Characterizing Natural Recovery after Traumatic Spinal Cord Injury

Abstract

The predominant tool used to predict outcomes after traumatic spinal cord injury (SCI) is the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI), in association with the American Spinal Injury Association (ASIA) Impairment Scale (AIS). These measures have evolved based on analyses of large amounts of longitudinal neurological recovery data published in numerous separate studies. This article reviews and synthesizes published data on neurological recovery from multiple sources, only utilizing data in which the sacral sparing definition was applied for determination of completeness. Conversion from a complete to incomplete injury is more common in tetraplegia than paraplegia. The majority of AIS conversion and motor recovery occurs within the first 6-9 months, with the most rapid rate of motor recovery occurring in the first three months after injury. Motor score changes, as well as recovery of motor levels, are described with the initial strength of muscles as well as the levels of the motor zone of partial preservation influencing the prognosis. Total motor recovery is greater for patients with initial AIS B than AIS A, and greater after initial AIS C than with motor complete injuries. Older age has a negative impact on neurological and functional recovery after SCI; however, the specific age (whether >50 or >65 years) and underlying reasons for this impact are unclear. Penetrating injury is more likely to lead to a classification of a neurological complete injury compared with blunt trauma and reduces the likelihood of AIS conversion at one year. There are insufficient data to support gender having a major effect on neurological recovery after SCI.

Keywords: neurological outcome; predicting outcome; prognosis; spinal cord injury; spontaneous recovery.

FIG. 1.

Illustrated are four International Standards for Neurological Classification of Spinal Cord Injury patterns that have been associated with a greater degree of recovery in those with an initial neurological injury (American Spinal Injury Association Impairment Scale A). Left to right: (1) the complete to incomplete transition based on sacral sparing; (2) in paraplegia, a sensory zone of partial preservation (ZPP) of at least three segments, here indicated below the T7 sensory level including T8 with some pinprick and T9 and T10 with only light touch; (3) some proximal motor sparing of hip flexors that is three or more levels below the neurological level of injury (NLI, here T7) with a motor score of less than 3/5; and (4) in tetraplegia, a motor ZPP of at least two segments (here, an NLI of C4 and some preservation, <3/5 in C5 and C6).