Idiopathische ventrale Rückenmarksherniation

Idiopathic spinal cord herniation is a very rare defect of the thoracic ventral dura, most often between Th 2 and Th 8, with consecutive herniation of the spinal cord into this defect. After a long history, sometimes years, clinical signs and symptoms of a progressive, more or less severe myelopathy ensue, leading to a Brown-Sequard syndrome or parapareses as typical manifestations. Neither cause nor mechanism of the herniation are fully understood, yet. Amongst others, disc disease, like calcified microspurs, trauma, inflammation, connective tissue disorder and inherited duplication of the dura are considered. The most relevant differential diagnoses are arachnoid cysts and arachnoidal webs, that may push the spinal cord ventrally but leave the dura intact, as well as tumors, ischemic and traumatic spinal cord lesions. Despite excellent imaging possibilities sometimes it happens that the actual diagnosis of a spinal cord herniation with an underlying dural defect can only be made during microsurgery. Surgery, also for only mildly symptomatic patients, is challenging but the procedure of choice. The surgical goal is to release the spinal cord and then, depending on its size and location, either to close, augment, or widen the underlying dural defect. The risk for postoperative new deficits is 5-12%. The halt of the clinical progression is considered a treatment success, with ¾ of patients having the chance of postoperative improvement. Surgery should be performed with intraoperative neuromonitoring (SSEP, MEP, D-wave) in experienced centers. Patients in whom the indication for surgery has not yet been made should be closely monitored, because most likely the natural history of idiopathic ventral spinal cord herniation is progressive.