A uncommon but potentially fatal illness known as malignant hyperthermia (MH) can develop in certain individuals if they are exposed to certain medications used for muscular relaxation or general anesthesia. Muscle stiffness, organ failure, and a sharp rise in body temperature are caused by it.
A genetic mutation that alters how the muscles react to substances involved in muscle contraction and relaxation, such acetylcholine and calcium, is the primary cause of muscular hypertrophy (MH). Due to the mutation, the muscles are more responsive and sensitive to these substances, particularly when they are induced by anesthetic medications like succinylcholine, sevoflurane, or halothane. These medications have the ability to massively release calcium from muscle cells, which can result in increased metabolism, heat generation, and muscular contraction.
The symptoms of MH usually occur during or shortly after surgery, but they can also occur up to several hours later. The symptoms can vary from person to person, but they generally include:
High fever: A rapid and extreme rise in body temperature, up to 40°C (104°F) or higher, that does not respond to cooling measures.
Muscle rigidity: A stiffening or tightening of the muscles, especially in the jaw, chest, or limbs, that makes it difficult to breathe or move.
Tachycardia: A fast and irregular heartbeat, up to 200 beats per minute or more, that can cause chest pain, palpitations, or fainting.
Tachypnea: A fast and shallow breathing, up to 40 breaths per minute or more, that can cause shortness of breath, wheezing, or cyanosis (bluish skin color).
Acidosis: A buildup of acid in the blood, due to increased metabolism and decreased oxygen delivery, that can cause nausea, vomiting, confusion, or coma.
Hyperkalemia: A high level of potassium in the blood, due to muscle breakdown and cell damage, that can cause muscle weakness, paralysis, or cardiac arrest.
Hypercalcemia: A high level of calcium in the blood, due to excessive calcium release from the muscles, that can cause muscle twitching, cramps, or seizures.
Rhabdomyolysis: A breakdown of muscle tissue, due to excessive heat and pressure, that can cause dark or bloody urine, kidney failure, or death.
If you have symptoms of MH, you should seek immediate medical attention, as MH can be fatal if not treated promptly. Your doctor may perform a physical exam, ask about your medical history and family history of MH, and order some tests, such as:
Blood tests: To check your levels of creatine kinase (CK), lactate, pH, potassium, calcium, and other markers of muscle damage, metabolism, and organ function.
Urine tests: To check your levels of myoglobin, a protein released from damaged muscle cells, and to assess your kidney function and hydration status.
Muscle biopsy: To take a small sample of muscle tissue and test it for the presence of the genetic mutation that causes MH, using a technique called the caffeine-halothane contracture test (CHCT). This test measures how much the muscle contracts when exposed to caffeine or halothane, which are substances that trigger MH.
Genetic testing: To analyze your DNA and look for the specific gene or genes that are associated with MH, such as the ryanodine receptor 1 (RYR1) gene or the calcium channel, voltage-dependent, L type, alpha 1S subunit (CACNA1S) gene.
The treatment of MH is aimed at stopping the exposure to the triggering drugs, reversing the symptoms, and preventing the complications. The main treatments for MH are:
Dantrolene: A medication that decreases heat generation, metabolism, and muscular contraction by preventing the release of calcium from muscle cells. The only known specific and efficient antidote for MH is dantrolene, which should be administered intravenously as soon as possible at a rate of 2.5 mg/kg. This dosage should be repeated every 5 to 10 minutes until the symptoms go away or a maximum of 10 mg/kg is achieved.
In order to restore normal body temperature, blood pressure, heart rate, respiration, and organ function, supportive care involves giving oxygen, fluids, cooling, and other interventions. Depending on the intensity and nature of the symptoms, this might involve dialysis, bicarbonate, insulin, glucose, breathing, intubation, intravenous fluids, ice packs, cooling blankets, and diuretics.
Monitoring: To observe and measure the vital signs, blood tests, urine tests, and muscle biopsy results, to assess the response to treatment and the risk of recurrence or complications.
While there is no sure way to prevent MH, there are some steps you can take to reduce your risk or severity of MH, such as:
Seeking help early: If you have symptoms of MH, do not hesitate to call for emergency medical assistance, as MH can be fatal if not treated promptly. The sooner you get help, the better your chances of survival and recovery.
Observing your treatment plan: If you receive a diagnosis of major depression (MH) and are given a treatment plan, be careful to adhere to the recommendations given by your physician or anesthesiologist. This might involve taking dantrolene either before or after surgery, abstaining from or minimizing the use of specific anesthetic medications, and getting frequent exams and scans. Your progress or result may be impacted by stopping or altering your therapy without first speaking with your physician or anesthesiologist.
Taking care of yourself: Since MH may have an impact on both your physical and mental health, it's critical that you look after your physical and mental needs. This includes maintaining a nutritious diet, getting enough sleep and exercise, abstaining from stress and tobacco use, and asking for emotional support from friends, family, or a therapist. These routines can help you stay healthy overall, prevent or lessen the effects of other variables that could exacerbate your mental health issues.
Notifying others: If you or your family has a history of mental health issues, you should let your physician, dentist, surgeon, anesthesiologist, and other medical professionals know. You should also wear a medical alert bracelet or necklace that will let them know what medications you should take or not take. This can assist in averting or becoming ready for any future MH episodes.
