Often associated with syringobulbia. Fluid-filled cavity (syrinx) within the substance of the spinal cord or brainstem.

• Characteristics - lack of sensation for noxious stimuli in fingers (painless cut or burn). Cape-like sensory defect over shoulders and back. Spasticity and weakness of the lower extremities. Muscular atrophy and fasciculations. Vertigo, nystagmus

Congenital (50%), intramedullary tumors