Anterior Cord Syndrome
Spinal cord injury from anterior spinal artery disruption causing motor paralysis
ICD-10: G83.82 · systemic condition
Anterior cord syndrome (ACS) is an incomplete spinal cord injury pattern caused by damage to the anterior two-thirds of the spinal cord — the territory supplied by the anterior spinal artery. It is characterized by bilateral motor paralysis and loss of pain and temperature sensation below the injury level, with preservation of the posterior columns: touch, proprioception, and vibration sense remain intact. This dissociation — the patient feels touch and position but cannot move or feel pain — is the clinical hallmark. The most common cause is anterior spinal artery occlusion or infarction, typically from aortic surgery, aortic dissection, hypotension, or embolism. Traumatic disc herniation compressing the anterior cord and severe cervical hyperflexion injury are other important mechanisms. ACS can also occur from aggressive surgical distraction or hypotension during complex spinal deformity correction. Among incomplete spinal cord injury syndromes, anterior cord syndrome carries the worst prognosis. Recovery of motor function occurs in fewer than 10% of patients. Sensory recovery from the preserved dorsal columns creates a painful dissociation — the patient has intact proprioception and touch but paralysis and loss of protective pain sensation, predisposing to pressure injuries and Charcot joint formation.
Anatomy & Pathology
The anterior spinal artery runs in a single longitudinal vessel along the ventral surface of the spinal cord, supplying the anterior horns (motor neurons), corticospinal tracts, and spinothalamic tracts. The posterior spinal arteries — two smaller vessels — supply the dorsal columns (proprioception and vibration). ACS selectively infarcts the anterior artery territory, sparing dorsal column function.
Symptoms
- Bilateral motor paralysis below the level of the lesion (flaccid acutely, spastic chronically)
- Loss of pain and temperature sensation bilaterally below the lesion
- Preservation of touch, vibration, and proprioception (posterior column sparing)
- Bladder and bowel dysfunction
- Absence of reflexes acutely (spinal shock); hyperreflexia after spinal shock resolves
- Painless injuries and pressure ulcers due to loss of protective pain sensation
- Sudden onset back pain at the time of cord infarction
Causes & Risk Factors
- Anterior spinal artery occlusion from aortic surgery (endovascular or open aortic repair)
- Aortic dissection extending to the ostia of spinal cord feeding arteries
- Traumatic anterior cord compression from severe cervical flexion injury with vertebral fracture
- Cervical disc herniation with massive central herniation compressing the anterior cord
- Hypotension-induced cord infarction during spine surgery or hemodynamic crisis
Treatment Options
Conservative
- Maintaining mean arterial pressure ≥85 mmHg (MAP augmentation) to maximize spinal cord perfusion in acute setting
- Comprehensive inpatient rehabilitation focusing on preservation of function in preserved modalities
- Pressure injury prevention protocols given loss of protective pain sensation
Surgical
- Emergency anterior decompression for compressive disc or bony lesion (offers some chance of recovery if done within 6–8 hours)
- Spinal stabilization for associated bony instability
- Intrathecal baclofen pump for chronic severe spasticity
When to see a spine specialist
Sudden onset of bilateral leg paralysis with preserved touch and position sense — particularly in the setting of aortic surgery, chest pain, or trauma — is a spinal cord emergency. Immediate evaluation with spinal MRI and hemodynamic support (MAP augmentation) should be initiated without delay. Early perfusion optimization offers the best chance of limiting cord infarction extent.
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Search spine specialists →Frequently Asked Questions
What makes anterior cord syndrome different from complete spinal cord injury?
In complete spinal cord injury, all motor, sensory, and autonomic function is absent below the level of injury. In anterior cord syndrome, the posterior columns are spared, meaning the patient retains touch, vibration, and proprioception. This is a defining feature that distinguishes ACS from complete injury, even though the motor and pain/temperature deficits are equally severe. The posterior column sparing also means that ACS is technically an incomplete injury with a theoretically better prognosis — though in practice, motor recovery is rare.
Why is anterior cord syndrome associated with aortic surgery?
The spinal cord is supplied segmentally by radicular arteries arising from the aorta. The artery of Adamkiewicz (arteria radicularis magna) is the dominant blood supply to the thoracolumbar cord, typically originating from the aorta at T8–L1. During aortic aneurysm repair or dissection repair, coverage or sacrifice of intercostal or lumbar arteries that supply this vessel can cause anterior spinal artery infarction. The risk is highest with thoracoabdominal aneurysm repairs and can be mitigated with CSF drainage, staged repair, and perfusion monitoring.
What is the prognosis for walking after anterior cord syndrome?
Prognosis for motor recovery in anterior cord syndrome is poor — fewer than 10–15% of patients recover functional ambulation. This contrasts sharply with central cord syndrome (50–75% ambulatory recovery) and Brown-Séquard syndrome (75–90% ambulatory recovery). The poor prognosis reflects the ischemic mechanism: infarcted tissue does not recover in the same way as compressed tissue, and the corticospinal tracts and anterior horn cells are permanently destroyed.