Impaired compliance of the intracranial vessels in complicated childhood migraine. Demonstration by transcranial Doppler-Sonography - A vascular model approach

Aim: To increase the diagnostic value of Doppler sonography a uniform lumped parameter model of pulsatile blood how in human arteries was derived from the serial and/or parallel connection of parallel oscillatory circuits. Methods and patients: In this setting the current (I) in the ohmic resistor (R) represents the volume flow in the vessel, the voltage (V) the blood pressure. The vessel compliance corresponds to the capacitance (C), the inductivity (L) represents the accelerated mass. The flow velocity (v) which is assessible non-invasively is given by v = I/A, where A is the cross-sectional area of the vessel. Mathematically, the model represents a two-dimensional Fourier-series of the input signal by the segments. Thus it seems to be evident that almost all forms of flow and pressure pulses can be generated. The equations of the model were solved numerically. Doppler-sonographically measured flow velocities in the ascending aorta were used as input signal. The parameters for A, R, L and C were optimized to gain the measured now spectrum in the target vessel as model response. Results: Application in 14 children (aged 3-16 yrs.) with complicated migraine during a symptom-free interval revealed a significantly lowered cross sectional area of the middle cerebral artery on the side of the higher flow velocities. For both middle and posterior cerebral arteries, a decreased vessel compliance (C) (mean -30%) was found, whereas values for R and L were within normal limits. Conclusion: These findings suggest an altered vascular compliance even between attacks. This may contribute to the pathogenesis of migraine through increased cerebral impedance resulting in impaired cerebral perfusion.