Ochronotic Lumbar Disc Herniation with Radiculopathy: Report of Two Cases

Alkaptonuria is a rare genetic disorder caused by deficiency of the enzyme homogentisic acid dioxidase (HGA). This deficiency leads to deposition of HGA and its products as an ochre-colored pigment in the large joints, intervertebral discs, skin, and within major arteries. Affection of the intervertebral discs mostly occurs at the thoracic and lumbar regions which ultimately results in degeneration, calcification, pseudo-blocked vertebra, and ankyloses in a stepwise manner. Rarely, an affected lumbar disc might herniate into the canal and cause radiculopathy before its calcification. Herein we present two women in whom neuroradiological evaluation of an acute left lower limb radiculopathy revealed a sequestrated L4-L5 disc herniation in both cases. Disc prolapse in these patients was associated with calcification of the thoracic and the upper lumbar intervertebral discs, compatible with ochronosis. Following removal of the pigmented disc material, both patients exhibited marked recovery. With careful review of the literature, we found that besides our cases, only 19 cases have been published previously