Intraoperative Discography for Detecting Concealed Lumbar Discal Cysts
A 28-year-old male presented with a several-week history of left L4 radiculopathy. He had sensory abnormalities in the L4 dermatomal area of the left leg, and the straight leg raising test was positive at 50 degrees. Magnetic resonance imaging (MRI) demonstrated a spherical, extradural, cystic mass behind the L3/4 intervertebral disc space, with high signal intensity on T2-weighted images () and low signal intensity on T1-weighted images.\nHis symptoms persisted after conservative treatment and surgical management was planned. A partial hemilaminectomy was performed and the thecal sac and L4 root were carefully manipulated, but the cyst was not found. It was assumed that the cyst was penetrated during the surgical manipulation. After surgery, the patient's symptoms disappeared but postoperative MRI showed that the cyst was still present ().\nOn the first postoperative day, a second operation was performed. Intraoperative discography was performed under C-arm fluoroscopic guidance. A long, 18-gauge needle was inserted into the disc space at the left paracentral region of L3-L4, through the area of the previous laminotomy, and 2 mL of radiopaque dye (Hexabrix, Guerbet Asia Pacific Ltd., Hong Kong) was injected. Care was taken not to injure the thecal sac or the nerve root (). The bluish cyst was then seen to be located ventrally on the thecal sac, under the peridural membrane. The cyst's location was the likely reason that it could not be visualized during the first operation. In addition, the cyst wall was thick and its margin could not be distinguished from the thecal sac. The discal cyst was penetrated with a 22-gauge needle and the cyst wall was cauterized using bipolar current. A second discography, after removal of the cyst, confirmed that the cyst was no longer present (). Postoperative MRI confirmed that the discal cyst had been removed ().