[Telephone enquiries on the topic of malignant hyperthermia: Evaluation of the content and subsequent diagnostic results at the MH Center Leipzig]. / Telefonische Anfragen zum Thema maligne Hyperthermie: Auswertung der Inhalte und der resultierenden Diagnostikergebnisse am MH-Zentrum Leipzig.

BACKGROUND: Malignant hyperthermia (MH) is an autosomal dominant metabolic myopathy. The in vitro contracture test (IVCT) is still considered to be the gold standard for diagnosing a disposition for MH. However, advances in genetic testing for MH disposition have supplemented or even replaced the invasive procedure of the IVCT. Information about MH can be obtained by either contacting the hotline for MH as a nationwide 24 h/7 days a week service or one of the regional MH centers. METHODS: The protocols of telephone conversations concerning MH at the MH Center University Leipzig were retrospectively analyzed. Data were collected from January 2011 to March 2015. Additionally, the results of the IVCT and genetic testing evolving from the counseling interviews were examined. RESULTS: A total of 205 telephone calls were documented during the period in question and an IVCT was performed as a consequence of 112 of the telephone calls. The IVCT resulted in 27 individuals being identified as MH susceptible which was subsequently diagnosed in 15 individuals with known familial MH disposition and 12 individuals were identified as new index patients. In 24 individuals a total of 13 different mutations were detected and of these 4 mutations were causative concerning MH. Of the 205 telephone calls 131 were private and 74 of medical professional origin. Among the private enquiries MH disposition within the family was a frequent reason for contacting the MH Center (61.8%). Conversations relating to MH-like symptoms during general anesthesia were carried out with 35.1% of medical doctors and with 22.9% of private callers. Advice about neuromuscular symptoms of unknown genesis was given to 15.3% of private individuals and to 24.3% of medical doctors. Overall MH topics were discussed with 23% (N = 17) of the medical profession and approximately half of these were anesthesiologists (N = 8). Not a single call was documented for the treatment of a suspected MH crisis. CONCLUSION: Private individuals and families affected by a MH disposition often showed good compliance with respect to counseling and diagnostics for MH and contacted the MH center more often than medical doctors. A more comprehensive cooperation with the medical profession is preferable and necessary to obtain a systematic and broad synopsis of characteristic and uncharacteristic signs and symptoms of MH. The telephone conversations analyzed as well as the diagnostic results (IVCT and genetic testing) underline that MH disposition is still a current and relevant topic.

Pharmacokinetics and clinical toxicity of prilocaine and ropivacaine following combined drug administration in brachial plexus anesthesia.

OBJECTIVE: Local anesthetics (LA) are often administered in combination for regional anesthesia in order to obtain the specific advantages (onset and duration of effect) of each drug. However, few data on the safety of such combinations are available and consequently plasma concentrations possibly associated with toxicity and interactions between the specific anesthetics are not sufficiently established. We measured pharmacokinetics and toxicity parameters of prilocaine and ropivacaine after combined use as single doses in brachial plexus blockade. METHODS: In an open clinical study using a combined dose regime (300 mg prilocaine followed immediately by 75 mg ropivacaine) total plasma concentrations of prilocaine and ropivacaine were measured serially in 60 patients using a gas-chromatographic method. The data were analyzed regarding a relationship with central nervous and cardiovascular toxicity. RESULTS: Following the administration in combination prilocaine and ropivacaine were rapidly absorbed. Mean prilocaine peak plasma concentrations (mean Cmax = 1.51 microg/ml) were measured between 15 and 30 min after injection. Highest ropivacaine plasma concentrations (mean Cmax = 1.12 microg/ml) were seen between 30 min and 1 hour after injection (calculated mean tmax = 44 min). One of 59 patients showed signs of myoclonus which were suspected of being due to intravascular injection. There was no relevant cardiovascular toxicity observed in terms of changes in the QRS complex, PQ interval prolongation, AV dissociation, occurrence of extrasystoles or sinus arrest. The pharmacokinetics of combined administration did not differ from those of prilocaine and ropivacaine given alone. CONCLUSION: The use of a combined prilocaine/ ropivacaine (300 mg/75 mg) dose regimen in patients given single dose for brachial plexus blockade can generally be regarded as safe with regard to peak plasma concentrations and cardiovascular toxicity and this holds true for patients with a higher perioperative risk profile (ASA III grading, American Society of Anesthesiologists). The considerable inter-individual variation in LA peak plasma concentrations observed in our patients and the one case of suspected accidental intravascular injection, highlight the necessity of adequate monitoring of the patients undergoing LA injections.

Mild clinical and histopathological features in patients who carry the frequent and causative malignant hyperthermia RyR1 mutation p.Thr2206Met.

OBJECTIVE: Malignant hyperthermia (MH) is a classically unapparent pharmacogenetic disorder of the skeletal muscles triggered by inhalational anesthetics or depolarizing muscle relaxants. The disposition to MH is inherited in an autosomal-dominant manner and is primarily due to mutations in the gene for the ryanodine receptor type 1 (RyR1). The present study intended to analyze whether mild muscular symptoms (elevation of the resting CK, cramps in the calves, slight calf hypertrophy) may be associated with susceptibility to MH and/or with histopathological changes. METHODS: A muscle biopsy was taken from 12 out of 44 blood relatives (three generations) of a large family and was investigated with the halothane/caffeine in vitro contracture test (IVCT). Afterwards a histological, histochemical and immunhistological examination was performed. Altogether in 29 persons the DNA was analyzed for mutations in the RyR1-gene. RESULTS: Eight persons were diagnosed as susceptible to MH (MHS) by the IVCT, 4 were MH negative. All MHS persons carried the MH causative c.6617C > T (Thr2206Met) mutation and showed slight clinical signs of a myopathy as well as mild biopsy changes with isolated hypotrophic fibers and disseminated small areas with reduction of oxidative staining (multi-minicore like lesions). The Thr2206Met mutation was identified in another further 9 relatives who also experienced mild myopathological features. Clinical MH incidents were not reported in this large family. CONCLUSION: The RyR1 Thr2206Met mutation is one of the most frequent mutations in the European MH population but carriers are normally healthy. In this study we could demonstrate that the MH causative Thr2206Met mutation may also be associated both with clinical symptoms of a mild myopathy and histopathological changes in the oxidative inter myofibrillar network.