Idiopathic thoracic spinal cord herniation: report of 10 patients and description of surgical approach.

STUDY
DESIGN: Ten patients with idiopathic spinal cord herniation were treated surgically to reduce the herniation. In 9 patients, a sling was passed between the spinal cord and the anterior dural hiatus. The results were analyzed with respect to the neurological symptoms and imaging.
OBJECTIVE: The study calls attention to an unusual condition with similar clinical presentation and characteristic imaging findings in the hope of improving early recognition and treatment. We present the outcome of treating patients with a safe technique that avoids the risks of primary dural closure and of cerebrospinal fluid leakage. SUMMARY OF BACKGROUND DATA: Over 100 patients with this disorder have been reported in the literature. Treatment in the past has included potentially hazardous attempts at primary dural closure of the dural hiatus, and the contraindicated step of biopsy, or even resection of herniated tissue. Various different surgical approaches have been used and the technique described by us has proved to be safe and effective.
METHOD: : Nine patients underwent treatment by a similar sling technique; 1 patient was treated by a 2-stage more complex approach, which we have since abandoned. We begin with a laminectomy over the suspected level of cord herniation, followed by dural opening. The dentate ligaments are sectioned and the dural defect may have to be enlarged to safely disengage the herniated cord. The cord is elevated by the dentate ligaments and a bovine pericardial sling is passed under the cord, thereby occluding the dural hiatus. The epidural cavity and site of herniation may be filled with a variety of material, and an expansile duraplasty is performed.
RESULTS: Sensory symptoms, weakness and spasticity, among the most common findings, improved in approximately one third of our patients. A long time interval between the appearance of symptoms, correct diagnosis, and appropriate treatment may reduce the chance of significant recovery. Severe pain may be a poor prognostic sign. The dural hiatus was located in the upper thoracic region in all of our patients.
CONCLUSIONS: Idiopathic spinal cord herniation presents with symptoms and signs of spinal cord dysfunction and a very characteristic imaging appearance. The condition can be treated safely, with the expectation of neurological stabilization and some improvement. The technique described minimizes cord manipulation. Postoperative imaging often reflects the long-standing incarceration of the spinal cord.