Anesthesia & Analgesia, Vol 85, 149-154, Copyright © 1997 by International Anesthesia Research Society
Classification of malignant hyperthermia-equivocal patients by 4-chloro- M-cresol
H Gilly, I Musat, R Fricker, RE Bittner, K Steinbereithner and HG Kress
L. Boltzmann Institute for Experimental Anaesthesiology and Research in Intensive Care Medicine, and Department of Anaesthesiology and General Intensive Care B, University of Vienna, Austria. Hermann.Gilly@AKH- WIEN.AC.AT
To clarify the contracture response to 4-chloro-m-cresol (4-CmC) in
malignant hyperthermia (MH) equivocal (MHE) muscle, we studied the effect
of cumulative concentrations of 4-CmC. In vitro contracture test (IVCT) was
performed in 35 probands according to the European MH test protocol.
Surplus muscle bundles were exposed to 4-CmC (25-200 micromol/L),
maintaining each concentration for 4 and 8 min. After 4 min exposure, the
contracture increase of MH susceptible (MHS) (n = 7) muscle specimens was
significantly (P = 0.05) greater at 50 micromol/L compared with either MHE
halothane sensitive (MHEh) (n = 13) or MH normal (MHN) (n = 15) classified
patients. Statistically significant differences (P < 0.05) were also
found at 75 micromol/L. Exposure for 8 min yielded significant differences
at 50 micromol/L only between MHS and MHEh. MHEh muscles revealed a
dose-response curve similar to that found in MHN specimens. MHS muscles
showed a significantly higher sensitivity to 4-CmC than either MHEh or MHN,
and, in the probands tested so far, MHEh and MHN muscles seem to
identically respond to 4- CmC, which seems to indicate a normal response in
MHEh probands, implying no MH susceptibility. Therefore, 4-CmC might reduce
the frequency of MHEh diagnosis based on standard halothane-caffeine IVCT.
However, since MHE individuals may also represent an aberrant genetic
status, with MH causing defects linked to unknown mutations, it is
premature to consider 4-CmC as a solution to the diagnostic uncertainty of
the true status of MHE probands. Presently, 4-CmC may provide supplementary
information for a more precise phenotypic categorization of MHE
individuals.