The word egophony refers to the increase in voice resonance on pulmonary auscultation. Although some authors treat egophony as the normal uptake of vocal vibrations, most consider it as a pathological element in the pulmonary evaluation of the patient.
Described by the father of auscultation, René Laënnec, as “bleating of a goat”, it is a particular type of bronchophony. In fact, the etymology of the term comes from the Greek words for "goat" and "sound." The semiological literature defines it as the change in the pronunciation of the letter "i" by the sound of the letter "e".
During the medical evaluation, the patient is asked to say “II (ii)” in a sustained manner, obtaining an “EE” or “EH” upon auscultation. Pulmonary fibrosis accompanied by pleural effusion is the main cause of auscultatory modification.
Liquid, unlike air, has a narrower molecular composition and allows the transmission of sound with greater ease and fidelity. The same does not happen when there is pneumothorax, bullae or condensation without effusion.
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It often happens that egophony is confused with a disease, when it is really a sign. It can be found in various medical conditions and is an unequivocal sign that something is not right at the lung level.
Like all pathological breath sounds, it has its own characteristics; among these, the following stand out:
- It is a change in the timbre of the sound, but not in the tone or volume.
- Makes the vocalization look like a peculiar nasal sound.
- It is frequently associated with bronchophonia and pectoriloquism, without being clinical synonyms.
- It is usually a unilateral finding in diseases that affect only one lung. Its presence in both hemithorax is unusual and should be studied in depth..
Several medical pathologies, some of their own lung and others systemic, can produce egophony. The most important ones with their particular characteristics are mentioned below:
Many lung infections are capable of generating egophony by two different mechanisms that can complement each other.
Consolidation of the parenchymal tissue and pulmonary effusion are frequent complications of severe pneumonias and represent the perfect environment for the appearance of egophony..
The egophony in these cases is due to the “enhanced” transmission of high-frequency sound through fluids. The same occurs in abnormal lung tissue, where lower frequency sounds are also filtered. These phenomena clean the auscultation and favor the uptake of vocal vibrations..
Although the most common cause of consolidated effusion pneumonia is bacteria, viral and fungal pneumonias can also cause them..
The local inflammatory response is a fundamental factor for the ideal acoustic conditions to be produced that allow the appearance of guttural noise.
Although most pleural effusions are infectious in origin, there are other important causes. Heart failure, cirrhosis or liver failure, hypoalbuminemia, and chronic kidney disease are causes of pleural effusion that can have clinical manifestations consistent with egophony..
The main difference with respiratory infections is that they are accompanied by fever, chills, rib pain and expectorations; likewise, other concomitant respiratory sounds such as rhonchi and crackles are auscultated. Both situations can present respiratory distress with intercostal pulling and tachypnea..
A significant characteristic of the egophony associated with pleural effusion is that it can only be heard in the area of the rib wall that reflects the area of the spilled lung..
Above the effusion, the egophony is not captured, and the rest of the usual lung sounds may even be diminished.
The hardening of the lung parenchyma also favors the appearance of egophony. It is the other ideal condition for the transmission of vocal vibrations; like pleural effusion, it has infectious and non-infectious causes.
A typical sound known as a tubal murmur can also be heard in the fibrotic region of the lung. Among the most common causes of pulmonary fibrosis are the following:
These can cause scar tissue in the lungs, considered fibrosis..
Chronic cigarette smoking eventually leads to pulmonary fibrosis and chronic obstructive pulmonary disease.
Contact of the respiratory tract with other substances such as asbestos, silica, heavy metals, carbon and even animal excrement can cause severe pulmonary fibrosis..
Some antibiotics used for a long time can cause pulmonary fibrosis. Nitrofurantoin is an example.
Certain antineoplastic, antiarrhythmic, anti-inflammatory and immunomodulatory drugs (such as steroids) have the adverse effect of hardening of the lung parenchyma.
Whether for therapeutic use, as part of cancer treatment, or for work-related issues such as radiological technicians, radiation is a major cause of tissue fibrosis. It does not only affect the lungs.
Numerous rheumatic and immune diseases can cause pulmonary fibrosis. It also happens as a consequence of the treatment of these pathologies.
Amyloidosis, sarcoidosis, rheumatoid arthritis, dermatomyositis, systemic lupus erythematosus, and scleroderma are some of these pathologies that can damage the lung..
One of the maxims in current medical practice is that symptoms are not treated, diseases are treated. Hence the need to clarify that egophony is not treated, the diseases that produce it are treated.
However, there are some common therapies for managing egophony, including the following:
It is the obvious treatment for a bacterial lung infection. The type of antimicrobial drug to be administered will be decided depending on the patient's symptoms, the severity of the condition and the germs isolated in blood cultures or studies of pleural fluid..
Without being formally considered antibiotics, antifungals and antivirals can be used if the etiology of the infection warrants it. These treatments are administered with the hospitalized patient in most cases..
A large number of rheumatological and immunological diseases are treated with steroids. By controlling the disease, the causes of egophony disappear, but steroids have an additional beneficial effect, since they produce a local anti-inflammatory effect at the lung level and promote bronchodilation.
Commonly used in heart failure and high blood pressure, they help eliminate excess fluid. Pleural effusion decreases with the use of diuretics and, therefore, egophony disappears.
Certain cases of pulmonary fibrosis warrant surgical treatment. Necrosis, the appearance of fistulas, pneumonic blocks or persistent effusions are treated with surgery, which can range from the placement of a chest tube to total pneumonectomy..
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