Cranial Fossa Development in Differing Subtypes of Crouzon Syndrome

Based on an established classification system of Crouzon syndrome subtypes, detailed regional morphology and volume analysis may be useful, to clarify Crouzon cranial structure characteristics, and the interaction between suture fusion and gene regulated overall growth of the calvarium and basicranium.

CT scans of 36 unoperated Crouzon syndrome patients and 56 controls were included and subgrouped as: type I. Bilateral coronal synostosis; type II. Sagittal synostosis; type III. Pansynostosis; type IV. Perpendicular combination synostosis.

Type I of Crouzon syndrome patients developed a slightly smaller posterior fossa (22%), and increased superior cranial volume (13%), which is the only subtype that develops a greater superior cranial volume. The effect of competing increased and decreased segmental volume is associated with a 24% enlargement of overall cranial volume (P = 0.321). In class III, the anterior fossa volume was increased by 31% (P = 0.007), while the volume of posterior fossa was decreased by 19% (P < 0.001). These resulted in a 7% (P = 0.046) reduction in the overall intracranial volume. Type II and type IV patients developed a trend toward anterior, middle, and posterior fossae, and entire cranial volume reduction.

Pansynostosis is the most often form of associated craniosynostoses of Crouzon syndrome, however bilateral coronal synostosis may not dominate this form of Crouzon syndrome. The anterior, middle and posterior cranial fossae may have simultaneously reduced volume if the midline suture synostosis is involved. Individualized treatment planning for Crouzon syndrome patient, theoretically should include the patient's age and temporal associated maldevelopment suture sequence.