The hypothetical role of congenital hypotonia in the development of early coronoid hyperplasia.

Background: Coronoid hyperplasia (CH) is an abnormal bony elongation of a histologically normal coronoid process. Its definitive cause remains unknown.

Objectives: To analyze the possible implication of congenital hypotonia in the pathogenesis of early coronoid overgrowth.

Patients And Methods: Two infants with congenital hypotonia were evaluated for limited mouth aperture. Bilateral CH was diagnosed. Transoral coronoidectomy was followed by an early dynamic physiotherapy program.

Results: Significant improvement of maximum interincisal opening was achieved. The review of the scientific literature proved the diagnosis of CH in the infant age group is extremely unusual and the etiology of the condition is still uncertain.

Conclusions: Besides mouth opening restriction, clinical features of coronoid hyperplasia in infants can include suction or deglutition anomalies, failure to thrive and recurrent episodes of choking or aspiration pneumonia. The authors hypothesize reduced fetal mandibular movements and deglutition as a result of congenital hypotonia may lead to relative hyperactivity of the temporalis muscle that is not counterbalanced by the infra and suprahyoid muscles, thereby facilitating coronoid overgrowth.