Motor Nerve Recovery in a Rabbit Model: Description and Validation of a Noninvasive Ultrasound Technique

Abstract

Purpose To develop and validate a noninvasive ultrasound technique for the longitudinal analysis of functional recovery after segmental peroneal nerve reconstruction in a rabbit model.Methods Twelve male New Zealand White rabbits underwent a 1-cm peroneal nerve autograft reconstruction. Ultrasound measurements were performed before surgery and at 1, 2, 4, 8, 12, and 16 weeks postoperatively. All rabbits were managed with manual restraint for the ultrasound procedure, avoiding the risks of anesthetics. At 12 and 16 weeks, we evaluated functional recovery using compound muscle action potential, isometric tetanic force measurements, wet muscle weight, and nerve histomorphometry. Data were compared with ultrasound measurements by calculating the Pearson correlation coefficient. We determined intra-rater and inter-rater reliability of the ultrasound measurements.Results Ultrasound demonstrated good correlation with isometric tetanic force measurements and wet muscle weight, good correlation with nerve histomorphometry, and moderate correlation with compound muscle action potential. Both intra-rater and inter-rater reliability of the ultrasound technique was excellent.Conclusions Ultrasound analysis of the tibialis anterior muscle provided a reliable method for analysis of functional recovery in a rabbit peroneal nerve reconstruction model. The noninvasive nature allowed for longitudinal follow-up within the same animal and measurement of early recovery without the use of anesthesia.Clinical relevance Application of this noninvasive technique can reduce the variability and sample size necessary in peripheral nerve reconstruction studies and may provide an ideal tool for comparative studies in larger animal models. (J Hand Surg Am. 2016;41(1):27e33.

Brachial plexus nerve injury and repair in a rabbit model part II: Does middle trunk injury result in loss of biceps function while repair results in recovery of biceps function

“…Only 47% of rabbits demonstrated motor recovery in the repair group. In previous studies of nerve reconstruction and motor recovery of the rabbit tibialis anterior, between 11 and 12.5% of animals exhibited no recovery (Bulstra et al, ; Giusti et al, ).…”

“…It is also quantitative and therefore more easily compared across studies. Another strength of the study is its use of two validated outcomes measures: isometric tetanic force and ultrasound‐measured cross‐sectional area (Bulstra et al, ; Giusti, Kremer, et al, ; Shin et al, ).…”

“…After Institutional Animal Care and Use Committee approval, 22 New Zealand white rabbits (3–4 kg) underwent a preoperative ultrasound of the bilateral biceps muscles to measure cross‐sectional area (Bulstra et al, ). The rabbits were randomized to have either the left side or right side middle trunk sharply divided, while the contralateral side served as the internal control for the experiment.…”

“…Ultrasound measurement of the bilateral biceps cross‐sectional area was performed without anesthesia and under manual restraint with the Bunny Snuggle jacket (Lomir Biomedical, Inc., Malone, NY) as previously described (Bulstra et al, ). Three separate measurements of cross‐sectional area were averaged for the operative and nonoperative side at four time points: prior to surgery, 4, 8 weeks postoperative and at the time of sacrifice 12 weeks after the surgical procedure.…”

“…Since zero force recovery was expected in the no repair group, the primary outcome was ultrasound‐measured cross‐sectional area rather than muscle force. Power calculations were based on previous studies of ultrasound measurements of cross‐sectional area of the rabbit tibialis anterior (Bulstra et al, ). To detect a difference in cross‐sectional area of 49% assuming a standard deviation of 20%, an alpha of 0.05 and unequal variances, 15 repair and 4 no‐repair rabbits would be needed to power the study at 80%.…”