Several studies have identified patterns of neurological and/or functional improvement over the first few months post-injury. The majority of these studies examine neurological and/or functional status and associated changes between rehabilitation admission and discharge. In addition, the Consortium for Spinal Cord Medicine (1999) has published a review of expected neurological and functional outcomes following SCI. This Clinical Practice Guideline refers to the work of Bracken et al. (1993; 1997), Geisler et al. (1991) and Waters et al. (1994a; 1994b) in noting that over half of the expected recovery occurs in the first 2 months following injury and recovery may continue but slows noticeably after 3-6 months. This change in neurological status may represent the natural course of recovery, however, it is uncertain as to the extent that rehabilitation practices play in enhancing this recovery.
The Consortium for Spinal Cord Medicine (1999) Clinical Practice Guideline provides a comprehensive consensus review itemizing expected functional achievements for individuals at every level of SCI. Table 4 summarizes various reports in the literature for neurological and/or functional status organized by jurisdiction and also by the time period for which the data was collected. As above, data were only included in this table if the underlying sample was deemed representative of an overall heterogeneous population of individuals with SCI (i.e., unselected sample of a single or multi-centre study).
The AIS represents an internationally recognized system for the classification of individuals with SCI, and as such, has been employed to characterize overall improvement in the neurological status of people with SCI (ASIA 2002). It is somewhat similar to earlier systems such as the Frankel grading classification system. The AIS is an ordinal 5 grade scale classifying individuals from “A” to “E” with “A” designating those with complete SCI and “E” designating individuals with normal sensory and motor function. Most notably, DeVivo (2007), Pagliacci et al. (2003), Celani et al. (2001), Marino et al. (1999) and DeVivo et al. (1991) employed large multi-centre databases and found that individuals with incomplete injuries (especially AIS B or C) were more likely to improve at least 1 grade over the course of rehabilitation. In particular, DeVivo et al. (1991) reported that 45.2% and 55.9% of those initially admitted as AIS B and C respectively improved at least 1 AIS grade as compared to only 10.3% and 7.3% of individuals initially classified as AIS A or D respectively. Over the period of 1973-2006, DeVivo (2007) reported that there was an 8.8% increase in likelihood that those classified as AIS A at admission would improve to AIS B at discharge. Other reports have presented similar findings and data culled from a sample of these investigations have been summarized in Figure 2. This Figure illustrates the proportion of persons assessed at each AIS (or Frankel) grade status (i.e., A, B, C or D) at discharge from rehabilitation relative to the proportion of people at each AIS level at rehabilitation admission for each of the studies (Burke et al. 1985; Marino et al. 1999; Sumida et al. 2001; Catz et al. 2002; Pagliacci et al. 2003; DeVivo 2007). This provides an indication of the degree of neurological recovery that occurs over the period of rehabilitation. It should be noted that for each study (i.e., jurisdiction) the admission and discharge time points are variable relative to the time of injury although these all are typically within the first six months following injury. In addition, all datasets consisted of relatively unselected patients with traumatic SCI, other than the report by Sumida et al. (2001) which included patients with SCI of both traumatic and nontraumatic etiology.
As one can see, it is striking how similar these patterns of AIS conversion rates are across health systems (i.e., Australia, Israel, Italy, Japan, USA) with only Catz et al. (2002) (i.e., Israel) providing somewhat disparate results. Overall, AIS A patients comprise from 40-50% of individuals admitted to SCI rehabilitation centers and a similar, but slightly reduced percentage of those are assessed AIS A at discharge. AIS B and AIS C patients comprise ~5-15% and ~10-30% respectively with moderate reductions in these percentages manifest at discharge. Conversely, those assessed AIS D comprise ~15-25% of those admitted which increases to ~25-35% by discharge.
The majority of patients assessed AIS A at admission remain so at discharge, whereas a much greater proportion of individuals assessed AIS B recovered significant motor function during rehabilitation so as to be assessed AIS C or D. The conversion rate is even greater for those assessed initially as AIS C but much less so for those assessed as AIS D.
These conversion rates appear similar across these studies and therefore provide a base for comparison with other findings. For example, Moslavac et al. (2008) reported data for a centre-based study in Croatia at which all national cases of SCI resulting from road traffic accidents received rehabilitative care. In this case, although 49% of people were AIS A at admission and 93% of these remained AIS A at discharge, there was a tendency for greater proportions of persons making conversions to AIS D or E of those assessed with an incomplete injury at admission.
Similarly, many individuals also make significant functional gains during comprehensive inpatient rehabilitation. Most often, functional status has been assessed at admission and discharge from rehabilitation using the FIM (De Vivo et al. 1991; Muslumanoglu et al. 1997; Tooth et al. 2003; Chan & Chan 2005) or MBI (Yarkony et al. 1987). Typically, functional gains are greater with rehabilitation for those with incomplete injuries as compared to complete injuries and for those with paraplegia as compared to those with tetraplegia (De Vivo et al. 1991; Muslumanoglu et al. 1997; Tooth et al. 2003; Chan & Chan 2005). In particular, DeVivo et al. (1991) reported similar average FIM gains for those with incomplete and complete paraplegia and incomplete tetraplegia (i.e., 37, 36 and 34 respectively) but much reduced gains for those with complete tetraplegia (i.e., 15). For the most part increases seen in the FIM have been attributed to motor FIM changes with little change in cognitive FIM scores at least partly due to an apparent ceiling effect (Chan & Chan 2005).
There is level 4 evidence that a significant proportion of people (~50%) initially assessed as AIS B and C will improve by at least 1 AIS grade in the first few months post-injury concomitant with inpatient rehabilitation. Fewer individuals (~10%) initially assessed as AIS A and D will improve by 1 AIS grade.
There is level 4 evidence that individuals make significant functional gains during inpatient rehabilitation, more so for those with complete and incomplete paraplegia and incomplete tetraplegia.