The authors describe two patients with intradural lumbar disc herniations, who had contradictory postoperative outcomes, according as preoperative diagnosis was made or not.
The first patient was a 65-year-old woman, who presented with low back pain and radiating pain on both legs. Spinal MRI demonstrated a huge compressing lesion to the dural sac with marked cranial migration at the level of L3-4. The preoperative diagnosis of intradural disc herniations was not made in this patient. The second patient presented at the age of 30 with sudden onset of low back pain that radiated into both legs along the lateral thigh. T2-weighted axial image of the spinal MRI demonstrated a sharp compressing lesion to the dural sac on T2-weighted sequence. Based on this finding, the diagnosis of intradural disc herniations was made preoperatively.
In the first patient, an extended L3 subtotal laminectomy was performed. However, a durotomy was performed because no clear disc herniation was found, and the disc fragments from within the dura were removed. One year after surgery, the patient can't walk without a cane because the complete neurologic deficit of the right ankle shows no improvement. In the second patient, anterior lumbar interbody fusion(ALIF) was performed without incident. Five months after surgery, the patient reports minimal back pain when sitting on a chair for prolonged periods of time.
Our cases highlight the importance of preoperative diagnosis in the treatment of intradural lumbar disc herniations. The potential presence of an intradural disc herniation must always be considered preoperatively when planning a surgery on a patient whose MRI study demonstrates the beak-like appearance on axial imaging as well as abrupt disconnection of the posterior longitudinal ligament(PLL). This association particularly results in the adequate surgical approach to reduce the chance of postoperative neurological deficit and ALIF can be an alternative in the treatment of intradural lumbar disc herniations.
