PALSY OF THE L5 NERVAL ROOT FOLLOWING RED UCTION OF HIGH-DEGREE SPONDYLOLISTHESIS AND SPONDYLOPTOSIS

Temporary or persistent paralysis of the fifth lumbar nerve root have been frequently reported as complications following reposition of high degree spondylolisthesis. According to an outcome analysis of sixty-f our patients, we found an increased incidence of motor damages after r eduction of Meyerding degree four anterolisthesis or spondyloptosis. T here were no signs of intradural root compression or nerve injury trac able. In order to detect extraforaminal strictures, the anatomic cours e of the lumbosacral plexus and its relation to neighbouring structure s, especially pelvivertebral connective tissue junctions were recorded in cadavric measurements. Beside an number of variations In origin an d course of the iliolumbar ligament complex, we observed a junction be tween os sacrum and the anterior part of the fifth lumbar vertebrae in 14/30 specimen, constantly running anterior to the fifth lumbar nerve root. In addition the nerve was fixed to the sacral periostium a few centimeters distal this crossing in about 20% of all cases. Pathophysi ological effects were measured in reposition trials, using a continous pressure monitoring system. A reposition of more than 20 mm resulted in a perineural pressure > 30 mmHg. This caused a nerve fiber deformat ion at the edge of the compressed nerve segment. Increased pressure le ads to a nodular displacement of perineural fat as well as intraneural fascicles.