Lateral medullary syndrome

Overview

Lateral medullary syndrome, also known as Wallenberg syndrome, is a neurological condition resulting from a stroke in the lateral part of the medulla oblongata - a portion of the brainstem. This syndrome is most commonly caused by an interruption of blood flow in the posterior inferior cerebellar artery (PICA) or the vertebral artery. The medulla controls several vital functions, including balance, coordination, swallowing, and autonomic regulation. Due to the involvement of multiple cranial nerve nuclei and nerve tracts, the syndrome presents with a characteristic set of sensory, motor, and autonomic symptoms.

Causes

Lateral medullary syndrome is primarily caused by an ischemic stroke, which results from obstruction of blood supply to the lateral medulla. Common causes include:

• Occlusion of the posterior inferior cerebellar artery (PICA)

• Occlusion of the vertebral artery

• Atherosclerosis – leading to narrowing or blockage of arteries supplying the brainstem

• Embolism – from the heart or proximal arteries, blocking smaller vessels

• Arterial dissection – particularly in younger patients following trauma or neck manipulation

Symptoms

The symptoms of lateral medullary syndrome vary depending on the extent of the infarction but commonly include a combination of the following:

• Vertigo and dizziness

• Nausea and vomiting

• Ataxia – uncoordinated movement, especially on the same side as the lesion

• Horner’s syndrome – ptosis (drooping eyelid), miosis (constricted pupil), and anhidrosis (lack of sweating) on the same side

• Dysphagia and dysarthria – difficulty swallowing and slurred speech due to involvement of the vagus and glossopharyngeal nerves

• Loss of pain and temperature sensation – on the opposite side of the body and the same side of the face

• Hiccups and hoarseness

• Nystagmus – involuntary eye movements

Diagnosis

Diagnosis of lateral medullary syndrome is based on clinical evaluation supported by imaging studies. Diagnostic steps include:

• Neurological examination – to identify the characteristic signs and symptoms of brainstem involvement

• MRI of the brainstem – the most sensitive imaging modality to detect infarction in the medulla

• Magnetic resonance angiography (MRA) or CT angiography – to identify vessel occlusion or dissection

• Cardiac evaluation – including echocardiography and ECG to detect potential sources of emboli

• Blood tests – to evaluate risk factors such as hypercoagulability, lipid levels, and glucose

Treatment

Treatment of lateral medullary syndrome focuses on managing the acute stroke, preventing complications, and rehabilitating affected functions. Treatment options include:

• Acute stroke care – includes antiplatelet therapy (e.g., aspirin), anticoagulation if indicated (e.g., in atrial fibrillation), and thrombolysis if within the treatment window

• Supportive care – including airway protection, nutrition (often via feeding tubes in dysphagia), and fluid management

• Rehabilitation therapy – physical, occupational, and speech therapy to regain motor skills and communication/swallowing functions

• Treatment of underlying causes – such as managing hypertension, diabetes, or cardiac conditions to prevent recurrence

Prognosis

The prognosis for lateral medullary syndrome varies depending on the severity of the infarction and the timeliness of treatment. Many patients experience partial or substantial recovery with appropriate rehabilitation. However, some deficits particularly swallowing difficulties, ataxia, or sensory loss, may persist long term. Early intervention, prevention of aspiration, and ongoing therapy significantly improve functional outcomes and quality of life. Life expectancy is typically not reduced unless complications such as aspiration pneumonia or recurrent strokes occur.