Diagnosis and treatment of spinal cord herniation: a combined experience.

OBJECT Idiopathic spinal cord herniation (ISCH) is an uncommon clinical entity typically presenting with lower-extremity myelopathy. Despite the existence of 85 ISCH cases in the literature, misdiagnosis and delayed diagnosis remain a major concern. METHODS The authors conducted a retrospective review of patients who underwent surgery for ISCH at their institutions between 1993 and 2004. Seven patients were treated for ISCH, five in New York and two in Buenos Aires. The patients' ages ranged from 32 to 72 years. There were three men and four women. The interval between the onset of symptoms and surgery ranged from 12 to 84 months (mean 42.1 months). Preoperatively, spinal cord function in four patients was categorized as American Spinal Injury Association (ASIA) Grade D, and that in the other three patients was ASIA Grade C. In all patients a diagnosis of posterior intradural arachnoid cyst had been rendered at other institutions, and three had undergone surgery for the treatment of this entity. In all cases, the herniation was reduced and the defect repaired with a dural patch. The follow-up period ranged from 10 to 147 months (mean 49.2 months). Clinical recovery following surgery varied; however, there was no functional deterioration compared with baseline status. Syringomyelia, accompanied by neurological deterioration, developed post-operatively in two patients at 2 and 10 years, respectively. CONCLUSIONS Patients presenting with a diagnosis of posterior intradural arachnoid cyst should be evaluated carefully for the presence of an anterior spinal cord herniation. Based on the authors' literature review and their own experience, they recommend offering surgery to patients even when neurological compromise is advanced.