Crouzon syndrome

Overview

Crouzon syndrome is a rare genetic disorder characterized by the premature fusion of certain skull bones, a condition known as craniosynostosis. This early fusion prevents the skull from growing normally, leading to abnormal head and facial shapes. Unlike some other craniosynostosis syndromes, Crouzon syndrome typically does not involve hand or foot abnormalities. The syndrome was first described by French neurologist Octave Crouzon in 1912. Affected individuals may have normal intelligence, although complications from increased intracranial pressure or hearing and vision problems can affect development.

Causes

Crouzon syndrome is caused by mutations in the FGFR2 gene (fibroblast growth factor receptor 2), and in some cases, the FGFR3 gene. These genes play a crucial role in the development and maintenance of bone and tissue. The disorder is inherited in an autosomal dominant pattern, meaning one copy of the altered gene is sufficient to cause the condition. However, many cases result from new (de novo) mutations with no prior family history.

Symptoms

Symptoms of Crouzon syndrome can vary in severity and typically become noticeable in infancy or early childhood. Common features include:

• Craniosynostosis: Premature fusion of skull sutures, leading to an abnormal head shape

• Midface hypoplasia: Underdevelopment of the upper jaw, cheekbones, and eye sockets

• Proptosis: Bulging eyes due to shallow eye sockets

• Strabismus: Misalignment of the eyes

• Beaked nose and short upper lip

• Dental issues: Such as crowded teeth or underbite

• Hearing loss: Due to narrow ear canals or middle ear infections

• Hydrocephalus: Accumulation of cerebrospinal fluid in the brain in severe cases

Hands and feet are typically normal, which distinguishes Crouzon syndrome from other craniosynostosis syndromes like Apert syndrome.

Diagnosis

Diagnosis of Crouzon syndrome is usually made based on physical features and confirmed through imaging and genetic testing. Diagnostic steps include:

• Physical examination: Identification of craniofacial abnormalities

• CT or MRI scans: To evaluate skull sutures and brain structures

• Genetic testing: To detect mutations in FGFR2 or FGFR3 genes

• Ophthalmologic and audiologic evaluations: To assess vision and hearing status

• Family history: Review to determine inheritance patterns

Treatment

Treatment for Crouzon syndrome focuses on correcting skull and facial abnormalities, preventing complications, and supporting developmental needs. A multidisciplinary team approach is essential. Common treatments include:

• Cranial surgery: Performed in infancy to relieve pressure and allow brain growth

• Midface advancement: To correct facial structure and improve breathing and eye protection

• Orthodontic care: To manage dental malocclusions

• Vision correction: Treatment for strabismus or other eye issues

• Hearing aids or ear tube insertion: For hearing impairment

• Speech and developmental therapy: If delays or communication issues are present

• Regular monitoring: For potential complications such as increased intracranial pressure or hydrocephalus

Prognosis

The prognosis for individuals with Crouzon syndrome is generally good with timely surgical and supportive care. Most affected individuals have normal intelligence and can lead productive lives. However, untreated or severe cases may lead to vision loss, hearing deficits, or neurological complications. Lifelong monitoring and coordinated care from specialists help improve quality of life and functional outcomes.