Craniosynostosis is a term that refers to the premature fusion of one or more cranial sutures (growth sites) leading to a suture specific deformity of the cranial vault and cranial base. In most instances the premature fusion occurs sporadically. However, there are examples of genetic disorders with familial inheritance patterns.
Craniosynostosis can affect any of the cranial vault growth sites: the metopic, sagittal, lamboid, and coronal sutures. Premature fusion of these sutures may occur unilaterally, bilaterally, or as a combination of multiple sutures.
- Metopic synostosis: ie trigonocephaly
- Sagittal synostosis; ie scaphocephaly
- Unilateral coronal synostosis; ie frontal plagiocephaly
- Bilateral coronal synostosis; brachycephaly
- Lamboid synostosis; occipital plagiocephaly
There are several key elements when craniosynostosis is suspected:
- Proper and accurate diagnosis
- Radiographic assessment with CT-Scan (this will also depict if other anomalies of the brain are present and confirm the clinical diagnosis)
- Ophthalmologic examination for papilledema (a clinical sign of increased intracranial pressure) genetic work up and consultation
Craniosynostosis is operated on for the following reason:
- Ideally within the 1st year of life to allow proper brain expansion and development.
- To avoid skull shape and facial distortion that may have cosmetic and functional impacts.
The most common form of craniosynostosis is sagittal synostosis with a birth prevalence of 190 in 1,000,000. Most sagittal synostosis cases are sporadic. The male to female ratio ranges between 3.5 to 7:1. Familial aggregation has been described, giving a 6% frequency in some familial pedigrees. In sagittal craniosynostosis, the skull is characterized by a narrow shape mediolaterally, with compensatory bossing (convex shaping) either anteriorly or posteriorly, or both.
Coronal synostosis is less common than sagittal, with a birth prevalence of 94 in 1,000,000, and is the only form of craniosynostosis that is more common in females (male to female ratio 1:2.
Some of the characteristic features of UNILATERAL CORONAL SYNOSTOSIS are:
- Flattening of the skull adjacent to the fused suture
- Bossing of the contralateral forehead
- Ipsilateral elevated, recessed and flattened supraorbital rim (bony part just underneath the eyebrow) – so called “Harlekin” deformity
- Depression of the contralateral supraorbital rim
- Nasal deviation away from the fused suture
- Chin deviation away from the fused suture
Patients with BICORONAL craniosynosis present with a shortened anteroposterior dimension, mediolateral widening, and increased skull height, referred to as turribrachycephaly. This condition is more ominous in the sense that if surgery is delayed, greater defects in mental function may develop. This is thought to be due to having both halves of the coronal suture actively restricting brain growth.
METOPIC craniosynostosis has a birth prevalence of 67 in 1,000,000, with a male to female ratio of 3.3:1. The premature closure of the metopic suture typically leads to a triangular shape of the forehead, and compensatory widening of of the posterior skull. ie trigonocephaly. Patients present with hypotelorism (narrow eye distance), recessed flattened supraorbital rim, bilateral shortening of the frontal bone, and a midline prominent bony ridge
Lambdoid craniosynostosis is the rarest form of single suture craniosynostosis. Unilateral Lambdoid craniosynostosis is characterized by flattening of the occiput (posterior skull) and posterior inferior displacement of the ear on the same side as the fused suture, with compensatory adjacent retro mastoid bulging. The skull base is asymmetric with deviation of the base of the skull (and foramen magnum) deviated toward the fused suture. Normally, it can be readily distinguished by physical exam from deformational plagiocephaly, a skull deformity induced by constant low grade pressure on the developing bone of the skull, and not related to sutural fusion. Deformational plagiocephaly is more common, since the rise in recommendation to place children supine for sleep to reduce the likelihood of sudden infant death syndrome. Surgical correction of deformational skull deformities is rarely indicated for this condition. The majority of patients show an excellent response to physical therapy and helmet molding.
If premature sutural fusion occurs with regularly occurring facial or extremity deformities , it may be a form of “syndromic craniosynostosis”.
Many different genetic abnormalities have been identified in the various forms of syndromic craniosynostosis .Syndromic craniosynostosis can affect any cranial suture, yielding similar deformities of the skull shape to that describe above. The degree of severity and the more frequent combination of involvement by more than one suture, help distinguish syndromic from non syndromic craniosynostosis. Therefore the surgical techniques used for syndromic deformities do not differ substantially from the techniques described above, except in the degree of change in skull form required and in the need for more comprehensive in skull reshaping to address the multiple suture involvement. Facial and extremity anomalies are also addressed separately.
Although Eugène Apert, a French pediatrician, is credited with detecting the syndrome, it was a British physician who described the syndrome in 1894. Apert syndrome accounts for approximately 3% of all craniosynostosis cases with an autosomal dominant inheritance pattern with a male-to-female ratio of 1:1. Apert syndrome has a unique skull growth pattern. Patients present with true megaloencephaly, mostly above the 95th percentile. Although patients present with bicoronal craniosynostosis, the central cranial defect extending from the anterior to posterior fontanelles( soft spots in the growing skull), allows vertical brain expansion resulting in a turricephalic (tower shaped) skull.
Characteristic ocular features are include hypertelorism, shallow orbits, proptosis, downslanting palpebral fissures, and occasionally the eyebrows have a break in continuity. The ears are commonly low set and posteriorly angulated. The nose is typically short with a depressed bridge and a round nasal tip. Patients present with a high arched palate, delayed dental eruption and malocclusion. The most notable characteristic for Apert’s syndrome is the complex, usually complete syndactyly of the hands and feet.
Crouzon syndrome, first described by the French neurologist Octave Crouzon in 1912, is characterized by craniosynostosis, maxillary hypoplasia, shallow orbits, and ocular proptosis. Crouzon syndrome accounts for 5% of all craniosynostosis with a birth prevalence of 15 to 16 per one million. The inheritance pattern includes a risk of passing this condition onto offspring of 50%. Abnormalities of the central nervous system include progressive hydrocephalus, chronic cerebellar herniation, and jugular foramen stenosis with venous obstruction. The premature closure of cranial sutures vary. Most commonly patients present with bilateral coronal craniosynostosis, but sagittal and metopic craniosynostosis are noted too. Premature closure of the cranial suture may be evident at birth or develop later in early infancy. Therefore, follow up is needed in suspected , but not confirmed cases.
Pfeiffer syndrome was first described by a German pediatrician in 1964. Pfeiffer syndrome is characterized by brachycephaly, broad thumbs or great toes, brachydactyly ( short digits), midface deficiency, ocular hypertelorism (widely separated eyes), downslanting palpebral (eyelid) fissures, and variable syndactyly. The inheritance pattern is autosomal dominant with a broad range of phenotypical penetrance.
TYPE OF SURGICAL TREATMENT in CRANIOSYNOSTOSIS
Initial surgical techniques like simple sutural strip craniectomies (a removal of a small segment of bone adjacent to the course of the fused suture) focused on decreasing the intracranial pressure by removing the fused suture. The thought was that it would allow the brain to expand normally. With time surgeons became disappointed with the degree of correction with this approach, and developed more comprehensive surgical approaches to take into account not only the need to release the fused suture, but to remodel both hypoplastic and compensatory bone abnormalities.
Is there an impact on IQ and neurodevelopment?
If treatment is delayed beyond one year some intellectual impairment may be seen. Although significant retardation may be seen in syndromic cases, this is rarely the case in non syndromic craniosynostosis and is usually not a direct result of the bony abnormality restricting brain growth. It is more likely that there was an associated brain maldevelopment independent of the bony abnormality (in the syndromic children). Synostosis induced abnormalities are more subtle, often spelling /learning disabilities.
What is the best time for surgery to take place?
The timing of surgery depends of several factors. In cases of recognizable increased intracranial pressure surgery should be performed as soon as possible. In general, surgery would ideally take place between 3 and 6 month of age (to be well within the one year “window”). By then the patient usually has the ability to withstand general anesthesia, the blood loss associated with the surgical procedure, and the bone is much more malleable and moldable. Ease of bone remodeling leads to a more favorable result, allowing more unrestricted brain growth and development to occur as early as possible.
How will the operation be performed?
The operation will be performed as a team approach, including a pediatric neurosurgeon acting as co-surgeons in a hospital setting that allows postoperative pediatric intensive care monitoring (with specialized intensivist doctors, anesthesiologists and nursing staff). Usually the children stay there for 1-2 days and will be then transferred to a regular floor. Usually they leave after 5-7 days after the surgery the hospital. Further information about the surgery, associated risks, and what is involved will be explained to you fully during your office visit.
During your consultation with Dr Bianca Knoll in Frankfurt, you will learn about the different treatment options. Depending on the individual case additional consults and radiographic imaging might be necessary (for example CT-scan of the skull and face (bone windows). If you have a copy of previously performed x-rays, CT-scans or medical and operative reports, photographs, please bring those with you for your consultation. During your consultation Dr Knoll will carefully listen to your concerns and examine you. She will then discuss these findings with you, and explain your available options during your consultation in our Frankfurt office. Dr Knoll and her team will be happy to provide you with further information about the procedure and answer your questions during your consultation in our office.
We totally understand that it can be impractical for some of our out of town / or international patients, to come into Frankfurt, to get a first impression. For these reason Dr Knoll’s office offers the possibility of an online consultation. However, a virtual consultation has it’s limitations, and does not replace an in person consultation.
SCIENTIFIC PUBLICATIONS RELATED TO CRANIOSYNOSTOSIS BY DR BIANCA KNOLL IN FRANKFURT – GERMANY
Click here to read full article
Knoll B, Shin J, Persing JA. The Bowstring Canthal Advancement – A New Technique to Correct the Flattened Supraorbital Rim in Unilateral Coronal Synostosis
J Craniofac Surg. 2005;16:492-497
Click here to read full article
Heller JB, Heller M, Knoll B, Gabbay J, Duncan C, Persing JA. Intracranial Volume and Cephalic Index Outcomes for Total Calvarial Reconstruction among Nonsyndromic Sagittal Synostosis Patients
Plast Reconstr Surg, 2008, 121(1):187-195
Knoll B, Persing JA. Craniosynostosis. In: Pediatric Plastic Surgery. Michael Bentz (ed). Appelton&Lange (Vol 1, pp 541-571)
Persing JA, Knoll B. Non-Syndromic Craniosynostosis. In PLASTIC SURGERY Indications and Practice. B Guyuron, E Eriksson, J Persing. K Chung, J Disa, A Gosain, B Kinney, JP Rubin (eds). Saunders/Elsevier (in print)
Knoll B, Persing JA. Correction of Malposition of the Orbits. In: Neurosurgical Operative Atlas. Vol 1. Setti S. Rengachary, Robert H. Wilkins (eds)
XIth Meeting of International Society of Craniofacial Surgery (ISCFS), Queensland, Australia, September 2005
– Cranial Volume and Cephalometric Measurements for Sagittal Synostosis – An Age Dependent Result
Heller JB, Knoll B, Persing JA
35th Annual Meeting of German Society of Plastic, Reconstructive, and Aesthetic Surgeons (DGPRÄC), Düsseldorf, Germany, October 2004
– Das “Bowstring canthal Advancement”: Eine neue Methode zur Korrektur des Ramus Supraorbitalis bei der Unilateralen Koronarsynostose –
Knoll B, Shin J, Persing JA
10th International Congress of International Society of Craniofacial Surgery, Monterey,USA, September 2003
– The Bowstring Canthal Advancement: A New Technique to Correct the Supraorbital Rim in Unilateral Coronal Synostosis –
Knoll B, Shin J, Persing JA