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Normal Variant Occipital Pneumatization

Tomblinson, Courtney M.*; Deep, Nicholas L.; Fletcher, Geoffrey P.*; Nelson, Kent D.*; Patel, Ameet C.*; Weindling, Steven M.; Lane, John I.§; Hoxworth, Joseph M.*

doi: 10.1097/MAO.0000000000001947

Objective: Evaluate prevalence and pattern of occipital pneumatization (OP).

Patients: Individuals with imaging evidence of OP on computed tomography (CT).

Intervention(s): High resolution CT scans of the temporal bone.

Main Outcome Measure: The prevalence and pattern of OP on 1000 CT scans performed at a large academic healthcare system.

Results: OP had a prevalence of 11.8% (n = 118) while occipital condyle pneumatization occurred in only 0.3%. Occipital air cells were right-sided in 27.1% (n = 32), left-sided in 51.7% (n = 61), and bilateral in 21.2% (n = 25), and OP was contiguous with the occipitomastoid suture. In cases of unilateral OP, the contralateral jugular foramen demonstrated relative enlargement (p = 0.006), but a direct association could not be established.

Conclusions: The occipital bone is an accessory site of skull base pneumatization in 11.8% of the population undergoing temporal bone CT, while air cell extension into the occipital condyle occurs more rarely. These occipital air cells have a left-sided predilection and are always in direct proximity to the occipitomastoid suture, suggesting developmental egress from the mastoid. OP is a normal variant and lacks features of craniocervical pneumatization, which is a rare disorder.

*Department of Radiology

Department of Otolaryngology, Mayo Clinic, Phoenix, Arizona

Department of Radiology, Mayo Clinic, Jacksonville, Florida

§Department of Radiology, Mayo Clinic, Rochester, Minnesota

Address correspondence and reprint requests to Joseph M. Hoxworth, M.D., 5777 E Mayo Blvd, Phoenix, AZ 85054; E-mail:

Financial Disclosures/External Funding: None.

The authors disclose no conflicts of interest.

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