A Case Series of Six Pediatric Patients with Lateral Skull Base Encephalocele Repairs Including Sternocleidomastoid Flap as an Option

Introduction: Encephaloceles of the lateral skull base are a rare and diverse condition characterized by bone defect with or without herniation of intracranial contents. These defects can predispose patients to complications including meningitis, CSF leak, seizure, and brain abscess. Lateral skull base encephaloceles can occur within the middle or posterior cranial fossae ([Fig. 1]), and thus multiple surgical approaches and materials can be used to repair these defects depending on location and etiology. This study examines different treatment options for this type of defect through a case series of pediatric patients treated via different approaches and highlights a repair using an alternative and less studied autologous sternocleidomastoid muscle graft due to immunocompromise and/or severe infection.

Methods: Retrospective chart review was conducted at a tertiary pediatric hospital with comprehensive lateral skull base services including neurosurgery, neurotology, radiation oncology, etc. Patients with lateral skull base encephaloceles were reviewed to analyze surgical approach, materials used for reconstruction, encephalocele etiology, age, and other factors.

Results: Six pediatric patients with lateral skull base encephaloceles were identified. Three encephaloceles were due to chronic otitis media and/or cholesteatoma and were repaired using bone pate. One patient had cystic fibrous dysplasia of the temporal bone causing encephalocele that was repaired with bone cement via a combined transmastoid and middle fossa craniotomy approach. Finally, two patients were treated using a vascularized sternocleidomastoid graft rotated to repair the defect; both patients were immunocompromised with extratemporal complications of mastoiditis (e.g., sigmoid sinus thrombosis, brain abscess). All repairs were successful without complication.

Discussion: This case series showcases lateral skull base reconstruction in a pediatric population, which is rare. Therefore, all etiologies and reconstructive techniques were included. 3 patients who had middle cranial fossa encephalocele from tegmen erosion had a repair with bone pate from mastoid cortex. The patient with fibrous dysplasia had encephalocele repair with bone cement, chosen for higher strength and availability given the weak fibrous bone. Finally, the 2 immunocompromised patients had a sternocleidomastoid flap graft placed ([Fig. 4]) to provide vascularized bulky tissue to repair the defect and promote infection-free healing.

Conclusion: Lateral skull base defects in the pediatric population have various etiologies that may steer surgeons toward various approaches and reconstructive materials. This case series showcases how a multidisciplinary approach using different methods for skull base reconstruction can be tailored to the needs of each patient. Additionally, the use of vascularized sternocleidomastoid graft is described as a possible option for encephalocele repair which has not been well described in the literature.