Coexistence of Trigonocephaly and Sylvian Arachnoid Cysts: A Coincidence?

Introduction The association between trigonocephaly and sylvian fissure arachnoid cysts (ACs) has been occasionally reported in the literature [1,2]. However, the real incidence of this association and its clinical relevance remain unknown. Methods The authors collected and retrospectively reviewed all clinical charts and CT scans of patients surgically treated for trigonocephaly at the Pediatric Neurosurgical Department of Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS from January 2014 to June 2023. Results During the study period, 136 patients with trigonocephaly underwent surgery. Analysis of the clinical charts revealed that in 39.7% of the cases (54/136), pre-operative CT scan depicted the presence of a sylvian fissure arachnoid cyst. Of these, AC was bilateral in 23 cases and unilateral in the remaining 31. All unilateral ACs were on the left side. The ACs were classified as Galassi grade I in 52 cases (96.3%) and Galassi grade II in 2 cases (3.7%)[3]. Interestingly, in one case we reported a Galassi grade I AC enlargement during follow-up, thereby necessitating surgical fenestration. Conclusion ACs and trigonocephaly are well-known conditions for pediatric neurosurgeons; however, their association is poorly defined. Despite the lack of reports on the incidence and clinical significance of this association, it is worth knowing that radiological follow-up is essential be in monitoring AC evolution.