Associated Conditions

MH Susceptibility and Associated Conditions

MH itself is not usually associated with other serious medical problems, such as hypertension, diabetes or similar diseases. MH or MH-like events however, have occurred in patients with underlying muscle diseases, such as muscular dystrophy and myotonia. Such patients typically display muscle weakness. MH has been linked to a rare disorder of muscle called Central Core disease and King Denborough Syndrome, a rarer muscle syndrome. Additionally, patients with certain forms of muscular dystrophy may develop life-threatening disturbances and muscle destruction on exposure to the triggering agents for MH. The clinical event may resemble MH in many ways, but is not considered “true” MH. In patients with Duchenne muscular dystrophy, succinylcholine should always be avoided or rhabdomyolysis may occur. Potent volatile agents may produce rhabdomyolysis in time, but most believe that brief exposure is a small risk. Patients with muscle disorders should be carefully evaluated by their anesthesiologist prior to surgery. Hypokalemic and hyperkalemic periodic paralysis are also associated with risk for MH. Hyperkalemic cardiac arrest may occur when MH trigger agents are administered to muscular dystrophy patients. Patients with osteogenesis imperfecta often develop fever during anesthesia. Myotonic patients will develop muscle rigidity with succinylcholine. There have been a few MH cases reported in patients with carnitine palmityl transferase deficiency and it is recommended to stay away from MH triggers in such patients. Neuroleptic Malignant Syndrome (NMS) is a syndrome that resembles MH but is precipitated by drugs acting centrally on dopaminergic pathways in the brain.

• Central Core Disease: is a disorder that affects muscles used for movement (skeletal muscles). This condition causes muscle weakness that ranges from almost unnoticeable to very severe.
• King Denborough Syndrome: (KDS) is a congenital myopathy associated with susceptibility to malignant hyperthermia, skeletal abnormalities and dysmorphic features with characteristic facial appearance. [1] Although the cause of King-Denborough syndrome is not fully understood, at least some cases have been attributed to the ryanodine receptor gene (RYR1), which has been tied to malignant hyperthermia and central core disease. [2]
• Multiminicore disease: is a disorder that primarily affects muscles used for movement (skeletal muscles). This condition causes muscle weakness and related health problems that range from mild to life-threatening.

1. Reed UC, Resende MB, Ferreira LG, Carvalho MS, Diament A, Scaff M, Marie SK. King-Denborough Syndrome: report of two Brazilian cases. Arq Neuropsiquiatr. 2002;:. Available at: http://www.ncbi.nlm.nih.gov/pubmed/12364941. September 23, 2008.
2. D’Arcy CE, Bjorksten A, Yiu EM, Bankier A, Gillies R, McLean CA, Shield LK, Ryan MM. King-Denborough Syndrome Caused by a Novel Mutation in the Ryanodine Receptor Gene. Neurology. 2008.