Endoscopic Endonasal Skull Base Approach for Treatment of a Basal Encephalocele in a Patient with Morning Glory Syndrome

Introduction: Morning glory syndrome is a congenital anomaly defined by optic disc dysplasia. The finding has also been described in association with several other conditions, including craniofacial abnormalities, pituitary deficiency, and basal encephalocele. Failure of midline craniofacial development seems to represent a common theme.

Method and Materials: A 34-year-old man with a previous diagnosis of morning glory syndrome was referred for evaluation of a basal encephalocele arising from the sphenoethmoidal region, with absence of the posterior nasal septum and significant extension into the nasal cavity. The patient had recently developed panhypopituitarism, although the encephalocele had not enlarged. There was no evidence of CSF leak and no history of meningitis. Visual status was unchanged based on regular ophthalmological surveillance for his morning glory syndrome. Given the significant intrusion into the nasal passage and the perceived risk of future CSF leak and meningitis, we opted for surgical repair of the encephalocele.

Results: The patient had an extremely attenuated anterior midline skull base with multiple areas of bony dehiscence, which was likely associated with his craniofacial anomalies. Because of this, a subfrontal transcranial approach was deemed too morbid. Furthermore, reports have documented the adherence of the optic nerves and pituitary tissue to the encephalocele, making standard reduction techniques less attractive for fear of damaging functioning neural structures. We chose the endoscopic endonasal skull base approach for fenestration and reduction of the encephalocele, using the redundant autologous nasal mucosa and harvested fat to pack the cavity. A second procedure was performed 4 months later after MRI suggested re-expansion of the encephalocele floor. The last procedure has proven durable at 6 months postoperatively, and no rhinorrhea has been reported. The patient's visual and endocrine statuses have remained stable through both treatments.

Conclusion: This case outlines the known association between morning glory syndrome and basal encephaloceles. If surgical repair is to be considered, we believe the endoscopic endonasal skull base approach should be considered in the presence of other anterior skull base defects. Furthermore, the approach offers direct visualization of critical neural structures that may be intrinsically associated with the encephalocele. We feel the approach is both safe and efficacious for this pathology.