Operative Treatment of Anterior Thoracic Spinal Cord Herniation

Abstract

Anterior thoracic spinal cord herniation is a rare cause of progressive myelopathy. Much has been speculated about the best operative treatment. However, no evidence in favor of any of the promoted techniques is available to date. Therefore, we decided to analyze treatment procedures and treatment outcomes of anterior thoracic spinal cord herniation to identify those factors that determine postoperative outcome. METHODS: An individual patient data meta-analysis was conducted, focusing on age, gender, vertebral segment of herniation, preoperative neurological status, operative interval, operative findings, operative techniques, intraoperative neurophysiological monitoring, postoperative imaging, neurological outcome and follow-up. Three cases from our own institution were added to the material collected. Bivariate analysis tests and multivariate logistic regression tests were used so as to define which variables were associated with outcome after surgical treatment of anterior thoracic spinal cord herniation. RESULTS: Brown-Séquard syndrome and release of the herniated spinal cord appeared to be strong independent factors, associated with favorable postoperative outcome. Widening of the dura defect is associated with the highest prevalence of postoperative motor function improvement when compared with the application of an anterior dura patch (P Ͻ 0.036). CONCLUSION: Most patients with anterior thoracic spinal cord herniation require operative treatment because of progressive myelopathy. Patients with Brown-Séquard syndrome have a better prognosis with respect to postoperative motor function improvement. In this review, spinal cord release and subsequent widening of the dura defect were associated with the highest prevalence of motor function improvement. D-wave recording can be a very useful tool for the surgeon during operative treatment of this disorder.

Unilateral Paramedian Transpedicular Approach for Repair of Anterior Transdural Spinal Cord Herniation: Report of a Case and Literature Review

“…Increasing awareness among the treating physicians is also a contributing factor towards increased cases being reported recently. The natural history of this condition is poorly understood as there are very few cases in the literature and most of them were treated surgically [1,2]. Massicotte et al [3] reported four cases in their series that were managed expectantly in the absence of motor weakness and had no evidence of neurological deterioration at long term follow-up.…”

“…Congenital causes implicate the possibility of a congenital dural defect/duplication of the dura with defect in the inner layer or presence of dorsal arachnoid cysts which is not infrequently associated with this condition [1,2]. Similarly, acquired etiology points it towards damage to ventral dura mater secondary to inflammation, remote spinal trauma, or thoracic disc herniation [1,2]. Irrespective of the etiology, this condition occurs only in the thoracic cord; normal kyphosis of the thoracic cord and ventral position of the midthoracic cord being implicated for the same.…”

“…MRI feature can be missed by clinicians not treating intradural pathologies or misdiagnosed as an arachnoid cyst. There are numerous instances in the literature reporting re-exploration due to missed thoracic spinal cord herniation which was treated as posterior thoracic arachnoid cyst [2,9]. Dorsal arachnoid space is almost always enlarged in cases of spinal cord herniation and though, posterior arachnoid cyst may exist in isolation, neurosurgeons consider suspecting a ventral dural defect when operating such cases [2,9].…”

“…The condition's rarity and variable clinical presentation can often result in missed diagnosis and delay in treatment [1,2]. Though pathogenesis and natural history remains uncertain, there is no differences in opinion over the need of surgery especially for symptomatic patients [3-9].…”

“…Though pathogenesis and natural history remains uncertain, there is no differences in opinion over the need of surgery especially for symptomatic patients [3-9]. Posterior midline approach with laminectomy has been the most common approach performed for spinal cord herniation in cases described in the literature [1,2,8]. Considering the anterior location of the dural defect, posterolateral approaches allow for better ventral visualization without retraction on the spinal cord [4,6].…”