Idiopathic Spinal Cord Herniation: A Case Report

Abstract

Abstract Title: Idiopathic Spinal Cord Herniation: A Case Report Background: Idiopathic Spinal Cord Herniation (ISCH) is a rare condition in which the spinal cord protrudes through an opening in the ventral dura mater of the spinal canal. It is most commonly seen in the thoracic spine and presents as a slowly progressive myelopathy and Brown-Sequard syndrome in 65% of patients. Literature on ISCH consists of fewer than 200 cases and misdiagnosis as posterior arachnoid cyst is believed to be common. Fortunately, advances in medical imaging as well as case reports like this one, are expanding our understanding of ISCH presentation and treatment. Case Presentation: A 53 y/o male presented with a four-year history of slowly progressive myelopathy and Brown-Sequard syndrome. MRI imaging was performed but was found inconclusive. Due to challenges in establishing a definitive pre-operative diagnosis, exploratory surgery was performed which identified an opening in ventral dura, and herniation of the spinal cord at the level of T7-T8. Laminectomy and durotomy were performed which allowed access to the spinal cord. The cord was relaxed and brought back into proper alignment within the spinal canal. The ventral opening was then successfully closed with a Duraseal patch. Upon follow up, our patient experienced near full relief of motor and sensory symptoms. Discussion: Idiopathic spinal cord herniation develops most exclusively at the thoracic level and most commonly in middle-aged women. Herniation of the spinal cord through the dura compresses the cord and leads to a wide range of symptoms – varying from mild motor-sensory deficits to Brown-Sequard syndrome. ISCH has previously been misdiagnosed as posterior arachnoid cyst, which causes a similar presentation due to compression of the ventral cord and nerve roots. Therefore, sagittal contrast MRI and CT myelogram is indicated. Multiple mechanisms of ISCH have been proposed, including developmental disorders, thoracic disc herniation, and history of trauma. Relative scarcity of elastic connective tissue in the ventral dura mater is a proposed contributive factor. As awareness grows and imaging technology improves, accurate diagnosis of ISCH is becoming increasingly possible. This diagnosis is crucial for proper surgical treatment and for optimal patient outcomes.