Transcranial Pulse Doppler Ultrasound Findings

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Journal of Neurology, Neurosurgery, and Psychiatry 1987;50:1504-1513

Transcranial pulsed Doppler ultrasound findings in
brain stem death
F J KIRKHAM,* S D LEVIN,* T S PADAYACHEE,t M C KYME,* B G R NEVILLE,*
R G GOSLINGt
From the Departments of Paediatrics* and Radiological Sciences,t Guy's Hospital, London UKSUMMARY Data are presented from transcranial insonation of the middle cerebral artery (MCA)
performed at intervals in 23 unconscious children for whom the outcome was subsequently poor.
Once an MCA signal had been observed over a 30 minute period with time averaged velocity less
than 10 cm s- and/or a direction of flow index, DFI, defined as 1 minus the ratio of reverse to
forward flow of lessthan 08, recovery to forward flow throughout diastole was never observed and
no patient recovered brain stem reflexes. Recovery of forward flow in diastole, and of brain stem
function, was seen in cases with time averaged MCA velocity in the range 10 to 25 cm s5- and with
reverse flow but a DFI of greater than 0-8 for short periods of time. All but one of the 13 children
fulfilling clinicalcriteria for brain stem death had MCA signals with time averaged velocity of less
than 10 cm/s and DFI of less than 0-8. This type of signal was not observed in five children who were
left in a persistent vegetative state.
'

Clinical criteria for the diagnosis of brain death are
now established' - and have been shown to be
reliable,4 5 provided that the cause has been ascertained, thepatient's temperature is above 35°C and
there are no drugs present. Although there is no evidence of a difference from adults, there is less experience with the criteria in children.6 ' It has therefore
been suggested that for this age group the clinical
diagnosis should be confirmed with tests such as cerebral angiography or cerebral blood flow (CBF)
studies.8
Paediatric neurointensive care hasdeveloped very
rapidly recently and an improvement in prognosis has
been reported for children with head injury,9 neardrowning,'0 and Reye's syndrome." Ideally,
aggressive treatment should be used only when there
is a chance of good recovery. A simple screening test
for early identification of children with irreversible
brain damage would therefore be useful.
A technique for obtaining Dopplersignals from the
basal cerebral arteries was described by Aaslid in
1982.1 2 The vessels are insonated transcranially using
a low carrier frequency of 2MHz which penetrates

bone sufficiently to allow back scattered Doppler signals to be obtained. Middle cerebral artery (MCA)
velocity may be reliably'3 and reproducibly'4 measured and appears to be a useful index of CBF."'
Several authorshave demonstrated abnormal
Doppler waveforms in the extracranial cerebral arteries of clinically brain dead patients. In 10 adults,
Yoneda'6 reported that reverse flow was always seen
in the common carotid artery in patients with an isoelectric EEG and non-filling of the intracerebral arteries on arteriography; Despland and De Crousaz'7
observed a similar signal in the common carotid in sixclinically brain dead individuals. Diagnostic accuracy
may be improved by the use of computerised waveform analysis.'8 However, demonstration that recovery is possible despite the finding of reverse flow in the
common carotid artery'9 means that this is not a useful confirmatory test of brain death. Low velocity and
reverse flow have been demonstrated in the internal
carotid and vertebralarteries of brain dead
patients.20 False positives have not been reported,
but the vessels may be difficult to insonate, particularly when the signal is small. The only previous
report of the findings in the intracerebral arteries was
Address for reprint requests: Dr F J Kirkham, Department of Pae- by McMenamin and Volpe2" who described the very
diatrics, Guy's Hospital, St Thomas Street, London...