Spinal Cord Strokes

Spinal Cord Vascular Supply

The arterial supply of the spinal cord is unique. A large single anterior spinal artery runs in the ventral midline from the spinomedullary junction at the foramen magnum to the filum terminale. In contrast paired smaller posterior spinal arteries are located on the dorsal surface, which often form a rich plexus of small vessels ( Fig. 89.1 ) . The central portion between the two zones of supply has often been called the border zone or watershed region of the spinal cord.

The anterior spinal artery originates from the two vertebral arteries at the base of the skull, feeds the medulla, and descends in the midline through the foramen magnum to supply the cervical spinal cord. The artery is fed by a series of 5–10 unpaired radicular arteries that originate from the vertebral arteries and the aorta and its branches. The blood supply is most marginal in the upper thoracic region (T2–T4) which has been referred to as the longitudinal watershed region of the spinal cord. The largest radicular artery, the artery of Adamkiewicz, arises from the aorta most often between the T9 and T12 regions.

The paired posterior spinal arteries are fed by smaller radicular arteries at nearly every spinal level. These supply the dorsal columns and posterior gray matter. The blood supply of the anterior portion of the cord is much more vulnerable than that of the posterior portion and can be decompensated by occlusion of a large radicular branch or lesions of the aorta.

Spinal Cord Ischemia and Infarction

The understanding of spinal cord infarction parallels the evolution of knowledge about the mechanism of brain infarcts.

Spinal cord infarctions can be subdivided as follows :

• Bilateral, predominantly anterior ( Fig. 89.2A ). These patients have bilateral motor and spinothalamic-type sensory deficits. Posterior column sensory functions (vibration and position sense) are spared.

  

• Unilateral, predominantly anterior ( Fig. 89.2B ). The motor deficit is a hemiparesis below the lesion and contralateral spinothalamic tract sensory loss—a Brown–Séquard syndrome.

• Bilateral, predominantly posterior ( Fig. 89.2C ). Posterior column type sensory loss below the lesion with variably severe bilateral pyramidal tract signs.

• Unilateral, mostly posterior ( Fig. 89.2D ). Ipsilateral hemiparesis and posterior column sensory loss.

• Central ( Fig. 89.2E ). Bilateral pain and temperature loss with spared posterior column and motor functions. Similar to the deficits produced by a syrinx.

• Transverse. Loss of motor, sensory, and sphincter functions below the level of the lesion. Anterior patterns are more common than posterior especially after aortic surgery.