Curriculum · Neurology
Medial medullary syndrome
What it is
Medial medullary syndrome is the medial syndrome of the medulla, and its artery is the anterior spinal artery. The structures affected are the medial ones: the pyramid, which carries the corticospinal tract, the medial lemniscus, and the hypoglossal nucleus with the fibers of CN 12. The lateral syndrome of the same level, lateral medullary or Wallenberg syndrome, belongs to PICA or the vertebral artery of the same side, so it is the artery and the medial or lateral position, not the level alone, that tell the two apart. The medial syndromes higher up follow the same plan: medial midbrain, or Weber syndrome, and medial pontine syndrome both come from paramedian branches of the basilar artery and both give contralateral motor impairment, with an ipsilateral CN 3 that is down and out and dilated in the midbrain and an ipsilateral CN 6 that cannot abduct in the pons.
How it presents
Three signs run together.
- Contralateral motor impairment, a contralateral hemiparesis sparing the face, from the corticospinal tract in the pyramid — though the medulla does not spare the lower face.
- Contralateral hemisensory loss of proprioception, vibration, fine touch and two-point discrimination, again sparing the face, from the medial lemniscus.
- The tongue deviates to the side of the lesion, an ipsilateral CN 12 sign.
Speech and swallowing problems, that is dysarthria and dysphagia, and tongue or palate deviation are the medullary localizing signs in general.