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Long Term Oral Dantrolene Improved Muscular Symptoms in a Malignant Hyperthermia Susceptible Individual

Unexpected MH deaths without exposure to inhalation anesthetics in pediatric patients.

Brandom, BW, & Muldoon, SM. Paediatric Anaesthesia. September 2013.

It is well documented that infants, children and adolescents with certain gene mutations are susceptible to malignant hyperthermia when exposed to certain medications including succinylcholine, a muscle relaxant, and inhalation anesthetics. However, fatal, MH-like episodes have also been documented in children not exposed to these known triggers.
This study looked at children who had MH-like episodes without being exposed to triggering agents. These children were found to have genetic mutations in the type 1 ryanodine receptor (RYR1). These events were similar to MH in that they included generalized muscle rigidity, elevated body temperature, and dangerous changes in blood pressure and heart rate. In addition to these similar features in presentation, these patients were successfully treated with standard MH treatments including giving dantrolene and other supportive measures. In addition, some family members with the same mutation were also found to have muscle biopsy results that would qualify them as MH susceptible.
Pediatric anesthesiologists must talk to the families of these children in order to diagnose underlying myopathies and connect them with the MH registry so that continued research may occur. This will help advance the diagnosis and treatment of future children and families affected. ~ Caroline So, MD – Allegheny Health Network, Pittsburgh, PA

Long term oral Dantrolene Improved Muscular Symptoms in a Malignant Hyperthermia Susceptible Individual.

Butala, BN, Kang, A, Guron, J, & Brandom, BW. Journal of Neuromuscular Diseases, 2016.

Dantrolene is a medication used for the treatment of acute malignant hyperthermia (MH) events as well as for chronic muscle spasms in some patients. There have been cases of patients taking dantrolene for short term or episodic muscular symptoms possibly related to MH. The patient in this case report had a well-documented family history of MH episodes as well as carried a genetic mutation in her ryanodine receptor type 1 gene. The patient took low-dose oral dantrolene for over 25 years for chronic muscle pain symptoms with great relief. She experienced no side effects of the medication. ~ Brian Butala, DO - Allegheny Health Network, Pittsburgh, PA

Temperature changes are not late signs of malignant hyperthermia: A NAMH Registry of MHAUS Study.

Larach MG, Allen GC, Brandom BW, Gronert GA, & Lehman EB. Presented to the American Society of Anesthesiologists (ASA), 2008
Malignant hyperthermia poses a significant risk to affected patients. Despite modern treatment and increased availability and access to dantrolene, it is estimated that still about 35% of patients who experience an episode of malignant hyperthermia will have a complication related to the disease. Despite being named after the abrupt rise in temperature, classic teaching suggests that an increase in temperature is a sign that occurs late in the process of an episode of malignant hyperthermia. In 2010, an updated article was published which re-examined the characteristics of the patients and sequence of events that occurred during an episode of malignant hyperthermia. Contrary to classic teaching, this study showed that an increase in temperature was one of the first three signs to occur in over half
the cases and was the first sign in some cases. Rapid diagnosis can lead to faster initiation of treatment and improved outcomes. Based on these results, closer monitoring of temperature even for short surgeries may be prudent. ~ Ryan Lefevre, MD – Baylor Scott & White Health

Is there a link between malignant hyperthermia and exertional heat illness?

Muldoon SM, Deuster P, Brandom BW, Bunger R. Exercise and Sport Sciences Reviews, 2004

It has been suggested that people who have experienced an episode of exertional heat illness may be more prone to malignant hyperthermia and vice versa due to a similar genetic mutation. Malignant hyperthermia (MH) is an anesthetic emergency that develops in response to certain anesthetic medications, specifically those given during general anesthesia - inhaled anesthetics and succinylcholine. MH is recognized by a constellation of findings including an increase in heart rate and blood pressure, elevated amount of acid in the body, muscle rigidity, and elevated body temperature (which is the basis of the disease’s name "malignant hyperthermia”). Serious consequences can result if the patient does not receive treatment with dantrolene, a muscle relaxant. These consequences include multi-organ failure and eventual death. MH is linked to a genetic mutation which causes the release of an excessive amount of calcium from certain parts of muscle cells. In the process of counteracting the massive calcium release, the body experiences deadly overheating. While the trigger of exertional heat illness (EHI) is different than that of MH, the end result of excessive body temperature is very similar. EHI is caused by prolonged exercise or work in hot temperatures leading to increased blood flow to muscles and less blood flow to vital organs, like the gastrointestinal system, which ultimately causes release of toxins and pro-inflammatory proteins into the body. This release of toxins and proteins causes elevated body temperature which then can lead to exertional heat stroke, a serious and life-threatening overheating that can result in multi-organ failure and death. The release of similar inflammatory proteins in both EHI and MH prompted research into a common link between MH and EHI. It was discovered through genetic testing for predisposition towards MH that a large number of people who have had one or more episodes of EHI tested positive for high susceptibility of MH. Thus, it is suggested that people with a history of EHI can be pre-disposed to having MH when undergoing anesthesia and that those with a history of MH can be predisposed to EHI. It is important for people who have a history of EHI to inform their surgeon and especially their anesthesiologist if they are planning on undergoing surgery so that proper safety precautions can be set up and alternate anesthetic medications can be used. Similarly, people with a history of MH should also be aware of their possibility of susceptibility to EHI. ~ Josephine Orrico, MD - Mount Sinai St. Luke's and Roosevelt

Long-term sequelae in patients who experienced a malignant hyperthermia event.

Werneid K, Riazi S, Brandom BW. Presented to the International Anesthesia Research Society (IARS) 2015
In the article Survey of Long-Term Sequelae in Survivors of a Malignant Hyperthermia Reaction, 23 people responded to a survey asking about the symptoms they experienced after an MH event. The most commonly reported symptoms were muscle and joint-related including muscle pain, muscle cramps and back/joint pain. Respondents stated their muscle and joint symptoms worsened over time and most people felt these symptoms were associated with their MH event. Additional symptoms reported by patients included heart palpitations, chest pain, headaches, dizziness, nausea/vomiting, heartburn/acid reflux and anxiety/depression. While the results of this survey cannot definitively say what symptoms are related to MH, it does warrant further investigations on the long-term consequences of MH. ~ Kate Balbi - Touro College of Osteopathic Medicine

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scientific understanding of MH and related disorders.