How Late Can Malignant Hyperthermia Occur?

Malignant hyperthermia normally occurs during surgery when an individual inhales volatile anesthetics or succinylcholine. However, the symptoms may take minutes or hours to appear, which is dependent on the patient and their reactive response. Malignant hyperthermia is an inherited disorder which involves an abnormality in the inherited or mutated genes of ryanodine receptor type 1 (RYR1) and CACNA1S. The condition involves the skeletal muscle which in turn results in a series of potentially life-threatening symptoms which can cause death if treatment is not given in good time. Patients susceptible to malignant hyperthermia can be children, younger adults, the elderly, males or females.

As long as the patient has an allergic reaction to the anesthetic used, they will develop the condition. Needless say, the period over which the condition will manifest varies from one patient to the other. It could also be affected by the type of anesthetic drug used.

How Late Can Malignant Hyperthermia Occur?

In various studies carried out on the onset of malignant hyperthermia and anesthetic drugs, it was found out that different drugs will impact onset of the condition at different times. One of the anesthetics which results in the faster manifestation of the condition is halothane if used alone. With respect to sevoflurane, desflurane, and isoflurane, the onset of malignant hyperthermia with sevoflurane is shorter compared to the period it will take for the condition to prevail in the presence of isoflurane and desflurane. In the presence of succinylcholine, which is a muscle relaxer, the time period for onset of malignant hyperthermia is shorter, regardless of the anesthetic used.

Malignant hyperthermia cases are more frequent when anesthetics and succinylcholine are used together. Malignant hyperthermia cases are common among patients who are in surgery or intensive care unit. Depending on how long the patient takes to react to the anesthesia used or succinylcholine, malignant hyperthermia can also develop after surgery. For fast progressive malignant hyperthermia, symptoms may start within the first hour of exposure. It could also last up to twelve hours for the condition to manifest and the first symptoms to be noted.

Clinical Representation Of Malignant Hyperthermia

Malignant hyperthermia can progress really fast and depending on the reactive response of the patient, the results could be fatal. It is therefore important that during surgery the surgeons and anesthesiologist present be keen on observing the first sign of the condition. Anesthetics are usually used during surgery or intensive care to induce temporary loss of consciousness and unresponsiveness. The manifestation of malignant hyperthermia starts with an increase in calcium levels in the muscles. This is because of abnormality in the ryanodine receptor, which is responsible for controlling calcium levels in the muscles. The high calcium levels cause hypermetabolism, which in turn, leads to high levels of carbon dioxide, acidity, heat production, and fast oxygen consumption.

If intervention is not done early enough, the condition can lead to multiple organ dysfunction and failure, and in worst case scenario, death. The early symptoms of malignant hyperthermia include; muscle rigidity, high fever, tachycardia, tachypnea, high oxygen consumption, increased carbon dioxide production, and hyperkalemia. On the other hand, later symptoms of malignant hyperthermia are myoglobin, increased temperatures, and multiple organ failure.


The consistency of anesthetics causing malignant hyperthermia is inconclusive since some patients do not develop the condition after their first exposure. However, in their second encounter, they could develop malignant hyperthermia and experience the common symptoms of the disorder. In terms of age, there is no barrier to who or who can’t get malignant hyperthermia. But, most cases of malignant hyperthermia occur in children and young adults. When it comes to gender, the male counterpart is more susceptible to the condition than females.

With the occurrence of malignant hyperthermia, it is also important to consider the time period of onset and the drug (anesthetic or succinylcholine) used. Primarily, anesthetics alone will cause a faster onset of malignant hyperthermia in comparison to the onset period in presence of succinylcholine. A patient may exhibit symptoms of the condition within the first hour or first twelve hours, depending on their reaction response time.