Introduction: The time window of decompression after spinal cord injury (SCI) is unclear. Several laboratory investigations have studied it in animal models using a paradigm of SCI followed by sustained compression.

Methods: A framework of primary injury severity classification was developed based on behavioral outcomes in the control groups. SCI was categorized as mild (BBB score 18-21 or Tarlov 5), moderate (BBB 9-18, Tarlov 4), and severe (BBB <9, Tarlov <4). The sustained compression was considered as mild (<30%), moderate (31-40%), and severe (>40%) based on the extent of canal compromise. The outcomes were categorized as good or poor based on mean scores greater or less than antigravity.

Results: For mild primary injury, a sustained mild to moderate compression for 6 hours resulted in poor functional recovery. This time window appears to be smaller for severe compression (<3 hours). On the other hand the timing of decompression doesn’t appear to affect outcomes after severe primary injury. In the moderate primary injury group good outcomes were reported after moderate compression for <12 and severe compression for <6 hours.

Conclusions: Primary injury strongly correlates with functional outcomes in the preclinical studies of SCI. Sustained compression also affects outcomes in time dependent manner. In clinical situations, however, the current methods of severity assessment are inadequate in the acute phase and have modest predictive value for partial injury. Accurate assessment of primary injury in clinical situation is imperative to identify patients with maximal recovery potential after surgical decompression.

Patient Care: This review of preclinical studies may provide preliminary data for future investigations to study timing of decompression after spinal cord injury.

Learning Objectives: Accurate assessment of primary injury is imperative to identify subjects with maximal recovery potential after surgical decompression.

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