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Medial Medullary SyndromeEdit

Medial medullary syndrome is a focal brainstem stroke syndrome caused by ischemia in the medial portion of the medulla oblongata. It is most commonly the result of occlusion of the anterior spinal artery or its medullary branches, leading to a discrete constellation of neurologic deficits that reflect the loss of all or part of the corticospinal tract, dorsal columns, and the hypoglossal nucleus. The syndrome is sometimes referred to by the eponym Dejerine syndrome, but the descriptive label Medial medullary syndrome remains the precise way to name the affected vascular territory anterior spinal artery territory and its clinical signature. Understanding the anatomical arrangement helps clinicians distinguish this condition from other brainstem syndromes that involve different vascular territories, such as Wallenberg syndrome.

Introductory overview Medial medullary syndrome presents with a small but characteristic set of signs that localize the lesion to the medial medulla. The integrity of the corticospinal tract, dorsal columns, and the hypoglossal nucleus is essential for smooth voluntary movement, sensation of body position, and tongue control, respectively. Stroke in this region interrupts these pathways on their respective sides, producing a pattern of distal weakness, sensory loss, and tongue weakness that is clinically recognizable in the acute setting. The condition is rare compared with hemispheric strokes, but its recognition is crucial because timely management of brainstem strokes improves outcomes and reduces long-term disability. Patients may present with abrupt onset of weakness in the body, loss of vibration and proprioception on the opposite side, and a tongue weakness that becomes evident when protruded. Early imaging with brain MRI and vascular studies is key to confirming the diagnosis and guiding treatment ischemic stroke care pathways.

Anatomy and Pathophysiology

  • Vascular supply

    • The medial medulla receives blood primarily from the anterior spinal artery and small perforating branches. Occlusion in this territory spares much of the lateral medulla, producing a distinctive set of signs that point to the medial aspect of the medulla. Understanding this supply explains why certain functions are impaired while others (such as facial pain and temperature sensation from the ipsilateral face) are preserved.

  • Neural structures affected

    • Corticospinal tract: descending motor fibers that run through the medullary pyramid are disrupted, leading to contralateral hemiparesis of the body.
    • Dorsal columns: the fasciculus gracilis and, less commonly, fasciculus cuneatus carry fine touch, vibration, and proprioception from the body; their interruption results in contralateral loss of these senses below the level of the lesion.
    • Hypoglossal nucleus or nerve fibers: the nucleus of the twelfth cranial nerve lies in the medulla; involvement causes ipsilateral tongue weakness, resulting in tongue deviation toward the side of the lesion on protrusion.

  • Localization and distinction

    • The combination of contralateral body weakness with loss of dorsal column–mediated senses and ipsilateral tongue weakness is highly suggestive of a medial medullary lesion. In contrast, lateral medullary (Wallenberg) syndrome, which arises from vertebral or posterior inferior cerebellar artery involvement, classically affects the vestibular nuclei, spinal trigeminal nucleus, and nucleus ambiguus, producing a different constellation of symptoms including hoarseness and dysphagia.

Clinical Features

  • Motor and sensory

    • Contralateral hemiparesis (body) from corticospinal tract involvement.
    • Contralateral loss of vibration and proprioception from disruption of the dorsal columns.
    • Ipsilateral tongue weakness with deviation of the protruded tongue toward the side of the lesion.

  • Additional findings

    • Mild ipsilateral dysarthria or slurred speech can occur due to tongue weakness.
    • Symptoms related to other brainstem regions (such as vertigo, dysphagia, facial numbness) are less typical in medial medullary syndrome and often point to alternate or additional lesion locations.

  • Distinguishing features

    • A key distinguishing feature from lateral medullary syndrome is the involvement pattern: medial medullary syndrome tends to spare nucleus ambiguus–related bulbar symptoms (hoarseness, dysphagia) that are common in lateral lesions, while presenting with tongue-related signs and contralateral corticospinal and dorsal column findings.

Diagnosis

  • Clinical assessment

    • The diagnosis begins with recognizing the triad of contralateral motor weakness, contralateral loss of proprioception/vibration, and ipsilateral tongue weakness. The timing is typically sudden, consistent with an ischemic event.

  • Imaging and tests

    • Magnetic resonance imaging (MRI) of the brain, especially diffusion-weighted imaging (DWI), is the preferred modality to identify acute brainstem infarction.
    • Vascular imaging (such as CT angiography or MR angiography) may reveal occlusion or stenosis of the anterior spinal artery or contributing vertebral artery disease.
    • Routine stroke workup includes vascular risk assessment, ECG to detect cardioembolic sources, and laboratory tests to evaluate risk factors such as hypertension, diabetes, and lipid disorders.

  • Differential diagnosis

    • Other brainstem stroke syndromes, including lateral medullary syndrome, medial pontine syndrome, and basilar artery syndromes, can mimic parts of Medial medullary syndrome. Distinguishing features on examination and targeted imaging help separate these conditions.

Etiology and Epidemiology

  • Causes

    • The predominant cause is occlusion of the anterior spinal artery or its medullary branches, often related to atherosclerotic disease or vertebral artery pathology. Less commonly, embolic events from proximal vessels or cardioembolic sources can contribute.

  • Risk factors

    • Shared vascular risk factors for ischemic stroke apply: hypertension, diabetes mellitus, hyperlipidemia, smoking, and advanced age.

  • Incidence and prognosis

    • Medial medullary syndrome is uncommon in the spectrum of brainstem strokes, but recognizing it promptly is important for secondary prevention and rehabilitation planning. Prognosis varies with the extent of infarction and the timeliness of treatment and supportive care.

Treatment and Prognosis

  • Acute management

    • General ischemic stroke care applies, including rapid evaluation for reperfusion therapy if the patient is within the therapeutic window and meets criteria. The applicability of thrombolysis or endovascular therapy depends on the individual vascular distribution and eligibility.
    • Supportive care, management of airway and swallowing safety, and prevention of complications are central to early care.

  • Secondary prevention

    • Risk factor control (blood pressure, lipids, glucose), antithrombotic therapy as indicated, and lifestyle modifications are important to reduce recurrence risk.

  • Rehabilitation

    • Motor and sensory deficits in the body and tongue function require multidisciplinary rehabilitation, including physical therapy, occupational therapy, and speech-language pathology.

Controversies and Debates

  • Terminology and classification

    • There has been discussion in the neurological literature about naming conventions for brainstem syndromes. Some clinicians prefer descriptive labels that specify the vascular territory and structures involved, while others continue to use traditional eponymous terms. The descriptive framework helps clinicians communicate the localization and mechanism more clearly, particularly in complex or atypical cases.

  • Evidence base and treatment guidance

    • Because medial medullary syndrome is relatively rare, much of the clinical guidance comes from case reports and small series rather than large randomized trials. This has implications for the strength of evidence guiding specific management decisions within the broader stroke care paradigm.

  • Diagnostic sensitivity

    • Early detection relies on high-quality imaging and clinical assessment. There is ongoing discussion about the best imaging strategies to identify small brainstem infarcts promptly, which can influence treatment decisions and prognostication.

See also