“Epistaxis” is the Latin word for the nosebleeds. Nose bleeding is very common and every one of us has experienced it at least once in our lifetime. As common as it is, 90% of nosebleeds do not have an identifiable cause after investigation. This is not a bad thing as it means that most nosebleeds have no sinister causes.
Our nose is supplied by blood from an internal and external arterial system. The external vascular supply comes from the vessel that brings blood to our face; hence it enter the nose from outside, causes the bleeding from the front of the nose where we get most of the bleeding. The internal vascular supply is more elaborate, coming off the vessels that bring blood directly to the brain. They supply the nose from the back under higher pressure and therefore nose bleed from the internal system tends generally to be more heavier; this is because we cannot press and stop the bleeding at the back for the nose with our fingers and also as the arterial blood pressure is stronger too.
So what causes nose bleeding? Several factors affect and cause nose bleeds. Firstly we need a blood vessel as the source, preferably near the surface of the lining. Vessels in the front of the nose are nearer the surface as the lining is thinner so nose bleeds from the front is therefore commoner. Next we also need a condition that makes the vessel more prone to bleeding. So, for example, if there is an existing inflammation like a nose allergy, infection or sinusitis, there is inflammation of the vessel with an engorgement by blood. Perhaps the wall of the vessel might be weak and breaks easily; we sometimes see this as the sole reason in the elderly population. Trauma from an accident to the nose or repeated trauma by the patient picking his/her nose can break the vessel too. Obviously nasopharyngeal cancers, cancers of the nose and sinuses, vascular tumors and malformations can cause bleeding too. All tumor growths require a good blood supply to feed their growth and hence may present as a nosebleed early on.
Our environment also plays an important part in causing nosebleeds. Our nose should be moist, and not dry. If it is dry, the lining breaks down and we bleed. So sudden changes in the environment make the nose drier and can cause bleeding. This happens if we fly especially for long journeys or go from a warm, humid climate to visit a dry climate like a winter skiing holiday in the Alps or if the temperature suddenly drops like during the Winter Solstice in Hong Kong. An underlying condition or drug may also cause dryness of the nose. Patients with radiotherapy to the nose for previous cancer or atrophic rhinitis (an inflammatory condition of the nose that has caused a reduction in the mucus secreting cells of the nose) will predispose the lining of the nose to easy breakdown and bleeding.
Interestingly also the internal passage size of our nose also affects our frequency of nose bleeding too, by creating a drier environment. If one’s nose is narrower on one side, there is more turbulence generated when we breathe normally. This turbulence causes local drying effects, lining breakdown and therefore bleeding. This narrowing can be caused by a deviated septum of the nose, enlarged turbinate from nose allergy or sinus polyps that narrow the passages themselves.
So epistaxis/nosebleeds are common. The cause/s of any nosebleed is varied and is the interplay between the anatomy of the nose, an underlying condition and environment factors. As mentioned earlier, most nosebleeds have no significant cause. However if any nose bleeding persists, recurs and/or is unusually heavy, it is always best to seek an assessment by your ENT Specialist to exclude all causes. Thankfully here too, most causes are easily treated.