Lumbar spinal stenosis in adult achondroplasia. An analysis of intervertebral disk alterations

Abstract

Lumbar spinal stenosis is a major contributor to disability in adults with achondroplasia. It arises from congenital dysplasia and acquired degenerative changes. The aim of the study was to characterize degenerative changes of the intervertebral disk in adult achondroplasia patients with lumbar spinal stenosis and to identify factors associated with the process. The study was a case series of adult achondroplasia patients. Clinical parameters were recorded. Radiographs were used to analyze spino-pelvic parameters. MRI of the lumbar spine was used to measure antero-posterior diameter of the canal and disk degeneration using the Pfirrmann grading system. Comparisons were done using the Kruskal–Wallis test and correlations using the Spearman coefficient. Eighteen patients were included: age 37 ± 17, female 12, size 127 ± 7 cm, weight 57 ± 13 kg. All had symptoms due to lumbar spinal stenosis. Antero-posterior diameters of the spinal canal differed according to level ( P < 0.05). Lower values were observed at T12–L1, L1–L2 and L2–L3 levels. The lumbar spinal stenosis was maximal at L2–L3 (9.9 ± 1.8 mm). Degrees of disk degeneration also differed according to level ( P < 0.05). Higher degrees of degeneration were observed at L1–L2, L2–L3 and L3–L4 levels. Most advanced degenerative changes were observed at L2–L3 (2.9 ± 1.4). Correlation analysis between disk degeneration and spino-pelvic parameters found a significant relationship with thoraco-lumbar kyphosis at L2–L3 level (0.55). Correlation analysis between antero-posterior diameter of the spinal canal and the spino-pelvic parameters found a significant relationship with lumbar lordosis at T12–L1 (0.66) and L2–L3 (0.89) levels, and with thoraco-lumbar kyphosis at L1–L2 level (−0.55). Spinal stenosis and disk degeneration mainly involve the upper part of the lumbar spine in adult achondroplasia patients. Thoraco-lumbar kyphosis and lumbar lordosis are related with these processes. The findings may be of importance in rehabilitation and in early prevention of spinal stenosis in the course of achondroplasia.