Sphenoid Wing Dysplasia
A developmental abnormality of the skull bone behind the eye
Quick Facts
- Type: Skull (bone) developmental abnormality
- Bone affected: Greater wing of the sphenoid bone
- Strong link: Neurofibromatosis type 1 (NF1)
- Main effect: Can affect the eye socket and eye position
Overview
Sphenoid wing dysplasia is an abnormal development of part of the sphenoid bone, a bone at the base of the skull that helps form the back of the eye socket. When the greater wing of this bone is poorly formed or absent, the wall between the eye socket and the brain cavity can be weakened or missing.
This condition is one of the recognized bone features of neurofibromatosis type 1 (NF1) and is uncommon outside of it. Many people with sphenoid wing dysplasia have no symptoms and it is found on imaging. In others, it can affect the position of the eye or, in combination with nearby nerve tumors, cause the eye to bulge or pulsate. Care is provided by specialists and depends on whether the condition is causing problems.
Symptoms
Sphenoid wing dysplasia is often symptom-free and discovered on a brain or skull scan. When it does cause symptoms, they relate to the eye and surrounding area:
- A bulging or forward-displaced eye (proptosis)
- An eye that appears to pulsate, because brain tissue and its pulsations are transmitted through the bony defect
- Asymmetry of the face or eye socket
- In some cases, downward displacement of the eye
Vision changes, a rapidly bulging eye, or new eye pain should be evaluated promptly by an eye or skull specialist.
Causes
Sphenoid wing dysplasia results from abnormal bone development, most often in the setting of a genetic condition.
- Neurofibromatosis type 1: This is the main associated condition; the abnormal bone development is considered one of the characteristic skeletal features of NF1.
- Associated nerve tumors: A nearby plexiform neurofibroma in the eye socket can contribute to changes in eye position.
It is present from early development and is not caused by injury or anything done after birth.
Risk Factors
- Neurofibromatosis type 1 (the principal risk factor)
- A family history of NF1
Sphenoid wing dysplasia is rare in people who do not have neurofibromatosis.
Diagnosis
Diagnosis is based on imaging and assessment of the eye and surrounding structures.
- CT scan: Shows the bony abnormality of the sphenoid wing clearly and is the main test for the bone.
- MRI scan: Used to assess the soft tissues, the eye socket, and any associated nerve tumor.
- Eye examination: To check vision, eye position, and eye movements.
- Evaluation for NF1: Looking for other features of neurofibromatosis.
Treatment
Treatment depends on whether the condition is causing symptoms or problems with the eye.
- Observation: Many people with no symptoms simply have periodic monitoring with imaging and eye checks.
- Surgery: Reconstructive surgery may be considered when there is significant eye displacement, a bulging or pulsating eye, or an associated tumor causing problems; the goal is to protect the eye and improve appearance and function.
- Management of associated tumors: Treatment of any nearby plexiform neurofibroma as part of the overall plan.
- Multidisciplinary care: Involving specialists in the skull base, eye, and neurofibromatosis.
Decisions are individualized, balancing the benefits and risks of surgery in a complex anatomical area.
Prevention
Sphenoid wing dysplasia cannot be prevented because it arises during bone development. The focus is on monitoring and early detection of problems:
- Regular follow-up for people with neurofibromatosis type 1
- Prompt evaluation of any change in eye position, bulging, or vision
- Genetic counseling for families affected by NF1
When to See a Doctor
See a doctor if you or your child develops a bulging eye, facial or eye-socket asymmetry, or changes in eye position, particularly with known neurofibromatosis. Seek prompt evaluation for:
- A rapidly bulging or pulsating eye
- New or worsening vision changes
- New eye pain or restricted eye movement
Frequently Asked Questions
What is sphenoid wing dysplasia?
It is an abnormal development of part of the sphenoid bone that forms the back of the eye socket. When this bone is poorly formed or absent, the wall between the eye socket and the brain cavity can be weakened, which can affect eye position.
Is sphenoid wing dysplasia linked to neurofibromatosis?
Yes. It is one of the recognized bone features of neurofibromatosis type 1 and is uncommon in people without that condition. People diagnosed with it are usually evaluated for other NF1 features.
Does it always cause symptoms?
No. Many people have no symptoms and it is found on imaging done for another reason. In others it can cause a bulging or pulsating eye or facial asymmetry, which may need treatment.
How is it treated?
Many symptom-free cases are simply monitored. Reconstructive surgery may be considered when there is significant eye displacement, a bulging or pulsating eye, or an associated tumor, and is performed by skull-base and eye specialists.
When should I see a doctor?
See a doctor for a bulging or pulsating eye, eye-socket asymmetry, vision changes, or new eye pain, especially if you have neurofibromatosis type 1.
References
- Children's Tumor Foundation. Neurofibromatosis Type 1.
- MedlinePlus, U.S. National Library of Medicine. Neurofibromatosis type 1.
- National Institute of Neurological Disorders and Stroke (NINDS). Neurofibromatosis.
- American Academy of Ophthalmology. Neurofibromatosis and the Eye.