RESUMO
Objective To observe any differences in the morphology of the lumbar multifidus (LM) muscles between normal subjects and persons with chronic lumbar disc herniation (CLDH).Methods Thirty-two persons with CLDH and thirty-five matched,healthy controls performed various maneuvers in prone lying.Ultrasound imaging was used to measure the antero-posterior diameter (A-P),lateral diameter (Lat),cross sectional area (CSA) and flattening ratio (FR) of the bilateral LM muscles at the L4/5 level.Results In the control subjects,A-P,Lat,CSA and FR were not significantly different between the left and right sides.In those with CLDH,A-P,Lat and CSA were significantly smaller on the painful side than on the no-pain side,and this difference showed asymmetry between the two sides.Average A-P,Lat,FR and muscle CSA were all significantly smaller among the CLDH subjects on both sides compared with the controls.Conclusion CLDH induces asymmetric local atrophy of the bilateral multifidus muscles which can be detected and measured using ultrasound.