An Overview of Mondini Syndrome

Mondini syndrome, also known as Mondini dysplasia or a Mondini malformation, describes a condition where the cochlea is incomplete, with only one and a half turns instead of the normal two and a half turns. The condition was first described in 1791 by the physician Carlo Mondini in an article titled "The Anatomic Section of a Boy Born Deaf." A translation from the original Latin of the article was published in 1997.

Carlo Mondini's original article had a very clear definition of the malformation that bears his name. Over the years, some physicians have used the term to describe other bony cochlear abnormalities. When discussing Mondini malformations, it is important to have a clear description of the cochlea and other inner ear structures as the name 'Mondini' may be confusing.

Causes

This is a congenital (present at birth) cause of hearing loss. A Mondini malformation occurs when there is a disruption in the development of the inner ear during the seventh week of gestation. This may affect one or both ears and may be isolated or occur with other ear malformations or syndromes.

Syndromes that are known to be associated with Mondini malformations include Pendred Syndrome, DiGeorge Syndrome, Klippel Feil Syndrome, Fountain Syndrome, Wildervanck Syndrome, CHARGE syndrome, and certain chromosomal trisomies. There are cases where Mondini malformations have been linked to autosomal dominant and autosomal recessive inheritance patterns as well as being an isolated occurrence.

Diagnosis

Diagnosis of Mondini malformations is made by radiographic studies, such as high-resolution CT scans of the temporal bones. 

Hearing Loss and Treatment 

The hearing loss associated with Mondini malformations can vary, although it is usually profound. Hearing aids are recommended when there is enough residual hearing to be beneficial. In cases where hearing aids are not effective, cochlear implantation has been done successfully.

Other Considerations

People with Mondini malformations may be at a higher risk for meningitis. The malformation may create an easier entry point to the fluid around the brain and spinal cord. In cases where there have been multiple (or recurrent) episodes of meningitis, surgery to close this entry point may be indicated.

Mondini malformation may also impact the balance system of the inner ear. Children with Mondini malformations may show developmental delays in their motor development due to decreased input to the brain from their balance system. In other cases, balance issues may not appear until adulthood.

The other complicating issue with Mondini deformity is increased risk of perilymphatic fistula which is a leakage of inner ear fluid through the oval or round windows of the cochlea. This can result in further progression of hearing loss in an impaired ear and it can cause severe vertigo. The only way to diagnose this condition is the surgically lift up the tympanic membrane and observe these areas for leakage,