No abstract

The aim of this study is to demonstrate the correlation between the decrease of the Ophthalmic Nerve Sheath Diameter (ONSD) assessed by Ultrasound after a Surgery of Optic Nerve Sheath Fenestration (ONSF) for the treatment of a Idiopathic Intracranial Hypertension (IIH) and its success in the perioperative period. A 21 year-old female diagnosed with IIH was scheduled for unilateral ONSF surgery. We evaluated the ONSD after and before the surgery. The measurements were: 71,5mm mean for the both eyes BEFORE the surgery (71,5mm for the LE and 71,5mm for the RE respectively) and 57,25mm, fifteen minutes AFTER the fenestration of the LE Optic Nerve Sheath (RE: 70mm LE: 44,5mm means). There was a difference in the Optic sheath in the Operated Left Eye (ONSD 54-35 mm) and we could estimate the location of the fenestration in the images. We think this is the ideal method to evaluate the response to the surgical treatment for the IIH patients as non-invasive, low cost and in-site technique. Having agreed consent for use of data and images we made an assessment of ONSD after the induction of the general anaesthesia for the surgery. Measurements were made applied the probe over the closed upper eyelid. A 10-MHz linear probe (Turbo, Sonosite, Bothell, WA) was placed with ultrasound gel over the eyelid. The two-dimensional mode was used and ONSD was measured 3mm posterior the outermost layer of the retina using the calliper of the machine and an axis perpendicular to the Nerve. CitationFor both optic nerves, two measurements were made, one in the horizontal plane and other in the perpendicular plane. The average of the two values corresponds as ONSD for each eye. For the Right Eye (RE) the measurement was 73-70mm (71,5mm average) and for the Left Eye (LE) was 75-68mm (71,5mm average). The global mean before surgery was 71,5mm.Fifteen minutes after the surgical closing of the eyelid we repeated the assessment of the ONSD and we tried to see the location of the cut in the Optic Nerve Sheath for the eye chosen by the surgeons (Figure 1 & 2). The new measurements were: RE: 70-70 mm and for the LE (the eye chosen for the fenestration): 54-35 mm. The global mean after the surgery was 57,25mm. A decrease in the sheath around the ON could demonstrate the place where the cut was made at the Nerve Sheath (Figure 2). DiscussionOptic nerve sheath fenestration provides an effective surgical treatment for patients in whom medical therapy fails. In our case, unilateral ONSF decreased the diameter of Nerve sheath in the ipsilateral (operated) eye almost immediately after the fenestration but not changes were seen in the contralateral (nonoperated) eye at the short time [2]. The reduction of grade of papilledema in operated eyes was greater than in nonoperated eyes, but nonoperated eyes also experienced significant reduction in the disc edema grade with the correct time [1,2]. Until this moment the mechanism for this bilateral surgical effect is not certain and could be related to decrease the CSF in both optic nerves sheath after ...