Lateral medullary syndrome (Wallenberg syndrome)

Findings

Axial FLAIR (Figure 1 and Figure 2) and T2-weighted (Figure 3 and Figure 4) images demonstrate mild signal hyperintensity in region of the left lateral and posterior medulla PICA territory.
Axial DWI (Figure 5 and Figure 6) and matching ADC maps (Figure 7 and Figure 8) demonstrate true restricted diffusion in the left lateral and posterior medulla PICA suggestive of cytotoxic edema fort an acute infarction.
3D TOF posterior circulation MIP projection (Figure 9) demonstrates absence of a normal left PICA. It's possibile to see the right PICA for comparison, arising from the distal right intracranial vertebral artery. There is also a mild narrowing of the basilar artery. It's possibile also to appreciate bith the superior cerebellar arteries.


Diagnosis: Lateral medullary syndrome (Wallenberg syndrome)


Adolf Wallenberg (November 10, 1862-1949) was a German internist and neurologist who first described the clinical manifestations (1895) and the autopsy findings (1901) in occlusions of the arteria cerebelli posterior inferior (Wallenberg syndrome).

Lateral medullary syndrome is characterized by sensory deficits affecting the trunk and extremities on the opposite side of the infarct and sensory, and motor deficits affecting the face and cranial nerves on the same side with the infarct. Other clinical symptoms and findings include ataxia, facial pain, vertigo, nystagmus, diplopia, Horner syndrome, and dysphagia. The cause of this syndrome is secondary to occlusion of the PICA near its origin. Similar symptoms may be produced by vertebral artery occlusion near the origin of the PICA.

Afflicted persons can have dysphagia resulting from involvement of the nucleus ambiguus and slurred speech (dysphonia and 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 can be damaged, resulting in loss of pain and temperature sensation to the opposite side of the body. Damage to the cerebellum can cause ataxia. Damage to the hypothalamospinal fibers disrupts sympathetic nervous system relay and gives symptoms analogous to Horner syndrome (ptosis, anhidrosis, and miosis).

In older patients, the most common cause of posterior circulation ischemia is thromboembolic disease resulting from accelerated atheromatous disease or embolic disease from a cardiac source. In young patients with posterior fossa ischemia, in addition to embolic disease, the diagnosis of arterial dissection should also be considered.
Wallenberg syndrome synonyms: dorsolateral medullary syndrome, lateral bulbar syndrome, lateral medullary infarction syndrome, and PICA syndrome.