[Relationships between piriformis muscle and sciatic nerve: radioanatomical study with 104 buttocks].

OBJECTIVE

The relationships between the piriformis muscle and the sciatic nerve are close and may be changing. In some cases, these relationships are the cause of a piriformis syndrome, an under-diagnosed etiology of non discal sciatica. The aim of the study was to explore, by the MRI, the sciatic nerve and the piriformis muscle. MATERIELS AND

METHODS

One hundred and four buttocks were explored by MRI for 52 randomly selected patients.

RESULTS

In 59.6% of cases, no variation of the piriformis muscle and sciatic nerve were found. In 26% of cases, the sciatic nerve was divided into the pelvis. In 9.6% of cases, it was divided into the pelvis, the piriformis muscle was bifid and the common peroneal nerve ran between both heads. The piriformis muscle was bifid in 10.6% of cases, hypertrophic in 13.5% of cases and atrophic in 2.9% of cases.