Transpalpebral transorbital neuroendoscopic (TONES) repair of orbital meningoencephalocele: a technical note

Intraorbital encephalocele (OMEC) is a rare entity in adults, usually secondary to an orbital pathology or prior trauma, in particular orbital roof fractures. Treatment of the OMEC is warranted to alleviate the pulsating exophthalmos and prevent potential visual decline. OMEC and orbital roof fractures have been predominantly treated via a craniotomy with a reconstruction of the orbital roof using various implants. With the advances in the endoscopic techniques, neuroendoscopy found its application in the treatment of orbital pathologies. We report a minimally invasive alternative: endoscopic transorbital repair of OMEC.The repair technique is described with illustrations and clinical images. Narrated operative video demonstrating the procedure is provided.Illustrative case: 50-year-old female presented with progressive right eye proptosis over 6 months. Computed tomography (CT) demonstrated bony erosion in the lateral orbital roof, and magnetic resonance imaging (MRI) showed a small hyperintense T2-weighted and T1-weighted contrast enhancing lesion in the orbit, in the area of the bony erosion. Intraoperatively, the lesion was found to be an orbital encephalocele. The orbital defect was successfully repaired by employing the 'sandwich' technique, in which a dural substitute reinforced with tissue glue were deployed without repair of the osseous orbital roof. The patient tolerated the procedure well with ultimate resolution of proptosis. The cosmetic outcome was excellent.The transorbital neuroendoscopic approach (TONES) presents a feasible, minimally invasive alternative treatment option for circumscribed intraorbital encephaloceles with minimal side effects, well tolerated by patients.