Traumatic fracture of optic canal is a severe injury to the optic nerve and often causes permanent visual loss, and it is difficult to treat. This study is to evaluate the effectiveness of decompression of optic canal by nasal endoscope. Operation of optic canal decompression was performed on 210 cases (212 sides) with traumatic fracture of optic canal. Clinical effectiveness was assessed based on improvement of visual acuity. After following up for 6 months to 2 years, visual improvement with more than one visual acuity level was observed on 101 sides (47.6%). Among them, an excellent effect (increasing 2 levels of visual acuity) was achieved on 72 sides (34.0%). Among 133 sides performed within 5 days of injury, 61 sides (45.9%) showed excellent effect (improved 2 levels of visual acuity). In contrast, when operation was performed after 5 days of injury, only 11 out of 79 sides (13.9%) showed excellent effect with improvement of 2 levels of visual acuity. And the overall effectiveness between the operations were performed within and after 5 days of injury was different significantly ( P < 0.05). Therefore, endonasal endoscopic optic decompression for traumatic optic neuropathy is an effective measure for patients with traumatic optical canal fracture. Operation within 5 days of injury significantly increases the success rate.
Traumatic optic neuropathy (TON) is an impact injury to the optic nerve and often a devastating cause of permanent visual loss after blunt or penetrating injury [
Between October 2003 and March 2010, 210 patients (212 sides) with optic canal fracture were enrolled in our department. The inclusion criteria included clinical findings of visual loss in patients due to head or mid-facial trauma or the presence of an ipsilateral afferent pupillary defect with normal eyesight in the other eye. Patients were excluded if their posttraumatic visual loss was not related to optic nervedys function, such as an open globe, traumatic cataract, vitreous hemorrhage, retinal detachment, choroidal rupture, or orbital compartment syndrome. Among the patients, the youngest patient is 4.5 years old, while the oldest patient is 64 years old. There were 164 male and 46 female patients. The imaging examinations confirmed the fracture of optic canal and intact eyeball in coronal and horizontal position by computed tomography (CT) scan. Among these patients, 158 cases (160 sides) were complicated with orbital wall fracture, 35 cases (22.2%) had zygomatic arch fracture, 41 cases (25.9%) had intracranial hematoma, and 6 patients (3.8%) suffered from cerebrospinal fluid rhinorrhea concurrently. These patients were hospitalized after injury for 2 hours to 22 days. Among 210 patients, 133 sides were operated within 5 days of injury. The study protocol followed the principles in the Declaration of Helsinki. Informed consent was obtained from the patient prior to all treatments and investigations.
Surgical operation for optic decompression by endoscopic endonasal approach was carried out between 3 hours and 3 days after admission. For tracheal intubation and general anesthesia, the operators opened the ethmoid sinus to expose sphenoid sinus and cleared hemorrhage and effusion in sphenoid sinus. The optic canal in sphenoid sinus was located and the existence of Onodi cells was determined. When the position of the optic canal cannot be identified, sphenoid sinus mucosa near the orbital apex is peeled. The uplift of optic nerve bone tube would then appear (
Before the operation, patients were given methylprednisolone (10 to 15 mg/kg/day) for one time. After operation, patients were given half dose of methylprednisolone in the first three days. These patients also received gastric mucosa protectants at same time.
Visual acuity (VA) levels include blindness, light perception (LP), hand motions (HM), finger counting (FC) and every rising line in visible vision chart by using LogMAR letters. Promoting a level and the improvement of the vision are regarded to be effective. These cases included 77 cases of blinds (36.3%), 43 cases of LP (20.3%), 37 cases of HM (17.5%), 42 cases of FC (19.8%), and 13 cases of visible vision chart (6.1%). There were 37 patients (17.5%) with vision defect.
Therapeutic efficacy was considered to be a dependent variable. The patients were divided into two groups according to the time of the operation (≤5 days vs. >5 days). The two group comparisons were performed, the basic demographic data of the two groups, and both adjusted and unadjusted for baseline visual acuity. All statistical analyses were performed using SPSS 13.0. P values < 0.05 were considered to be statistically significant.
There were 101 sides (47.6%) with visual improvement of more than one visual acuity level were observed in this study, and among them there were 72 sides (34.0%) with visual improvement of more than two visual acuity level. According to different timing of operation on the success rate of surgery, 61 sides (45.9%) improved 2 levels of visual acuity were observed, and 12 sides (9.0%) improved 1 level of visual acuity were achieved when the operation was performed within 5 days of injury. And the overall effectiveness was seen in 73 sides (54.9%). In contrast, when the operation was performed later than 5 days after injury, 11 out of 79 sides (13.9%) showed improvement of 2 levels of visual acuity, and there were 17 out of 79 sides (21.5%) which showed one level improvement of visual acuity, and the overall effectiveness was seen in 28 out of 79 sides (35.4%). The overall effectiveness between the operations performed within and after 5 days of injury were different significantly (P < 0.05). There was no any severe surgical complication occurred in all patients.
In this report, we analyzed the outcome of 212 sides of optical canal decompression on 210 patients. The overall effectiveness was observed on 101 sides following optical canal operation with visual improvement of more than one visual acuity level (47.6%). Importantly, among them there were 72 sides which achieved an excellence effect by increasing 2 levels of visual acuity (34.0%). This demonstrates the effectiveness of optical canal decompression via endonasal endoscopic approach.
We further analyzed the impact of the timing of operation on the success rate of surgery. Among 210 patients (212 sides), 133 sides were operated within 5 days of injury. Excellent effect as determined by improving 2 levels of visual acuity was achieved on 61 sides (45.9%). Good effect as determined by improving 1 level of visual acuity was achieved on 12 sides (9.0%). The overall effectiveness was seen in 73 sides (54.9%). In contrast, when the operation was performed later than 5 days after injury, the success rate decreased significantly. There were 79 out of 212 sides which were operated after 5 days (between 5 to 14 days) of injury. In this population, 11 out of 79 sides (13.9%) showed excellent effect with improvement of 2 levels of visual acuity. There were 17 out of 79 sides (21.5%) which showed good effects with one level improvement of visual acuity. The overall effectiveness was seen in 28 out of 79 sides (35.4%) (P < 0.05 in comparison to who has operation performed within 5 days of injury in the population). The molecular mechanisms underlying such drastic different outcome in these two populations remain to be determined. Earlier animal studies in rats revealed that after intraorbital optic nerve transection, retinal ganglion cells survive for 5 days and then die abruptly in large numbers, largely due to apoptosis [
In our practice of optic canal decompression by nasal endoscope, we felt that several skills are helpful in minimizing surgical complications. The foremost important issue is the identification of optic canal in external wall of sphenoid sinus. This often is the bottleneck for the beginner surgeons. There are three steps in clinical practice that are important for identifying the optic canal. Step one is the careful examination of CT image before surgery. Before operation patients should receive sinus and orbital apex coronal CT in order to identify the location of Onodi cells. The coronal image is helpful in understanding the morphological characteristics of Onodi cells [
After making an accurate judgment of the location of the optic canal, the position of the fracture line should be checked. Gentle and accurate management of the optic nerve bone are essential in preventing further optic nerve injury by the fractures. Similarly, using low temperature saline wash in the application of steel drill can prevent the production of heat. Overexertion of the fracture line should be avoided to prevent nerve injury by fracture segmenta. When bone is thin enough, it can be stripped off by elevator. When the haemorrhage occurred in the optic nerve bone and surrounding structures, a gentle suppression of cotton piece with physiological saline is useful. The adrenaline cotton piece should be avoided because it can cause eye artery spasm leading to further vision damage. In the event of no obvious optic canal fracture was observed, the incision of both tendon ring and nerve sheath membrane is necessary as recommended by Thaker A [
Cavernous sinus is below optic canal [
branch of sheath artery. These arteries are often located in the optic ventral side or outside of optical nerve. Accordingly, when the dura mater needs to be cut, the best parts of incision are above the lateral wall of optic nerve sheath. This could avoid damaging the eye arteries [
In summary, endonasal endoscopic optic decompression for TON is an effective measure for patients with traumatic optical canal fracture, and operation within 5 days of injury significantly increases the success rate.
We thank Dr. Huanquan Liao (the First Affiliated Hospital, Sun Yat-sen University) for manuscript review and discussions.
Luo, R.J., Yan, Z.C., Xia, W.T., Zeng, X.P., Xu, R. and Chen, H.X. (2017) Effectiveness of Optic Decompression by Endoscopic Endonasal Approach on Patients with Traumatic Frac- ture of Optic Canal. Open Access Library Journal, 4: e3682. https://doi.org/10.4236/oalib.1103682