The condition usually consists of: Sensation to the face is preserved, due to the sparing of the trigeminal nucleus.

The anterior spinal artery arises bilaterally as two small branches near the termination of the vertebral arteries which descend anterior to the medulla and unite at the level of the foramen magnum.

The infarction (which arises in the paramedian branches of the anterior spinal artery and/or the vertebral arteries) leads to death of the ipsilateral medullary pyramid, the medial lemniscus, and the hypoglossal nerve fibers that pass through the medulla.

The trigeminal nucleus is also spared, since most of it is higher up in the pons, and the spinal part of it found in the medulla is lateral to the infarct.

[citation needed] Ipsilateral signs and symptoms - flaccid paralysis (lmn) paralysis and atrophy of one half of tongue (hypoglossal nerve)[citation needed] Contralateral signs and symptoms-spastic (umn) paralysis of trunk and limbs (contralateral corticospinal tract) Impaired tactile, proprioceptive and vibration sense of trunk and limbs (contralateral medial lemniscus)[citation needed]