Lampl et al1 correctly state that an inadequate transtemporal window may falsely indicate no blood flow, especially in older women, thus decreasing the sensitivity of transcranial Doppler (TCD) in confirming brain death. They suggest that the routine additional use of the transorbital approach when using TCD to confirm brain death increases the efficacy of the examination.
de Freitas GR, André C. Routine Insonation of the Transorbital Window for Confirming Brain Death: a Double-Edged Sword. Arch Neurol. 2003;60(8):1169. doi:10.1001/archneur.60.8.1169-a