Does sciatic parasacral injection spread to the obturator nerve? An anatomic study

Anatomical variation in bifurcation and trifurcations of sciatic nerve and its clinical implications: in selected university in Ethiopia

BACKGROUND

The Sciatic nerve is the widest nerve of the body. It consists of two components, namely: the tibia and the common peroneal components derived from the ventral rami of L4 to S3 spinal nerves of the lumbosacral plexus. It exits the pelvis through the greater sciatic foramen below the Piriformis muscle and descends between the greater trochanter of the femur and ischial tuberosity of the pelvis to the knee. The purpose of this study is to identify the course and variations in branching pattern of the sciatic nerve which may lead to various clinical manifestations.

METHODS

Twenty-eight formalin fixed cadavers comprising of 56 lower limbs are used for this study, of which six specimens were female cadavers. Dissection of gluteal region and posterior compartment of the thigh was done to expose the sciatic nerve. Variations in the sciatic nerve anatomy; their relationship to Piriformis muscle and a point of bifurcation and trifurcation were noted and recorded.

RESULTS

Forty-two lower limbs (75 %) showed normal anatomy of sciatic nerve. Fourteen regions (25 %) showed variations in the sciatic nerve, of which six regions (11 %) showed a variation of the sciatic nerve in relation to Piriformis muscle, three regions (5 %) showed trifurcation of the sciatic nerve and five regions (9 %) showed variation in the origin of the sural nerve.

CONCLUSION

The knowledge regarding the level of division and distribution of the sciatic nerve and its location is of great importance. The sciatic nerve is frequently involved in daily medical practice of neurology, orthopedics, rehabilitation and anesthesia. Its long course makes it vulnerable to nerve injury. Even in this era the cadaver is the best means to study anatomy. It emphasizes proper clinical implications, for the surgeons to practice efficient surgical recombination and avoid errors.

Comparison of Parasacral and Posterior Sciatic Nerve Blocks Combined with Lumbar Plexus Block

OBJECTIVE

The aim of this study is to compare the effects of parasacral and posterior Winnie approaches when combined with the inguinal paravascular approach for lumbar plexus block.

METHODS

After the approval of the Ethics Committee, 40 patients scheduled to undergo arthroscopic knee surgery were enrolled. The patients were randomly assigned into two groups in a double-blind manner to perform sciatic nerve block either by the parasacral technique (Group I) or by the posterior approach (Group II).

RESULTS

The obturator nerve motor block success rate was found to be 80% (16/20) in Group I, whereas it was 10% (2/20) in Group II (p<0.05).

CONCLUSION

Inguinal paravascular block with parasacral sciatic nerve block led to a much higher incidence of obturator nerve motor block when compared to the inguinal paravascular block with posterior sciatic nerve block during knee arthroscopies.