Duration of neuronal stretch correlates with functional loss.
Postoperative cranial nerve weakness or paralysis is not uncommon in many otolaryngologic surgical procedures. Our study used a rat model to test the hypothesis that the length of time that a nerve is under tension may be an important variable in the amount of postoperative paresis. Forty Sprague-Dawley rats were divided into 4 groups that underwent either a sham operation or a traction injury for 1, 2, or 5 minutes. The traction injury was performed with a vessel loop placed around the sciatic nerve with 50 g of tension. Traction injury for 1 or 2 minutes did not result in any statistical differences in the motor capabilities of the lower limb. However, those animals with a stretch injury for 5 minutes had a significant loss of function (P < 0.01) when compared with all other groups. Histologic examination of nerves harvested on postoperative day 7 showed no evidence of mechanical injury. This study demonstrates that even minimal tension, if maintained for a significant amount of time, may result in postoperative weakness.
Fowler
S S
SS
Department of Otolaryngology-Head and Neck Surgery, Loyola University Medical Center, Maywood, IL, USA.
Leonetti
J P
JP
Banich
J C
JC
Lee
J M
JM
Wurster
R
R
Young
M R
MR
D000818:Animals; D020209:Cranial Nerve Injuries / Q000209:etiology*; D008297:Male; D013517:Otorhinolaryngologic Surgical Procedures / Q000009:adverse effects*; D010291:Paresis / Q000209:etiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors