Метоптық сүйек тігізілісінің туа бойынан дамуы және тригоноцефалия

Congenital condition of premature fusion of the metopic suture

Trigonocephaly is a congenital condition due to premature fusion of the metopic suture (from the Greek , "forehead"), leading to a triangular forehead. The premature merging of the two frontal bones leads to transverse growth restriction and parallel growth expansion. It may occur as one component of a syndrome together with other abnormalities, or in isolated form. The term is from the Greek , "triangle", and , "head".

Trigonocephaly can either occur in a syndrome or isolated, all by itself. Trigonocephaly is associated with the following syndromes: Bohring Opitz syndrome, Muenke syndrome, Jacobsen syndrome, Baller–Gerold syndrome and Say–Meyer syndrome. The etiology of trigonocephaly is mostly unknown although there are three main theories. (9p22–24, 11q23, 22q11, FGFR1 mutation), metabolic (TSH suppletion in hypothyroidism) or pharmaceutical (valproate in epilepsy).

The second theory says that synostosis begins when the fetal head gets hindered in the pelvic outlet during birth.

The third theory predominates disturbed brain formation of the two frontal lobes as the main issue behind synostosis. Limited growth of the frontal lobes leads to an absence of stimuli for cranial growth, therefore causing premature fusion of the metopic suture.

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.

A form of surgery is the so called fronto supraorbital advancement and remodelling. Firstly, the supraorbital bar is remodelled by a wired greenstick fracture to straighten it. Secondly, the supraorbital bar is moved 2 cm. forward and fixed only to the frontal process of the zygoma without fixation to the cranium. Lastly, the frontal bone is divided into two, rotated and attached to the supraorbital bar causing a nude area (craniectomy) between the parietal bone and frontal bone. Bone will eventually regenerate since the dura mater lies underneath (the dura mater has osteogenic capabilities). This results in an advancement and straightening of the forehead.

The so called 'floating forehead technique' 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.

Aesthetic outcome of metopic synostosis surgery is persistently good with reoperation hazards below 20%. In 1981 Anderson advised that craniofacial operations for synostosis should be as extensive as necessary after a study of 107 cases of metopic and coronal synostosis.

The highest rate of neurological problems of single suture synostosis are seen in patients with trigonocephaly. Trigonocephaly is seen more in males than females ranging from 2:1 to 6.5:1. Hereditary relations in metopic synostosis have been found of which 5.5% were well defined syndromic. 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.

In former times people born with malformed skulls were rejected based upon their appearance. This still persists today in various parts of the world even though the intellectual development is often normal. 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. Hippocrates described trigonocephaly as follows: Men's heads are by no means all like to one another, nor are the sutures of the head of all men constructed in the same form. Thus, whoever has a prominence in the anterior part of the head (by prominence is meant the round protuberant part of the bone which projects beyond the rest of it), in him the sutures of the head take the form of the Greek letter 'tau', τ.

Hermann Welcker coined the term trigonocephaly in 1862. He described a child with a V shaped skull and a cleft lip.

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.