Types of Fatigue

Over 100 years ago William Osler, the father of internal medicine, divided fatigue into three types. The first is the lassitude and malaise associated with systemic illness such as tuberculosis, cancer, rheumatoid arthritis, etc. The second is the weakness associated with muscle and nerve disorders resulting from ordinary exertion. The last is a painful weariness – the cause of which often eludes investigation.

These categories provide a useful framework in attempting to diagnose the cause of an individual’s fatigue. Duration further categorizes the symptom. Most patients with prolonged, unexplained fatigue have the third type of fatigue described by Osler, a painful weariness.

Fatigue that is less than one-month in duration is often due to a passing virus, stress, or other causes that are difficult to define. The relatively brief nature of the problem eliminates the need for an intense medical investigation, and, unless the problem becomes recurrent, it can be dismissed as one of life’s minor problems.

Persistent, significant fatigue, however, is not a minor problem. Even a loss of 10% of a person’s vigor removes enthusiasm and joy from the day’s tasks. Fatigue pulls down the mood and makes everything an effort. Approximately 15% of the general population suffers from chronic fatigue, unrelieved by rest, lacking an adequate medical explanation.

Approximately 25% of patients visiting a medical doctor complain of fatigue. Less than half will be explained by a medical illness.

Fatigue caused by medical conditions has certain characteristics. A serious medical problem will occasionally present itself as unexplained fatigue before other symptoms become apparent but, inevitably, other symptoms will appear. For instance, a person with pancreatic cancer may first notice fatigue before the appearance of abdominal pain and the other symptoms of cancer occur. Therefore, the longer fatigue persists without other symptoms, the less likely a serious medical condition will serve as the eventual explanation.

Fatigue caused by a medical problem has other characteristics as well. Usually patients with typical, diagnosable, medical problems note that their energy is highest in the morning and slowly winds down over the course of the day as if the store of vigor slowly depletes. A nap may recharge the person.

Fatigue that remains unexplained usually has different characteristics. Many times, a person has a bimodal curve of energy, worse in the morning, improving with the day, fading in the afternoon, and, finally, getting a second wind at night. A nap can actually worsen things. Additionally, sleeping a long time can produce an overslept sensation.

Patients with less serious medical problems can, in certain circumstances, have fatigue with the absence of other symptoms, as is the case with hypothyroidism. Patients with low thyroid may notice tiredness before the other symptoms appear. These include dry skin, constipation, cold intolerance, etc. Likewise, a patient with anemia can feel tired before noticing other symptoms such as pale skin or obvious blood loss.

Causes of fatigue are often easy to figure out. Usually a visit to the doctor and a standard panel of blood tests provides a definite answer. If, after a thorough exam and appropriate blood tests, no answer is apparent, it is unlikely that a medical explanation will be found.

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Sinus Fatigue

A little less than 10 years ago a research project that I had been working on for many years was published in the Archives of Internal Medicine. The observation that propelled me into the relationship described in the article related to my first experiences as a clinician.

I was aware that sinusitis caused fatigue years before I became a doctor because of personal experience and conversations with others who also suffered from sinus problems. I was surprised that my own doctor seemed unaware of the association and I was surprised that fatigue was not listed as a symptom in the general medical texts that I searched in college.

Nothing changed in medical school. Although the lists of illnesses that caused fatigue was quite long, and the lectures on the subject quite thorough, no one that I can recall mentioned sinusitis as a cause of fatigue.

When I first started practice my experience confirmed my own observations that patients with sinusitis were fatigued but, again, a thorough search of the medical literature produced nothing. I then started noticing that patients with a primary complaint of fatigue often, on more detailed questioning, acknowledged sinus symptoms but considered the sinus issue quite minor compared to the more pressing complaint of fatigue.

After trying to redirect the focus towards the sinus issue and initiating treatment, patients would usually notice a great improvement in fatigue. Patients found this puzzling. In fact, often a patient would return months later with the primary complaint of serious fatigue completely having forgotten the link with sinusitis. Once again I would treat the sinusitis and the fatigue would remit.

In the late 1980s I began to see some notice in the medical literature. A consensus conference of ear, nose and throat physicians in 1987 described fatigue as one of the diagnostic criteria for making the diagnosis of chronic sinusitis. I reported several cases of patients diagnosed as having chronic fatigue syndrome who experienced a complete or nearly complete resolution of fatigue following sinus surgery.

Nothing on the subject was mentioned in the internal medicine literature, an unfortunate omission since internists are the doctors who treat fatigue.

I was curious about how common sinus problems are found in patients with a primary complaint of unexplained chronic fatigue. This is how the project unfolded.

I examined 297 consecutive patients who were younger than 41 years, administered a detailed questionnaire and performed a battery of screening laboratory tests. Young patients were chosen in an effort to exclude the illnesses of older age groups that might confound the results.

Of the 297 patients, 65 (22%) noted unexplained fatigue that has persisted for more than one month, fatigue unexplained by the lack of rest, illness, or undo physical or mental exertion. Fifteen (23%) of these patients met the diagnostic criteria for chronic fatigue syndrome, an illness characterized by prolonged and severe fatigue.

When the 65 patients with unexplained chronic fatigue were compared to the remaining group of 232 patients most sinus symptoms were much more common in the group with unexplained chronic fatigue: facial pressure (80% vs 13%), heavy-headedness (80% vs 8%), nasal obstruction (87% vs 42%), frontal headache (53% vs 6%), sore throat (33% vs 8%) and cervical node tenderness (60% vs 6%.)

Of note, symptoms usually associated with unexplained illnesses such as gastrointestinal problems, sleep disturbance, and psychiatric illness were similar in the group with unexplained chronic fatigue when compared to the group with fatigue explained by a physical or mental illness.  However, sinus symptoms were much more common in the former when compared to the latter.

The results confirmed my suspicion that there is a peculiar and predominant relationship between chronic sinusitis and unexplained fatigue.