In metopic synostosis or trigonocephaly there is a prominent keel in the midline with retrusion of the lateral orbit and bitemporal narrowing. The standard treatment is completed within the first year of life and involves not only bilateral advancement of the lateral orbit but transverse expansion of the supraorbital bar as well. The frontal bone needs reshaping to match the reconstructed bandeau.
After the exposure of the forehead and the orbits, a bifrontal craniotomy beginning 1 cm superior to the superior orbital rim and extending to behind the coronal sutures is outlined.
Burr holes are first placed at the vertex avoiding the sagittal sinus and nasal frontal region as well as temporally. An epidural dissection between these points is made.
The neurosurgeon then completes the osteotomies using a craniotome.
After the bone flap is removed, the dura is freed from the anterior and middle fossae in the epidural plane.
The dura is protected with neurosurgical cottonoids.
Malleable retractors are used intracranially to retract and protect the dura and intraorbitally to protect the orbital contents when performing the osteotomies.
The supraorbital bar is then osteotomized.
A vertical osteotomy near the pterion (1) is followed by a horizontal osteotomy to the lateral orbital rim (2). An oblique osteotomy is then made through the orbital rim (3) and a transverse osteotomy is completed at the nasal frontal junction (4).
Orbital roof osteotomy
With the brain carefully retracted, a right angle saw is then turned intracranially and the orbital roof is osteotomized beginning at pterion laterally and ending at the nasal frontal osteotomy medially, joining the osteotomy made extra cranially across the nasal frontal region.
Mobilization of the supraorbital bar
An osteotome is then inserted at the pterion and the lateral orbital wall osteotomy completed on both sides, releasing the supraorbital bar.
4. Reshaping and replacement of the supraorbital bar
The bar is cut in the midline and a cranial bone graft taken from the frontal bone flap is inserted between the two hemi-orbital segments. This bone graft varies from 10-20 mm depending on the severity of the deformity. It is held in place with a resorbable plate.
The construct is frequently not stable enough and often a larger bone graft is placed on the endocranial surface spanning the central bone graft and affixed with wires or sutures.
Closing wedge osteoctomies are then made at the lateral orbit endo cranially and the bar is reshaped. The new shape is maintained with resorbable plates placed intra- or extra-cranially.
The reshaped supraorbital bar is then replaced in the now transversely expanded and laterally advanced position.
Frequently there is no bony gap temporally but if the orbit needs more lateral advancement, a cranial bone graft is placed in the temporal gap and stabilized with a resorbable plate (insert).
The advanced bar is then stabilized. A wire or suture is placed between the stable lateral orbital rim and the bar.
Pearl: To improve the stability of the advanced segment, a cranial bone graft may also be wedged and placed in the orbital roof between the stable posterior segment and the advanced anterior segment.
5. Reshaping and replacement of the frontal bone
The frontal bone flap is then cut in two in the midline. The segments are forcefully bent with bone bending forceps to make them malleable and shapeable.
Replacement and fixation
The two frontal bone pieces are then replaced with an inter-positional bone graft harvested from the posterior edge of each flap. The bone flaps are affixed to the supraorbital bar with resorbable sutures or resorbable plates which are also used to span the bone graft and hold it in position between the right and left frontal bone segments.
Alternatively, the two bone flaps may be joined in the midline without an interposed graft if they match well to the supraorbital bar.
Grafting of coronal bone gap
The coronal bone gap created from the advancement and harvesting of bone is then filled with particulate bone shavings harvested with a manual hand-held burr-hole instrument or commercial harvester (eg, Safe scraper) from the frontal bone flap or the posterior skull.
This picture demonstrates the large volume of particulate bone that can be harvested from the inner surface of a bone flap using a hand-held burr-hole instrument.
6. Aftercare following transcranial and Le Fort III procedures in infants and children
Most surgeons favors placement of a bulb suction drain under the scalp for 3-5 days. Resorbable skin sutures are often used.
A circumferential head dressing is utilized for 48 hours. The neurosurgeon may request placement of a lumbar drain if significant dural tears have occurred during surgery. Patients should spend at least 1-2 days in an intensive care unit for neurological monitoring.
Keeping the patient’s head in an upright position postoperatively may significantly improve periorbital edema and pain. Some surgeons use injectable corticosteroids during surgery to reduce periorbital swelling.
To prevent orbital emphysema, nose-blowing should be avoided for at least 10 days.
The following perioperative medications are controversial. There is little evidence to make strong recommendations for postoperative care.
Avoidance of aspirin or nonsteroidal antiinflammatory drugs (NSAIDs) for 7 days.
Analgesia as necessary.
Antibiotics (many surgeons use perioperative antibiotics. There is no clear advantage of any one antibiotic, and the recommended duration of treatment is debatable.).
Nasal decongestant may be helpful for symptomatic improvement in some patients.
Steroids may help with postoperative edema. Some surgeons have noted increased complications with perioperative steroids.
Ophthalmic ointment should follow local and approved hospital protocol. This is not generally required in case of periorbital edema. Some surgeons prefer it. Some ointments have been found to cause significant conjunctival irritation.
Regular perioral and oral wound care has to include disinfectant mouth rinse, lip care if intraoral incision has been used.
Postoperative examination by an ophthalmologist may be requested, although sever periorbital edema may prevent useful assessment. The following signs and symptoms are usually evaluated:
Postoperative imaging has to be performed within the first days after surgery to verify accuracy of surgery. 3-D imaging (CT, cone beam) is recommended.
Remove sutures from skin after approximately 7-10 days if nonresorbable sutures have been used. Apply ice packs for the first 12 postoperative hours as able although infants and young children do not tolerate this well (may be effective in a short term to minimize edema). Avoid sun exposure and tanning to skin incisions for several months.
Soft diet can be taken as tolerated until there has been adequate healing of any maxillary vestibular incision. In children and infants age appropriate diets are then prescribed. Patients in MMF will remain on a liquid diet until such time the MMF is released.
Clinical follow-up depends on the complexity of the surgery, and whether the patient has any postoperative problems. Most patients are discharged at postoperative day 3-5 and seen again in 2-3 weeks.
In patients undergoing monoblock or Le Fort III distraction, distraction typically begins at day five at 1 mm/day and is assessed weekly with plane radiographs and clinical examination until the desired position is reached. After advancement a period of consolidation of 1-3 months is recommended before the retractors are removed.
In patients undergoing conventional advancement with intermaxillary fixation, MMF is kept in place for 4-6 weeks. Routine oral hygiene is prescribed. Patients with arch bars and/or intraoral incisions and/or wounds must be instructed in appropriate oral hygiene procedures. The presence of the arch bars or elastics makes this a more difficult procedure. A soft toothbrush (dipped in warm water to make it softer) should be used to clean the surfaces of the teeth and arch bars. Elastics are removed for oral hygiene procedures. Chlorhexidine oral rinses should be prescribed and used at least 3 times a day to help sanitize the mouth. For larger debris, a 1:1 mixture of hydrogen peroxide/chlorhexidine can be used. The bubbling action of the hydrogen peroxide helps remove debris. A Waterpik® is a very useful tool to help remove debris from the wires. If a Waterpik is used, care should be taken not to direct the jet stream directly over intraoral incisions as this may lead to wound dehiscence.
The patient needs to be examined and reassessed regularly and often. Additionally, ophthalmological, ENT, and neurological/neurosurgical examination may be necessary. If any clinical signs for meningitis or mental disturbances develop, professional help has to be sought. Due to the young age of many patients, routing CT-scans are performed only if clinically indicated to avoid excessive radiation exposure.