Overview
Hyperostosis cranialis interna (HCI) is a very rare bone disorder where the skull bones grow abnormally thick and dense on the inside. This overgrowth of bone happens along the inner surface of the skull, particularly in the base and vault of the skull. As the bone grows inward, it can press on the nerves that pass through the skull, causing a range of symptoms. The condition is also sometimes referred to by its full descriptive name, which reflects the key feature: abnormal bone hardening (hyperostosis) inside (interna) the skull (cranialis). Because the growing bone puts pressure on cranial nerves — the nerves that control things like facial movement, hearing, smell, and vision — people with HCI often experience facial pain, hearing loss, and problems with facial muscles. Symptoms usually begin in early adulthood and tend to get worse over time as the bone continues to thicken. The forehead area may also appear more prominent in some individuals. There is currently no cure for HCI. Treatment focuses on managing symptoms, such as using pain medications for headaches and facial pain, and surgical procedures to relieve pressure on specific nerves when needed. Because this condition is so rare, most people are managed by a team of specialists including neurologists, ENT doctors, and clinical geneticists. Early diagnosis is important so that nerve damage can be monitored and treated before it becomes severe.
Key symptoms:
Facial pain or numbnessHearing loss, often progressiveHeadachesFacial muscle weakness or paralysis (similar to Bell's palsy)Loss of smell (anosmia)Vision changes or lossRinging in the ears (tinnitus)Dizziness or balance problemsProminent or enlarged forehead appearanceDifficulty swallowing in some cases
Autosomal dominant
Passed on from just one parent; each child has about a 50% chance of inheriting it
Adult
Begins in adulthood (age 18 or older)
Treatments
No FDA-approved treatments are currently listed for Hyperostosis cranialis interna.
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Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to Hyperostosis cranialis interna.
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Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
Rare disease caregiving can be isolating. Connect with counseling and peer support.
Family & Caregiver Grants
Financial assistance programs specifically for caregivers of rare disease patients.
Social Security Disability
Learn how rare disease patients may qualify for SSDI/SSI benefits.
Questions for your doctor
Bring these to your next appointment
- Q1.Which nerves are currently being affected, and how do we monitor them over time?,How often should I have CT scans or other imaging to track the bone growth?,At what point would you recommend surgery, and what does nerve decompression involve?,Should my children or siblings be tested for this condition?,Are there any clinical trials or research studies I could participate in?,What pain management options are available, and what are the risks of long-term use?,Are there any specialists or centers with more experience treating HCI that you would recommend?
Common questions about Hyperostosis cranialis interna
What is Hyperostosis cranialis interna?
Hyperostosis cranialis interna (HCI) is a very rare bone disorder where the skull bones grow abnormally thick and dense on the inside. This overgrowth of bone happens along the inner surface of the skull, particularly in the base and vault of the skull. As the bone grows inward, it can press on the nerves that pass through the skull, causing a range of symptoms. The condition is also sometimes referred to by its full descriptive name, which reflects the key feature: abnormal bone hardening (hyperostosis) inside (interna) the skull (cranialis). Because the growing bone puts pressure on cranial
How is Hyperostosis cranialis interna inherited?
Hyperostosis cranialis interna follows a autosomal dominant inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Hyperostosis cranialis interna typically begin?
Typical onset of Hyperostosis cranialis interna is adult. Age of onset can vary across affected individuals.
Which specialists treat Hyperostosis cranialis interna?
3 specialists and care centers treating Hyperostosis cranialis interna are listed on UniteRare, sourced from ClinicalTrials.gov principal investigators, published research, and the NPPES NPI registry.