Anterior Cord Herniation—Surgical Video

Anterior cord herniation is due to a ventral displacement of the spinal cord through a defect in the dura and/or arachnoid.¹ Though the condition is rare, some case reports are available.^1-3 The neurological symptoms can slowly deteriorate over several years.³ A Brown-Séquard-like syndrome is the most common presenting neurological finding.²^,⁴ Asymptomatic cases may be discovered incidentally.⁴ However, when progressive neurological deficits are present, surgical exploration should be considered. Surgery is not without risks of impaired neurological function postoperatively, and intraoperative neurophysiological monitoring is important during the surgical procedure. We present a case of progressive impairment of lower extremity function, particularly gait function, due to anterior cord herniation (Video 1). The patient was initially managed conservatively, but due to rapid deterioration of motor function of the left leg accompanied by gait disturbance over the last year, surgical exploration was recommended, and the patient consented. Laminectomy was followed by dural opening. The denticulate ligament was cut for mobilization of the spinal cord, and the anterior dural defect was identified. The spinal cord could be freed and was carefully luxated from the defect, and a dural substitute was put in place to cover the dural defect. Throughout the procedure, D-wave and sensory evoked potentials could not be detected, but motor evoked potentials (MEPs) were present at the initiation of the surgery. However, the MEPs was lost during the end of the surgical procedure. Complete loss of MEPs during spinal surgery is a strong predictor of permanent deficits.⁵ Despite this, the patient had an uneventful recovery and could walk 700 m with crutches 3 months postoperatively, showing continuous improvement.