[Muscular ultrasonic diagnosis. Etiological approach to various backaches].

Certain cases of mechanical back pain present unusual clinical and ultrasonographic features involving the posterior lumbar muscle groups, which can be used to distinguish various types. The clinical examination may isolate a juxta-vertebral territory in which pressure triggers or exacerbates the back pain; anaesthesia of this territory is accompanied by pain relief. Ultrasonography may reveal a hypoechogenic area in this muscle territory in which histomorphometric and ultrastructural studies, performed in three cases, revealed endomysial and perimysial adiposis associated with atrophy probably due to peripheral neuropathy.