]Burkman JM, Posner KL, Domino KB. Analysis of the clinical variables associated with recrudescence after malignant hyperthermia reactions. Anesthesiology. 2007 May;106(5):901-6. http://www.ncbi.nlm.nih.gov/pubmed/17457120?tool=bestpractice.com

Fulminant MH

The presence of rapidly increasing core temperature and evolution of multisystem organ dysfunction indicates that intervention is needed from intensive care specialists, hematologists, and specialists in supporting every major organ. Without rapid treatment the patient will die. Even if dantrolene is administered quickly and the body rapidly cooled, the patient may experience multiorgan system failure including cerebral edema and herniation, cardiovascular collapse, and coagulopathy.[103]Larach MG, Brandom BW, Allen GC, et al. Cardiac arrests and deaths associated with malignant hyperthermia in North America from 1987 to 2006: a report from the North American Malignant Hyperthermia Registry of the Malignant Hyperthermia Association of the United States. Anesthesiology. 2008 Apr;108(4):603-11. http://www.ncbi.nlm.nih.gov/pubmed/18362591?tool=bestpractice.com These symptoms may be treatable, but unless the abnormal metabolic process is stopped with dantrolene, edema, coagulopathy, and organ failure are likely to worsen.