[Pyramidal syndrome. Apropos of 4 cases treated by surgery and review of the literature].

PURPOSE OF THE STUDY: The authors report 4 observations of Piriformis syndrome, defined as a truncked sciatalgy with sciatic nerve and branches located compression at the buttock passing through the subpiriformis canal.

MATERIAL: 4 sportive patients, 26 to 41 years old have been treated surgically after an average of one year and a half of evolution and failure of conservative treatments. The surgical procedure consisted in section of the piriformis muscle and neurolysis of the sciatic nerve.

METHODS: The follow-up ranged from one year and a half. The observations were confronted with 11 english language publications, representing 20 observations.

RESULT: 2 excellent results. One fair. The result of the last patient is uninterpreted due to a post-operative deficiency of the inferior gluteus nerve. But the pre-operative symptomatology has completely disappeared.

DISCUSSION: Symptomatology associated a trunked sciatalgy arising during effort and during a long time sitting position, without lumbar pain. Paresthesy and dyspareunia can sometimes added. The specifics clinical signs are pain induced by palpation at the sacrum lateral edge, perception of a tense piriformis ("sausage shaped mass"), pain reproduction by stretching the piriformis (Freiberg) or by its opposite tensing (Pace and Nagle, Beatty). The complementary exams first allow to eliminate all rachidian or discal aetiology. The diagnosis is based on CT, MRI and bone scan which can show modifications of the piriformis muscle and especially the electrommyogram which confirms the syndrome and specifies the compression level. The aetiology is changeable, mainly represented by modification of piriformis (hypertrophy, contracture or micro traumatisms due to sport or after-effects of direct traumatism) and by anatomical modifications of the sciatic nerve, passing completely or in part through the muscle. First, the treatment must be conservative by sport rest, correction of occupational diseases, local injections and especially stretchings. The results are more often favourable. In case of failure and diagnosis certitude, the surgical treatment is the neurolysis of the sciatic nerve and the muscle section at the musculo-tendinous junction.

CONCLUSION: This syndrome must be known but, in spite of its proved authenticity now, must stay an exceptional diagnosis and be based on irrefutable criteria.