What is Malignant Hyperthermia Susceptibility (MHS)?
Malignant Hyperthermia Susceptibility (MHS) is a potentially life-threatening condition that is triggered by certain anesthetic agents. It is characterized by a hypermetabolic state resulting in rapid increase in body temperature and severe muscle contractions. MHS is an inherited disorder and can be particularly concerning in pediatric patients due to their developing physiology.
What Triggers Malignant Hyperthermia?
MHS is often triggered by exposure to specific anesthetic agents, particularly volatile anesthetics like sevoflurane and desflurane, and the muscle relaxant succinylcholine. These agents can induce a hypermetabolic reaction in susceptible individuals, leading to symptoms such as high fever, muscle rigidity, and hypercapnia.
How is MHS Diagnosed in Children?
Diagnosing MHS typically involves a combination of family history, clinical presentation, and specialized tests. The most definitive test is the
caffeine-halothane contracture test (CHCT), which involves muscle biopsy. Genetic testing can also be used to identify mutations in the
RYR1 and
CACNA1S genes, which are commonly associated with MHS.
Rapid rise in body temperature (hyperthermia)
Muscle rigidity
Tachycardia (rapid heart rate)
Hypercapnia (elevated carbon dioxide levels)
Metabolic acidosis
Myoglobinuria (presence of myoglobin in urine)
Prompt recognition and treatment are critical to prevent severe complications and mortality.
What is the Treatment for Malignant Hyperthermia?
The first-line treatment for an acute malignant hyperthermia crisis is
dantrolene, a muscle relaxant that inhibits calcium release from the sarcoplasmic reticulum. Alongside administering dantrolene, supportive measures include cooling the patient, providing 100% oxygen, and correcting metabolic acidosis with intravenous bicarbonate.
How Can Malignant Hyperthermia be Prevented in Pediatric Patients?
Prevention is primarily focused on avoiding known triggers. It is crucial for pediatric patients with a family history of MHS to be identified and for their medical records to be flagged. Alternative anesthesia protocols that do not include triggering agents should be used.
What is the Prognosis for Children with MHS?
With early recognition and prompt treatment, the prognosis for children with MHS can be very good. However, there may be a need for ongoing monitoring and avoidance of triggering agents throughout their life. Education and awareness among healthcare providers and families are essential for optimizing outcomes.
What are the Genetic Implications?
MHS is often inherited in an autosomal dominant pattern, meaning that only one copy of the defective gene is needed for an individual to be at risk. This also implies a 50% chance of passing the susceptibility to offspring. Genetic counseling can be beneficial for families to understand the inheritance patterns and risks involved.
Are There Any Long-Term Complications?
If not promptly treated, MHS can lead to severe complications such as muscle breakdown (rhabdomyolysis), renal failure due to myoglobinuria, and disseminated intravascular coagulation (DIC). Long-term follow-up may be necessary to monitor for any residual effects and prevent future episodes.
