What is Wallenberg or Lateral medullary syndrome?
Wallenberg syndrome (Lateral medullary syndrome) is a rare neurological syndrome, caused by a stroke in the vertebral artery or its largest branch- posterior inferior cerebral artery (PICA) [1,2]. PICA is one of the 3 major arteries that provide blood supply to Cerebellum. The syndrome involves many important structures in the cerebellum, causing a wide variety of symptoms. The onset of the syndrome is usually acute with severe vertigo.
Anatomy of the arteries supplying blood flow to the Cerebellum.
Image source: Wikipedia.org
Stroke affected area and structures in it.
Image source: medchrome.com
Wallenberg syndrome is caused by thrombosis of Vertebral or Posterior Inferior Cerebellar Artery. The thrombus causes infarction in a wedge of medulla oblongata. Medulla oblongata is the continuation of the spinal cord in the skull. It is the lowest part of the brainstem. Through various tracts, medulla oblongata delivers sensory and motor information to the spinal cord. If this part of the brain is damaged, the information from the brain can´t be delivered to other structures, causing a variety of symptoms. Although much rarer, but this syndrome can be caused by a localized brain hemorrhage or a tumor [1,2,4].
There is a variety of underlying conditions that can cause thrombosis of the arteries:
- Trombophylia- state of hyper-coagulation. Usually caused by genetic or autoimmune disorders, like Antiphospholipid Antibody syndrome.
- Endothelial cell injury- caused by trauma, infection or surgery, leads to forming of a blood clot in the location of injury.
- Disturbed blood flow- which can cause venous stasis and forming of blood clots. Disturbed blood flow can be caused by heart failure, malignancies, atrial fibrillation[5, 6].
Depending on the structures involved, there are a variety of symptoms. The most common of them are 
- Horner´s triad- miosis (constricted pupil), partial ptosis (falling of the upper eye lid) and anhidrosis (Loss of facial sweating in one side of the face)[ 8].
- Ipsilateral ataxia– loss of full control of movements in arm and leg on the same side of the lesion
- Contralateral hypalgesia- lack of pain and sensation of the face on the opposite side of the lesion
Other symptoms caused by Wallenberg syndrome are:
- Disphagia- trouble with swallowing, both food and liquid
- Dysphonia- trouble speaking due to physical disorder in the mouth
- Decreased gag reflex
- Nausea and vomiting
- Nystagmus– rapid involuntary movements of the eyes
- Vertigo-sensation of spinning and balance disturbance
- Severe stabbing pain of the face in the same side as the lesion
- Sense of falling towards the side of affected brain area
- Headache [1,2,4]
Diagnosis of the Wallenberg Syndrome is based on clinical examination, imaging studies and other tests. Clinical examination consists of:
- Anamnesis- questions about the complaints of the patient, onset of symptoms, family and social history, drug, past medical disease history.
- Neurological examination-assessment of sensory and motor functions :
- Mental status evaluation
- Cranial nerve examination- sense of smell, eye movement, pupil reaction, sensory status of the face, motor function of facial muscles, tongue movements, ability to talk, hearing.
- Motor function examination- checking the strength and tone of muscles.
- Checking tendon reflexes
- Checking sensation
- Cerebellum function: checking gait coordination, finger to nose test.
- Other organ system evaluation- pulse, breathing, kidney function, abdominal examination.
After the initial assessment, imaging studies have to be done to find the cause for the occurring symptoms :
- Computed tomography (CT) scan uses X-rays to create and image of the brain. It will show the localization of brain infarction and its size. CT angiography might be used. For this procedure a dye is injected in the bloodstream to better view the blood vessels.
- Magnetic resonance imaging shows a very detailed image of the soft tissue. MRI will show the damaged brain tissue and determine the cause (blood clot, hemorrhage or tumor).
Blood tests are prescribed to evaluate the balance of electrolytes in the blood, speed of blood clotting, blood sugar and lipid levels.
Echocardiography can be used to determine if the origin of the blood clot is the heart .
There is no cure for this condition. Usually symptomatic treatment is used- that means doing a variety of procedures and manipulations to relieve the occurring symptoms:
- If swallowing is impaired, feeding tube might be inserted to provide the necessary nutrition.
- Speech impairment- prescription of speech therapy
- Pain medication or anti-epileptic drugs can help to manage chronic pain
- Other drug treatments to prevent further development of blood clots, such as statins and aspirin.
- Management of high blood pressure
To reduce or dissolve the thrombus that is blocking the artery, blood thinners, such as heparin or warfarin can be prescribed. To use blood thinners doctor has to be sure, that Wallenberg Syndrome is not caused by a brain hemorrhage, otherwise it can further aggravate the condition. In severe cases intravascular surgery can be used to remove the blood clot. This treatment option is not commonly used, because the location of the blood clot is hard to reach.
The prognosis for patients that have suffered stroke depends on the size and location of the lesion. Some patients experience decrease in their symptoms just a few weeks or months after the stroke. For some patients the damage might be persistent and they might have a permanent neurological disability.
There have not found the reason why this kind of stroke occurs. It is a rare condition that causes severe damage. There is a correlation between Wallenberg syndrome and artery, heart disease, blood clotting disorders and minor neck trauma.
There are steps that can be taken to prevent occurrence of Wallenberg syndrome and any other stroke. These steps include:
- Identifying the risk factors, such as high blood pressure, underlying diseases, lifestyle risk factors.
- Reducing the identified risk factors by making the necessary lifestyle changes (losing weight, quitting smoking, introducing physical activities) and medical precautions ( managing diabetes and high blood pressure)
- Recognizing the symptoms of a stroke and responding to them.
- Saha R, Alam S, Hossain MA. Lateral Medullar Syndrome (Wallenberg´s syndrome) – A case report. Faridpur med. Coll. J. 2010; 5(1):35-36.
Available online: http://www.banglajol.info/index.php/FMCJ/article/viewFile/6813/5203
- Kim JS Et Al, Spectrum of Lateral Medullary Syndrome. Correlation between Clinical Findings and Magnetic Resonance Imaging in 33 Subjects. Stroke 1994, 7(25):1405-1410.
Available online: http://stroke.ahajournals.org/content/strokeaha/25/7/1405.full.pdf