Stickler syndrome Health Article

Demographics

No studies have been done to determine Stickler syndrome prevalence. An approximate incidence of Stickler syndrome among newborns is estimated based on data on the incidence of Pierre-Robin sequence in newborns. One in 10,000 newborns have Pierre-Robin sequence, and 35% of these newborns subsequently develop signs or symptoms of Stickler syndrome. These data suggest that the incidence of Stickler syndrome among neonates is approximately one in 7,500.

Signs and symptoms

Stickler syndrome may affect the eyes and ears, skeleton and joints, and craniofacies. It may also be associated with coronary complications.

Ocular symptoms

Near-sightedness is a common symptom of Stickler syndrome. High myopia is detectable in newborns. Common problems also include astigmatism and cataracts. Risk of retinal detachment is higher than normal. Abnormalities of the vitreous humor, the colorless, transparent jelly that fills the eyeball, are also observed. Type 1, the more common vitreous abnormality, is characterized by a persistence of a vestigial vitreous gel in the space behind the lens, and is bordered by a folded membrane. Type 2, which is much less common, is characterized by sparse and irregularly thickened bundles throughout the vitreous cavity. These vitreous abnormalities can cause sight deterioration.

Auditory symptoms

Hearing impairment is common, and some degree of sensorineural hearing loss is found in 40% of patients. The degree of hearing impairment is variable, however, and may be progressive. Typically, the impairment is high tone and often subtle. Conductive hearing loss is also possible. It is known that the impairment is related to the expression of type II and IX collagen in the inner ear, but the exact mechanism for it is unclear. Hearing impairment may be secondary to the recurrent ear infections often associated with cleft palate, or it may be secondary to a disorder of the ossicles of the middle ear.

Skeletal symptoms

Skeletal manifestations are short stature relative to unaffected siblings, early-onset arthritis, and abnormalities at ends of long bones and vertebrae. Radiographic findings consistent with mild spondyloepiphyseal dysplasia. Some individuals have a physique similar to Marfan syndrome, but without tall stature. Young patients may exhibit joint laxity but it diminishes or even resolves completely with age. Early-onset arthritis is common and generally mild, mostly resulting in joint stiffness. Arthritis is sometimes severe, leading to joint replacement as early as the third or fourth decade.

Craniofacial findings

Several facial features are common with Stickler syndrome. A flat facial profile referred to as a "scooped out" face results from underdevelopment of the maxilla and nasal bridge, which can cause telecanthus and epicanthal folds. Flat cheeks, flat nasal bridge, small upper jaw, pronounced upper lip groove, small lower jaw, and palate abnormalities are possible, all in varying degrees. The nasal tip may be small and upturned, making the groove in the middle of the upper lip appear long. Micrognathia is common and may compromise the upper airway, necessitating tracheostomy. Midfacial hypoplasia is most pronounced in infants and young children, and older individuals may have a normal facial profile.

Coronary findings

Mitral valve prolapse may be associated with Stickler syndrome, but studies are, as yet, inconclusive about the connection.

Diagnosis

Stickler is believed to be a common syndrome in the United States and Europe, but only a fraction of cases are diagnosed since most patients have minor symptoms. Misdiagnosis may also occur because symptoms are not correlated as having a single cause. More than half of patients with Stickler syndrome are originally misdiagnosed according to one study.

While the diagnosis of Stickler syndrome is clinically based, clinical diagnostic criteria have not been established. Patients usually do not have all symptoms attributed to Stickler syndrome. The disorder should be considered in individuals with clinical findings in two or more of the following categories:

• Ophthalmologic. Congenital or early-onset cataract, myopia greater than -3 diopters, congenital vitreous anomaly, rhegmatogenous retinal detachment. Normal newborns are typically hyperopic (+1 diopter or greater), and so any degree of myopia in an at-risk newborn, such as one with Pierre-Robin sequence or an affected parent, is suggestive of the diagnosis of Stickler syndrome. Less common ophthalmological symptoms include paravascular pigmented lattice degeneration and cataracts.
• Craniofacial. Midface hypoplasia, depressed nasal bridge in childhood, anteverted nares (tipped or bent nasal cavity openings), split uvula, cleft hard palate, micrognathia, Pierre-Robin sequence.
• Audiologic. Sensorineural hearing loss.
• Joint. Hypermobility, mild spondyloepiphyseal dysplasia, precocious osteoarthritis.

It is appropriate to evaluate at-risk family members with a medical history and physical examination and ophthalmologic, audiologic, and radiographic assessments. Childhood photographs may be helpful in the evaluation of adults since craniofacial findings may become less distinctive with age.