Idiopathic ventral spinal cord herniation: This condition is a rare anomaly where the spinal cord herniates through a defect in the dura mater, often presenting with progressive myelopathy. It is considered the most likely diagnosis due to the specific presentation of ventral spinal cord herniation.

Traumatic spinal cord injury: Trauma can cause herniation of the spinal cord, especially if there is a dural tear or other injury to the spinal canal.
Spinal cord tumor: Tumors, such as meningiomas or neurofibromas, can cause compression or herniation of the spinal cord.
Spinal arachnoid cyst: These cysts can compress or displace the spinal cord, mimicking herniation.

Spinal epidural abscess: This is a serious infection that can compress the spinal cord and requires urgent treatment to prevent permanent damage or death.
Spinal subarachnoid hemorrhage: Bleeding into the space surrounding the spinal cord can cause rapid deterioration and requires immediate intervention.
Acute spinal cord infarction: This is a rare but devastating condition where the blood supply to the spinal cord is interrupted, leading to infarction of the spinal cord tissue.

Spinal cord herniation due to congenital defects: Conditions like spina bifida or diastematomyelia can lead to abnormal development of the spinal cord and surrounding structures, potentially causing herniation.
Inflammatory or demyelinating diseases: Conditions such as multiple sclerosis, neuromyelitis optica, or sarcoidosis can cause inflammation or demyelination of the spinal cord, potentially leading to herniation or compression.
Vascular malformations: Abnormalities of the blood vessels, such as arteriovenous malformations, can cause compression or herniation of the spinal cord.