Page 55 - Ultrasonography in Prehospital and Emergency Medicine - Rein Ketelaars

Besides arterial occlusions, vasospasm due to aneurysmal subarachnoid hemorrhage may be detected by transcranial US. However, its diagnostic accuracy varies widely depending on the vessel, the diagnostic criteria and timing.91 Anecdotal evidence exists on other intra- cranial pathologies which may be detected by PHUS such as intracranial hematomas and ventricular system enlargement.92,93
The biggest limitation of the application of transcranial US is the ability to obtain US images through the temporal window (Figure 2.9). This is the thinnest part of the temporal bone that allows penetration of the US beam at a suitable angle and distance in relation to basal portions of the major cerebral arteries and the circle of Willis. This procedure may be very demanding and requires training and experience. Therefore, transcranial US might not be suitable for every ultrasound-equipped (H)EMS service.
The therapeutic applications of transcranial US in ischemic stroke are discussed in the inter- ventions section of this paper.
Figure 2.9 Ultrasound transducer positioned at the temporal window
The ultrasound transducer is positioned at the site where the temporal bone is thinnest and the ultrasound beam
is least obstructed penetrating the skull.
Reproduced with permission. Image courtesy of Rob Stoffels and Yvonne Houben.
ABCDE of prehospital ultrasonography 53
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