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Temporal artery tap: usefulness and limitations in carotid sonography
M A Kliewer1, K S Freed, B S Hertzberg
1Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA.
Purpose:
To examine the effectiveness of percussion of the superficial temporal artery for identification of the external carotid artery (ECA).
Materials And Methods:
The temporal artery tap maneuver was performed on 324 carotid arteries (163 patients). Evidence for transmission of the effect of the temporal tap was sought in the pulsed Doppler ultrasound waveforms of the ECA, common carotid artery (CCA), and internal carotid artery (ICA). The location and severity of stenotic lesions were recorded. The relative amplitudes of the oscillations created by the tap were compared.
Results:
The temporal tap effect could be seen in 262 ECAs (81%), 174 CCAs (54%), and 106 ICAs (33%). The tap effect can be seen in the ICA at all grades of ICA disease. When the oscillations were seen in only one of the two major branches, that branch was always the ECA. When the temporal tap effect was found in the ICA, the amplitudes of the oscillations were the same as or greater than those of the ECA in 26% of cases.
Conclusion:
Waveform oscillations from the temporal tap maneuver often can be found beyond the ECA in the CCA and ICA. Thus, the temporal tap alone may not reliably distinguish the ECA from the ICA or CCA.