Predictive power of TCD especially for vessels difficult to insonate
(ICA and ACA) can be improved with transcranial color coded duplex sonography .
As for patient safety, ultrasound guidance for deep regional blocks is associated with significant limitations despite its popularity, which can be attributed to either the ultrasound machine (decreased ability to insonate
deep neural structures) or the operator (errors in perception or interpretation in needle-nerve proximity during deep regional blocks) .
For the TCD measure and registration, a pulsed Doppler transducer gated at a focal depth of 45-60 mm was placed over the temporal bone to insonate
the main stem of the ipsilateral MCA; the TCD transducer was fixed with a head frame, and the peak systolic MCAV was recorded continuously.
Trans-vaginal probe insonate
at higher frequency i.e.
Transcranial Doppler (TCD), first described in 1982 , is a noninvasive ultrasound (US) study that involves the use of a low-frequency ([less than or equal to] 2 MHz) transducer probe to insonate the basal cerebral arteries through relatively thin bone windows.
The transtemporal window, located above the zygomatic ridge between the lateral canthus of the eye and auricular pinna, is most frequently used and can insonate the middle (MCA), anterior (ACA), posterior cerebral arteries (PCA), and terminal internal carotid artery (ICA) [2, 3].
We can subject this vessel to ultrasound waves, or insonate
, through the skull and monitor its patency [absence of blockage].
Although it is used infrequently, the submandibular approach may be used to insonate
the retromandibular and extradural segments of the ICA (Fig 6), if a patient's condition warrants or permits it.
For LACS, we were not able to insonate
deeply enough and therefore relied on MRI and CT findings from the pre-INTRACAROTID-SODIUM-NITROPRUSSIDE phase.