In Schwartz-Jampel syndrome micrognathia and jaw muscle rigidity may result in difficult or impossible tracheal intubation. Since the dose-response relationship to muscle relaxants is unknown in this rare disease we assessed by mechanomyography the neuromuscular response to the rocuronium in a two-year-old child with Schwartz-Jampel syndrome (SJS) Type 1 B. Rocuronium's dose-response curve was markedly shifted (3.5-fold dose) to the right when compared to healthy children and intubation conditions were improved. This resistance to NDMR may result from a lower acetylcholine degradation rate suggested as being the consequence of mutation of the gene encoding perlecan (HSPG2) in SJS. Thus, considerably higher doses of NDMR than usual may be required for facilitation of tracheal intubation in patients with SJS. Since evidence for genetic heterogeneity of SJS exists we also recommend incremental doses of a rapidly acting NDMR with continuous monitoring of neuromuscular function so as to assess the optimum relaxant dose.
Dose-response Relationship - Muscle Relaxants - Perlecan - Acetylcholinesterase
