Sparing of sensation to pin prick predicts recovery of a motor segment after injury to the spinal cord.

We have reviewed 59 patients with injury to the spinal cord to assess the predictive value of the sparing of sensation to pin prick in determining motor recovery in segments which initially had MRC grade-0 power. There were 35 tetraplegics (18 complete, 17 incomplete) and 24 paraplegics (19 complete, 5 incomplete), and the mean follow-up was 29.6 months. A total of 114 motor segments initially had grade-0 power but sparing of sensation to pin prick in the corresponding dermatome. Of these, 97 (85%) had return of functional power (> or = grade 3) at follow-up. There were 479 motor segments with grade-0 power but no sparing of sensation to pin prick and of these only six (1.3%) had return of functional power. Both of the above associations were statistically significant (chi-squared test, p < 0.0001). After injury to the spinal cord, the preservation of sensation to pin prick in a motor segment with grade-0 power indicated an 85% chance of motor recovery to at least grade 3.