Wallenberg Syndrome

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Wallenberg syndrome


Wallenberg syndrome is a type of brain stem stroke manifested by imbalance, vertigo, difficulty swallowing, hoarseness of voice, and sensory disturbance. It is caused by blockage in one of the arteries supplying the medulla and cerebellum .


The first clinical description was given by Gaspard Viesseux in 1808 and published by Alexander John Gaspard Marcet in 1811. But it wasn't until 1895 that Adolf Wallenberg eloquently described the different symptoms and signs and confirmed the findings during autopsy. The syndrome is also known as lateral medullary infarct (LMI) or posterior inferior cerebellar artery syndrome (PICA).

It usually affects people over 40 years of age. They tend to have vascular risk factors such as hypertension, high cholesterol, and diabetes. Wallenberg syndrome can also occur in younger people, but the underlying causes are different.


Wallenberg syndrome is rare, and accurate estimates about incidence are unavailable. In a large stroke registry in Sweden gathered by Norving and Cronquist in 1991, only about 2% of all strokes over a six-year period were caused by LMI.

Causes and symptoms

The stroke occurs in the medulla and cerebellum. The medulla controls such important functions as swallowing, speech articulation, taste, breathing, strength, and sensation. The cerebellum is important for coordination. The blood supply to these areas is via a pair of vertebral arteries and its branch, called the posterior inferior cerebellar artery (PICA).

Initially, the PICA was thought to be the blocked major artery, but this has been disproved from autopsy studies. In eight out of 10 cases, it is the vertebral artery that is occluded due to plaque buildup or because of a clot traveling from the heart. In younger patients, the vertebral artery dissection causes the infarct. The area of the stroke is only about 0.39 in (1 cm) vertically in the lateral part of the medulla and does not cross the midline.

Fully 50% of patients report transient neurological symptoms for several weeks preceding the stroke. During the first 48 hours after the stroke, the neurological deficit progresses and fluctuates. Dizziness , vertigo, facial pain , double vision, and difficulty walking are the most common initial symptoms. The facial pain can be quite bizarre with sharp jabs or jolts around the eye, ear, and forehead. Patients feel "seasick" or "off-balance" with nausea and vomiting. Objects appear double, tilted, or swaying. Along with gait imbalance, it becomes nearly impossible for the patient to walk despite good muscle strength. Other symptoms include hoarse voice, slurred speech, loss of taste, difficulty swallowing, hiccups, and altered sensation in the limbs of the opposite side.

The eye on the affected side has a droopy eyelid and a small pupil. The eyes jiggle when the person moves around; this is called nystagmus. There is decreased pain and temperature perception on the same side of the face. The limbs on the opposite side show decreased sensory perception. Voluntary movements of the arm on the affected side are clumsy. Gait is "drunken," and patients lurch and veer to one side.


Accurate diagnosis usually requires the expertise of a neurologist or a stroke specialist. It is common for an inexperienced physician to dismiss the symptoms of nausea, vomiting, and vertigo as being caused by an ear infection or viral illness. Diagnosis requires a thorough physical exam and neuroimaging. CT scans are insensitive and can detect only a large stroke or bleed in the cerebellum. Magnetic resonance imaging (MRI) scans are far superior, with the stroke showing up as a tiny bright spot in the medulla.

Treatment team

The team includes a neurologist or stroke specialist for initial diagnosis, workup, and medical management. Rehabilitation requires a physical therapist, occupational therapist, and speech therapist. Depending on whether complications arise, a neurosurgeon and a critical care physician may be involved.


Treatment for Wallenberg syndrome is mostly symptomatic. The size of the underlying blocked artery is too small to allow any mechanical or chemical re-opening. Aim of treatment is to alleviate symptoms, modify underlying risk factors, and prevent complications and future strokes.

Medical therapy

Blood thinners like heparin are given intravenously in some patients for the first few days to stop further formation and propagation of the clot. Following that, the patient usually has to take other blood thinners such as aspirin for life. Medications are also used to control high blood pressure and cholesterol. Pain in Wallenberg syndrome can sometimes be quite severe and disabling. A variety of analgesics like Tylenol or narcotics are used. Some patients need anti-seizure medications like gabapentin for pain management. Medications are also used for symptomatic treatment of vomiting and hiccups.

Surgical therapy

If the stroke is sufficiently large, the dead tissue swells up and can push the medulla downwards, impairing its vital functions and causing death. In this case, a neurosurgeon can remove a part of the skull to allow for the brain to swell.

Recovery and rehabilitation

Physical therapy focuses on improving balance and coordination. Assistive devices such as a cane, walker, or wheelchair may be used. Occupational therapy is used to help with daily activities like eating, which may be difficult due to clumsiness and incoordination. Speech training helps with articulation that has been impaired due to vocal cord paralysis. Special attention should be paid to food consistency to prevent aspiration. Initially, patients require pureed or semi-solid food. After initial treatment in the hospital, patients will need short-term placement in a nursing home or rehabilitation facility before going home. Modifications in living environment may include hand rails, non-slip rugs, etc.


Prognosis is usually quite encouraging both in the short and the long term. Nausea and vomiting disappear within a week. Clumsiness, difficulty swallowing, and gait imbalance improve over six months to a year. However, there is a 10% death rate due to complications like aspiration pneumonia, breathing difficulty, and cardiac arrhythmias.

Special concerns

Depression is very common among stroke survivors who face quite a challenge resulting from the abrupt change in lifestyle. They benefit from counseling, social support, and using antidepressant medications. There are several stroke support groups that help the patients and their families cope with the stroke and its aftermath.



"Vertebrobasilar Occlusive Disease." Chapter 11 in StrokePathophysiology, Diagnosis, and Management, edited by Henry J. M. Barnett, OC, MD, FRCP; J. P. Mohr, MD; Bennett M. Stein, MD; and Frank M. Yatsu, MD. New York, NY: Churchill Livingstone, 1998.

"Medullary Infarcts and Hemorrhages." Chapter 41 in Stroke Syndromes, edited by Julien Bogousslavsky, MD, and Louis R. Caplan, MD. New York, NY: Cambridge University Press, 2001.

Parker, James N., MD, and Philip M. Parker, PhD, eds. The Official Patient's Sourcebook on Wallenberg's Syndrome: A Revised and Updated Directory for the Internet Age. San Diego, CA: ICON Health Publications, 2002.


Kim, J. S. "Pure Lateral Medullary Infarction: Clinical-radiological Correlation of 130 Acute, Consecutive Patients." Brain 126 (May 2003): 18641872


National Stroke Association. 9707 East Easter Lane, Englewood, CO 80112. (303) 649-9299; Fax: (303) 649-1328. [email protected] <http://www.stroke.org>.

American Stroke Association. 7272 Greenville Avenue, Dallas, TX 75231. (800) 242-8721 or (888) 4STROKE. <http://www.strokeassociation.org>.

National Rehabilitation Information Center. 4200 Forbes Blvd, Suite 202, Lanham, MD 20706-4829. (301) 562-2400 or (800) 346-2742; Fax: (301) 562-2401. [email protected] services.com. <http://www.naric.com>.

Chitra Venkatasubramanian, MBBS, MD