Medial medullary syndrome

Overview

Medial medullary syndrome, also known as Dejerine syndrome, is a rare neurological condition caused by a lesion in the medial portion of the medulla oblongata, a structure in the brainstem. This syndrome results in a characteristic triad of neurological deficits: contralateral hemiparesis (weakness on the opposite side of the body), contralateral loss of proprioception and vibration sense, and ipsilateral hypoglossal nerve palsy (tongue weakness on the same side as the lesion).

Medial medullary syndrome is typically the result of an infarction (stroke) involving the anterior spinal artery or one of its branches. Due to the critical role of the medulla in motor and sensory pathways, the condition causes profound functional impairment, often requiring immediate medical intervention and long-term rehabilitation.

Causes

The most common cause of medial medullary syndrome is an ischemic stroke involving the anterior spinal artery or the vertebral artery that supplies the medial portion of the medulla oblongata. Causes include:

• Atherosclerosis: Plaque buildup in the vertebral or anterior spinal arteries leading to narrowing or blockage

• Embolism: A clot or debris from the heart or proximal arteries that travels to the anterior spinal artery

• Vertebral artery dissection: Tearing in the vessel wall leading to occlusion

• Small vessel disease: Due to hypertension or diabetes affecting the penetrating arteries

Rarely, tumors, demyelinating diseases like multiple sclerosis, or infections can mimic or contribute to similar medullary lesions.

Symptoms

Medial medullary syndrome presents with a classic triad of signs resulting from damage to specific structures in the medial medulla:

1. Contralateral hemiparesis:

   • Weakness or paralysis of the arm and leg on the side opposite the lesion

   • Due to damage to the corticospinal tract

2. Contralateral loss of proprioception and vibration:

   • Affects fine touch, vibration, and position sense

   • Results from involvement of the medial lemniscus

3. Ipsilateral hypoglossal nerve palsy:

   • Weakness and atrophy of the tongue on the same side as the lesion

   • On protrusion, the tongue deviates toward the side of the lesion

Additional symptoms may include dysarthria (slurred speech), dysphagia (difficulty swallowing), and respiratory irregularities in severe cases.

Diagnosis

Diagnosis of medial medullary syndrome relies on clinical assessment and neuroimaging studies to confirm the location and cause of the lesion. Key diagnostic steps include:

• Neurological examination:

  • Identification of the classic triad of symptoms helps localize the lesion to the medial medulla

• Magnetic Resonance Imaging (MRI):

  • Preferred imaging modality to visualize infarcts in the brainstem

  • Diffusion-weighted imaging (DWI) can detect acute ischemic changes

• Magnetic Resonance Angiography (MRA) or CT Angiography:

  • Used to assess the vertebral and anterior spinal arteries for stenosis or occlusion

• Electrocardiogram (ECG) and echocardiography:

  • Help identify cardiac sources of emboli

• Blood tests:

  • To identify risk factors such as hyperlipidemia, diabetes, or coagulation disorders

Prompt identification and differentiation from other brainstem syndromes, such as lateral medullary (Wallenberg) syndrome, are essential for appropriate treatment.

Treatment

Treatment of medial medullary syndrome focuses on addressing the underlying cause (typically ischemic stroke), minimizing neurological damage, and facilitating recovery. Management strategies include:

Acute Phase

• Thrombolytic therapy:

  • If the patient presents within 4.5 hours of symptom onset and meets criteria, intravenous alteplase (tPA) may be administered

• Antiplatelet therapy:

  • Aspirin or clopidogrel to prevent further clot formation

• Blood pressure management:

  • To prevent stroke progression and recurrence

• Oxygen and fluid support

Subacute and Long-Term Management

• Physical therapy: To improve muscle strength, coordination, and mobility

• Speech therapy: Especially helpful for patients with dysarthria or hypoglossal nerve involvement

• Occupational therapy: To assist with daily activities and improve independence

• Management of risk factors: Control of hypertension, diabetes, high cholesterol, and smoking cessation

• Anticoagulation: If cardioembolic source is identified (e.g., atrial fibrillation)

Prognosis

The prognosis for medial medullary syndrome varies depending on the size of the lesion, the extent of neurological damage, and the speed of treatment initiation. Key considerations include:

• Recovery potential: Some patients experience partial to substantial recovery with aggressive rehabilitation

• Persistent deficits: May include permanent weakness, speech difficulties, or sensory loss

• Mortality risk: Low compared to lateral medullary syndrome, but increases with bilateral involvement or delayed treatment

• Quality of life: Can be significantly improved with early rehabilitation and multidisciplinary care

Early intervention, supportive therapy, and long-term rehabilitation are critical to optimizing recovery and minimizing disability.