Audiology: Alport Syndrome Alport Syndrome

Audiology: Alport Syndrome

Alport Syndrome (also known as hereditary nephritis and nerve deafness) is a genetic syndrome affecting the kidneys, inner ears, and eyes. It was recognized by Dr. Cecil Alport in 1927, and named for him in 1961. (NKF, 2010) the disorder results from genetic mutations affecting collagen proteins. (Favor, Gloeckner, Janik, & Klempt, 2007) in turn, these faulty collagen proteins impair hearing by affecting the inner ear organ of Corti, which transforms sound waves into nerve impulses for the brain. (NIH, 2009) Hearing abnormalities generally do not develop until late childhood or early adolescence, primarily affect males, and are associated with renal symptomology. Hearing aids are generally effective for hearing loss due to Alport Syndrome complications. (Alport Syndrome Foundation, 2010)

The most common symptom of Alport Syndrome is actually hematuria (blood in the urine). As otoscopic examination findings are normal, diagnosis is not made based on these results; however, patients have bilateral type a curve tympanometry. (Viveiros, 2006) in many cases, bilateral high-frequency sensorineural hearing loss (SNHL) may develop by late childhood or early adolescence. In addition, SNHL will eventually develops in approximately 85% of affected males, as well as in some females (but only about 10%). (Kashtan, 2010)

Early on, hearing impairment is only detected through audiometry; typically it is bilateral hearing loss specifically to high tones ranging in frequency from 2000 to 8000 hertz (Hz). The audiometric curve types most often associated with hearing loss in Alport Syndrome are mild drop in high frequencies, and flat curves. (Abreu Alves & al, 2008) Later in life, sloping sensorineural hearing loss can occur, and in some cases, complete deafness. Other hearing abnormalities and test results typical of Alport's Syndrome can include hearing loss at 4000 Hz, loudness recruitment, high SISI scores, absent tone decay, and Type II Bekesy tracings. (Northern & Downs, 1974)

In China, otoacoustic emissions studies on patients with Alport Syndrome have determined, specifically by way of distortion product otoacoustic emission (DPOAE) tests, that the location of pathological changes due to Alport Syndrome are located in the basilar membrane (Zhang & McPherson, 2005). Other studies have found "no statistically significant average difference between left and right ears for average values of TOAE (transitory otoacoustic emissions) response amplitude with no contralateral acoustic stimulation in patients with Alport's syndrome. (Abreu Alves & al, 2008)"