Trigonocephaly

Trigonocephaly
Trigonocephaly in a boy with 1q22–1q23.1 duplication
Specialty	Medical genetics

Trigonocephaly is a congenital condition due to premature fusion of the

Trigonocephaly can either occur in a syndrome or isolated, all by itself. Trigonocephaly is associated with the following syndromes:

The second theory says that synostosis begins when the fetal head gets hindered in the pelvic outlet during birth.^[14][15]

Intrinsic brain malformation

The third theory predominates disturbed brain formation of the two

Trigonocephaly in two cases of microcephaly

Other conditions and syndromes with trigonocephaly include:

• Arthrogryposis, cleft palate, craniosynostosis, and impaired intellectual development
• Atypical glycine encephalopathy
• Blepharophimosis-intellectual disability syndrome, Verloes type
• Bohring-Opitz syndrome
• Coffin-Siris syndrome
• Greig cephalopolysyndactyly syndrome
• Holoprosencephaly
• Mandibulofacial dysostosis-microcephaly syndrome
• MEGF8-related Carpenter syndrome
• Microcephaly, primary autosomal dominant
• Mucolipidosis type II
• Orofaciodigital syndrome type 14
• Paris-Trousseau thrombocytopenia
• Potocki-Lupski syndrome
• Simpson-Golabi-Behmel syndrome type 1
• Trichothiodystrophy, photosensitive
• Trigonocephaly-bifid nose-acral anomalies syndrome

Diagnosis

Diagnosis can be characterized by typical facial and cranial deformities.^[2][19]

Observatory signs of trigonocephaly are:

• a triangular forehead seen from top view leading to a smaller anterior cranial fossa
• a visible and palpable midline ridge
• ethmoidal hypoplasia

• problems in behaviour, speech and language
• mental retardation[20]^[21]
• neurodevelopmental delays such as
  autism spectrum disorder (ASD), and conduct disorder (CD).^{[22][23][24][25]} Many of these delays become evident at school age.^[26]

Treatment is surgical with attention to form and volume. Surgery usually takes place before the age of one since it has been reported that the intellectual outcome is better.[27]^{[28][20][21][22][29][30][31][32][excessive citations]}

A. Fronto-supraorbital advancement and remodelling – before remodelling

B. Fronto-supraorbital advancement and remodelling – after remodelling

Fronto-supraorbital advancement and remodelling

A form of surgery is the so-called fronto-supraorbital advancement and remodelling.

The so-called 'floating forehead technique'[2] combined with the remodelling of the supraorbital bar is derived from the fronto-supraorbital advancement and remodelling. The supraorbital bar is remodelled as described above.^[34][35] The frontal bone is split in two pieces. Instead of using both pieces as in fronto-supraorbital advancement and remodelling, only one piece is rotated and attached to the supraorbital bar. This technique also leaves a craniectomy behind.^[36]

Other

• Suturectomy^[2]

The simplest form of surgery for trigonocephaly was suturectomy.^{[37][21][34][38][39]} However, as this technique was insufficient to correct the deformities, it is not used anymore.

• Distraction osteogenesis^[2]

Distraction osteogenesis is based on creating more cranial space for the brain by gradually moving the bones apart. This can be achieved by using springs.^[40]

• Minimal invasive endoscopic surgery^[2]

These approaches are 2D solutions for a 3D problem, therefore the results are not optimal. Distraction osteogenesis and minimal invasive endoscopic surgery are yet in experimental phase.

Outcomes

Surgical

Trigonocephaly seems to be the most compliant form of craniosynostosis for surgery.^[22] Because of standardization of current surgical approaches there is no surgical mortality and complications are few to none.^[2][41][42] The simple suturectomy is presently insufficient to adjust the complicated growth restrictions caused by metopic synostosis.^[2] On the other hand, the fronto-supraorbital advancement and remodelling and the 'floating forehead technique' create sufficient space for brain growth and result in a normal horizontal axis of the orbits and supraorbital bar. The fronto-supraorbital advancement and remodelling is the most used method nowadays.^[41] Over the past few years^[when?] distraction osteogenesis has been gradually acknowledged since it has a positive effect on hypotelorism.^{[citation needed]} Expanding the distance between the orbits using springs seems to be successful.^{[2][43][44][45]} However, there are discussions whether hypotelorism really needs to be corrected.^[46] The minimal invasive endoscopic surgery has been gaining attention since the early '90s, however, it has technical limitations (only strip craniectomy is possible).^[2] Attempts have been made to reach beyond these limits.^{[47][48][49][50][51]}

Aesthetic

The incidence of metopic synostosis is roughly between 1:700 and 1:15,000 newborns globally (differs per country).[11]^[55] Trigonocephaly is seen more in males than females ranging from 2:1 to 6.5:1.^{[37][56][27][28]} Hereditary relations in metopic synostosis have been found of which 5.5% were well defined syndromic.^[11] Maternal age and a birth weight of less than 2500g may also play a role in trigonocephaly.^[57] These data are based on estimations and do not give factual information.

Only one article gives valuable and reliable information regarding the incidence of metopic synostosis in the Netherlands. The incidence in the Netherlands showed an increase from 0.6 (1997) to 1.9 (2007) for every 10,000 live births.^[58]

History

In former times people born with malformed skulls were rejected based upon their appearance.^[1][59] This still persists today in various parts of the world even though the intellectual development is often normal.^[2] The Austrian physician Franz Joseph Gall presented the science of phrenology in the early 19th century through his work The Anatomy and Physiology of the Nervous System in General, and of the Brain in Particular.^[60]

Via a photo shown on a Facebook page, the mother of a child previously diagnosed with this condition recognised the symptoms and reported them to the family involved, resulting in an immediate diagnosis that medical professionals had overlooked in all earlier consultations.[64]

References