| malignant hyperthermia (MH) has been reported as non-existent in children less than 1 yr old, although several unconfirmed reports have been published. A case report of MH in a 6-month-old child is presented, with confirmation of MH susceptibility by in vitro contracture testing of quadriceps muscle at 13 yr old. Genetic analysis revealed a novel RYR1 mutation that substitutes arginine 2452 for tryptophan in a region of the calcium channel mutated in several other MH pedigrees. ( info) |
12/306. A double mutation in families with periodic paralysis defines new aspects of sodium channel slow inactivation. Hyperkalemic periodic paralysis (HyperKPP) is an autosomal dominant skeletal muscle disorder caused by single mutations in the SCN4A gene, encoding the human skeletal muscle voltage-gated Na( ) channel. We have now identified one allele with two novel mutations occurring simultaneously in the SCN4A gene. These mutations are found in two distinct families that had symptoms of periodic paralysis and malignant hyperthermia susceptibility. The two nucleotide transitions predict phenylalanine 1490-->leucine and methionine 1493-->isoleucine changes located in the transmembrane segment S5 in the fourth repeat of the alpha-subunit Na( ) channel. Surprisingly, this mutation did not affect fast inactivation parameters. The only defect produced by the double mutant (F1490L-M1493I, expressed in human embryonic kidney 293 cells) is an enhancement of slow inactivation, a unique behavior not seen in the 24 other disease-causing mutations. The behavior observed in these mutant channels demonstrates that manifestation of HyperKPP does not necessarily require disruption of slow inactivation. Our findings may also shed light on the molecular determinants and mechanism of Na( ) channel slow inactivation and help clarify the relationship between Na( ) channel defects and the long-term paralytic attacks experienced by patients with HyperKPP. ( info) |
13/306. An unusual case of malignant hyperthermia during desflurane anesthesia in an African-American patient. Implications: malignant hyperthermia is an uncommon, heritable condition triggered by anesthesia and is followed by an increase in temperature that may be fatal without prompt treatment. It is rare with desflurane and in black individuals of African descent. We present a case of malignant hyperthermia in an African-American patient during desflurane anesthesia. ( info) |
14/306. exercise rhabdomyolysis in military aircrew: two cases and a review of aeromedical disposition. INTRODUCTION: exercise rhabdomyolysis (ER) is a rare, sometimes catastrophic condition where muscle fibers breakdown in response to exertion and release their breakdown products into the circulation. While ER was brought to the medical community's attention largely through reports from military training establishments we are unaware of ER having resulted from the activities of military aircrew. This paper reports two cases of ER in military aircrew and discusses the condition and the approaches taken in determining their future aeromedical disposition. case reports: rhabdomyolysis occurred in two military pilots as a result of their aircrew duties. One, an experienced pilot, suffered rhabdomyolysis as a result of centrifuge based G-training, while the other, a cadet in training, suffered rhabdomyolysis precipitated by exertion during moderately warm weather. Further investigation revealed the second case to also have the malignant hyperthermia Trait. AEROMEDICAL DISPOSTION: After wide consultation and lengthy deliberations both of these aircrew were returned to their full previous flying status. No further complications or recurrences have occurred. ( info) |
| fluoroquinolones cause myalgia, but this complication is not clearly documented. We describe a patient who developed myalgia and rhabdomyolysis during fluoroquinolone treatment. The patient was a 33-year-old man treated with norfloxacin for common cystitis. He complained of general muscular fatigue, tendon disorders, and articular pain during treatment. When the antimicrobial agent was stopped, symptoms decreased, with persistence of slight myalgia for 10 days. rhabdomyolysis was detected. Six months later, investigation by 31P magnetic resonance spectroscopy revealed an oxidative disorder and an abnormal abundance of phosphomonoesters. in vitro contracture tests led to a diagnosis of malignant hyperthermia susceptibility. Our case shows that for any subject presenting myalgia with rhabdomyolysis triggered by fluoroquinolone treatment, the presence of a latent myopathy should be investigated. ( info) |
16/306. Anaesthetic management of a child with a positive family history of malignant hyperthermia for posterior fossa surgery in the sitting position. A 6-year-old boy with a positive family history of malignant hyperthermia presented for posterior fossa craniectomy and excision of medulloblastoma. A nontriggering anaesthetic was therefore planned using infusions of propofol and remifentanil and a vapour free anaesthetic system delivering an oxygen/air mixture. The surgery was carried out with the child in the sitting position. ( info) |
| We report the case of a 31-year-old man with Graves' disease who manifested malignant hyperthermia during subtotal thyroidectomy. His past medical history and family history were unremarkable. Before surgery, his condition was well controlled with propylthiouracil, beta-adrenergic blocker and iodine. During the operation, anesthesia was induced by intravenous injection of vecuronium and thiopental, followed by suxamethonium for endotracheal intubation. anesthesia was maintained with nitrous oxide and sevoflurane. One hour after induction of anesthesia, his end tidal carbon dioxide concentration (ET(CO2)) increased from 40 to 50 mmHg, heart rate increased from 90 to 100 beats per min and body temperature began to rise at a rate of 0.3 degrees C per 15 min. Suspecting thyroid storm, propranolol 0.4 mg and methylprednisolone 1,500 mg were administered, which, however, had little effect. Despite the lack of muscular rigidity, the diagnosis of malignant hyperthermia was made based on respiratory acidosis. Sevoflurane was discontinued and dantrolene was given by intravenous bolus. Soon after the treatment, ET(CO2), heart rate and body temperature started to fall to normal levels. His laboratory findings showed abnormally elevated serum creatine phosphokinase and myoglobin but normal thyroid hormone levels. Since dantrolene is efficacious in thyrotoxic crisis and malignant hyperthermia, an immediate intravenous administration of dantrolene should be considered when a hypermetabolic state occurs during anesthesia in surgical treatment for a patient with Graves' disease. ( info) |
18/306. Hyperpyrexia in the emergency department. The differential diagnosis of the hyperpyrexic patient in the emergency department is extensive. It includes sepsis, heat illness including heat stroke, neuroleptic malignant syndrome, malignant hyperthermia, serotonin syndrome and thyroid storm. Each of these possible diagnoses has distinguishing features that may help to differentiate one from another. However, establishing the correct diagnosis is a challenge in the setting of the obtunded emergency patient who gives no history and where there may be limited access to any past medical or drug history. This paper presents such a case and reviews the features of the differential diagnoses and management of the hyperpyrexic patient. ( info) |
19/306. Intolerance to neuroleptics and susceptibility for malignant hyperthermia in a patient with proximal myotonic myopathy (PROMM) and schizophrenia. We report a patient with proximal myotonic myopathy who was treated with neuroleptics because of exacerbating schizophrenia. Under therapy with fluanxol, the patient developed muscle stiffness and oculogyric cramps. Treatment with both amisulpride and olanzapine lead to markedly elevated serum creatine kinase levels. An in-vitro contracture test was positive for halothane. Thus, in patients with all kinds of multisystemic myotonic myopathies, a susceptibility for malignant hyperthermia and intolerance towards neuroleptics should be taken into account. ( info) |
| hypokalemic periodic paralysis is in most cases related to mutations within the dihydropyridine receptor gene. Susceptibility to malignant hyperthermia has been linked to a different part of the same gene, but is more frequently caused by mutations within the ryanodine receptor gene. We report the association of the two disorders in a patient for whom the most frequent mutations for hypokalemic periodic paralysis were not found. This suggests further genetic heterogeneity of this condition, the interest of this case residing in the known coupling between dihydropyridine and ryanodine receptors. ( info) |