IS Case 291: Anomalous midline occipital suture

Nate Johnson, MD

Imaging Sciences URMC 2009
Publication Date: 2009-08-05


Patient is a one-day-old infant with seizure activity status post-vacuum assisted delivery.


Well corticated midline vertical linear lucency identified through the superior aspect of the occipital bone.


Anomalous midline occipital suture


Throughout the course of development of the occipital bone six ossification centers are present. Knowledge of the location of these centers is necessary to assist with understanding of the location of accessory fissures. The foramen magnum is surrounded by four of these centers of ossification. Laterally the exoccipital bones form the boundary with the basioccipital bone anteriorly and the supraoccipital bone superiorly. At the mid-aspect of the supraoccipital bone inferiorly an indentation called Kerckring's process may be found. Superior to the transverse occipital fissure there are two more ossification centers present named the interparietal portion of the occipital bone. These bones normally fuse in the midline but lack of fusion may lead to a midline defect through the superior-most aspect of the occipital bone which extends inferiorly to the expected location of the transverse occipital fissure. This pattern is seen in our patient and is consistent with un-fused interparietal ossification centers of the occipital bone.


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