Type 2C has so far only been found in one Italian family, and type 2D had only been found in 2 unrelated patients as of 2018. The number of known cases of type 2E that involved neurological abnormalities was reported to be 23 as of 2017, while the number of the rest is unknown. Type 3 is rarer than types 1, 2 and 4, comprising less than 2% of cases. Type 4 appears to encompass around a fifth of cases (19%). Of its subtypes, type 4C is by far the most common (about 71% of type 4), followed by type 4A (19%) and type 4B (10%).It is estimated that Waardenburg syndrome is present in 2–5% of congenitally deaf people. Congenital deafness comprises around half of deafness as a whole. About 1 in 30 students in schools for the deaf have Waardenburg syndrome. The variable presentation of the syndrome makes it difficult to arrive at precise figures for its prevalence. History
Early descriptions
In 1916, Dutch ophthalmologist Jan van der Hoeve (1878–1952) described a pair of twin girls with deafness and a particular type of blepharophimosis, believed to be the dystopia canthorum found in Waardenburg syndrome types 1 and 3. Blepharophimosis describes eyelids which are underdeveloped such that they permanently cover part of the eyes. In 1926, German physician Irmgard Mende described a family of four generations in which five children had symptoms of depigmentation of hair, skin and eyes, deafness and a "mongoloid" appearance. (Waardenburg later attributed this description to the dystopia canthorum.)
Whilst hearing loss is a common symptom in many diseases of the ear, for example in otosclerosis (abnormal bone growth in the ear), the white, chalky patches on the tympanic membrane are fairly characteristic of tympanosclerosis. Cholesteatoma is similar in appearance but the whiteness is behind the tympanic membrane, rather than inside. Classification
Myringosclerosis refers to a calcification only within the tympanic membrane and is usually less extensive than intratympanic tympanosclerosis, which refers to any other location within the middle ear such as the ossicular chain, middle ear mucosa or, less frequently, the mastoid cavity. Treatment
Hearing aids are a common treatment for hearing loss disorders. A more specific treatment is surgical, involving excision of the sclerotic areas and then further repair of the ossicular chain. There are several techniques, sometimes involving two surgeries; success rates are, however, variable. Damage to the inner ear as a result of surgical procedures is a possible and serious concern, as it can result in forms of sensorineural deafness. Prognosis
In most cases, tympanosclerosis does not cause any recognisable hearing loss up to ten years after the initial disease onset. Sclerotic changes seem to stabilise, but not resolve or dissolve, after 3 years. Epidemiology
Myringosclerosis seems to be more common than tympanosclerosis. Most research has not been conducted upon the general, healthy population, but rather those with otitis media or patients who have had tympanostomy tubes in prior procedures. Of the children studied who had glue ear, and who were treated with tympanostomy tubing, 23-40% of cases had tympanosclerosis.