Types of Optic nerves : Their anatomical significance for endoscopic nasal surgery

Dr. Santosh R. Konde; Dr. Abhijeet Pawar; Dr. Priya Bhole

Volume : VII, Issue : IX, September - 2017

Types of Optic nerves : Their anatomical significance for endoscopic nasal surgery

Dr. Santosh R. Konde, Dr. Abhijeet Pawar, Dr. Priya Bhole

Abstract :

Aim : To define direct anatomical relations of the sphenoid sinus, ethmoidal sinuses and optic nerve and the incidence of Type III optic nerves detected on multidetector CT with their surgical significance.

Methods :

This retrospective, descriptive study involved 150 consecutive patients. All patients underwent computerized tomography (CT). The relationship of the optic nerve and the sphenoidal and ethmoidal sinuses was classified. The presence of dehiscence in the bone structures, forming the optic canal, was checked. Dehiscence was defined as absence of visible bone density located between the sinus and the optic nerve. Protrusion of the optic nerve into the sphenoidal sinus was defined as optic nerve surrounded

by pneumatised space in atleast 180^O of its circumference .

Results

The most common type optic nerve was type I, where the optic nerve is located immediately adjacent to the lateral or superior wall of the sphenoidal sinus, without impression on the sinus wall. Dehiscence(Type II optic nerve) was documented in 110 (36.66%) optic nerves. Optic nerves were seen directly coursing through the sphenoid sinus (Type III) in 20 (6.67%) optic nerves. Type IV optic nerves were seen in 14 (4.67%)optic nerves.

Conclusion

Surgeons and ophthalmologists should be aware of high frequency of dehiscence of sphenoidal sinus walls when operating on patients considering the rate of dehiscence and the percentage of optic nerves seen coursing throught the posterior paranasal sinuses, especially when evaluating risks and complications of surgical procedures or when diagnosing

inflammatory or tumorous processes in the close vicinity of posterior paranasal sinuses.