Wallenberg Syndrome: Brain Stem Stroke Affecting Eye Movement

Essential Insights: Understanding and Responding to Wallenberg Syndrome

Table of Contents

• Understanding Wallenberg Syndrome: A Rare Brain Stem Stroke
• How Lateral Medullary Syndrome Affects Vision and Eye Movement
• Recognizing Key Symptoms of Wallenberg Syndrome
• What Causes Posterior Circulation Strokes in the Brain Stem?
• Diagnostic Approaches for Lateral Medullary Syndrome
• Treatment Options and Recovery from Wallenberg Syndrome
• Living with Wallenberg Syndrome: Long-term Management
• When to Seek Emergency Care for Brain Stem Stroke Symptoms

Understanding Wallenberg Syndrome: A Rare Brain Stem Stroke

Wallenberg syndrome, also known as lateral medullary syndrome, is a rare neurological condition resulting from a stroke in the brain stem, specifically in the lateral part of the medulla oblongata. This particular type of posterior circulation stroke affects critical pathways that control various bodily functions, including eye movement, balance, sensation, and swallowing.

The syndrome was first described by Adolf Wallenberg, a German neurologist, in the early 20th century. What makes this condition particularly challenging is its complex presentation and the vital nature of the affected brain region. The medulla oblongata controls essential autonomic functions such as breathing, heart rate, and blood pressure, while also serving as a conduit for nerve pathways travelling between the brain and spinal cord.

Unlike strokes affecting the anterior circulation (which typically cause more recognisable symptoms like one-sided weakness), Wallenberg syndrome presents with a distinctive constellation of symptoms that can be puzzling to both patients and clinicians. The brain stem’s compact anatomy means that even a small infarction can produce widespread and seemingly unrelated symptoms, making this syndrome a significant diagnostic challenge in neuro-ophthalmology and neurology.

How Lateral Medullary Syndrome Affects Vision and Eye Movement

Lateral medullary syndrome can profoundly impact the visual system and eye movement control due to the involvement of critical neural pathways in the brain stem. The visual disturbances in Wallenberg syndrome primarily stem from damage to structures responsible for coordinating eye movements and maintaining visual stability.

One of the most common neuro-ophthalmic manifestations is nystagmus—involuntary, rhythmic eye movements that can be horizontal, vertical, or rotatory. This occurs because the stroke affects the vestibular nuclei or their connections, which normally help stabilise vision during head movements. Patients often describe their vision as “bouncing” or “jumping,” particularly when looking in certain directions.

Diplopia (double vision) is another frequent complaint, resulting from misalignment of the eyes due to damage to the pathways controlling coordinated eye movements. This can manifest as horizontal, vertical, or torsional diplopia, depending on which specific eye movement pathways are affected.

Skew deviation—a vertical misalignment of the eyes—may also occur, along with ocular tilt reaction, where there’s a combination of head tilt, skew deviation, and ocular torsion. These manifestations result from disruption to the vestibulo-ocular pathways that normally maintain proper eye alignment relative to gravity and head position.

Additionally, some patients experience oscillopsia, an illusion that the visual world is moving when it’s actually stationary. This disturbing symptom results from the brain’s inability to compensate for small eye movements, creating significant visual instability and disorientation.

Recognizing Key Symptoms of Wallenberg Syndrome

Wallenberg syndrome presents with a distinctive pattern of symptoms that reflect the complex anatomy of the lateral medulla. Recognising these symptoms promptly is crucial for timely diagnosis and intervention. The clinical presentation typically includes both neuro-ophthalmic and broader neurological manifestations.

The cardinal symptoms of lateral medullary syndrome include:

• Vertigo and dizziness: Often severe and accompanied by nausea and vomiting due to involvement of vestibular nuclei
• Dysphagia: Difficulty swallowing resulting from damage to the nucleus ambiguus
• Hoarseness: Changes in voice quality due to vocal cord dysfunction
• Ipsilateral facial sensory deficits: Numbness and pain on the same side of the face as the lesion due to trigeminal nucleus involvement
• Contralateral body sensory deficits: Reduced pain and temperature sensation on the opposite side of the body
• Ipsilateral Horner’s syndrome: Ptosis (drooping eyelid), miosis (constricted pupil), and anhidrosis (reduced sweating) on the same side as the lesion
• Ataxia: Uncoordinated movements and difficulty walking due to cerebellar pathway involvement
• Nystagmus and diplopia: As discussed in the previous section

Notably, unlike many other types of stroke, Wallenberg syndrome typically does not cause weakness in the limbs, as the corticospinal tracts that control voluntary movement pass through a different part of the medulla. This absence of hemiparesis can sometimes lead to delayed diagnosis, as many healthcare providers initially look for limb weakness when evaluating for stroke.

What Causes Posterior Circulation Strokes in the Brain Stem?

Wallenberg syndrome results from a posterior circulation stroke affecting the lateral medulla, with several distinct mechanisms potentially responsible. Understanding these causes is essential for both prevention and management strategies.

The most common cause of lateral medullary syndrome is occlusion or stenosis of the vertebral artery, which supplies blood to the posterior portion of the brain, including the brain stem. This occlusion typically occurs due to atherosclerosis—the buildup of fatty deposits and plaque within the arterial walls. Risk factors for atherosclerosis include hypertension, diabetes, smoking, hyperlipidaemia, and advanced age.

In younger patients, vertebral artery dissection is a significant cause of Wallenberg syndrome. This involves a tear in the inner lining of the artery, which can occur spontaneously or following trauma, including seemingly minor neck movements or manipulations. The dissection creates a false lumen within the arterial wall, potentially leading to blood flow obstruction or thrombus formation.

Less commonly, lateral medullary syndrome may result from:

• Embolism from a cardiac source, such as atrial fibrillation
• Small vessel disease affecting the penetrating branches of the vertebral or basilar arteries
• Compression of the vertebral artery by tumours or bony structures
• Vasculitis affecting the posterior circulation
• Hypercoagulable states predisposing to thrombosis

The posterior circulation, including the vertebral and basilar arteries, is anatomically more variable and often narrower than the anterior circulation, potentially making it more vulnerable to certain pathological processes. Additionally, the brain stem’s high metabolic demands and limited collateral circulation make it particularly sensitive to even brief interruptions in blood flow.

Diagnostic Approaches for Lateral Medullary Syndrome

Diagnosing Wallenberg syndrome requires a comprehensive approach combining clinical assessment with advanced neuroimaging. The distinctive pattern of symptoms often suggests the diagnosis, but confirmation and determination of the underlying cause are essential for appropriate management.

The diagnostic process typically begins with a thorough neurological examination, with particular attention to cranial nerve function, eye movements, sensory testing, and coordination. Neuro-ophthalmic assessment is crucial, as eye movement abnormalities provide valuable localising information. This may include evaluation for nystagmus, skew deviation, ocular alignment, and vestibulo-ocular reflexes.

Neuroimaging plays a central role in confirming the diagnosis. Magnetic resonance imaging (MRI) of the brain, particularly diffusion-weighted imaging (DWI), is the gold standard for identifying the medullary infarction characteristic of Wallenberg syndrome. The lesion typically appears as a hyperintense signal in the lateral medulla on DWI sequences. In some cases, especially in the acute phase, the infarct may be small and difficult to visualise, requiring thin-slice techniques or repeat imaging.

Vascular imaging is essential to identify the underlying cause and guide treatment decisions. This may include:

• MR angiography (MRA) of the head and neck
• CT angiography (CTA)
• Catheter angiography in selected cases
• Doppler ultrasonography of the vertebral arteries

Additional investigations may be warranted to identify stroke risk factors or alternative diagnoses. These might include cardiac evaluation (echocardiography, ECG, Holter monitoring), blood tests for hypercoagulable states, inflammatory markers, and lipid profiles. Comprehensive stroke evaluation is essential, as Wallenberg syndrome represents one manifestation of cerebrovascular disease that may affect multiple territories.

Treatment Options and Recovery from Wallenberg Syndrome

The management of Wallenberg syndrome encompasses acute intervention, secondary prevention, and rehabilitation tailored to specific symptoms. Treatment approaches must address both the underlying vascular pathology and the functional impairments resulting from the brain stem infarction.

In the acute phase, management follows standard stroke protocols, though with important considerations specific to posterior circulation strokes. If diagnosed within the appropriate time window, intravenous thrombolysis may be considered, though the benefit-risk ratio differs somewhat from anterior circulation strokes. For large vessel occlusions, endovascular thrombectomy might be an option in selected cases, particularly with basilar or proximal vertebral artery occlusions.

Secondary prevention focuses on reducing the risk of recurrent stroke through:

• Antiplatelet therapy (e.g., aspirin, clopidogrel) or anticoagulation if indicated
• Management of vascular risk factors including hypertension, diabetes, and hyperlipidaemia
• Lifestyle modifications including smoking cessation, dietary changes, and physical activity
• In cases of significant vertebral artery stenosis, endovascular stenting may sometimes be considered

Symptom-specific treatments are crucial for improving quality of life and functional outcomes. These may include:

• Vestibular rehabilitation for vertigo and balance problems
• Swallowing therapy and modified diet for dysphagia
• Speech therapy for dysarthria
• Prism glasses or eye patches for diplopia
• Pain management for neuropathic pain
• Physical therapy for ataxia and coordination problems

Recovery from Wallenberg syndrome is variable and depends on factors including the extent of the infarction, age, comorbidities, and access to rehabilitation services. Many patients experience significant improvement in symptoms over weeks to months, though some deficits may persist long-term. The brain’s neuroplasticity allows for substantial functional recovery in many cases, particularly with intensive rehabilitation.

Living with Wallenberg Syndrome: Long-term Management

Long-term management of Wallenberg syndrome requires a multidisciplinary approach addressing persistent symptoms, preventing complications, and optimising quality of life. While many patients experience significant recovery, some degree of residual impairment is common, necessitating ongoing care and adaptation strategies.

Persistent neuro-ophthalmic symptoms often require specialised management. Chronic nystagmus may be treated with medications such as gabapentin, baclofen, or memantine in selected cases. For persistent diplopia, prism glasses may provide a long-term solution, while botulinum toxin injections into selected extraocular muscles can be beneficial in some cases. Regular neuro-ophthalmological follow-up is important to monitor these symptoms and adjust treatments accordingly.

Swallowing difficulties may persist and require ongoing assessment by speech and language therapists. Some patients need long-term dietary modifications or, rarely, alternative feeding methods. Aspiration risk must be carefully monitored and managed to prevent pneumonia, a significant complication.

Balance and coordination problems often improve with vestibular rehabilitation but may require long-term adaptations. These might include:

• Home modifications to reduce fall risk
• Use of mobility aids
• Ongoing balance exercises
• Adaptation of daily activities

Neuropathic pain, particularly facial pain, can be challenging to manage and may require medications such as anticonvulsants, antidepressants, or referral to pain specialists. Psychological support is often beneficial, as chronic pain can significantly impact mood and quality of life.

Beyond physical symptoms, many patients with Wallenberg syndrome experience psychological challenges, including anxiety, depression, and adjustment difficulties. These deserve recognition and appropriate treatment, which may include counselling, cognitive-behavioural therapy, or medication when indicated.

Support groups and patient organisations can provide valuable information, emotional support, and practical advice for those living with the long-term effects of brain stem stroke. Connecting with others who understand the unique challenges of this condition can be tremendously beneficial for both patients and caregivers.

When to Seek Emergency Care for Brain Stem Stroke Symptoms

Recognising the warning signs of a brain stem stroke and seeking immediate medical attention can be life-saving and significantly improve outcomes. The symptoms of Wallenberg syndrome often develop rapidly and require urgent evaluation, as timely intervention is crucial in limiting the extent of brain tissue damage.

Key warning signs that should prompt immediate emergency care include:

• Sudden severe dizziness or vertigo: Particularly when accompanied by difficulty walking or standing
• Abrupt onset of double vision or other visual disturbances: Including blurred vision, visual field defects, or difficulty focusing
• Sudden difficulty swallowing or choking on food or liquids
• Unexplained numbness or altered sensation: Especially if it affects one side of the face and the opposite side of the body
• Sudden severe headache: Particularly in the back of the head or neck
• Slurred speech or hoarseness developing acutely
• Sudden loss of coordination or balance: Including difficulty walking or performing fine motor tasks

It’s important to emphasise that brain stem strokes may present differently from the more widely recognised symptoms of anterior circulation strokes. The absence of limb weakness does not rule out a stroke, and the combination of vertigo, facial numbness, and swallowing difficulties should raise immediate concern.

The acronym “BE