Question:

I had hand surgery 7-8 months ago and have not had any taste since then. I seem to have a bit of heightened sense of smell though. I had general anestesia and the surgery took about an hour longer than they anticipated. I have had tests to rule out any brain or other disorders. If it was nerve damage from the tube, I understand that the nerve heals about an inch a month. It has now been about 7 and half months. Any ideas what I can do to regain my taste. This is very depressing and I have lost a lot of weight.

Answer:

It sounds as though you’ve been told that the anesthetic 7-8 months ago had something to do with your unfortunate loss of taste. My own belief is that this is unlikely. There are a few reports of this type of problem after general anesthesia but no clear proof that the one causes the other, and no explanation of how anesthesia might cause loss of taste or smell.

Although you say you have a heightened sense of smell, keep in mind that what we think of as taste is mostly (about 80%) due to the sense of smell. It would be very unusual for you to have an improved sense of smell together with a loss of the sense of taste. Your sense of smell can be affected by blockage of airflow to the areas of the nose where olfaction (smell) takes place. This can be due to sinusitis or allergies, or such things as polyps or tumors in the nose. The breathing tube you had during an anesthetic for hand surgery would not have been placed in the nose, but rather in the mouth. To knock out the taste areas, located mainly on the tongue, you would have to seriously damage both of the lingual nerves. For something like this to be the outcome of a normal anesthetic seems very, very unlikely.

The other main cause of loss of smell is damage or decreased function of the olfactory nerves, anywhere from the nose through to its connections in the brain. Examples include loss of smell after upper respiratory infection, head injury, depression, liver disease, “toxins”, Alzheimer’s disease, and multiple sclerosis. Diabetes, smoking, high blood pressure and any one of a hundreds of different medicines may also cause problems.

Although we are learning new things all the time about the effects of anesthetic drugs on the brain and nerves, anesthetic drugs have not been proven to cause permanent loss of taste or smell. Even with a prolonged anesthetic these drugs are cleared from the system within hours. One key fact is that there is a gradual loss of the senses of taste and smell with aging, with a particularly abrupt decline in the sixth and seventh decade of life.

Another important fact is that respiratory infection is the most frequent (25%-33%) cause of nerve-related loss of smell. This type of loss more commonly affects women (70%-80% of cases), and is more frequent in people 65 years or more of age. One third of patients will improve after 6 months, but the longer the loss of function is present, the less the chances of recovery because the lining of the nose that contains the special nerve cells for smell can be permanently damaged by certain viruses.

So, here’s a scenario. A person in his sixties or seventies (the people most likely to receive general anesthesia) whose sense of taste is beginning to decline gets a viral respiratory infection that permanently damages the smell receptors. If he or she happens to have a general anesthetic around this time it would be natural, in the absence of any other obvious explanation, to put two and two together – the anesthetic caused the loss of taste or smell. Two statistically common events coincide, and, wrongly, the one is attributed to the other.

If you have more questions about this, please send your question to the ENT expert at NetWellness, or ask your doctor for a referral to an ENT doctor who specializes in this type of disorder and can identify treatable causes such as nasal polyps. In about 5% of patients without symptoms of polyps (such as nasal congestion), polyps are discovered to be the cause of disordered smell or taste.

For more information:

Go to the Anesthesia health topic.