Spinal Cord Herniation: A Missing Piece in the Pathogenesis of Amyotrophic Lateral Sclerosis and Multiple Sclerosis?

<i>Background:</i> Idiopathic spinal cord herniation (SCH) is a rare and often misdiagnosed condition characterized by displacement of the spinal cord through an anterior defect of the dural sac. This condition determines continuous focal trauma of the spinal cord, causing slowly progressive myelopathy. The peculiar MR scan findings, particularly sagittal T₂-weighted images, allow its recognition. <i>Objective:</i> Herein, we report 3 cases of SCH and suggest a possible association with trauma-related neurodegenerative or chronic inflammatory diseases. <i>Methods:</i> We reviewed the clinical files of all patients admitted to our hospital with a history and signs of progressive myelopathy (paraparesis and/or lower extremity hypoesthesia) who were diagnosed with SCH by MRI. <i>Results:</i> We found 3 female patients (37, 69 and 68 years of age) with a diagnosis of SCH. Two of them presented with concomitant, relatively rare disabling neurological diseases, namely amyotrophic lateral sclerosis and multiple sclerosis. The third patient underwent surgery and gradually recovered over 6 months. <i>Conclusions:</i> Persistent central nervous system trauma due to idiopathic SCH might provide an unexpected hint about the pathogenesis of amyotrophic lateral sclerosis and multiple sclerosis.