Abstract

Neurovascular reactivity in patients with focal epilepsy

Author(s): Gulnur Tekgol Uzuner, Nevzat Uzuner

Background: Complex neurovascular activation by transcranial Doppler (TCD) has not been
presented at the moment in drug-responsive patients with focal epilepsy. The objective of
this study is to assess the neurovascular activation to complex visual stimulation of drugresponsive
patients with focal epilepsy during interictal period.

Methods: Twenty-five patients with focal epilepsy and 25 healthy subjects were screened for
this study in our Neurosonology Laboratory. We performed transtemporal TCD recordings
from the P2-segments of both posterior cerebral arteries (PCA) simultaneously during
complex visual stimulation, at least, ten days after last epileptic attack. The individual reactivity
was defined as a relative increase of the blood flow velocities as a percentage change of the
baseline values.

Results: Most of the patients have an epileptic focus in the temporal lobe documented by the
EEG. The Doppler data of the epileptic sides and non-epileptic sides were analysed separately.
The complex visual reactivity was significantly higher at the epileptic side in the patients
(52.5%) from those of the controls (36.8%) (p=0.002).

Discussion: In contrast to the earlier reports of the studies that were found diminished
neurovascular reactivity to simple or complex visual stimulation using TCD, our study showed
the temporal and occipital region of the patients with focal epilepsy have hyperactive
neurovascular units at the epileptic side during the interictal period when comparing with
the healthy subjects. However, to emphasise the importance of investigating neurovascular
coupling in further studies are needed.