Trigonocephaly

Trigonocephaly

In this pathology different degrees of dysmorphia of the anterior cranial fossa and the presence of associated anomalies of the skull might enable specific subgroups to be identified.

Neurosurgeons, maxillofacial and plastic surgeons will be increasingly concerned with trigonocephaly because of the increase in prevalence observed over the last two decades. Cytogenetic alterations are probably underestimated in this craniosynostosis, considering the high rate of neurodevelopmental retardation compared to other single-suture synostoses. Genetic counseling is, therefore, more and more effective in this pathology. An objective method to evaluate the cosmetic results of both endoscopic and open surgeries is necessary, as some under-corrections have been reported with minimally invasive surgery 1).

Epidemiology

The cause of trigonocephaly is attributed to premature closure of the metopic suture.

Trigonocephaly is a relatively uncommon form of craniosynostosis, with an incidence of 0.3 per 1000 live births.

The prevalence of trigonocephaly increased during the last two decades both in Europe and in the United States, but no clear contributing factors have yet been identified 2).

Etiology

Chromosomal abnormalities described in metopic synostosis comprised deletion of chromosome 11q24, deletion or trisomy of 9p and deletion of 7p, deletions of 3q, 13q, 12pter, 22q11, and duplication of 15q25. SMAD6 mutations should be systematically screened for in familial cases. 3).

Diagnosis

Trigonocephaly diagnosis.

Review

The aim of a review of Mocquard et al. was to report on recent advances in trigonocephaly since the last report on craniosynostosis published in 2006.

The review was conducted in accordance with the PRISMA guidelines. Research focused on four main topics: epidemiology, neurodevelopmental disorders, genetics and surgical techniques.

Forty reports were included. The prevalence of trigonocephaly increased during the last two decades both in Europe and in the United States, but no clear contributing factors have yet been identified. Neurodevelopmental disorders are frequent in syndromic trigonocephaly and not particularly rare in non-syndromic cases (up to 34%). Developmental retardation (speech, motor or global) was almost always present in children exposed to valproic acid. Chromosomal abnormalities described in metopic synostosis comprised deletion of chromosome 11q24, deletion or trisomy of 9p and deletion of 7p, deletions of 3q, 13q, 12pter, 22q11, and duplication of 15q25. SMAD6 mutations should be systematically screened for in familial cases. Recent advances in surgical techniques have mainly concerned endoscopic-assisted procedures, as they significantly reduce perioperative morbidity.

Neurosurgeons, maxillofacial and plastic surgeons will be increasingly concerned with trigonocephaly because of the increase in prevalence observed over the last two decades. Cytogenetic alterations are probably underestimated in this craniosynostosis, considering the high rate of neurodevelopmental retardation compared to other single-suture synostoses. Genetic counselling is therefore more and more effective in this pathology. An objective method to evaluate the cosmetic results of both endoscopic and open surgeries is necessary, as some under-corrections have been reported with minimally invasive surgery 4).

Treatment

Trigonocephaly treatment.

Case series

Trigonocephaly case series.

Case reports

A patient with microcephaly and trigonocephaly, moderate intellectual disability, speech and language delay, and poor social interaction in addition to minor but atypical dysmorphic features. This report provides further insight into the pathogenicity of the Xp22.31 duplication by extending knowledge of its clinical features. This case, in association with those reported in the literature, indicates that the Xp22.31 duplication may contribute to cause pathological phenotypes with minor facial dysmorphisms, microcephaly, and intellectual disability as main features 5).


The diagnosis of a combination of both Sturge-Weber syndrome and trigonocephaly has been reported. Ristow et al., presents a patient with the unusual findings of a Sturge-Weber syndrome and simultaneous trigonocephaly induced by premature metopic synostosis. Thus, the rare combination of a port-wine stain involving the first division of the trigeminal nerve with the diagnosis of a craniosynostosis justifies the indication of a prophylactic magnetic resonance imaging acquisition before craniofacial surgeries, in order to prevent seizures and stroke-like episodes triggered by the surgical intervention 6).

References

1) , 2) , 3) , 4)

Mocquard C, Aillet S, Riffaud L. Recent advances in trigonocephaly. Neurochirurgie. 2019 Nov;65(5):246-251. doi: 10.1016/j.neuchi.2019.09.014. Epub 2019 Sep 27. Review. PubMed PMID: 31568780.
5)

Pavone P, Corsello G, Marino S, Ruggieri M, Falsaperla R. Microcephaly/Trigonocephaly, Intellectual Disability, Autism Spectrum Disorder, and Atypical Dysmorphic Features in a Boy with Xp22.31 Duplication. Mol Syndromol. 2019 Jan;9(5):253-258. doi: 10.1159/000493174. Epub 2018 Oct 2. PubMed PMID: 30733660; PubMed Central PMCID: PMC6362926.
6)

Ristow O, Freudlsperger C, Berger M, Bächli H, Hoffmann J, Engel M. Combination of Sturge-Weber Syndrome and Trigonocephaly. J Craniofac Surg. 2016 Aug 24. [Epub ahead of print] PubMed PMID: 27557468.

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