CRANIOFACIAL MORPHOLOGY OF SPINAL MUSCULAR-ATROPHY

Spinal muscular atrophy (SMA) is the second most common neuromuscular disease of childhood. It is the most common fatal recessive neuromuscu lar disease. This study is the first to evaluate the craniofacial grow th of SMA patients. The results pertain to a sample of 25 SMA patients , between 5 and 32 y of age, who were case matched with unaffected nor mal controls. Group differences for 25 measures, derived from tracings of standardized cephalometric radiographs, were evaluated using multi variate analysis of variance. The SMA group showed excessive vertical development, particularly of the lower face. They demonstrated relativ ely larger anterior than posterior facial heights, due in part to a sm aller cranial base angulation and a more anteriorly positioned mandibu lar ramus. Anteroposterior skeletal discrepancies of SMA patients, due to the combined effects of a protrusive maxilla and a retrusive mandi ble, were moderate. The interincisal angle of the SMA group was smalle r than normal, due primarily to proclined maxillary incisors. Relative to palatal length, the SMA group had smaller anterior cranial base an d mandibular corpus lengths. These results suggest abnormal craniofaci al growth patterns of SMA patients. The etiology of the observed abnor malities seems to be complex and multifaceted, but attention to the tr eatment of malocclusion may be important for optimal nutrition and res piratory function.