Impaired vasoreactivity of the basilar artery system in patients with brainstem lacunar infarcts

Purpose: Diminished vasoreactivity (VR) has been evidenced in patients with hemispheric small vessel disease, however, there is no data regarding vert ebrobasilar (VB) territory VR changes in patients with subcortical vascular encephalopathy located in the brainstem. Therefore, we compared the cerebr al blood flow velocity (CBFV) responses of the VB system during different v asoregulatory challenges in healthy volunteers to those in patients with br ainstem lacunar infarcts. Methods: In 20 patients with brainstem lacunar in farcts and in 10 healthy volunteers the VR of the VB system was measured by analyzing the CBFV changes during different stimulation paradigms (ventila tion, tilting and acetazolamide tests). During transcranial Doppler registr ation the systemic blood pressure and the expiratory partial CO2 pressure w ere monitored. Results: During hypercapnia the VR was significantly higher in the control group than in the patient group (10.1 +/- 4.9 vs. 3.4 +/- 5. 0 cm/s/kPa, p = 0.0025). In a subgroup of patients with mean baseline CBFV <25 cm/s the VR was 1.5 +/- 2.4 cm/s/kPa, while patients with mean baseline CBFV >25 cm/s showed a significantly higher value (7.8 +/- 6.9 cm/s/kPa). Furthermore, in patients with mean baseline CBFV <25 cm/s the pulsatility i ndex was significantly higher than in patients with mean baseline CBFV >25 cm/s (1.11 +/- 0.26 vs. 0.86 +/- 0.19, p = 0.0325), reflecting significantl y higher vascular resistance in the former group. Although CBFV measurement s during tilting and acetazolamide tests tended to support these findings, they showed no significant differences between patients and controls. Concl usion: Patients with cerebral microangiopathy involving the brainstem showe d impaired VR in the VB flow territory in association with baseline CBFV.