This report deals with the successful treatment of a giant aneurysm located at the caudal basilar trunk in a 19-yr old boy. The aneurysm had been declared to be inoperable by several authorities in the field of neurosurgery. A series of neuroradiological interventions was performed in order to block the aneurysm with the help of a detachable balloon or, at least, to induce spontaneous thrombosis of the aneurysm sac by reducing blood flow within the caudal basilar artery. Transcranial Doppler sonography proved to be a helpful guide for therapeutic decision-making from one interventional step to the next in this adventurous field of treatment. The changing sonographic findings of the vertebrobasilar system during the course of the treatment and during the functional tests, as well as the favourable outcome, have made this case worth reporting.
