The disease otosclerosis involves the abnormal growth of bones within the ear. The increase in bone mass disrupts the normal hearing process and can cause hearing loss over time. Estrogen, a sex hormone, helps regulate the formation and destruction of bones, especially in women. The onset and progression of otosclerosis and its association with estrogen is not well understood, but research has elucidated some connections.
Estrogen Properties
Estrogen refers to a group of steroid hormones produced in the ovaries. Although present in both men and women, estrogen is the primary sex steroid in women and present at significantly higher levels, especially in women of reproductive age. Among its numerous functions, estrogen most importantly regulates a woman's menstrual cycle, stimulates the growth of the uterus and endometrium in preparation of a potential pregnancy and promotes the development of secondary sex characteristics during puberty. Estrogen also helps maintain bone integrity by reducing bone breakdown and increasing bone formation, according to "Basic & Clinical Endocrinology."
Ear Structure and Otosclerosis
The ear consists of three distinct areas--the outer, middle and inner ear. The outer ear receives and channels sound waves into the external ear canal, which ends at the ear drum. These sound waves vibrate against the ear drum, which then transmits the signals through three small bones in the middle ear called the malleus, incus and stapes, known collectively as the ossicles. Otosclerosis can cause abnormal growth in any of the three ossicles, but it typically affects the stapes, according to the National Institute on Deafness and Other Communication Disorders.
Pregnancy and Otosclerosis
The cause of otosclerosis remains unclear; however, research shows that otosclerosis runs in families and may be hereditary. Women acquire the disease at a higher rate than men, especially during pregnancy. Though not fully understood, the hormonal changes associated with pregnancy have been attributed as a possible cause. During pregnancy, estrogen is at significantly elevated levels for long periods of time, and the growth of the ossicles may be due to estrogen's function in increasing bone formation and strength. Pregnancy in particular increases the frequency of otosclerosis onset.
Symptoms and Diagnosis
Otoslcerosis usually causes conductive hearing loss, which is associated with problems with the outer and middle ear. The main symptoms include gradual hearing loss, which may be better in noisy environments than in quiet ones, and ringing in the ears, a condition known as tinnitus. Other symptoms some people experience are dizziness and balance issues. Diagnosis procedures include hearing loss and balance assessments performed by an otologist or audiologist. CT scans of the temporal area of the head are also used to identify abnormally sized ossicles.
Treatment
For minor hearing loss, the use of a properly fitted hearing aid helps to regain hearing ability. Surgical treatment involves the removal of the enlarged stapes and its replacement with a prosthetic. Patients who undergo this procedure, called a stapedectomy, usually recapture 100 percent of their former hearing ability. For pregnant women, estrogen blockers may help in reducing the enlarged bone, but the treatment has not been thoroughly studied.
References
- "Basic & Clinical Endocrinology;" Francis S. Greenspan, David G. Gardner; 2003
- National Institute on Deafness and Other Communication Disorders: Otosclerosis
- MedlinePlus: Otosclerosis
- Timothy Hain, MD: Otosclerosis
