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Lateral medullary syndrome
Classification and external resources

Medulla oblongata, shown by a transverse section passing through the middle of the olive. (Lateral medullary syndrome can affect structures in upper left: #9, #10, #11, #12, #13, and #14.)
ICD-10 G46.4
DiseasesDB 10449
eMedicine emerg/834
MeSH D014854

Lateral medullary syndrome (also called Wallenberg's syndrome and posterior inferior cerebellar artery syndrome) is a disease in which the patient has difficulty with swallowing or speaking or both owing to one or more patches of dead tissue (known as an infarct) caused by interrupted blood supply to parts of the brain.


Signs and symptoms

This syndrome is characterized by sensory deficits affecting the trunk (torso) and extremities on the opposite side of the infarction and sensory deficits affecting the face and cranial nerves on the same side with the infarct. Specifically, there is a loss of pain and temperature sensation on the contralateral (opposite) side of the body and ipsilateral (same) side of the face. This crossed finding is diagnostic for the syndrome. Although this is outlined below, a detailed anatomical explanation of the crossed findings can be found in the article on the trigeminal nerve. Other clinical symptoms and findings are swallowing difficulties (dysphagia),[1] slurred speech, ataxia, facial pain, vertigo, nystagmus, Horner's syndrome, diplopia, and possibly palatal myoclonus. The cause of this syndrome is usually the occlusion of the posterior inferior cerebellar artery (PICA) at its origin.

The affected persons have difficulty in swallowing (dysphagia) resulting from involvement of the nucleus ambiguus, as well as slurred speech (dysphonia, dysarthria). 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's 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.

Clinical B1000 diffusion weighted MRI image showing an acute left sided dorsal lateral medullary infarct


Features of lateral medullary syndrome
Dysfunction Effects
vestibular nucleus vestibular system: vertigo, diplopia, nystagmus, vomiting
inferior cerebellar peduncle Ipsilateral cerebellar signs including ataxia
central tegmental tract palatal myoclonus
lateral spinothalamic tract contralateral deficits in pain and temperature sensation from body
spinal trigeminal nucleus ipsilateral loss of touch pain and temperature sensation from face
nucleus ambiguus (which affects vagus X and glossopharyngeal nerves IX) dysphagia, hoarseness, diminished gag reflex
descending sympathetic fibers ipsilateral Horner's syndrome


The three major arteries of the cerebellum: the SCA, AICA, and PICA. (Posterior inferior cerebellar artery is PICA.)
Human brainstem blood supply description. PICA is #11.

It is the clinical manifestation resulting from occlusion of the posterior inferior cerebellar artery (PICA) or one of its branches or of the vertebral artery, in which the lateral part of the medulla oblongata infarcts, resulting in a typical pattern. The most commonly affected artery is the vertebral artery, followed by the PICA, superior middle and inferior medullary arteries.


Treatment for lateral medullary syndrome is symptomatic. A feeding tube may be necessary if swallowing is very difficult. Speech/swallowing therapy may be beneficial. In some cases, medication may be used to reduce or eliminate pain. Some doctors report that the anti-epileptic drug gabapentin appears to be an effective medication for individuals with chronic pain. The small size of the affected PICA does not lend itself to surgical recanalisation.[2]

One of the most unique and difficult to treat symptoms that occur due to Wallenberg's syndrome are interminable, violent hiccups. The hiccups can be so severe that patients often struggle to eat, sleep and carry on conversations. Depending on the severity of the blockage caused by the stroke, the hiccups can last for weeks. Unfortunately there are very few successful medications available to mediate the inconvenience of constant hiccups.

Long term treatment generally involves the use of blood thinners like Coumadin. Patients will often remain on these medications or an aspirin regimen for the rest of their lives in order to minimize the risk of another stroke. Other medications may be necessary in order to suppress high blood pressure and risk factors associated with strokes.

Treatment for this disease can be disconcerting because some individuals will always have residual symptoms due to the severity of the blockage. Two patients may present with the same initial symptoms right after the stroke has occurred, but after several months one patient may fully recover while the other is still severely handicapped. [3]


The outlook for someone with lateral medullary syndrome depends upon the size and location of the area of the brain stem damaged by the stroke. Some individuals may see a decrease in their symptoms within weeks or months. Others may be left with significant neurological disabilities for years after the initial symptoms appeared.[2]


This syndrome was first described in 1808 by Gaspard Vieusseux,[4]. First descriptions by Wallenberg were in 1895 (clinical) and 1901 (autopsy findings).

See also


External links


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