Transcranial Doppler in neurosurgery.

This chapter describes the use of the transcranial Doppler apparatus in neurosurgery. The principles of Doppler insonation, the techniques of recording and the use of activation techniques is described. The relationship between blood flow and blood velocity is discussed, and the interaction of various pharmacological agents. The establishment of normal values for the laboratory and various vessels insonated is emphasised. The use of indices particularly the pulsatility index is described together with its variations. Cerebral vascular reactivity measurements and the interaction of Doppler recordings with raised intracranial pressure, useful in assessment of cerebral perfusion pressure as in head injury and in terminal cases, is documented. The use of transcranial Doppler in management of head injury and subarachnoid haemorrhage is described. The latter is probably the most useful routine place for Doppler measurement in neurosurgical practice and the documentation of the onset and progress of vasospasm is the final portion of the chapter.