Trigonocephaly is a congenital condition due to premature fusion of the

metopic suture The frontal suture is a fibrous joint that divides the two halves of the frontal bone of the human skull, skull in infants and children. Typically, it completely fuses between three and nine months of age, with the two halves of the frontal bone ...

(), 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 A syndrome is a set of medical signs and symptoms which are correlated with each other and often associated with a particular disease or disorder. The word derives from the Greek language, Greek σύνδρομον, meaning "concurrence". When a sy ...

together with other abnormalities, or in isolated form. The term is .

Cause

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. Trigonocephaly is probably a multifactorial congenital condition, but due to limited proof of these theories this cannot safely be concluded.

Intrinsic bone malformation

The first theory assumes that the origin of pathological synostosis lies within disturbed bone formation early on in the pregnancy. Causes can either be genetic (9p22–24, 11q23, 22q11, FGFR1 mutation), metabolic ( TSH suppletion in

hypothyroidism Hypothyroidism is an endocrine disease in which the thyroid gland does not produce enough thyroid hormones. It can cause a number of symptoms, such as cold intolerance, poor ability to tolerate cold, fatigue, extreme fatigue, muscle aches, co ...

) or pharmaceutical (

valproate Valproate (valproic acid, VPA, sodium valproate, and valproate semisodium forms) are medications primarily used to treat epilepsy and bipolar disorder and prevent migraine headaches. They are useful for the prevention of seizures in those with ...

epilepsy Epilepsy is a group of Non-communicable disease, non-communicable Neurological disorder, neurological disorders characterized by a tendency for recurrent, unprovoked Seizure, seizures. A seizure is a sudden burst of abnormal electrical activit ...

Fetal-head constraint

The second theory says that synostosis begins when the fetal head gets hindered in the

pelvic outlet The lower circumference of the lesser pelvis is very irregular; the space enclosed by it is named the inferior aperture or pelvic outlet. It is an important component of pelvimetry. Boundaries It has the following boundaries: * anteriorly: the pub ...

during birth.

Intrinsic brain malformation

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.

Other conditions and syndromes

Other conditions and syndromes with trigonocephaly include: *

Arthrogryposis Arthrogryposis (AMC) describes congenital joint contracture in two or more areas of the body. It derives its name from Greek, literally meaning 'curving of joints' (', 'joint'; ', late Latin form of late Greek ', 'hooking'). Children born with one ...

cleft palate A cleft lip contains an opening in the upper lip that may extend into the nose. The opening may be on one side, both sides, or in the middle. A cleft palate occurs when the palate (the roof of the mouth) contains an opening into the nose. The ...

, craniosynostosis, and impaired intellectual development * Atypical glycine encephalopathy * Blepharophimosis-intellectual disability syndrome, Verloes type * Bohring-Opitz syndrome * Coffin-Siris syndrome *

Greig cephalopolysyndactyly syndrome Greig cephalopolysyndactyly syndrome is a disorder that affects development of the limbs, head, and face. The features of this syndrome are highly variable, ranging from very mild to severe. People with this condition typically have one or more ...

Holoprosencephaly Holoprosencephaly (HPE) is a cephalic disorder in which the prosencephalon (the forebrain of the embryo) fails to Prenatal development, develop into two Cerebral hemisphere, hemispheres, typically occurring between the 18th and 28th day of gestati ...

* Mandibulofacial dysostosis-microcephaly syndrome * MEGF8-related Carpenter syndrome *

Microcephaly Microcephaly (from Neo-Latin ''microcephalia'', from Ancient Greek μικρός ''mikrós'' "small" and κεφαλή ''kephalé'' "head") is a medical condition involving a smaller-than-normal head. Microcephaly may be present at birth or it m ...

, primary autosomal dominant * Mucolipidosis type II * Orofaciodigital syndrome type 14 * Paris-Trousseau thrombocytopenia * Potocki-Lupski syndrome * Simpson-Golabi-Behmel syndrome type 1 *

Trichothiodystrophy Trichothiodystrophy (TTD) is an autosomal recessive inherited disorder characterised by brittle hair and intellectual impairment. The word breaks down into ''tricho'' – "hair", '' thio'' – "sulphur", and ''dystrophy'' – "wasting away" or lit ...

photosensitive Photosensitivity is the amount to which an object reacts upon receiving photons, especially visible light. In medicine, the term is principally used for abnormal reactions of the skin, and two types are distinguished, photoallergy and phototoxicity. ...

* Trigonocephaly-bifid nose-acral anomalies syndrome

Diagnosis

Diagnosis can be characterized by typical facial and cranial deformities. Observatory signs of trigonocephaly are: * a triangular forehead seen from top view leading to a smaller

anterior cranial fossa The anterior cranial fossa is a depression in the floor of the cranial base which houses the projecting frontal lobes of the brain. It is formed by the orbital plates of the frontal, the cribriform plate of the ethmoid, and the small wings and ...

* a visible and palpable midline ridge * hypotelorism inducing ethmoidal

hypoplasia Hypoplasia (; adjective form ''hypoplastic'') is underdevelopment or incomplete development of a tissue or organ.3D-CT, röntgenography,

MRI Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and rad ...

) show: * epicanthal folds in limited cases * teardrop-shaped orbits angulated towards the midline of the forehead ('surprised coon' sign) in severe cases * a contrast difference between a röntgenograph of a normal and a trigonocephalic skull * anterior curving of the metopic suture seen from

lateral Lateral is a geometric term of location which may also refer to: Biology and healthcare * Lateral (anatomy), a term of location meaning "towards the side" * Lateral cricoarytenoid muscle, an intrinsic muscle of the larynx * Lateral release ( ...

view of the cranium on a röntgenograph * a normal

cephalic index The cephalic index or cranial index is a number obtained by taking the maximum width (biparietal diameter or BPD, side to side) of the head of an organism, multiplying it by 100 and then dividing it by their maximum length (occipitofrontal diame ...

(maximum

cranium The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

width / maximum cranium length) however, there is bitemporal shortening and biparietal broadening The neuropsychological development is not always affected. These effects are only visible in a small percentage of children with trigonocephaly or other suture synostoses.

Neuropsychological Neuropsychology is a branch of psychology concerned with how a person's cognition and behavior are related to the brain and the rest of the nervous system. Professionals in this branch of psychology focus on how injuries or illnesses of the brai ...

signs are: * problems in behaviour, speech and language * mental retardation * neurodevelopmental delays such as

attention deficit hyperactivity disorder Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterised by symptoms of inattention, hyperactivity, impulsivity, and emotional dysregulation that are excessive and pervasive, impairing in multiple con ...

(ADHD),

oppositional defiant disorder Oppositional defiant disorder (ODD) is listed in the DSM-5 under ''Disruptive, impulse-control, and conduct disorders'' and defined as "a pattern of angry/irritable mood, argumentative/defiant behavior, or vindictiveness." This behavior is usu ...

(ODD),

autism spectrum disorder Autism, also known as autism spectrum disorder (ASD), is a neurodevelopmental disorder characterized by differences or difficulties in social communication and interaction, a preference for predictability and routine, sensory processing di ...

(ASD), and

conduct disorder Conduct disorder (CD) is a mental disorder diagnosed in childhood or adolescence that presents itself through a repetitive and persistent pattern of behavior that includes theft, lies, physical violence that may lead to destruction, and reck ...

(CD). Many of these delays become evident at school age.

Treatment

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.

Fronto-supraorbital advancement and remodelling

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 The term zygoma generally refers to the zygomatic bone, a bone of the human skull that is commonly referred to as the cheekbone or malar bone, but it may also refer to: * The zygomatic arch, a structure in the human skull formed primarily by parts ...

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 The parietal bones ( ) are two bones in the skull which, when joined at a fibrous joint known as a cranial suture, form the sides and roof of the neurocranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four bord ...

and

frontal bone In the human skull, the frontal bone or sincipital bone is an unpaired bone which consists of two portions.'' Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bo ...

. 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.

'Floating forehead technique'

The so-called 'floating forehead technique' 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. 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.

Other

* Suturectomy *

Distraction osteogenesis Distraction osteogenesis (DO), also called callus distraction, callotasis and osteodistraction, is a process used in orthopedic surgery, podiatric surgery, and oral and maxillofacial surgery to repair skeletal deformities and in reconstructive su ...

* Minimal invasive endoscopic surgery 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 Craniosynostosis is a condition in which one or more of the fibrous sutures in a young infant's skull prematurely fuses by turning into bone (ossification), thereby changing the growth pattern of the skull. Because the skull cannot expand perpe ...

for surgery. Because of standardization of current surgical approaches there is no surgical mortality and complications are few to none. The simple suturectomy is presently insufficient to adjust the complicated growth restrictions caused by metopic synostosis. 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. Over the past few years distraction osteogenesis has been gradually acknowledged since it has a positive effect on hypotelorism. Expanding the distance between the orbits using springs seems to be successful. However, there are discussions whether hypotelorism really needs to be corrected. The minimal invasive endoscopic surgery has been gaining attention since the early '90s, however, it has technical limitations (only strip craniectomy is possible). Attempts have been made to reach beyond these limits.

Aesthetic

Aesthetic Aesthetics (also spelled esthetics) is the branch of philosophy concerned with the nature of beauty and taste, which in a broad sense incorporates the philosophy of art.Slater, B. H.Aesthetics ''Internet Encyclopedia of Philosophy,'' , acces ...

outcome of metopic

synostosis Synostosis (; plural: synostoses) is fusion of two or more bones. It can be normal in puberty (e.g. fusion of the epiphyseal plate to become the epiphyseal line), or abnormal. When synostosis is abnormal it is a type of dysostosis. Examples of ...

surgery Surgery is a medical specialty that uses manual and instrumental techniques to diagnose or treat pathological conditions (e.g., trauma, disease, injury, malignancy), to alter bodily functions (e.g., malabsorption created by bariatric surgery s ...

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. Surgery does not provide a 100% natural outcome, mostly there will be minor irregularities. Reoperations are usually performed on more severe cases (including syndromic metopic synostosis). The hypotelorism and temporal hollowing are the most difficult to correct: the hypotelorism usually remains under corrected and a second operation is often needed for correction of temporal hollowing.

Neurological

The highest rate of neurological problems of single suture synostosis are seen in patients with trigonocephaly. Surgery is performed generally before the age of one because of claims of better intellectual outcome. Seemingly surgery does not influence the high incidence of neurodevelopment problems in patients with metopic synostosis. Neurological disorders such as ADHD, ASD, ODD and CD are seen in patients with trigonocephaly. These disorders are usually also associated with decreased IQ. The presence of ADHD, ASD and ODD is higher in cases with an IQ below 85. This is not the case with CD which showed an insignificant increase at an IQ below 85.

Epidemiology

The incidence of metopic synostosis is roughly between 1:700 and 1:15,000 newborns globally (differs per country). 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. Maternal age and a birth weight of less than 2500g may also play a role in trigonocephaly. 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.

History

In former times people born with malformed skulls were rejected based upon their appearance.Strickler M, van der Meulen J, Rahael B, Mazolla R. Craniofacial malformations. Edinburgh, London, Melbourne, New York: Churchill Livingston, 1990. This still persists today in various parts of the world even though the intellectual development is often normal. The Austrian physician

Franz Joseph Gall Franz Joseph Gall or Franz Josef Gall (; 9 March 175822 August 1828) was a German neuroanatomist, physiology, physiologist, and pioneer in the study of the localization of mental functions in the brain. Claimed as the founder of the pseudoscienc ...

presented the science of

phrenology Phrenology is a pseudoscience that involves the measurement of bumps on the skull to predict mental traits. It is based on the concept that the Human brain, brain is the organ of the mind, and that certain brain areas have localized, specific ...

in the early 19th century through his work ''The Anatomy and Physiology of the Nervous System in General, and of the Brain in Particular''.Phrenology. http://www.phrenology.org/

Hippocrates Hippocrates of Kos (; ; ), also known as Hippocrates II, was a Greek physician and philosopher of the Classical Greece, classical period who is considered one of the most outstanding figures in the history of medicine. He is traditionally referr ...

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 A cleft lip contains an opening in the upper lip that may extend into the nose. The opening may be on one side, both sides, or in the middle. A cleft palate occurs when the palate (the roof of the mouth) contains an opening into the nasal cavi ...

Popular culture

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.

References

External links

{{Medical resources , ICD11 = {{ICD11, LB70.0Y , ICD10 = {{ICD10, Q, 75, 0, q, 65 , ICD9 = {{ICD9, 756.0 , ICDO = , OMIM =190440 , OMIM_mult = , MedlinePlus = , eMedicineSubj = , eMedicineTopic = , DiseasesDB = 33252 Congenital disorders of musculoskeletal system