Spinal cord blood supply

7 min read Last updated April 8, 2026

Why anaesthetists care (clinical links)

  • Spinal cord perfusion depends on the balance between inflow and outflow pressures; ischaemia can occur with hypotension, raised CSF pressure, or interruption of segmental feeders.
    • SCPP ≈ MAP − max(CSF pressure, venous pressure).
    • Practical: maintain MAP; avoid high intrathoracic/venous pressures; consider CSF drainage in selected aortic surgery pathways.
  • Anterior spinal artery territory (motor pathways) is more vulnerable than posterior territory; anterior cord syndrome is a key pattern to recognise.
    • Motor weakness/paralysis + loss of pain/temperature below lesion; dorsal column modalities (vibration/proprioception) relatively spared.
  • High-risk settings: thoracoabdominal aortic aneurysm repair, aortic cross-clamping, prolonged hypotension, severe anaemia/hypoxia, spinal deformity surgery, epidural haematoma/abscess, vasculitis/embolism.
  • Neuraxial anaesthesia: sympathectomy reduces MAP; if severe/prolonged, can reduce SCPP (especially in patients with compromised segmental supply).
    • Management principle: treat hypotension early (vasopressors + fluids as appropriate) and avoid sustained low MAP in vulnerable patients.

Applied anatomy patterns that map to blood supply

  • Central cord (sulcal arteries from ASA) supplies anterior horns and adjacent white matter; infarction can cause motor deficits and segmental LMN signs.
  • Peripheral cord (pial plexus/vasocorona) supplies outer white matter; watershed risk between central and peripheral territories.

Core arterial anatomy (high-yield)

  • Longitudinal arteries: 1 anterior spinal artery (ASA) + 2 posterior spinal arteries (PSA).
    • ASA runs in anterior median fissure; PSAs run posterolaterally near dorsal root entry zones.
  • Territories: ASA supplies anterior ~2/3 of cord; PSAs supply posterior ~1/3.
    • ASA: anterior horns, corticospinal tracts, spinothalamic tracts, intermediolateral cell columns (sympathetic outflow T1–L2).
    • PSA: dorsal columns (vibration, proprioception), dorsal horns (variable).
  • Reinforcement by segmental medullary (radiculomedullary) arteries from vertebral, deep/ascending cervical, posterior intercostal, lumbar, and sacral arteries.
    • Not every segment has a large feeder; supply is discontinuous with a few dominant radiculomedullary arteries.
  • Artery of Adamkiewicz (great anterior segmental medullary artery): dominant feeder to ASA for lower thoracic/lumbar enlargement.
    • Most commonly arises from a left posterior intercostal artery between T9–T12 (range ~T5–L2).
    • Clinical: interruption during aortic surgery can cause anterior spinal artery syndrome and paraplegia.
  • Pial arterial network (vasocorona) encircles cord and connects ASA and PSAs; gives penetrating branches to peripheral cord.

Venous drainage (often examined)

  • Intrinsic venous network drains to longitudinal anterior and posterior spinal veins, then via radicular veins to epidural venous plexus (Batson plexus).
  • Epidural venous plexus is valveless; venous pressure can rise with increased intrathoracic/abdominal pressure and can reduce SCPP.
    • Examples: high PEEP, coughing/straining, pneumoperitoneum, IVC obstruction, raised CVP.

Physiology of spinal cord perfusion

  • Perfusion pressure concept: SCPP ≈ MAP − max(CSF pressure, venous pressure).
    • Spinal canal is a closed compartment: raised CSF pressure (e.g., oedema/haematoma) can critically reduce perfusion even with normal MAP.
  • Autoregulation exists but is less robust than cerebral circulation and can be impaired by ischaemia, inflammation, anaemia, and extremes of PaCO2.
    • Hypercapnia tends to vasodilate spinal cord vessels; hypocapnia tends to vasoconstrict (directionally similar to brain), but clinical impact is less predictable.
  • Watershed vulnerability: mid-thoracic cord (classically ~T4–T8) has fewer large segmental feeders and is prone to ischaemia during systemic hypoperfusion.

Clinical syndromes and localisation

  • Anterior spinal artery syndrome: bilateral motor weakness + loss of pain/temperature; dorsal column function preserved; may have autonomic dysfunction (e.g., hypotension, bladder/bowel).
  • Posterior spinal artery infarction: loss of vibration/proprioception, sensory ataxia; motor relatively preserved.
  • Central cord (sulcal artery) infarcts can produce segmental LMN weakness and dissociated sensory loss depending on level/extent.

Aortic surgery and spinal cord protection (principles)

  • Mechanisms of injury: interruption of segmental feeders (incl. Adamkiewicz), embolism, prolonged hypotension, raised CSF pressure, reperfusion injury.
  • Protection strategies (conceptual): maintain MAP/SCPP, limit cross-clamp time, reimplant key intercostals when appropriate, CSF drainage to lower CSF pressure, avoid anaemia/hypoxia, normothermia or controlled hypothermia depending on protocol, neuromonitoring (MEPs/SSEPs).
    • MEPs are more sensitive to anterior cord (motor) ischaemia than SSEPs (dorsal column).
Describe the arterial blood supply of the spinal cord.

Aim for a structured answer: longitudinal arteries, segmental reinforcement, territories, and key named vessel.

  • Longitudinal system: 1 anterior spinal artery (ASA) and 2 posterior spinal arteries (PSA).
  • ASA supplies anterior ~2/3; PSAs supply posterior ~1/3 of the cord.
  • Reinforcement by segmental medullary (radiculomedullary) arteries arising from vertebral/cervical, intercostal, lumbar and sacral arteries.
  • Pial arterial plexus (vasocorona) links ASA and PSAs and supplies peripheral cord.
  • Artery of Adamkiewicz is the dominant feeder to the ASA for lower thoracic/lumbar cord; commonly left-sided T9–T12 (range T5–L2).
What structures are supplied by the anterior spinal artery, and what clinical syndrome results from its occlusion?

Link anatomy to deficits.

  • ASA supplies anterior horns, corticospinal tracts, spinothalamic tracts, and intermediolateral cell column (sympathetic outflow).
  • Occlusion → anterior spinal artery syndrome: bilateral motor weakness/paralysis and loss of pain/temperature below lesion, with relative preservation of vibration/proprioception (dorsal columns).
  • May include autonomic dysfunction (bladder/bowel, sexual dysfunction, hypotension depending on level).
Describe the venous drainage of the spinal cord and explain why it matters clinically.

Examiners often want: valveless plexus and implications for perfusion and spread of disease.

  • Anterior and posterior spinal veins drain into radicular veins and then the epidural venous plexus (Batson plexus).
  • Epidural venous plexus is valveless → venous pressure changes transmit readily; raised CVP can reduce SCPP.
  • Clinical: high PEEP/pneumoperitoneum/straining can increase venous pressure; also facilitates spread of infection/metastases to spine.
Define spinal cord perfusion pressure and list factors that reduce it during anaesthesia.

Give the equation and then practical causes.

  • SCPP ≈ MAP − max(CSF pressure, venous pressure).
  • Reduced MAP: neuraxial sympathectomy, haemorrhage, deep anaesthesia, cardiogenic shock, aortic cross-clamp release.
  • Raised CSF pressure: spinal canal haematoma/abscess, cord oedema, tight surgical closure, impaired CSF drainage.
  • Raised venous pressure: high PEEP, high intrathoracic pressure, pneumoperitoneum, raised CVP, IVC obstruction.
Where is the spinal cord most vulnerable to ischaemia and why?

Watershed concept + feeder distribution.

  • Mid-thoracic cord (classically ~T4–T8) is a watershed region with fewer large segmental medullary feeders.
  • Lower thoracic/lumbar enlargement depends heavily on the artery of Adamkiewicz; interruption can cause severe deficits.
What is the artery of Adamkiewicz? Include typical origin and clinical relevance.

A common FRCA viva topic in vascular/aortic contexts.

  • Largest anterior segmental medullary (radiculomedullary) artery supplying the ASA to the lower thoracic and lumbar cord.
  • Typically arises from a left posterior intercostal artery between T9–T12 (range ~T5–L2).
  • At risk during thoracoabdominal aortic surgery; loss can cause anterior spinal artery syndrome/paraplegia.
How do MEPs and SSEPs relate to spinal cord blood supply during aortic surgery?

Link monitoring modality to cord territory.

  • MEPs assess motor pathways (corticospinal/anterior cord) and are sensitive to ASA territory ischaemia.
  • SSEPs assess dorsal column function and may remain preserved in anterior cord ischaemia.
  • Anaesthetic implications: MEPs are depressed by volatile agents and neuromuscular blockade; TIVA and minimal/controlled NMB often required.
A patient develops paraplegia after thoracoabdominal aneurysm repair. Outline the likely mechanism and immediate management priorities.

Think: restore SCPP and address reversible causes quickly.

  • Likely mechanism: spinal cord ischaemia (ASA territory) due to interruption of segmental feeders (incl. Adamkiewicz), hypotension, raised CSF pressure, embolism, or reperfusion injury.
  • Immediate priorities: increase MAP (vasopressors/inotropes), optimise oxygenation and Hb, reduce CSF pressure if a drain is in place (or urgent consideration per protocol), avoid high CVP/PEEP, correct acid-base and temperature.
  • Urgent imaging/assessment for compressive causes if neuraxial techniques used (epidural haematoma) and involve surgical/vascular and neuro teams early.
Explain why dorsal column modalities may be preserved in anterior spinal artery syndrome.

This tests territorial anatomy.

  • Dorsal columns are predominantly supplied by the posterior spinal arteries and pial network, not the ASA.
  • Therefore ASA infarction preferentially affects motor and spinothalamic pathways while sparing vibration/proprioception.

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