Ultrasound findings in spontaneous carotid artery dissection. The value of duplex sonography
M. Sturzenegger
Department of Neurology, University of Bern, Switzerland.
Extracranial and transcranial Doppler and duplex sonographic findings in
six patients with internal carotid artery dissection proven by angiography
is reported. Extracranial Doppler analysis showed occlusion without a
recordable signal from the internal carotid artery at any level or stenosis
with accelerated flow in the high cervical segment. Transcranial Doppler
findings demonstrated the hemodynamic consequences of the internal carotid
artery occlusion or stenosis with collateral flow across the circle of
Willis and also showed the dampened pulse wave of the middle cerebral
artery ipsilateral to the dissection. In duplex sonography, the indirect
signs indicating internal carotid artery dissection were a patent carotid
bifurcation and proximal internal carotid artery segment but with no or
only a short systolic flow signal. Atherosclerotic wall changes were
absent, an important finding that suggests nonatherosclerotic stenosis or
occlusion. Direct signs making the diagnosis likely were a tapering of the
internal carotid artery lumen distal to the bulb, an irregular membrane
crossing the vessel lumen, and the demonstration of a true lumen with flow
and a false one without flow. While cerebral angiography is still
considered the gold standard, ultrasound may become the primary modality
for early diagnosis. Doppler and duplex examinations help to indicate
angiography and are the methods of choice for follow-up investigations.
They clearly demonstrate spontaneous recanalization with normalization of
carotid circulation or, in case of persistent occlusion, improvement of
collateral blood supply. Sequential examinations may prove helpful to
determine the duration of anticoagulant treatment.
