Spinal cavernous malformations.

Spinal cavernous malformations are rare intramedullary vascular lesions of the central nervous system. Most are located in the thoracic spine. Patients present with either acute neurologic deficit or gradual deterioration. Weakness is the most common presenting symptom. The annual hemorrhage risk is 2.1%. Diagnosis is made by magnetic resonance imaging as these lesions are occult on angiography. Surgical removal is indicated in patients with hemorrhage and neurologic deficit. All lesions are approached posteriorly by laminectomy. Dorsal cavernous malformations are exposed by focused laminectomy of the level or levels overlying the lesion with minimally facet violation. Ventral and lateral lesions are approached by laminectomy including a level above and level below as well as unilateral radical facetectomy. After midline dural opening, the dentate ligament is divided and retracted to allow up to 90° of rotation of the spinal cord. Microsurgical treatment is associated with 42% symptom improvement and 50% symptom stabilization. Postoperative worsening is associated with longer preoperative duration of symptoms. Therefore we recommend consideration of early surgery for cavernous malformation removal in patients with symptoms attributable to the lesion.