Article
Endoscopic transnasal approach to optic nerve decompression: anatomical and microsurgical study
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Published: | May 30, 2008 |
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Objective: Although traumatic injury to the optic nerve is a relatively frequent event, its management remains controversial. In the iterature recommendations for conservative treatment, medical treatment and surgical therapy are found. Traditional surgical approaches to optic nerve decompression (OND) are the craniotomy approach, the extranasal transethmoidal approach, the transorbital approach, and the intranasal microscopic approach. Because of advances in instrumentation and surgical techniques, the purely endoscopic transnasal approach the anatomic landmarks of OND are described in detail. The anatomical study was performed on 6 human fresh cadaver heads injected with coloured silicone rubber. All dissections were performed with the assistance of rigid endoscopes with 0° and 30° lenses.
Results: A standard endoscopic trans-sphenoidal approach affords a complete view of the sellar floor. The optico-carotid recess and optic nerve bulging were identified through the lateral wall of the sphenoid sinus. The decompressive step of the approach starts with the identification of the lamina papiracea at the orbital apex. This manoeuvre permits the identification of the distal opening of the optic canal corresponding to the annulus of Zinn. Once a full bone decompression was accomplished, the annulus of Zinn and the dural sheath covering the canalicular portion of the optic nerve were opened with a sickle scalpel. The anatomical relationships between the optic nerve and the ophthalmic artery were analyzed. The distances from the lateral walls of the pituitary floor to the annulus were measured.
Conclusions: Even if the management of traumatic optic neuropathy is still controversial, with no clear consensus, OND has been reported to have a favourable outcome by many surgeons. Surgical results of the endoscopic approach to OND seem comparable to those seen with the more invasive techniques but it is potentially associated with a lower morbidity and a more rapid postoperative recovery.