The prevalence of chronic symptoms and their association with quality of life in people with malignant hyperthermia susceptibility

Background: Malignant hyperthermia susceptibility (MHS) is a skeletal muscle disorder leading to potentially life-threatening reactions in the presence of triggers, most often, volatile anesthetic drugs. MHS is caused by mutations in the RYR1, CACNA1S, and STAC3 genes, but the genetic cause remains unknown in about half of patients. Although Malignant Hyperthermia is a well-known acute event, scarce literature about quality of life (QoL) of MHS patients suffering from chronic symptoms affects the ability to provide them with appropriate care, leading to patient frustration for healthcare providers being unable to determine the etiology of their symptoms. The purpose of this study was to describe the reported symptoms and quality of life and their association in individuals that have MHS. Methods: Participants were recruited through the North American Malignant Hyperthermia Registry (NAMHR) for a descriptive, cross-sectional study. Participants were included in the study if they were eighteen years of age or older, and were diagnosed as MHS by documented mutation in either RYR1 or CACNA1S genes, or by a positive muscle contracture test. Sample characteristics, PROMIS pain intensity, PROMIS neuropathic pain, PROMIS nociceptive pain, RAND SF-36 and Chronic MH Symptoms questionnaires were sent to potential participants. Results: One hundred and thirty-seven individuals were contacted about the study. Twenty-two (16.1%) participants identified by NAMHR reported back with study interest. All 22 identified participants were mailed study questionnaires, of which, 19 (86.4%) responded. PROMIS pain t-score varied between individuals (PROMIS pain intensity minimum T-score 30.7, maximum T-score 56.3; PROMIS neuropathic pain minimum T-score 36.2, maximum T-score 66.4; PROMIS nociceptive pain minimum T-score 30.3, maximum T-score 68.9). Participants reported muscle cramping, pain and noted thermoregulation dysfunction as MHS symptoms. There was no statistical evidence to show bleeding tendencies in MHS population. RAND SF-36 QoL demonstrated lower QoL compared to general population of similar age means. Conclusions: Individuals with chronic MHS symptoms have an association with QoL decrease. Comorbid conditions compound symptom reporting. Limited understanding of chronic symptoms impedes quality care in MHS patients by delayed detection and symptom treatment. Additional studies are needed to refine understanding and increase awareness