1254 - Predictors of wrist extensor muscle recovery following acute traumatic spinal cord injury: A model systems replication study

Prognosticating return of functional hand grasp via tenodesis is important for treating patients with tetraplegia from spinal cord injury (SCI). A 1993 study by Browne et al. found that C5 sharp-dull discrimination, at least trace C6 myotome strength, and at least antigravity C5 myotome strength at the initial neurological exam were all independently predictors of one-year antigravity wrist extensor strength. However, this small single center study has never been replicated. The aim of our study was to test these prediction rules with a larger national dataset.

Design:

The SCI Model System (SCIMS) database was used to identify patients with ASIA impairment scale (AIS) A or B with neurologic level of injury (NLI) at C4 or C5. Patients were identified with initial C6 myotome less than antigravity within 30 days of injury. All patients were ≥18 years old and laterality was preserved during analysis of one-year C6 motor recovery. Sensitivity, specificity, positive predictive value (PPV), and negative predictive values (NPV) were calculated for each of the prediction rules noted by Brown et al.

Results:

Of the 35,675 patients identified, 219 one-year C6 motor recovery outcomes met criteria and were analyzed. The average age was 37-year-old and most (86%) were male. Differing greatly from the seminal study, the positive predictive values were: 57% if initial C5 sharp-dull discrimination was present, 61% if initial C5 myotome strength was antigravity, and 74% if initial C6 myotome strength was at least a 1/5 or 2/5.

Conclusions:

Having C5 sharp-dull discrimination was not as predictive of one-year ipsilateral antigravity C6 motor recovery as had previously been shown. Instead, having at least trace C6 motor strength was a better predictor of regaining one-year ipsilateral antigravity wrist extension.