Title: The Effect of Distal Epineural Resection of The Recipient Nerve on Axonal Regeneration in Terminolateral
Neurroraphy
Authors:Selahattin Özmen, MD, Osman Latifoglu, MD, Sühan Ayhan, MD, Reha Yavuzer, MD, Gülay Nurlu, MD,
Kenan Atabay, MD.
Introduction: When neither end-to-end neurroraphy nor nerve grafts are available for restoration of the nerve continuity
following nerve damage, end-to-side neurroraphy is an alternative. Unfortunately, end-to-side neurroraphy is not
successful yet to restore lost function enough as end-to-end neurroraphy. We aimed to find out the impact of distal
epineural resection of the recipient nerve on axonal regeneration in end-to-side neurroraphy.
Materials and Method: Forty male wistar rats, with an average weight of 225±25 gr. were used in the study. Under
ketamin-HCl + Benzetonium-Cl anesthesia, right hind limb of the animal was used as operative leg, and left hind limb as
control leg. Sciatic, peroneal and tibial nerves were isolated. Peroneal nerve was transected at a point about one cm
proximal to the bifurcation of the tibial nerve. The proximal stump of the peroneal nerve was buried into the splitted
gluteal muscle fibers and sutured with 6/0 nylon.
Forty rats were included in four groups.
In group I (n=10) (Fig 1), no any other procedure was performed. An epineural window was created in groups II, III and
IV. We did not do any epineural resection, instead splitted the epineural fibers, while creating epineural window on tibial
nerve. In group II (n=10) (Fig 2), the distal stump of the severed peroneal nerve was sutured to the epineural window
with 4 epineural sutures by 10/0 nylon, in an end-to-side fashion. In group III (n=10) (Fig 2), about 1 mm of distal stump
of the severed peroneal nerve was buried into the epineural window and sutured with 4 epineural sutures using 10/0
nylon. In group IV (n=10) (Fig 2), about 1 mm of the epineurium was resected circumferentially from the distal stump of
the severed peroneal nerve, and then buried into the epineural window of the tibial nerve like group III, by 4 epineural
sutures using10/0 nylon.
Fig I
Fig II
Fig 1-2: Anastomosis in the control and experimental groups (S: Sciatic nerve, T:Tibial nerve, P: Peroneal nerve, G:
Gluteus muscle, TA: Tibialis Anterior muscle, GK: Gastrocnemius muscle)
At the third postoperative month, functional evaluation was performed with walking track analysis and
electromyographic studies. Tibial function index (TFI), peroneal function index (PFI) and sciatic function index (SFI)
were calculated. By electrophysiological studies gastrocnemius (GC) and tibialis anterior (TA) muscles of both
experimental and control groups were evaluated electromyographically at the third month postoperatively. Muscle
contraction amplitude, latency, and area of contraction wave were determined for control and experimental limbs.
Experimental limb/control limb proportions of these measured values were calculated for each group.
Following functional evaluation animals were sacrificed. Anterior tibial and gastrocnemius muscles of both hindlimbs
were taken and fixed in 10% formol solution following wet-muscle weight measurement.
Peroneal (CNP) and tibial (CNT) nerves of the control hindlimb were taken and fixed in Karnovsky solution. In the
experimental limb, biopsies were taken from proximal peroneal nerve stump (NPP), distal peroneal nerve (NPD),
anastomosis zone (AN), tibial nerve proximal (NPD) and distal (NPD) to anastomosis. Nerve specimens were fixed in
Karnovsky solution. Histomorphometric analysis of nerve and muscle specimens, including muscle fiber diameter, nerve
fiber count and myelin thickness, was performed.
Statistical analysis was done with SPSS 10.0 software using ANOVA and Tukey tests.
Results:
Walking Track Analysis: No statistically important difference was determined between groups for TFI (p>0.05)
(ANOVA-Tukey). There was statistically highly important difference between PFI of group I and PFI of group II and
group IV (p<0,05) (ANOVA-Tukey). This difference was very significant between group I and group IV (p<0,01). No
statistically important difference was determined for PFI values, between group I and III, and between groups II, III and
IV (p>0,05) (ANOVA-Tukey)
Electrophysiological Evaluation: Muscle contraction amplitude, latency, and area of contraction were determined for
GC and TA muscles of both limbs. No statistically important difference was determined between control and
experimental limbs for the donor (GC) muscle. For the recipient (TA) muscle no statistically important difference was
detected between experimental groups (groups II, III and IV) (p<0,05), however, there was statistically significant
difference between control (group I) and experimental groups (p<0,05) (ANOVA-Tukey).
Wet Muscle Weight : There was not any statistically important difference between wet muscle weight-experimental
limb)/wet muscle weight-control limb) proportions of all groups for neither donor (GC) nor recipient (TA) muscles
(p>0,05) (ANOVA-Tukey). Whereas, a slightly lower proportion was determined for tibialis anterior muscle in group I.
Quantitative nerve Analysis for peroneal nerve
Total myelinated axon number was significantly lower in group I NPD compared to control group (p<0,01) (ANOVATukey. No statistically important difference was determined between NPD of control and experimental groups.
Mean axon area was significantly greater in CNP than other groups (p<0,01) (ANOVA-Tukey). No statistically
important difference was determined between other groups (p>0,05) (ANOVA-Tukey.
Mean myelin diameter was significantly greater in CNP than other groups (p<0,01) (ANOVA-Tukey). In addition,
statistically important difference was determined between group I NPD and other groups (p<0,05) (ANOVA-Tukey).
Mean myelinated axon diameter was significantly greater in CNP than other groups (p<0,01) (ANOVA-Tukey). In
addition, statistically important difference was determined between group I NPD and other groups (p<0,05) (ANOVATukey).
Quantitative nerve analysis for tibial nerve
Total myelinated axon number was greater in NTP than in CNT, possibly due to axonal sprouting (p<0,05) (ANOVATukey).
No statistically important difference was determined between control and experimental groups for mean axon area, mean
myelin diameter and mean myelinated axon diameter (p>0,05) (ANOVA-Tukey).
Histology
Tibialis anterior and gastrocnemius muscles of control and experimental legs were stained with hematoxylene&eosin and
mason&trichrome stain, and evaluated histologically. In group I, fibrotic changes were noted. In group II, III and IV no
important difference was determined between experimental and control groups.
The recipient NPD portion of peroneal nerve was highly fibrotic and there was few myelinated axons in group I (Fig 3).
In the experimental groups, histological examination of NPD revealed many small diameter-myelinated axons
(Fig 3). The thickest myelin sheet was in group I, the thinnest was in group III.
Group I NPD
Group II NPD
Group III NPD
Group IV NPD
Fig 3: Histological view of distal peroneal nerve in the control and experimental groups
In the anastomosis area, the regenerating axons were passing from tibial nerve (donor) to peroneal nerve (recipient) (Fig
4). No functional loss in donor nerve or in donor muscle was determined. Healing was superior in-group IV. No
statistically important difference was found out between groups II, III and IV but group I.
P
T
Fig 4: Anastomosis zone between tibial and peroneal nerves (T: Tibial nerve, P: Peroneal nerve)
Conclusion: End-to-side anastomosis supplies a degree of peripheral nerve regeneration without any evident donor nerve
function loss. However, new studies must be done for improving regenerative capacity of the technique.
Abstract ID#: 982
Password: 385730
Category Selection: Scientific Poster Session
Presentation Format: Scientific Paper (6 minute)
Presentation Date:
Presenter's : Selahattin Özmen, MD, Osman Latifoglu, MD, Sühan Ayhan, MD, Reha Yavuzer, MD, Gülay Nurlu, MD,
Kenan Atabay, MD.