The Role of CT/Discography in Assessing Postoperative Disc Herniation

Successful management of patients with persistent or recurring pain after lumbar disc surgery requires comprehensive evaluation to accurately localize the anatomic sources of pain. The results of reoperation for recurrent disc herniation are uniformly good, whereas those of reoperation for scar tissue are poor. There have been few studies comparing the ability of enhanced MRI and CT/discography to distinguish between scar tissue and recurrent disc herniation. We evaluated 23 patients with recurring pain after lumbar disc surgery. Two neurosurgeons independently reviewed CT/discography and MRI of each patient before and after gadolinium enhancement. To determine the accuracy, sensitivity, and specificity of each test, responses were compared with surgical findings and CT/discography was found to be more sensitive and specific in distinguishing between scar and recurrent disc herniation. Characteristics associated with recurrent disc herniation include nonenhanced or rim-enhanced abnormality surrounding a low signal on enhanced MRI. and extension of contrast into the epidural space on CT/discography. For determining the need to repeat open disc surgery, combined MRI and CT/discography is more accurate and sensitive than either test alone.

Partial Posterior Canal Labyrinthectomy for Pontine Cavernous Angioma

The transpetrosal approach to the anterior portion of a brain stem lesion with intact hearing is often limited by portions of the labyrinth. The technique of partial labyrinthectomy, by which the posterior and superior semicircular canals, maximizes surgical exposure while preserving hearing. We report the case of a patient who underwent a modified partial labyrinthectomy involving resection of the posterior semicircular canal only in the area of the labyrinth. Technical modification of the partial labyrinthectomy approach simplifies tumor removal while preserving hearing.