Arterial infarction of spinal cord

An arterial medullary ischemic infarction (a form of spinal vascular accident) refers to acute spinal cord injury caused by a sudden and critical decrease in oxygen supply. If perfusion is quickly restored, the event may not result in permanent spinal cord damage (TIA = transient ischemic attack). In the more common scenario, the ischemic area leads to a permanent necrotic zone (established stroke).

These are very rare occurrences. The preferred locations are thoraco-lumbar and sacral.

Although not well understood and poorly codified in terms of management, this is a medical emergency. The functional prognosis is usually very poor.

Etiologies

The most common causes are aortic and iatrogenic pathologies.

• Aortic pathologies ++++
  • Aortic atheroma:
    • In this case, the clinical evolution can be insidious (differential diagnosis: degenerative motor neuron diseases) with the development of chronic paraparesis.
  • Aortic dissection:
    • By extension of the dissection into the intercostal or lumbar arteries or by compression of these arteries.
    • Spinal ischemia is the third neurological manifestation of aortic dissections (after peripheral nerve damage and strokes).
    • → Typically results in a total transverse thoracic infarction (middle or lower thoracic), with the cervical cord usually spared due to its vascularization from the vertebral arteries. Rarely, a lumbosacral infarction can occur due to an abdominal aortic dissection.
  • Aortic coarctation:
    • A possible cause of spinal stroke when the coarctation occurs distal to the origin of the subclavian artery (the spinal arteries are then included in the collateral network, where systolic blood pressure is typically higher).
    • Mechanisms of possible spinal infarctions:
      • Blood diversion away from the caudal spinal cord.
      • Morphological changes in the spinal arteries due to hypertension.
    • Possible clinical manifestations: variable sensory-motor and/or sphincter deficits, intermittent neurological claudication.

• Iatrogenic:
  • Diagnostic angiographies or interventional radiology (for spinal arteriovenous malformations, renal tumors, pulmonary arteriovenous fistulas, hemoptysis, etc.).
  • Aortic surgery (++ of aortic coarctation).

• Occlusions of one or more vertebral arteries:
  • Atherosclerosis
  • Dissection
• Occlusions of intercostal and lumbar arteries
  • Exceptionally described in cases of rib resections, thoracoplasty, pneumonectomy, sympathectomies, or extensive spinal orthopedic surgery.

• Primary occlusions of spinal and intramedullary arteries:
  • Infectious pathologies: syphilis, tuberculosis, shingles, fungal meningitis, Lyme disease.
  • Inflammatory pathologies: sarcoidosis, isolated granulomatous vasculitis of the spinal cord, Horton’s disease, lupus, polyarteritis nodosa, Sjögren’s syndrome, rheumatoid disease, radiation therapy.
  • Hematological conditions: sickle cell disease, antiphospholipid antibody syndrome, prothrombin gene mutation.
  • Intrathecal injections.
• Low blood flow = hemodynamic:
  • Due to prolonged severe hypotension, shock, prolonged cardiocirculatory arrest, cardiovascular surgery, myocardial infarction, certain cardiac conduction disorders.
  • → Infarcts typically located around T4, generally secondary to concomitant cerebral anoxia.
• Embolisms in radicular or spinal arteries:
  • Cardio-embolisms: Due to bacterial or neoplastic endocarditis, atrial myxoma, myocardial infarction, etc.
  • Cholesterol emboli.
  • Various: gas emboli (hyperbaric chamber), embolisms of intervertebral disc fragments through an adjacent vascular breach.
• Spinal cord compressions:
  • An infarct due to vascular occlusion can occur during any spinal cord compression (including tumor-related, post-traumatic, Paget's disease, severe kyphoscoliosis), leading to sudden clinical decompensation.

Clinical Presentation

A spinal cord infarction usually presents with a phase of "spinal shock": acute onset of flaccid paraparesis or tetraparesis with decreased or absent reflexes below the affected level. After 24 hours to several weeks, reflexes reappear, evolving into hyperreflexia and spasticity below the lesion (areflexia may persist at the level of the infarct due to lower motor neuron involvement).

Specific clinical patterns:

• Transient spinal ischemic attacks:
  • Extremely rare.
  • Highly variable: paraplegia or tetraplegia, paresthesias in the lower limbs, proprioceptive ataxia.
  • Uncertain significance. No series has demonstrated a link between spinal TIA and a subsequent established infarction.
  • Main differential diagnosis: transient spinal symptoms from dural arteriovenous fistulas with perimedullary venous drainage.

• Total transverse infarctions:
  • Sudden deficit: acute massive flaccid paraplegia or tetraplegia + sphincter disorders + complete anesthesia below the affected level (possible band of relative hypoesthesia above).
  • May result from:
    • Multiple emboli → urgent search for an embolic source (++ aortic pathologies and cardio-embolisms).
    • Occlusion of a vessel supplying two radiculomedullary arteries, one to the anterior spinal artery and the other to the posterior spinal network.
  • Poor functional prognosis.

• Anterior spinal artery territory infarction:
  • Total infarctions:
    • The most common spinal infarction.
    • Typically located in the thoraco-lumbar region (territory of the Adamkiewicz artery) → manifests with spinal pain followed by the rapid onset of neurological deficit: flaccid paraplegia + early sphincter disorders + thermoalgesic anesthesia, generally with preservation of other sensory modalities.
    • Rarely, sphincter disorders are absent (due to an intact sacral supply to the conus medullaris).
    • Rarely, isolated infarction of the conus medullaris occurs with sphincter + sensory disorders + distal motor deficits in the lower limbs with absent Achilles reflexes (due to occlusion of an existing sacral supply).
    • In the case of cervical infarction: tetraplegia +- respiratory disorders (high lesion).
  • Partial infarcts (limited to the central territory = sulcocommissural arteries) :
    • Usually bilateral, with a characteristic radiological appearance of "owl’s eyes or snake bite."
    • The motor deficit typically has a distal predominance.
    • Sometimes manifests as a proximal motor deficit in the upper limbs ("man in a barrel") + abolition of myotatic reflexes ± pain.
    • Sometimes unilateral (due to double anterior spinal arteries, each vascularizing one hemicord, or alternating right-left vascularization of each hemicord by sulcal arteries not bifurcating at the midline).
    • → Brown-Séquard syndrome (++ incomplete due to the absence of proprioceptive disturbances).

• Infarct in the posterior spinal territory (posterior third of the spinal cord)
  • Multiple afferents supplying the posterior spinal arteries + complex anastomotic networks → very rare.
  • Clinically very variable. Usually characterized by a predominance of paresthesias and loss of vibratory sensation in the sublesional territory. Other possible symptoms include paraparesis or unilateral clinical signs.

• Centromedullary infarct
  • Can be isolated or result from the upward extension of a total transverse infarct.
  • Generally associated with hemodynamic failure: cardiac arrest, mitral stenosis, prolonged arterial hypotension, etc. Reported cases also include neoplastic epiduritis or spinal trauma.
  • Typically spares the peripheral white matter while affecting the centromedullary gray matter.

Complementary Examinations

For diagnostic purposes:

• Spinal MRI:
  • Infarct visible from the 6th hour (T2 hyperintensity, iso-intense on T1).
    • Very early detection possible with diffusion sequences.
    • The differential diagnosis can be challenging with myelitis.
  • MRI is useful before the 6th hour, even without diffusion sequences, to rule out differential diagnoses, particularly surgical emergencies (compressive etiologies, etc.).
  • An indirect and highly suggestive sign sometimes observed: vertebral infarct (T1 and T2 hypersignal).

• For etiological purposes, depending on the clinical context:
  • Lumbar puncture: Always performed after the MRI, may be useful to rule out differential diagnoses or rare infectious and vasculitic causes of spinal infarcts.
  • Abdominal ultrasound, transesophageal echocardiography, thoracoabdominal CT scan: To exclude an aneurysm or aortic dissection.
  • Angio-MRI or angiography.
  • Blood tests, cardiac ultrasound, electrocardiogram, etc.

Treatment and Management

• Etiological treatment if possible.
• Prevention of pressure ulcers, sphincter care with intermittent catheterization if necessary, early rehabilitation.
• General care, thromboembolic prophylaxis (SC clexane), preventive doses of PPIs.
• No evidence-based management (EBM) exists for other treatments. However, management can be based on ischemic stroke protocols (antiplatelet agents, lipid-lowering agents, blood pressure control, and other cardiovascular risk factors), adapted on a case-by-case basis.

Prognosis

Overall acute phase mortality is 10-20%. 40-60% of survivors will have severe sequelae. Most recovery occurs within the first month, and any remaining deficit at one year is usually considered permanent.

The presence of proprioceptive disorders, complete paraplegia, or sphincter dysfunction in the acute phase indicates a poor prognosis.

Bibliography

EMC, traité de Neurologie, 2018

Mullen MT, Spinal cord infarction: Clinical presentation and diagnosis, UpToDate, 2024

Mullen MT, Spinal cord infarction: Epidemiology and etiologies, UpToDate, 2024

Mullen MT, Spinal cord infarction: Treatment and prognosis, UpToDate, 2024

Osborn AG et al, Brain, Elsevier, 2018