Question: I am a brain injury survivor who occasionally travels by plane and noticed that traveling this way increases my head pain. I don’t know the cause of this extra discomfort, but I wonder if my head is affected by the air pressure within the plane’s cabin? If [your organization] has published articles in the past about this topic, would you please send me a copy. If you haven’t any previously published information, would you consider it for a future article? I would like to know what is happening when I fly and if anything can be done to prevent this from happening.
Answer: Brain Injury Source, Volume 2, Issue 3, Ask the Doctor
Nathan D. Zasler, MD, FAAPM&R, FAADEP, CIME
Thank you for your "Ask The Doctor" question. You bring up an interesting point that has not been written about, to the best of my knowledge, in the context of post traumatic headache pain.
I would make the following comments with the understanding that you did not stipulate what type of headache problem you actually have. If you have read one of the prior columns in this section, you will know that a generic diagnosis of post traumatic headache is really of no help in terms of guiding treatment interventions, as it does not stipulate a specific cause for the headache condition.
High altitude headache has long been recognized as a headache condition in and of itself. It does not correlate per se with concurrent post traumatic headache. Altitude headache is uncommon below 8,000 feet and appears with increasing frequency at higher elevations. Above 12,000 feet, it is more or less universal in persons not acclimated to altitude. (This assumes that there is no compensation for the pressure differential or decreased oxygen content in the atmosphere.)
Other complications of more severe high altitude reactions include cerebral edema, stroke and retinal hemorrhage. Altitude headache often appears hours after exposure to low oxygen tension and is not generally relieved by administration of oxygen. Persons with altitude headache are uncomfortable when lying down. The headache is aggravated by maneuvers that increase intracranial pressure such as coughing, straining, head jolting and, particularly, exertion. This makes sense given the presumed mechanism, as discussed above.
In the new ICD-10 classification for headache, high altitude headache falls under the general classification of "headache associated with the disturbance of the metabolic state hypoxia due to…" As per the ICD-10 classification for this type of headache, one of the diagnostic criteria is that the headache disappears within seven days after normalization of the metabolic state.
Hypoxic headache has been described as occurring within 24 hours after acute onset of hypoxia with a PAO2 of 70 mmHG or less or in chronic hypoxic patients with PAO2 persistently at or below this level.
The basis for hypoxia leading to headache is not entirely clear, although some useful understanding may be gleaned from the current understanding of the interaction of hypoxia with cerebral circulatory physiology. Hypoxia leads to increased cerebral blood flow, presumably through a direct metabolic influence. This increase in cerebral blood flow is achieved by vasodilatation, which has been thought to be painful, with stretching of the vessel wall in turn exciting trigeminal sensory neurons in the cerebral circulation. Many conditions can lead to hypoxia including high altitude, as well as normal altitude, low oxygen environments, both of which are associated with reduced ambient (environmental) oxygen content.
Treatment with Acetazolamide, a carbonic anhydrase inhibitor, at a dose of 250 milligrams every 8 hours before and during the exposure to altitude, may reduce manifestations of pressure/oxygen in climatization. Furosemide (Lasix), a diuretic, at a dose 80 milligrams every 12 hours, may also be used. For some individuals, the symptoms are unrelieved and descent to a lower altitude is the only thing that is effective in relieving the headache.
In the context of someone with post traumatic headache, an individual with "decreased physiologic stress tolerance" may find any physiologic stress, including high altitudes, particularly in sub-optimally pressurized planes, physiologically taxing. It may come as a surprise to readers, but commercial planes typically are only pressurized to an equivalent of 6,000 to 8,000 feet. I have also seen patients with post-traumatic epilepsy who have developed headaches that were epilepsy related and/or actual seizures when flying at high altitude, particularly in what may have been sub-optimally pressurized planes.
There is very little specific information on this topic and it certainly warrants further research. Thanks for your inquiry.
Nathan D. Zasler, MD, FAAPM&R, FAADEP, CIME
Medical Director, Concussion Care Center of Virginia
CEO & Medical Director, Tree of Life
Suggested Readings
Appenzeller O: Altitude headache. Headache. 12:126-130, 1972.
Houston CS: High altitude illness. JAMA. 236:2193-2195, 1976.
ICD-10 Guide for Headaches. Cephalagia: An International Journal of Headache. 17 (S19). Pgs. 38 & 736, Oct. 1997.
Meyer JS & Dalessio DJ: Headache associated with chemicals, toxins, systemic infection and metabolic disorders (toxic vascular headache). In: Wolf’s Headache and Other Head Pain. D Dalessio & S Silverstein (Eds.) 6th Edition. New York: Oxford University Press, 1993.
Singh L, Khana P & Srivastava MG: Acute mountain sickness. NEJM. 280:175-184, 1960.