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Intercostal, Ilioinguinal, and Iliohypogastric Nerve Transfer after Lumbar Spinal Cord Injury:
An Anatomical Feasibility and Experimental Study
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Ahmed Aly Toreih , Asser Sallam, Ahmed I Maaty , Cherif Maurice , Mohsen Hassan Zaghlol
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Suez Canal University, Faculity of Medicine, Physical medicine, Rheumatology and Rehabilitation, Faculty of Medicine,
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Suez Canal University, Anatomy, Faculty of Medicine, Suez Canal University, Surgery, Anaesthesiology & Radiology,
Faculty of Veterinary Medicine, Suez Canal University, Faculty of Veterinary Medicine- Suez Canal Uni
INTRODUCTION:
Spinal cord injury has been investigated in various animal studies. One promising therapeutic approach involves the
transfer of peripheral nerves originating above the level of injury into those originating below the level of injury. The overall
goal of this study is to evaluate in cadaveric and animal models the feasibility of nerve transfer for reinnervation of the
lower limbs to restore some hip and knee motor functions in order to be utilized in patients with lumbar spinal cord
transection.
METHODS:
Five cadavers were dissected bilaterally to expose intercostal, ilioinguinal, and iliohypogastric nerves, along with femoral,
superior and inferior gluteal nerves. A lateral thoracic approach was used to identify and expose intercostal nerves. An
ilio-inguinal approach was used to identify the ilioinguinal nerve. The iliohypogastric nerve originated from the same
lumbar spinal cord segment (L-1) as the ilioinguinal nerve, and had a similar path and diameter as that nerve. Ease of
access and ability to transfer the intercostal nerves to the superior and inferior gluteal nerves, and transfer the ilioinguinal,
and iliohypogastric nerves to the femoral nerve were assessed. The gluteal nerves were explored through a posterior
approach to the hip and the femoral nerve was explored through the same ilio-inguinal approach used to identify the
donor nerves. The distance between nerve endings and diameter were measured to determine if a direct neurorrhaphy is
possible.
Then, 10 dogs were utilized. Two stages of the investigation will be scheduled. The first stage is induction of lumbar cord
hemi-transection below the level of L1. The second stage is based on the anatomical feasibility study to perform the
following nerve transfers in dogs: To restore hip abduction and extension, the 12th intercostal and subcostal nerves were
transferred to the cranial gluteal and caudal gluteal nerve. To restore knee extension, the ilio-inguinal and ilio-hypogastric
nerves were transferred to the femoral nerve.
Postoperative Course in the Animal Model: Following a period of 3-6 months, clinical and electrophysiological evaluation
of the recipient nerves and their motor targets were performed. Electrical stimulation was carried out to the transferred
nerves at three and six weeks postoperatively. Nerve conduction studies of the recipient nerves as well as
electromyography were performed to detect signs of regeneration. To compare between pre- and postoperative findings,
Mann-Whitney-U-test and X2-test were applied. A p value < 0.05 was considered to be statistically significant.
RESULTS:
In the cadaveric model, the 11th intercostal and subcostal nerves were of sufficient length to be transferred in a tensionfree manner to the superior and inferior gluteal nerves. The average length of available intercostal nerve required to reach
the gluteal nerves in a tension-free manner was determined to be as follows: T-11 (16.8 cm), and T-12 (13.8 cm).
Similarly, the length of the ilioinguinal and iliohypogastric nerves ranged from 14 cm to 15.5 cm; it is sufficient to be
transferred in a tension-free manner to the femoral nerve.
Electrophysiological studies in dogs showed improved conduction velocity and amplitude during early follow-up (p<0.05).
At 12 weeks postoperatively, the mean conduction velocity of gluteal and femoral nerves increased to 96.1 and 92.8% of
the contralateral control nerve (p<0.05), respectively. Clinically, there was significant recovery of the motor power of the
quadriceps femoris and glutei to near normal levels (M4 grade) (p<0.05).
DISCUSSION AND CONCLUSION:
Intercostal, ilioinguinal, and iliohypogastric nerves are suitable donors to transfer to the gluteal and femoral nerves after
spinal cord injury to restore some hip and knee motor functions with detectable levels of activity in recipient nerves and
their target musculature.