4) VASCULAR DISEASES - ANTERIOR SPINAL ARTERY SYNDROME
The spinal cord is not as susceptible to vascular disorders as the brain but infarction and hemorrhage do occur. Damage from such lesions reflects the pattern of the blood supply where a) posterior spinal arteries supply the dorsal part of the cord, 2) anterior spinal arteries supply the anterior 2/3rds of cord, and 3) the arterial vasocorona in the pial plexus supplies the periphery of the anterolateral cord.
A Sample Case: A sudden bilateral weakness of the legs occurred in a young woman causing her to seek medical attention.
The neurologic exam revealed bilateral loss of pain and temperature sensation in the legs without loss of discriminative touch or vibratory sense. At first the lower limb paralysis was flaccid and areflexic but after several weeks spasticity, hyperreflexia, and Babinski signs appeared. After an initial period of incontinence bowel and bladder control was regained.
Spinal shock - An infarction of the anterior spinal artery usually involves the gray and white matter (less frequently only the gray) of the anterolateral cord. The suddenness of the lesion leads to "spinal shock" and hence the voluntary and involuntary paralyses and areflexia.
With recovery from spinal shock you might expect to see evidence of lower motor neuron signs at the level of the lesion with upper motor neurons signs below. Recovery of bowel and bladder function indicates some sparing of the descending autonomic fibers which are in the lateral white funiculus, perhaps due to vessels of the pial plexus.
The sensory signs, i.e, bilateral loss of pain and temperature sense, are indicative of injury to the spinothalamic tracts in the lateral white funiculi with sparing of the posterior white columns which are supplied by the posterior spinal arteries.