Table 1.
The number of sensory fibers within each of the sciatic nerve branches (peroneal, tibial, sural) that contributes to each of the Dorsal root ganglias (DRGs; L3, L4, and L5) was taken from (Swett et al., 1991).
| Sural-SNI | Tibial-SNI | Sensory neurons1 | ||
|---|---|---|---|---|
| # (%) Injured sensory neurons | # (%) Injured sensory neurons | #neurons (% of a given sciatic nerve branch)1 | #sensory neurons in DRG mean2,3 | |
| L3-DRG1 | 113(∼0.8%) | 65 (∼0.5%) | 65 (2.4% of peroneal) | |
| 48 (1.0% of tibial) | ||||
| 0 (0% of sural) | ||||
| L4-DRG1 | 5,367 (43%) | 2,208 (18%) | 2133 (79% of peroneal) | 12,496 (12,000–12,991) |
| 3234 (68.1% of tibial) | ||||
| 75 (4.5% of sural) | ||||
| L5-DRG1 | 1,967 (13%) | 2065 (13%) | 501 (18.6% of peroneal) | 15,321 (15,000–15642) |
| 1466 (30.9% of tibial) | ||||
| 1564 (93.4% of sural) | ||||
| #/type neurons injured in each SNI | 7,447 sensory (68%)1 | 4,338 sensory (39%)1 | ||
| 1,614 motor | 700 motor | |||
| 13,200 sensory3 | 8,200 sensory3 | |||
| 1,600 motor | 600 motor | |||
| 4,800 sympathetic | 2,600 sympathetic |
Sprague–Dawley rats: 1(Swett et al., 1991) and 2(McKay Hart et al., 2002). Wistar rats: 3(Schmalbruch, 1986). To estimate the percentage of injured sensory neurons within each DRG we used the total number of sensory neurons reported for the L4-DRG and L5-DRG in two studies (Schmalbruch, 1987; McKay Hart et al., 2002). Since no values were available for L3-DRG we used an average value of those reported for the L4-L5 DRG (13,908). Although those two studies used different rat species (Sprague–Dawley and Wistar rats), they found a comparable number of sensory neurons within the DRG and of motor fibers within the various sciatic nerve branches. However, the number of sensory fibers within each of the sciatic nerve branches was very different, being almost double in Wistar rats than in Sprague–Dawley rats. We are showing the values from the Schmalbruch study, since it also provides us with the number of sympathetic fibers within each of the sciatic nerve branches, which allowed us to provide an estimate of the number of sympathetic fibers that would be expected to be injured in both spared nerve injurys (SNIs). This was done to help us in the discussion.