[Peroperative echography in pediatric neurosurgery. Experience in a series of 40 procedures].

Forty neurosurgical operations (supra-tentorial: 27; infra-tentorial: 10; intra-spinal: 3) have been performed under real time ultrasonography control. The supra-tentorial anatomical Landmarks visualized on the screen were the base of the skull, the cranial vault, the falx cerebri and the ventricles. The infra-tentorial landmarks were the petrous bone, the tentorium and the brainstem. The dura-mater, the subarachnoid space and the medulla were easily detected in the spinal canal after laminectomy. Intra operative real time ultra sonography performed on the dura-mater or on the cortex allows the detection of pathological structures. Tumors, whatever their location, are hyperechogenic; cysts, on the contrary, are hypoechogenic. Tumors are therefore precisely delimited by intra operative ultrasonography; thus the amount of normal nervous tissue which must be removed to reach a subcortical or intra medullary tumor can be reduced to a minimum. Moreover, the use of intra operative ultra sonography gives control ever the completeness of tumor removal as it shows any residual tumor intra operatively. Echography also facilitates other operations such as placement of a ventricular catheter, tapping of an abscess or biopsy of a tumor. Large arterial vessels or arterio-venous malformations are easily located because their pulsations are visible on the screen. For all these reasons, real time ultrasonography should always be available in the operating theater. In this series, it has provided essential information in 15 cases out of 40.