Bicoronal Non-Syndromic Craniosynostosis
Non-syndromic bicoronal craniosynostosis is a condition that leads to premature closure of both coronal sutures but is not associated with any syndrome or associated deformities or conditions.
Although the majority of bicoronal synostosis is of the syndromic type (Apert, Crouzon, Pfeiffer, Carpenter, etc.) there are a number of patients who present with premature closure of both coronal sutures yet, have no syndromic connection. These patients are otherwise normal and present with no evidence of developmental delays or any other systemic problem. We have been successfully treating these patients using our minimally invasive endoscopic techniques for a number of years with superb results. The key to successful outcomes is treating these patients as early and as young as feasibly possible.
The coronal sutures are located on either side of the head and adjoin the soft spot in the middle. Their function is to allow the frontal lobes of the brain to grow and move forward. This in turn allows the forehead, eyes, eyebrows and nose to also move forward and downward. Premature closure of both sutures results in a number of deformities related to these structures' inability to advance normally.
Open coronal sutures (red areas) allow both frontal lobes to grow and advance forward (green arrows).
Closed coronal sutures keep the frontal lobes from moving forward and cause a shallow and foreshortened frontal cranial vault (red arrows).
Normal brain growth allows the bones around the eyes and face to move forward.
Premature bicoronal synostosis keeps the bones from moving forward and causes the mid face and eye sockets to be recessed and the forehead to bulge abnormally.
The patient's head, as seen from above, is wide and shallow (brachycephaly). The eyes protrude in front of the eye brows and eye sockets (proptosis). The side of the eyes tend to angulate downward and because the brain can't grow forward, it grows tall causing the forehead and cranial vault to be high ( turricephaly). The patients are otherwise normal with no evidence of fused fingers or toes (syndactilty), wide and broad thumbs or fused elbows.
Patient presents with significant forehead protrusion as seen on this photo that shows the nose tip aligned with the forehead (green line).
This patient has angulated and inferiorly displaced eyes and eye sockets as demonstrated by the green lines.
A very narrow and shallow anterior cranial fossa and frontal area is seen on this top view of the head.
CT scanning is the gold standard test for making the appropriate diagnosis. The closed sutures are very evident as are all of the other aforementioned clinical findings. MRI scans are used as an adjunct to better visualize the brain and intracranial structures, if indicated.
3-D CT scan of patient showing ridging of both closed coronal sutures.
CT scan cross section of the skull slightly above the eyes show widening of the cranium (yellow arrows) and foreshortening of the front to back distance (red arrows).
3-D CT scan of a normal adult showing the distance between the orbits and side of the skull (red arrows).
3-D CT of baby with bicoronal synostosis showing widening of the skull and increased distance between the orbits and the side of the skull (red arrows).
Positioning in Surgery
The patient is placed on his/her back in the OR table with the head on a head holder in neutral position. This allows access to both coronal sutures as well as to the midline and side of the head.
Two small (less than an inch) incisions are made on the scalp on either side of the midline along the closed coronal sutures. The goal is to remove a small amount of bone that extends from the soft spot to the side of the skull where the suture ends. This is done on both sides, totally releasing the frontal bones from the parietal bones.