A) Coronal T2-weighted neurographic image section. The yellow arrows indicate the sciatic nerves at the point of passage through the sciatic notch - the sciatic nerve on the left demonstrates hyperintensity.

B) Axial T1-weighted MR image showing asymmetry in the size of the piriformis muscles. This may reflect either hypertrophy on the right or atrophy and spasm on the left. Muscle spasm may change the shape and hardness of a muscle without altering its total volume.

C) Curved reformat image of the sacral spinal nerves, lumbo-sacral plexus and proximal sciatic nerves again showing the hyperintensity consistent with irritation of the left sciatic nerve and its antecedents.

D) Axial T2-weighted image showing hyperintensity and loss of fascicluar detail in the left sciatic nerve at the point of passage through the sciatic notch.