Types of cervical disc herniation and relation to myelopathy and radiculopathy.

Cervical disc herniation is divided into three types with respect to the intraspinal location of the herniated mass: median, paramedian and lateral herniations. Median herniation presses the spinal cord against the lamina and deforms it into a boomerang shape in a cross section, thereby giving rise to myelopathy of the central cord syndrome or transverse lesion syndrome, according to Crandall's classification. Paramedian herniation presses the spinal cord unilaterally and deforms it into a comma shape. The symptoms and signs produced are not always those of the Brown-Sequard syndrome. Radiculopathy is produced by compression of a root in patients with a wide spinal canal in which the spinal cord is thereby able to avoid compression. Lateral herniation presses a nerve root at the anterolateral corner of the spinal canal to the inlet of the foramen, thereby giving rise to radiculopathy. Of our 202 patients with myelopathy, 36% had median herniation and 64% had paramedian herniation. Of our 24 patients with radiculopathy, 12% had paramedian herniation and 88% had lateral herniation. Other matters pertinent to the management of patients are described.