Spinal Cord Injury

Spinal cord injury (SCI) is damage to the spinal cord from trauma or, less commonly, from non-traumatic causes, producing partial or complete loss of motor, sensory, and autonomic function below the level of injury. An initial mechanical insult is followed by a secondary cascade of ischaemia and inflammation, and acute management centres on stabilising the spine and, where indicated, decompressing the cord.

Definition

Spinal cord injury is structural or functional damage to the spinal cord, most often traumatic, that interrupts ascending and descending pathways and causes neurological deficit below the level of the lesion.

Scope

The topic covers the biphasic pathophysiology of acute SCI, the concept of injury level and completeness, the role and timing of surgical decompression, and the systemic consequences that shape acute care. It treats SCI as a neurosurgical and critical-care entity; long-term functional restoration is addressed in the related rehabilitation topic. The entry is a reference orientation and not a source of clinical protocols.

Core questions

• How do primary mechanical injury and the secondary injury cascade each contribute to deficit?
• What do injury level and completeness mean, and how are they classified?
• What does the evidence show about the timing of surgical decompression?
• Which systemic complications dominate the acute and subacute course?

Key concepts

• Primary versus secondary injury
• Complete versus incomplete injury
• Neurological level of injury
• Spinal shock
• Early decompression
• Mean arterial pressure support
• Venous thromboembolism risk

Mechanisms

The primary injury is the immediate mechanical disruption of axons, neurons, and microvasculature at the moment of trauma. This triggers a secondary injury cascade over hours to days, comprising ischaemia, excitotoxicity, oxidative stress, inflammation, and oedema that extends the zone of damage (Ahuja, 2017). Because secondary injury is potentially modifiable, acute care targets factors that worsen it, and surgical decompression is thought to limit ongoing mechanical and ischaemic insult; the timing of decompression has been associated with neurological outcome in cohort and pooled analyses (Fehlings, 2012; Badhiwala, 2021). The level and completeness of the lesion determine the pattern of deficit.

Clinical relevance

SCI is a defining acute neurosurgical emergency and a major cause of lifelong disability, and understanding its biphasic mechanism informs critical reading of decompression-timing and acute-care research. This entry describes the disorder for reference and does not provide management protocols, blood-pressure targets, or individualised treatment guidance, which rest with treating clinicians.

Epidemiology

Traumatic SCI most often results from road traffic collisions, falls, violence, and sport, and affects a predominantly young, male population, though falls account for a growing share in older adults; the resulting disability imposes substantial lifelong burden (Ahuja, 2017). Cervical injuries carry particular risk of respiratory compromise and of venous thromboembolism during immobilisation (Dhall, 2013).

History

Once regarded as uniformly untreatable, SCI care was transformed over the twentieth century by organised acute and rehabilitative systems and by recognition of the secondary injury cascade as a therapeutic target. Contemporary research has formally tested the timing of surgical decompression, with the STASCIS cohort and later pooled analyses informing the debate over early intervention (Fehlings, 2012; Badhiwala, 2021).

Debates

How early should the cord be decompressed after acute injury?

Cohort and pooled individual-patient analyses have associated earlier decompression with better neurological recovery, but the optimal window and its applicability across injury patterns remain under study rather than settled.

Key figures

• Michael Fehlings
• Christopher Ahuja
• Jetan Badhiwala

Seminal works

• ahuja-2017
• fehlings-2012
• badhiwala-2021

Frequently asked questions

What is the difference between primary and secondary injury in SCI?

Primary injury is the immediate mechanical damage at the moment of trauma, while secondary injury is the delayed cascade of ischaemia, inflammation, and oedema that extends the damage over the following hours and days and is the main target of acute care.

Why does the timing of decompression matter?

Because the secondary injury cascade unfolds over time, relieving ongoing mechanical compression sooner is thought to limit further ischaemic damage; cohort and pooled analyses have associated earlier decompression with improved neurological outcomes, though the optimal timing remains under study.