Wallenberg Syndrome (Lateral Medullary Syndrome)

The most common brainstem stroke syndrome is lateral medullary syndrome, also known as Wallenberg syndrome. It results from ischemic strokes affecting the lateral part of the medulla oblongata. Key features include contralateral sensory deficits, ipsilateral cranial nerve deficits, ataxia, vertigo spells, and dysphagia.

1. Cause: Wallenberg syndrome results from a stroke in the brainstem, specifically affecting the lateral part of the medulla oblongata. The most common arteries involved are the vertebral artery or the posterior inferior cerebellar artery (PICA).

2. Symptoms:
– Contralateral Sensory Deficits: Loss of pain and temperature sensation on the opposite side of the body (due to involvement of the lateral spinothalamic tract).
– Ipsilateral Cranial Nerve Deficits: Sensory deficits of the face and cranial nerves on the same side as the lesion.
– Ataxia: Difficulty walking and maintaining balance.
– Vertigo Spells: Associated with nystagmus (eye movement) and falling.
– Dysphagia: Difficulty swallowing.
– Dysarthria and Dysphonia: Slurred speech and altered vocal quality.
– Autonomic Symptoms: Bradycardia, changes in blood pressure, and disruption of sympathetic nervous system function.

3. Anatomical Basis:
– The vertebral artery supplies the lateral medulla, and its occlusion leads to ischemia.
– Specific nuclei and pathways affected include the spinothalamic tract, nucleus ambiguus, Deiters’ nucleus, and inferior cerebellar peduncle.

Here’s the PICA mnemonic to help you remember Wallenberg syndrome:

• P: Pain and Temperature Loss on the opposite side of the body (due to spinothalamic tract involvement).
• I: Ipsilateral Cranial Nerve Deficits (facial sensory loss, dysphagia, dysarthria).
• C: Cerebellar Signs (ataxia, vertigo, nystagmus).
• A: Autonomic Symptoms (bradycardia, blood pressure changes).

Think of it as Pikachu (PICA-chu) with these features! PICA – chew (for dysphagia).

References:
(1) Lateral medullary syndrome – Wikipedia. https://en.wikipedia.org/wiki/Lateral_medullary_syndrome.
(2) Wallenberg Syndrome – Osmosis. https://www.osmosis.org/answers/wallenberg-syndrome.
(3) Wallenberg’s Syndrome | National Institute of Neurological Disorders …. https://www.ninds.nih.gov/health-information/disorders/wallenbergs-syndrome.