Sagittal Synostosis

Sagittal synostosis (scaphocephaly) is the most common form of isolated (non-syndromic) craniosynostosis, representing about half of all cases of craniosynostosis. Boys tend to have this type of craniosynostosis more than girls with a ratio of 4 boys to each girl with sagittal synostosis. As seen in the figure below, the sagittal suture runs lengthwise along the top of the skull. The direction of growth at the cranial sutures is away from the suture (perpendicular to the suture). Normal growth at the sagittal suture provides width to the middle and back parts of the skull. In sagittal synostosis the sagittal suture is closed and this normal transverse growth is lost causing the skull to be abnormally narrow at the middle and back regions. The skull is forced to grow at the remaining open sutures to make space for the growing brain. This compensatory growth at the open sutures causes the skull to grow longer than normal from front to back and also causes increased width and projection (bossing) of the forehead.

Sagittal Suture CT Lateral
Sagittal Top Down View

Scaphocephaly describes the general head shape in sagittal synostosis, but there is a fair amount of variability in the head shape depending upon how the compensatory growth is distributed. In some children, there is more fullness (bossing) and increased height of the forehead as the dominant feature. In others, the back of the head may be more significantly affected with a longer, narrow and coned shape. In most patients, the changes in head shape resulting from sagittal synostosis are evenly distributed throughout the head. The figures below show a two month old child with the characteristic changes of sagittal synostosis including increased width and forward projection of the forehead (bossing), increased length of the skull and narrowing of the middle and back portions of the skull.

This is boy presented at 2 months of age with fullness of the forehead and some narrowing by the temples.

This is boy presented at 2 months of age with fullness of the forehead and some narrowing by the temples.

The top down view of his head shows the characteristic elongated and narrow skull shape caused by sagittal synostosis. Note that the back of he head is narrower than the forehead which is not normal.

The top down view of his head shows the characteristic elongated and narrow skull shape caused by sagittal synostosis. Note that the back of he head is narrower than the forehead which is not normal.

Again, fullness of the forehead and an elongated head shape visible. In this child's case, the back of the head is more severely affected. In his case there is a narrowed bullet-shape (coning) of the back of the head.

Again, fullness of the forehead and an elongated head shape visible. In this child's case, the back of the head is more severely affected. In his case there is a narrowed bullet-shape (coning) of the back of the head.

Treatment

There are two main types of surgical options for treating sagittal synostosis. Strip craniectomy procedures remove a strip of bone from the skull, including the closed sagittal suture, in order to allow the brain to remodel the skull as it grows. These techniques are usually combined with a molding helmet that is worn after surgery in order to direct the growth of the brain and skull more efficiently. Strip craniectomy procedures are usually performed before age 4 months of age. Open cranial vault remodeling procedures normalize the head shape by removing large segments of the skull bones that are reshaped by hand and then reattached to the skull using suture or plates that the body will dissolve in time. Open cranial vault remodeling is usually performed between 6-12 months of age.

Strip Craniectomy

For patients less than 4 months of age, I prefer to perform minimally invasive (endoscopic) extended strip craniectomy. This procedure use very small incisions - only about 1.5 inches long - placed at the ends of the sagittal suture. Through these small incisions a 2 inch wide strip of bone, including the closed sagittal suture, is removed. Additional wedges of bone are removed behind the coronal sutures and in front of the lambdoid sutures. These additional cuts allow the parietal bones of the skull to move outward passively which immediately widens the skull and relieves constriction on the brain. Removing these wedges of bone also makes it easier for the brain to grow and passively reshape the skull with minimal resistance from the bone. After the procedure a helmet is worn to harness the growth of the brain and improve the efficiency of reshaping the skull. Infants are able to heal large bone defects of the skull with new bone up until about 1 year of age. The areas where bone is removed in this strip craniectomy procedure typically heal in by age 3-6 months. The figures below show the location of the bone excision in red and expected movement of the skull bones in blue and green. Read more about my approach minimally invasive extended sagittal strip craniectomy.

The image above shows a side view of a CT scan of a baby with sagittal synostosis. The locations of bone excision in a minimally invasive extended strip craniectomy are shown in RED. The blue arrow indicates how rotation of the occiput (back of head) shortens the head from front to back. 

The image above shows a side view of a CT scan of a baby with sagittal synostosis. The locations of bone excision in a minimally invasive extended strip craniectomy are shown in RED. The blue arrow indicates how rotation of the occiput (back of head) shortens the head from front to back. 

The above image shows the top down view of the same patient's skull. Again, the central dark red area shows the wide sagittal strip craniectomy. The lighter red triangles extend down to the squamosal suture. These bone excisions allow the bone flaps to hinge on the flexible squamosal sutures and widen the skull indicated by green arrows. As the side bone flaps (parietal bones) move outward the back portion of the skull rotates up and forward like a drawbridge opening.

The above image shows the top down view of the same patient's skull. Again, the central dark red area shows the wide sagittal strip craniectomy. The lighter red triangles extend down to the squamosal suture. These bone excisions allow the bone flaps to hinge on the flexible squamosal sutures and widen the skull indicated by green arrows. As the side bone flaps (parietal bones) move outward the back portion of the skull rotates up and forward like a drawbridge opening.

Open Cranial Vault Remodeling

Children with sagittal synostosis who present at an age of older than 4 months are treated with open cranial vault remodeling. Excellent results can be achieved with open cranial vault remodeling, so parents should not despair if their child is diagnosed with sagittal synostosis after age 4 months of age. After the age 4 months the skull bones are typically too stiff to achieve the desired changes in head shape using strip craniectomy procedures.  Surgery is usually performed between ages 6-12 months old for open cranial vault remodeling. There are many, many techniques used for open cranial vault remodeling for sagittal synostosis. Common strategies of open cranial vault remodeling procedures include the following elements. An incision is made from ear to ear. The skull bones are removed from the most abnormal areas of restricted and compensatory growth. The bones are then reshaped by hand and reattached to one another and the skull with dissolvable sutures or dissolvable plates to correct the head shape. In general, cranial vault remodeling procedures for sagittal suture craniosynostosis are aimed at restoring the normal proportions of the skull by increasing the width and decreasing the length of the skull. The figures below show a patient before and after open cranial vault remodeling for sagittal synostosis. Note that this patient had more severe compensatory growth n the front of the skull.

The picture on the left shows a boy with significant narrowing of the back portion of the skull and significant compensatory growth of the forehead. The image on the right shows the same patient 2 years after surgery. 

The picture on the left shows the same infant with sagittal synostosis demonstrating significant compensatory growth of the forehead. The image on the right shows the same patient 2 years after surgery. 

The minimally invasive extended strip craniectomy procedure for sagittal synostosis has several advantages when compared to traditional open procedures. The procedure and anesthesia time are shorter for the minimally invasive extended strip procedure (2-3 hours anesthesia time) than open procedures (4-6 hours anesthesia time). The hospital stay is shorter - 2 days for the minimally invasive strip procedure - compared to a 4-7 day hospital stay for open cranial vault remodeling procedures. The blood transfusion rates are lower for the minimally invasive procedure - 50% or less - compared to almost 100% for open cranial vault remodeling procedures (CVR). There is significantly less scarring in the scalp with the minimally invasive strip procedure and these incisions tend to heal better and are much less visible than the ear-to-ear scars required for open CVR procedures. Unlike open procedures, a molding helmet is worn for about 1 year after the minimally extended strip craniectomy whereas no helmet is needed after open CVR. Both strip craniectomy and open CVR procedures are safe and have equivalent complication and revision rates. Read more about my approach minimally invasive extended sagittal strip craniectomy. The minimally invasive sagittal strip gallery images show many representative cases demonstrating typical results.

 

Before and after photos for minimally invasive extended strip craniectomy

metopic synostosis

coronal synostosis

lambdoidal synostosis

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