Lateral medullary syndrome (also called Wallenberg syndrome and posterior inferior cerebellar artery syndrome) is a disease in which the patient has a constellation of neurologic symptoms due to injury to the lateral part of the medulla in the brain, resulting in tissue ischemia and necrosis.
Clinical symptoms include swallowing difficulty, or dysphagia, slurred speech, ataxia, facial pain, vertigo, nystagmus, Horner syndrome, diplopia, and possibly palatal myoclonus.
Affected persons have difficulty in swallowing (dysphagia) resulting from involvement of the nucleus ambiguus, as well as slurred speech (dysarthria) and disordered vocal quality (dysphonia) . Damage to the spinal trigeminal nucleus causes absence of pain on the ipsilateral side of the face, as well as an absent corneal reflex.
The spinothalamic tract is damaged, resulting in loss of pain and temperature sensation to the opposite side of the body. The damage to the cerebellum or the inferior cerebellar peduncle can cause ataxia. Damage to the hypothalamospinal fibers disrupts sympathetic nervous system relay and gives symptoms analogous to Horner syndrome.
Nystagmus and vertigo, which may result in falling, caused from involvement of the region of Deiters’ nucleus and other vestibular nuclei. Onset is usually acute with severe vertigo.
Palatal myoclonus may be observed due to disruption of the central tegmental tract.