Wallenberg Syndrome

Definition

Wallenberg syndrome, also known as lateral medullary syndrome, is a rare neurological condition caused by a stroke or infarction in the lateral portion of the medulla oblongata, the lowermost part of the brainstem. This syndrome is characterized by a unique set of symptoms related to the disruption of various cranial nerve functions.

5 Must Know Facts For Your Next Test

1. Wallenberg syndrome is characterized by a unique constellation of symptoms, including vertigo, nystagmus, ipsilateral facial sensory loss, contralateral body sensory loss, and dysphagia.
2. The disruption of the lateral spinothalamic tract in Wallenberg syndrome leads to the characteristic pattern of sensory deficits, with ipsilateral facial numbness and contralateral body numbness.
3. Involvement of the descending sympathetic fibers in the lateral medulla can result in Horner's syndrome, characterized by ipsilateral ptosis, miosis, and anhidrosis.
4. Damage to the nucleus ambiguus in the lateral medulla can impair the function of the glossopharyngeal (IX) and vagus (X) cranial nerves, leading to dysphagia and dysphonia.
5. Wallenberg syndrome is typically caused by a stroke or infarction in the posterior inferior cerebellar artery (PICA) territory, which supplies the lateral medulla.

Review Questions

• Explain the characteristic sensory deficits observed in Wallenberg syndrome and how they relate to the underlying anatomical lesion.
  • In Wallenberg syndrome, the disruption of the lateral spinothalamic tract in the lateral medulla leads to a characteristic pattern of sensory deficits. Specifically, there is ipsilateral (same side) facial numbness or loss of pain and temperature sensation due to the involvement of the descending trigeminal fibers. Conversely, there is contralateral (opposite side) body numbness or loss of pain and temperature sensation, as the lateral spinothalamic tract carries these sensory modalities from the body to the thalamus. This dissociated sensory pattern is a hallmark of Wallenberg syndrome and is directly related to the anatomical location of the lesion in the lateral medulla.
• Describe the potential impact of Wallenberg syndrome on cranial nerve function and the associated clinical manifestations.
  • Wallenberg syndrome can disrupt the function of several cranial nerves due to its location in the lateral medulla. Damage to the nucleus ambiguus, which contains the motor nuclei of the glossopharyngeal (IX) and vagus (X) cranial nerves, can lead to dysphagia (difficulty swallowing) and dysphonia (impaired speech). Additionally, involvement of the descending sympathetic fibers in the lateral medulla can result in Horner's syndrome, characterized by ipsilateral ptosis (drooping eyelid), miosis (pupillary constriction), and anhidrosis (lack of sweating) on the affected side. These cranial nerve-related manifestations are crucial diagnostic features of Wallenberg syndrome and can significantly impact the patient's quality of life.
• Analyze the underlying vascular etiology of Wallenberg syndrome and explain how it contributes to the specific pattern of neurological deficits observed in this condition.
  • Wallenberg syndrome is typically caused by a stroke or infarction in the territory of the posterior inferior cerebellar artery (PICA), which supplies the lateral medulla. The involvement of the PICA territory leads to the selective damage of the lateral medulla, resulting in the characteristic neurological deficits observed in Wallenberg syndrome. The specific pattern of sensory, motor, and autonomic disturbances is directly related to the anatomical structures affected within the lateral medulla, including the lateral spinothalamic tract, nucleus ambiguus, and descending sympathetic fibers. Understanding the vascular etiology and its relationship to the affected neuroanatomical structures is crucial for accurately diagnosing and managing Wallenberg syndrome.

Related terms

Medulla Oblongata: The medulla oblongata is the lowermost part of the brainstem, responsible for regulating vital autonomic functions such as respiration, heart rate, and blood pressure.

Lateral Medullary Infarction: A type of ischemic stroke that specifically affects the lateral (side) region of the medulla oblongata, leading to the development of Wallenberg syndrome.

Cranial Nerves: The 12 pairs of nerves that originate directly from the brain and are responsible for various sensory, motor, and autonomic functions in the head and neck region.