Cluster headache: orbital hemodynamic changes during Valsalva maneuver.
BACKGROUND: The clinical features of cluster headache (CH) disclose some vascular changes in the symptomatic region, but few instrumental studies have assessed orbital hemodynamics in patients with this disorder. METHODS: Orbital blood flow reactivity elicited by Valsalva maneuver (VM) was studied with ophthalmic artery eco-Doppler in 16 patients (14 men and 2 women; mean age: 41.2) suffering from episodic CH and in 18 healthy controls. Patients were examined twice: first, in a cluster period (between pain attacks), and second, in a remission period. Each time peak-systolic and end-diastolic flow velocities were recorded in both ophthalmic arteries at rest and during all phases of VM. RESULTS: Valsalva phase IV was consistently associated with an increment of blood flow velocities through the ophthalmic arteries. Unlike controls, patients showed an asymmetric vascular reactivity. In the cluster period peak-systolic flow velocity increments were lower on the symptomatic side than on the asymptomatic side (14.1% vs. 34.4%; P < .001), while in remission end-diastolic flow velocity increments were higher in the previously symptomatic orbit (129% vs. 72.9%; P < .05). Vascular reactivity on the asymptomatic side was always similar to that of healthy controls. CONCLUSIONS: In episodic CH, the symptomatic orbit shows an abnormal vascular reactivity. During the cluster period, basal vasodilation and hyperemia could preclude it from admitting a much greater amount of blood at the end of Valsalva. During remission, there might be some latent vascular changes that lead to supersensitive vasodilator responses and/or opening of arteriovenous shunts under certain circumstances such as Valsalva. These phenomena could be relevant in the pathophysiology of CH.