Cerebral vasoreactivity in Andeans and headache at sea level

Area of Science:

• Neurology
• Altitude Medicine
• Physiology

Background:

• Headache and chronic mountain sickness (CMS) are prevalent in Cerro de Pasco, Peru (4338 m).
• Migraine with aura affects 24% of men in this high-altitude population, with frequent attacks.
• Cerebral vasoreactivity is crucial for regulating blood flow in the brain.

Purpose of the Study:

• To investigate cerebral vasoreactivity to CO2 and nitric oxide (NO) in high-altitude natives.
• To compare vasoreactivity at high altitude (Cerro de Pasco) and at sea level (Lima).
• To explore the link between impaired vasoreactivity and migraine in this population.

Main Methods:

• Utilized transcranial Doppler ultrasound to measure middle cerebral artery (MCA) vasoreactivity.
• Assessed response to CO2 rebreathing and isosorbide dinitrate (IDN), an NO donor.
• Measurements were taken in native residents of Cerro de Pasco, including those with CMS, both at altitude and after relocation to Lima (150 m).

Main Results:

• Cerebral vasodilatation in response to both CO2 and NO was found to be defective in Andean natives.
• This impairment was observed both at high altitude and at sea level.
• Incapacitating migraine was associated with impaired cerebral vasoreactivity to these physiologic vasodilators.

Conclusions:

• Defective cerebral vasoreactivity to physiologic vasodilators is a characteristic of Andean natives.
• This impairment may play a role in the susceptibility to migraine.
• Genetic factors influencing endothelial function could underlie susceptibility to migraine.