Eccentric compression of the spinal canal causing dominantly contralateral-side symptoms.

In this retrospective study, five patients are described in whom the dural sac at the thoracic and lumbar spine was compressed by a herniated disk or stenosis, located eccentrically in the spinal canal. In all of them, the symptoms or neurologic findings were dominantly in the limb contralateral to the side of compression. All five patients were operated on and the compressing disk or lamina was removed, resulting in immediate improvement of symptoms. In only one of the patients was the compression at the common level of L4-L5. In the remaining four patients, compression was at the low thoracic or upper lumbar spine. With the exception of one patient, the area of canal compression was greater than 50%.