Lateral medullary syndrome occurs as a result of either vertebral or cerebellar artery occlusion. Ischemia of brain tissue and the tracts passing through the medulla manifest with various symptoms, most commonly ataxia, nystagmus, voice changes, dysphagia and sensory deficits. The diagnosis is made clinically and with the help of magnetic resonance imaging. Treatment includes symptomatic measures and anticoagulant drugs.
The clinical presentation of patients with this syndrome may significantly vary and depends on which site and vessel is affected. Symptoms may appear abruptly, which is the case in the majority of patients, but they may gradually occur as well. Patients in whom trigeminal nerve nuclei and pathways are damaged, ipsilateral facial pain or loss of pain and temperature sensation may be present and if the spinothalamic tract is affected, contralateral sensory loss is observed . Vestibular nuclei involvement may present with nystagmus, diplopia, blurred vision, nausea, vomiting and vertigo. Dysphagia, dysphonia, dysarthria, hoarseness and in rare cases, stridor are symptoms that are reported in patients in whom nucleus ambiguus is affected [8[ . Cerebellar involvement includes symptoms such as gait abnormalities, weakness and ataxia. Horner's syndrome and headaches are also common findings in these patients, while hiccups may be reported as well .
The initial diagnosis of lateral medullary syndrome can be made based on findings encountered during physical examination, but a definite diagnosis is made through imaging techniques such as CT, MRI and MR angiography . CT scan, as an initial diagnostic method, can provide clues about the location of the infarction, but MRI is still the gold standard in the diagnosis of this syndrome. MRI of the endocranium can provide more specific images in comparison to CT and can detect medullary infarction with greater sensitivity and specificity. More importantly, it can determine its exact location, and thus identify the artery that was damaged. MR angiography is a method that wherein contrast is used to visualize vessels supplying the medulla. It provides an optimal view of the affected arteries. Stenosis of the vessel lumen, presence of intramural hematomas and dissection of the vessel may all be identified with this diagnostic method  .
Additional tests that can be made during the diagnostic protocol include evaluation of blood pressure, levels of cholesterol and triglycerides and a complete blood count. Hypertension is a significant risk factor in these patients, and should be diagnosed and properly treated if present. Platelet count may be raised, which is why antiplatelet therapy is one of the main treatment strategies in these patients.
Treating patients with lateral medullary syndrome includes symptomatic treatment as well as antiplatelet medications. The scope of symptomatic therapy depends on the associated findings. Hypertension should be corrected with angiotensin-converting enzyme inhibitors (ACEs), angiotensin-receptor blockers, diuretics, beta blockers or calcium antagonists, while pain is managed with non-steroidal anti-inflammatory drugs (NSAIDs). In patients with poor general condition, nasogastric tube placement for adequate nutrition, orotracheal intubation and assisted ventilation may be necessary.
The use of antiplatelet therapy is still not standardized in patients with lateral medullary syndrome, but their role in the treatment of cervical artery dissection and other cerebrovascular events seems to be beneficial . Aspirin belongs to the group of NSAIDs, but one of its main properties is prevention of platelet aggregation, thus promoting anticoagulatory mechanisms in the cerebral vessels, while clopidogrel is an antiplatelet agent that reduces the rate of platelet formation. However, these agents should be used with caution, because in the case of arterial dissection, several complications may occur, including subarachnoid hemorrhage, formation of pseudoaneurysms and dislocation of thrombi that may occlude other vessels. Surgery is rarely indicated as a therapeutic strategy, as the occluded vessels lie deep in the endocranium and are not accessible without extensive tissue damage. But in patients who are not responding to therapy, it may be performed.
Speech therapy may be often necessary, as patients may present with severe dysarthria that may persist for a prolonged period of time. Repetitive transcranial magnetic stimulation (rTMS) has been used in management of dysphagia with promising results, but further studies are necessary prior to its introduction in clinical practice .
The prognosis depends on the location and severity of occlusion. Patients may recover without any sequelae, but neurological deficits may persist for a prolonged period of time and can become permanent in cases of severe ischemia. Certain studies have established mortality rates of about 11% in the acute phase of illness, while the long-term prognosis is generally good, with only a few patients experiencing recurrences and sequelae .
The principal cause of lateral medullary syndrome is occlusion of either vertebral or posterior inferior cerebellar artery (PICA). The vertebral artery is a much more common site of occlusion. Pathogenic mechanisms include arteriosclerosis, formation of blood clots, embolism, or in some cases, dissection of the arterial vessel. In rare cases, occlusion of the basilar or extracranial segments of the vertebral artery is observed .
This condition seems to affect male patients more commonly than women, typically in late adulthood. Various studies have confirmed this finding, and several risk factors have been established. Hypertension and preexisting arteriosclerosis have been identified as the most important risk factors in these patients , while other factors, such as coronary heart disease, diabetes mellitus, cocaine abuse, trauma, infectious encephalitis and brain tumors have all been linked to the development of this syndrome.
The pathogenesis of lateral medullary syndrome starts with blood vessel stenosis and obstruction, most commonly on the grounds of preexisting hypertension and atherosclerosis . Vessels that are affected supply the structures in the brain stem, including the medulla oblongata, pons, cerebellum and various cranial nuclei. Once the blood vessel is occluded, oxygen and nutrients cannot reach the target tissue, which leads to ischemia and development of neurological deficits. Several cranial nerves and tracts can be damaged, primarily the nuclei of the vestibular and trigeminal nerves, while the spinothalamic tract, nucleus ambiguus and other sites may be damaged. Symptoms such as facial pain may be seen in patients with trigeminal nuclei ischemia, since it is responsible for sensory innervation of the face, while vestibular nuclei are responsible for coordination. The inferior cerebellar peduncule can also be affected by ischemia, which is involved in maintaining balance and gait. The spinothalamic tract carries signals responsible for pain and temperature contralaterally, while nucleus ambiguus is a network of motor neurons that innervate various structures in the oropharynx, including the pharyngeal and soft palatal muscles and the larynx, giving typical symptoms of hoarseness, dysphonia and dysphagia.
One of the most common clinical findings in patients - Horner's syndrome, is presumed to occur due to the damage of the descending sympathetic fibers that originate in the hypothalamus.
For cerebrovascular insults, including lateral medullary syndrome, factors such as hypertension, smoking, alcohol consumption, poor dietary habits and physical inactivity are all presumed to increase the risk for its development. Significant steps in terms of prevention can be made, including regular blood pressure control, which sometimes necessitates pharmacologic therapy, while cessation of smoking and reduction in daily alcohol intake is recommended. Changes in dietary habits, as well as regular exercise are proven to have beneficial effects on the cardiovascular system.
Lateral medullary syndrome is a form of cerebral infarction that occurs in the brain stem and primarily due to occlusion of vertebral and cerebellar arteries although arterial dissection may also be a cause. It was initially described more than 100 years ago as Wallenberg syndrome after the German physician who was the first to document the typical neurological features associated with the condition . It is caused by vessel occlusion due to atherosclerosis, clot formation, or embolization of vertebral or posterior inferior cerebellar artery (PICA), while basilar and external parts of the vertebral artery can also be sites of occlusion. Ischemia leads to impaired nutrient and oxygen delivery to the tissues with the development of symptoms which may appear either abruptly or insidiously. This syndrome more commonly develops in male adults, usually in late adulthood. Hypertension is presumed to be the main risk factor. Clinical presentation depends on the areas which are affected. These may include nucleus ambiguus, cerebellum, vestibular or trigeminal nuclei, spinothalamic tract, and other parts of the brain stem. Common symptoms include ataxia, weakness, gait disturbances, vertigo, dysphonia, dysarthria, hoarseness, diplopia and nystagmus, while dysphagia and aspiration are seen as well . Horner's syndrome, comprised of ptosis, anhydrosis and miosis is commonly encountered in these patients and should immediately suggest cerebellar infarction in the differential diagnosis. Lateral medullary syndrome is diagnosed on clinical grounds, while magnetic resonance imaging (MRI) is used to confirm medullary infarction. Magnetic resonance angiography may identify the exact blood vessel that is damaged, and treatment is aimed at alleviating symptoms together with antiplatelet therapy, usually with aspirin or clopidogrel. In severe cases, nasogastric tube insertion and intubation may be necessary because of poor general condition. Surgical treatment is reserved for patients who do not respond to therapy.
Lateral medullary syndrome (also known as Wallenberg syndrome, after the physician who initially described the neurological features of the disease) is a form of stroke that occurs due to inadequate oxygen and nutrient supply of various parts of the brain because of arterial occlusion. The most important risk factor is presumed to be hypertension, in which atherosclerosis of blood vessels predisposes individuals to this syndrome. Arteries that are involved include the vertebral artery, through which blood travels from the neck into the brainstem, and the posterior inferior cerebellar artery (PICA), which supplies portions of the little brain. When obstruction of blood flow through the affected blood vessel occurs, oxygen delivery is impaired, leading to onset of various symptoms. Patients may present with balance disturbances, difficulties in swallowing, facial pain, voice changes, vision problems and loss of pain sensation. Symptoms may appear either abruptly or slowly, and depend on which site of the brain is affected. The physician can make a presumptive diagnosis during physical examination, while a definite diagnosis is made through imaging of the head. Magnetic resonance imaging (MRI) is the diagnostic technique of choice because it provides a clear view of the brain and is able to identify the part of the brain that is affected. Magnetic resonance angiography is used as it is a superior method to identify which vessel is damaged and is performed by injecting a contrast into the bloodstream, which aids in depicting which vessels are affected. Treatment includes symptomatic therapy, which may range from pain management to placement of feeding tubes and assisted ventilation, as well as anticoagulant therapy, which aims at reducing formation of blood clots that may further occlude the arterial vessels. Because this disorder is linked to hypertension, significant preventive measures can be performed, including regular blood pressure therapy, proper dietary habits, regular exercise and avoiding cigarette smoking and alcohol consumption. The prognosis of this syndrome is good, but significant neurological deficits may persist for a prolonged period of time, and even fatal outcomes are reported, which is why a timely diagnosis and immediate treatment is very important.