Genetic Hearing Loss Associated with Musculoskeletal Disorders Flashcards
What is crouzon’s syndrome?
Premature closure of cranial sutures with resulting craniostenosis (contracted skull); most common craniosynostoses syndrome
How is crouzons inherited?
Autosomal dominant
Spontaneous mutation fairly common and of paternal origin
What are some characteristics of crouzons?
Abnormal shape of the head and appearance of face
A major problem is maxillary hypoplasia
Bulging eyes/vision problems caused by shallow eye sockets
Mild ocular hypertelorism (increased space b/w eyes), orbital proptosis
Occasional cleft lip and palate
Mental status is normal
What are the audiologic findings of crouzons?
Atresia of the EAM with ossicular deformity
Absent or narrowed oval and/or round window
Conductive hearing loss is common but mixed hearing loss is also reported
Vestibular system is normal
What is stickler syndrome?
Collagen disorder affecting architecture of collagen-based tissues
Three types (I, II, and III)
Virtually all mutations involve premature stop codons (nonsense mutations)
How is stickler syndrome characterized?
Characterized by a distinctive facial appearance, eye abnormalities, hearing loss, and joint problems
~30% show premature degeneration of joints leading to skeletal/joint abnormalities beginning in the 3rd or 4th decade
Flat mid face and occasionally cleft or high arched palate
Severe myopia; cataracts and glaucoma can occur but blindness rare
What are the audiologic findings of stickler syndrome?
Associated with a mixed or progressive high frequency SNHL
Hearing loss is reported in about 60% of stickler syndrome type 1 patients and about 90% in sticker syndrome type 2 patients
What is achondroplasia?
Short-limbed dwarfism
What are the clinical features of achondroplasia?
An average-size trunk with short arms and legs
Enlarged head and frontal bossing
Short stubby hands
Legs frequently bowed of because lax knee ligaments
Intelligence is generally normal
Lordotic lumbar spine with prominent buttocks
Short and narrow pelvis
Reproductive fitness reduced primarily because of social difficulties in finding a mate
What are the audiologic findings of achondroplasia?
> 90% report history of ear infections with >70% report CHL
Otosclerosis also reported
What is osteogenesis imperfecta?
Generalized connective tissue disorder characterized mainly by bone fragility
Besides bone fragility, what are other characteristics of osteogenesis imperfecta?
Blue sclera
Cardiovascular problems
What audiologic findings are present in those with osteogenesis imperfecta?
Conductive or mixed hearing loss in ~ 50% of families
Hearing loss begins in the late teens progressing gradually to profound deafness
Tinnitus and vertigo by the end of the 4th to 5th decade
What is the transmission of achondroplasia?
Autosomal dominant
> 80% cases are sporadic representing new mutations associated with increased paternal age
Can achondroplasia be lethal for offspring?
Homozygosity, with both parents affected, has been reported but it proves lethal for the offspring
