Intraneural hematoma with extrinsic compression: experimental study in rats and therapeutic options

Intraneural hematoma can result in the median nerve in the carpal tunnel after trauma or coagulation disorders. The decision for expectant management or decompressive surgical techniques is still controversial. Fifty male Wistar rats were divided into five groups. The sciatic nerve was wrapped around with a silastic device in four groups. In group A, the sciatic nerve was just wrapped by the silastic tube. In group B, an intraneural injection of autologous blood was added. In group C, after the hematoma creation, the silastic device was removed and a longitudinal epineurotomy was performed. In group D, the silastic device was removed after the hematoma, but the nerve was not opened. In group E (sham-operated), the sciatic nerve was exposed without hematoma or compression. Nerve function recovery was assessed periodically over 61 days using the Bain-Mackinnon-Hunter Sciatic Function Index (SFI). Group A (extrinsic compression) presented initial SFI of -26.29 +/- 2.89, with return to baseline values on the fifth postoperative day. Group B (hematoma and extrinsic compression) exhibited the poorest function (SFI of -85.23 +/- 3.51) after surgery and recovery in 23 days. Group C (liberation of silastic and hematoma drainage through epineurotomy) and group D (only removal of the silastic tube) presented similar initial SFI values of -32.78 +/- 7.45 and -45.13 +/- 6.84, respectively. In both the groups, the SFI values returned to baseline level on fifth postoperative day. The statistical analysis of SFI identified a significant difference (P < .0001) between the expectant management (group B) and the descompressive surgery approach (groups C and D) by 1st to 19th postoperative day. The number of degenerative fibers and density of degenerative fibers were statistically significantly longer in group B when compared with the other groups. There was no statistical difference between the other groups when these parameters were analyzed. Thus, immediate decompressive procedures of the intraneural hematoma provide a faster functional recovery and reduce the damage to the axon fibers.