Intracranial Pressure in Experimental Models of Headache

Not Applicable

Completed

Brief Summary: The purpose of this study is to determine whether increased pressure in the head is elevated in people who suffer from High Altitude Headache. We hypothesise that head pressure will be elevated in people with High Altitude Headache.

Detailed Description: High Altitude Headache is the primary symptom of Acute Mountain Sickness. However, at present the reason why some individuals suffer from High Altitude Headache and others do not remains unknown. It is widely believed that elevated pressure within the brain leads to stretching of pain sensitive fibres and thus headache. However, evidence of raised intracranial pressure during High Altitude Headache is currently unavailable. Therefore, this study aims to examine a proxy measure of intracranial pressure (Optic Nerve Sheath Diameter) in persons visiting High Altitude, half of whom have been given the drug acetazolamide that is known to reduce headache symptoms.

Recruitment & Eligibility

Inclusion Criteria

Exclusion Criteria

Arm && Interventions

Group	Intervention	Description
Placebo	Lactose monohydrate	Placebo (LACTOSE MONOHYDRATE) will be given to subjects at fifteen, twenty and thirty two hours post hypoxic exposure (3777m).
Acetazolamide	Acetazolamide	Arm 1: ACETAZOLAMIDE (250mg) will be given to subjects at fifteen, twenty and thirty two hours post hypoxic exposure (3777m).

Primary Outcome Measures

Name	Time	Method
Change in Optic Nerve Sheath Diameter by Ultrasonography	Optic Nerve Sheath Diameter: baseline, 24 hours.	Baseline is defined as the average of the 3 hour and 12 hour normoxia measurement. 24 hours is defined at the 24 hour hypoxia measurement. Optic nerve sheath diameter obtained by ultrasonography of the eye. Increased optic nerve sheath diameter suggests greater intra cranial pressure.

Secondary Outcome Measures

Name	Time	Method
Change in Fluid Balance	Fluid Balance: baseline, 24 hours.	Baseline is defined as the average of the 3 hour and 12 hour normoxia measurement. 24 hours is defined at the 24 hour hypoxia measurement. Urine output was recorded by 24 hour urine collection and fluid intake by 24 hour food diaries. Fluid balance was calculated as: (urine output (L) / fluid intake (L) ) \* 100.
Change in High Altitude Headache by Visual Analogue Scale	High Altitude Headache: baseline, 24 hours.	Baseline is defined as the average of the 3 hour and 12 hour normoxia measurement. 24 hours is defined at the 24 hour hypoxia measurement. Outcome measured using visual analogue scale, where 0 mm is no headache and 100 mm is maximum headache.
Change in Blood Oxygen Saturation	Blood Oxygen Saturation: baseline, 24 hours.	Baseline is defined as the average of the 3 hour and 12 hour normoxia measurement. 24 hours is defined at the 24 hour hypoxia measurement.
Change in Optic Nerve Sheath Diameter	Optic Nerve Sheath Diameter: baseline, 36 hours.	Baseline is defined as the average of the 3 hour and 12 hour normoxia measurements. 36 hours is defined at the 36 hour hypoxia measurement.