Assessment: Transcranial Doppler ultrasonography: Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology

To the Editor:

The American Academy of Neurology Therapeutics and Technology Assessment Subcommittee presented a remarkable report on the transcranial Doppler ultrasonography (TCD) applications for clinical use.1 The use of TCD to diagnose cerebral circulatory arrest and brain death (BD) is of interest.

Bernat2 recently discussed that irreversibility has been a prerequisite for BD confirmation in every set of BD diagnostic criteria, arguing that “the only reliable proof of irreversibility is demonstrating the complete absence of intracranial circulation.” An advantage of TCD that the Subcommittee emphasized, TCD “can be performed at the bedside and repeated as needed or applied for continuous monitoring,” make this technique applicable to the intensive care environment to comatose, intubated, and unresponsive patients. A major limitation is that “it can demonstrate cerebral blood flow velocities only in certain segments of large intracranial vessels,” does not decrease its potentiality to access an intracranial circulatory arrest.1

Several other techniques have also shown to be useful, but contrary to TCD, it is almost always mandatory to move patients outside the ICU.1,3⇓

The subcommittee compared TCD sensitivity and specificity in different clinical settings. It is notable that the highest percentages corresponded to TCD for detecting circulatory arrest (91 to 100% and 97 to 100%).1 Although there is no perfect ancillary test in clinical practice,3 these values …