Report of a Novel Bilateral Variation of Sciatic and Inferior Gluteal Nerve

The sciatic nerve is thickest nerve of sacral plexus which innervates many muscles and vast areas of skin of lower limb. It leaves pelvis via the greater sciatic foramen, emerge into gluteal region by passing under piriformis muscle, and descends beneath the gluteus maximus to divide into its terminal branches; tibial and common peroneal nerve at the superior angle of popliteal fossa. In some cases, sciatic nerve divides into tibial and common peroneal nerve in a higher level and one of them or both pass through or over the piriformis muscle. As in conditions like intramuscular injections, gluteal surgeries and piriformis syndrome such variations may increase risk of injury, it is important for medical team to be aware of them. In this paper, by reporting many variations in a cadaver, we emphasize the importance of anatomical variations especially for surgeons and nurses.

Contralateral L-6 nerve root transfer to repair lumbosacral plexus root avulsion: experimental study in rhesus monkeys

Object Nerve transfer is used for brachial plexus injuries but has rarely been applied to repairs in the lower extremities. The aim of this study was to evaluate the feasibility and effectiveness of using the contralateral L-6 nerve root to repair lumbosacral plexus root avulsions. Methods Eighteen rhesus monkeys were randomized into 3 groups. In the experimental group, the left L4–7 and S-1 nerve roots were avulsed and the right L-6 nerve root was transferred to the left inferior gluteal nerve and the sciatic nerve branch innervating the hamstrings. In the control group, the left L4–7 and S-1 nerve roots were avulsed and nerve transfer was not performed. In the sham operation group, the animals underwent a procedure that did not involve nerve avulsion and nerve transfer. Functional outcomes were measured by electrophysiological study, muscle mass investigation, and histological study. Results The mean amplitudes of the compound muscle action potentials from the gluteus maximus and biceps femoris in the experimental group were higher than those in the control group but lower than those in the sham group (p < 0.05). The muscle mass and myofiber cross-sectional area of these muscles were heavier and larger than those in the control group (p < 0.05). The number of myelinated nerve fibers of the inferior gluteal nerve and the branch of the sciatic nerve innervating the hamstrings in the control group was significantly smaller than the number in the experimental and sham groups (p < 0.01). Conclusions In this animal model, the contralateral L-6 (analogous to S-1 in humans) nerve root can be used to repair lumbosacral plexus root avulsion.