Polycythaemia vera and cerebral blood flow: a preliminary study with transcranial Doppler

The purpose of this study has been to investigate by ultrasonographic methods the flow velocities of cerebral arteries because increased blood viscosity due to haematocrit elevation can cause neurological symptoms in polycythaemia vera patients, because of the resulting decrease in cerebral flow.

Twenty newly diagnosed patients, with haemoglobin values of > 18 g dl-1 and/or an haematocrit of > 50%, were examined by transcranial Doppler. Recordings were performed in basal conditions and after pharmacological and/or phlebotomic treatment, when haematocrit values were < or = 50%. Blood velocities were evaluated in middle (MCA), anterior (ACA), posterior (PCA) cerebral arteries and in the basilar (BA) artery.

Basal recordings showed decreased velocities (MCA: 39.40 +/- 9.34 cm s-1; ACA: 34.05 +/- 10.25 cm s-1; PCA: 31.46 +/- 5.97 cm s-1; and BA: 27.47 +/- 7.42 cm s-1); pre- and post-treatment value differences observed in MCA, ACA and BA were highly significant (P < 0.001).

A decrease in cerebral flow could be a risk for multifocal micro-ischaemic cerebral infarctions leading, after several years, to a multi-infarct dementia; an early reduction in erythrocyte burden should be very useful in polycythaemic patients in preventing lacunar lesions.