title: Histomorphologic examination of skeletal muscle preparations does not differentiate between malignant hyperthermia-susceptible and -normal patients.
abstract: BACKGROUND
  It has been suggested that malignant hyperthermia (MH) can be diagnosed by specific myopathologic alterations. The purpose of this study was to investigate whether there are characteristic myopathologic changes in skeletal muscles of MH-susceptible (MHS) compared with MH-normal (MHN) patients.
  
  
  METHODS
  Four hundred forty patients with clinical suspicion of MH were classified as MHN, MH equivocal (MHE), or MHS by the in vitro contracture test with halothane and caffeine. In addition, a small muscle sample excised from each patient was analyzed by histologic, histochemical, immunohistochemical, and computer-aided morphometric methods.
  
  
  RESULTS
  MHN was diagnosed in 243 patients, MHE was diagnosed in 65, and MHS was diagnosed in 132. No myopathologic abnormalities were found in 53.5% of the MHN, 53.9% of the MHE, and 56.1% of the MHS patients. Thirty-five percent of all patients showed one, 9.8% showed two, and only 0.9% showed three different pathologic findings within skeletal muscle preparations. The frequency of pathologic findings did not differ between the MHN and the MHS patients; only fiber type I predominance was observed more often in MHN. MHE patients could not be assigned to a diagnostic group by detection of myopathologic alterations. In six clinically unaffected patients, a former unrecognized myopathy, such as central core disease, was diagnosed. This disease is characterized by a specific alteration (cores).
  
  
  CONCLUSIONS
  Histologic differences between MHS and MHN statuses could not be demonstrated in this study. Histopathologic examinations can neither improve the diagnosis of MH nor contribute to a better definition of the MH status. However, histopathologic examinations might be useful to detect formerly unrecognized specific myopathies.
authors.affiliation: Department of Anesthesiology, University Hospital Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Franziska
authors.initials: F
authors.lastname: von Breunig
authors.forename: Frank
authors.initials: F
authors.lastname: Wappler
authors.forename: Christian
authors.initials: C
authors.lastname: Hagel
authors.forename: Verena
authors.initials: V
authors.lastname: von Richthofen
authors.forename: Marko
authors.initials: M
authors.lastname: Fiege
authors.forename: Ralf
authors.initials: R
authors.lastname: Weisshorn
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Stavrou
authors.forename: Jochen
authors.initials: J
authors.lastname: Schulte am Esch
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001284:Atrophy; D002648:Child; D002675:Child, Preschool; D004198:Disease Susceptibility; D005260:Female; D006801:Humans; D006984:Hypertrophy; D008297:Male; D008305:Malignant Hyperthermia / Q000209:etiology / Q000473:pathology*; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000473:pathology; D018482:Muscle, Skeletal / Q000473:pathology*; D009336:Necrosis