Wallenberg Syndrome

Introduction

According to the National Institute of Neurological Disorders and Stroke, Wallenberg Syndrome (aka Lateral Medullary Syndrome) is a neurological condition caused by compromise of the vertebral artery (VA) or posterior inferior cerebellar artery (PICA), ultimately leading to infarction of the lateral medulla. Stroke occurring in this region of the brainstem often leads to a variety of deficits including (but not limited to), difficulties swallowing, nausea and vomiting, hoarseness, dizziness, vertigo, nystagmus, as well as balance and gait coordination problems. Wallenberg Syndrome was first described in 1808 by Gaspard Vieusseux. However, a more detailed description was given in 1895 by Adolf Wallenberg himself, which highlighted this condition as an infarction of the lateral medulla oblongata following occlusion of the PICA (Nicholson et al., 2009).

Clinically Relevant Anatomy

The vertebral artery (VA) runs along the ventro-lateral aspect of the brainstem supplying the medulla. The VA branches off to form the posterior inferior cerebellar artery (PICA) which runs dorsally and crosses over/supplies the lateral medulla on its way to the cerebellum. Structures that make up the lateral medulla include the inferior cerebellar peduncle, vestibular nuclei, trigeminal nucleus and tract, spinothalamic tract, descending sympathetic fibres, nucleus ambiguus and nucleus solitarius.

Clinical Picture/Complications 

Due to the very compressed placement of nuclei and tracts within the lateral medulla, Wallenberg Syndrome (resulting from a stroke in the VA or PICA) often leads to abnormalities in many systems, including: vestibulo-cerebellar, sensory, bulbar, respiratory, and autonomic.

Some common symptoms of Wallenberg Syndrome include:

• Dizziness
• Vertigo
• Nausea and vomiting
• Difficulty with balance and ambulation
• Difficulty maintaining sitting posture
• Blurry vision
• Horizontal or rotational nystagmus
• Crossed hemisensory disturbance
• Ipsilateral reduction in pain and temperature sensation over the face
• Contralateral reduction in pain and temperature sensation over trunk
• Hoarseness
• Poor gag reflex
• Ataxia
• Dysphonia
• Dysphagia
• Diplopia

Epidemiology/Etiology/Prognosis

A study reviewing 25 cases of Wallenberg Syndrome found the incidence to be highest in middle-aged men at 55.06 years of age (Srivastava et al., 2015). The greatest risk factor for Wallenberg Syndrome is currently believed to be atherosclerosis, which is often linked to a history of hypertension, diabetes, and smoking (Gregory et al., 2014). The long-term outlook varies quite substantially, with some individuals seeing a decrease in symptoms within weeks, whereas others may have symptoms persist for years (Srivastava et al., 2015). With appropriate treatment, clinical monitoring, and post-stroke care, the prognosis for recovery remains positive. Majority of patients have minimal deficits at six months, and over 85% have been found to attain functional independence with ambulation within a year (Gregory et at., 2014). Overall, researchers have yet to confidently determine why this type of stroke occurs.