Complete avulsion of the optic nerve. A clinical, angiographic, and electrodiagnostic study

Optic Nerve Avulsion from Optochiasmal Region Secondary to an Animal Attack: A Case Report

ABSTRACT

Optic nerve avulsion without bone fracture was observed in four cases in the literature. This case is unique with its cranial effects and complications. A 50-year-old Caucasian female patient attacked by an animal on her left eye was admitted. Traumatic subarachnoid hemorrhage in the suprasellar cistern and epidural hematoma was observed upon brain computed tomography (CT). Enucleation and duraplasty were performed on the patient whose epidural hemorrhage did not increase. Two weeks after being discharged, the patient presented to the emergency room again with numbness on the right side of her face and sensory aphasia. The patient was followed up by medical treatment with left temporoparietal infarction and had completely recovered. Optic nerve avulsion secondary to trauma is a topic that needs to be carefully investigated due to potentially fatal complications. This article was written to share our experience with this rare condition and its case management.

FOCAL RETINAL ISCHEMIA REVEALED BY MULTIMODAL IMAGING AFTER TRAUMATIC PARTIAL OPTIC NERVE AVULSION

PURPOSE

Traumatic optic neuropathy can have varying presentations. Blunt focal trauma can lead to optic nerve avulsion with underlying retinal findings. A case of partial optic nerve avulsion after finger poke injury leading to focal retinal ischemia is reported.

METHODS

Visual acuity, fundus photography with fluorescein angiography, and spectral-domain optical coherence tomography were performed to document the findings in a 16-year-old man who presented after a finger poke injury to the left orbit during a water polo match.

RESULTS

On initial presentation, examination revealed decreased visual acuity with a fixed left pupil and afferent pupillary defect by reverse. On slit-lamp examination of the left eye, a hyphema was present. Dilated fundus examination revealed layering vitreous hemorrhage over the posterior pole and an avulsed vitreous base. On follow-up, a gap temporal to the optic nerve head consistent with a partial optic nerve avulsion was noted once the vitreous hemorrhage cleared. Multimodal imaging revealed retinal ischemia temporal to the disc on fluorescein angiography with corresponding changes in the inner retinal layers and retinal nerve fiber layer using spectral-domain optical coherence tomography.

CONCLUSION

Clinicians should have a high suspicion for optic nerve avulsion if a patient presents with new vitreous hemorrhage and afferent pupillary defect after a finger-poke injury. Optic nerve avulsion injury can cause retinal ischemia, likely because of interruption of retinal blood flow as a result of nerve shearing injury. Multimodal imaging can reveal focal retinal injury and aid in proper diagnosis and follow-up.

Traumatic Optic Neuropathy

A host of different types of direct and indirect, primary and secondary injuries can affect different portions of the optic nerve(s). Thus, in the setting of penetrating as well as nonpenetrating head or facial trauma, a high index of suspicion should be maintained for the possibility of the presence of traumatic optic neuropathy (TON). TON is a clinical diagnosis, with imaging frequently adding clarification to the full nature/extent of the lesion(s) in question. Each pattern of injury carries its own unique prognosis and theoretical best treatment; however, the optimum management of patients with TON remains unclear. Indeed, further research is desperately needed to better understand TON. Observation, steroids, surgical measures, or a combination of these are current cornerstones of management, but statistically significant evidence supporting any particular approach for TON is absent in the literature. Nevertheless, it is likely that novel management strategies will emerge as more is understood about the converging pathways of various secondary and tertiary mechanisms of cell injury and death at play in TON. In the meantime, given our current deficiencies in knowledge regarding how to best manage TON, "primum non nocere" (first do no harm) is of utmost importance.

Optic Nerve Avulsion and Retinal Detachment After Penetrating Ocular Trauma: Case Report

Optic nerve avulsion is a rare pathology with poor prognosis usually seen after blunt trauma. The optic nerve is separated from the sclera by indirect forces due to the relatively weak structure of the lamina cribrosa area. Here we describe an 11-year-old boy who experienced optic nerve avulsion and retinal detachment after penetrating ocular trauma.

Efferent influences on the bioelectrical activity of the retina in primates

PURPOSE

The existence of retinopetal (sometimes referred to as "efferent" or "centrifugal") axons in the mammalian optic nerve is a topic of long-standing debate. Opposition is fading as efferent innervation of the retina has now been widely documented in rodents and other animals. The existence and function of an efferent system in humans and non-human primates has not, though, been definitively established. Such a feedback pathway could have important functional, clinical, and experimental significance to the field of vision science and ophthalmology.

METHODS

Following a comprehensive literature review (PubMed and Google Scholar, until July 2016), we present evidence regarding a system that can influence the bioelectrical activity of the retina in primates.

RESULTS

Anatomical and physiological evidences are presented separately. Improvements in histological staining and the advent of retrograde nerve fiber tracers have allowed for more confidence in the identification of efferent optic nerve fibers, including back to their point of origin.

CONCLUSION

Even with the accumulation of more modern anatomical and physiological evidence, some limitations and uncertainties about crucial details regarding the origins and role of a top-down, efferent system still exist. However, the summary of the evidence from earlier and more modern studies makes a compelling case in support of such a system in humans and non-human primates.

Optical coherence tomography in optic nerve head avulsion

Early diagnosis of optic nerve head (ONH) avulsion may be difficult due to an obscured fundus view. Although B-scan ultrasonography is more useful than MRI and CT imaging, it has limited sensitivity and specificity. Optical coherence tomography (OCT) can be used to identify optic nerve pathology. Utilization of OCT has not been widely reported in the diagnosis of ONH avulsion. Two cases OCT use in ONH avulsion are reported. The utility of OCT in the diagnosis of ONH avulsion is of limited value.

Longterm follow-up of children with traumatic optic nerve avulsion

PURPOSE

We report the longterm follow-up of children with optic nerve avulsion (ONA) caused by traumatic events. The remarkable differences in courses and outcomes may elucidate the spectrum of ONA-associated symptoms and injuries.

METHODS

During the last 15 years, three children with ONA were referred to our department. These cases are presented with special attention to their longterm follow-up.

RESULTS

Two patients suffered from complete ONA after head injury. The third patient presented with partial ONA caused by a bicycle accident. Longterm follow-up varied between 7 and 15 years. In the first patient, a pale swollen retina without any visible retinal vasculature was observed early in the course of follow-up. The retina later completely detached. In the second patient, extended fibroglial scarring occurred and an extremely large epiretinal membrane formed and was finally released spontaneously into the vitreous. The third patient developed only mild fibroglial scarring and retinal pigment epithelium hyperplasia. The optic nerve head in this patient came to resemble a morning glory disc.

CONCLUSIONS

Optic nerve avulsion can adopt different courses and outcomes in different patients. Final visual outcome seems to depend on the degree of visual acuity immediately after injury. Substantial intraocular architecture changes can occur as a result of ONA.

[Optic nerve head avulsion: a case report]

Optic nerve head avulsion is a rare condition. It consists in a rupture of the nerve fibers at the level of the lamina cribrosa followed by a retraction of these fibers into the intact optic sheath. We report a case of optic nerve head avulsion following globe contusion. The association of a sudden forced globe rotation, a possible acute proptosis, and a sudden rise in intraocular pressure likely caused the avulsion. The presence of intraocular hemorrhages did not prevent examination of the optic nerve head region, which showed a crater. Initial visual acuity was no light perception. An orbit bone fracture was ruled out after CT examination. The patient was treated with general antibiotics and eyedrops (antibiotic/corticosteroid and atropine). No visual recovery was observed.

Traumatic evulsion of the globe

PURPOSE

To report the clinical and pathologic findings in 3 cases of traumatic evulsion of the globe, during which the optic nerve and its sheath were disrupted at different locations and to varying extents.

METHODS

Case series (3 patients).

RESULTS

We describe the clinical, gross, and microscopic pathologic findings in 3 globes that were traumatically evulsed from their orbits. The optic nerves and sheaths were disrupted at 2 different locations and in 2 distinct combinations. Two of these variations in discontinuity of the nerve and/or its sheath were unique. In 1 case, the eye and optic nerve sheath were evulsed without the nerve; in another case, the nerve and sheath were pulled from the posterior sclera at the lamina cribrosa.

CONCLUSIONS

Traumatic evulsion of the globe may cause the optic nerve and its sheath to be disrupted at varying distances from the eye and may involve the optic nerve and its sheath together or separately. To the best of our knowledge, no cases have been reported in which orbital trauma caused the globe and optic nerve sheath to be removed together, leaving the nerve behind, or in which disruption of the optic nerve at the lamina cribrosa resulted in a complete posterior scleral defect. Three theories are proposed to explain possible mechanisms leading to optic nerve disruption during traumatic evulsion of the globe.

Traumatic optic neuropathy

Knowledge concerning the pathophysiologic mechanisms of traumatic optic neuropathy is limited. The optic nerve is a tract of the brain. Therefore, the cellular and biochemical pathophysiology of brain and spinal cord trauma and ischemia provide insight into mechanisms that may operate in traumatic optic neuropathy. The dosage of methylprednisolone (30 mg/kg/6 hours) which was successful in the National Acute Spinal Cord Injury Study 2 (NASCIS 2) evolved from the unique pharmacology of corticosteroids as antioxidants. The management of traumatic optic neuropathy rests on an accurate diagnosis which begins with a comprehensive clinical assessment and appropriate neuroimaging. The results of medical and surgical strategies for treating this injury have not been demonstrated to be better than those achieved without treatment. The spinal cord is a mixed grey and white matter tract of the brain in contrast to the optic nerve which is a pure white matter tract. The treatment success seen with methylprednisolone in the NASCIS 2 study may not generalize to the treatment of traumatic optic neuropathy. Conversely, if the treatment does generalize to the optic nerve, NASCIS 2 data suggests that treatment must be started within eight hours of injury, making traumatic optic neuropathy one of the true ophthalmic emergencies. Given the uncertainties in the treatment, ophthalmologists involved in the management of traumatic optic neuropathy are encouraged to participate in the collaborative study of traumatic optic neuropathy.

Ultrasonography in optic nerve head avulsion

The diagnosis of post traumatic optic nerve avulsion is often obscured by the presence of concomitant vitreous haemorrhage. Electrodiagnostic tests, CT scan and fluorescein angiography have not proved helpful in substantiating the diagnosis of this entity in the early stages. We herein present the echographic features in a case of post traumatic optic nerve avulsion that, to the best of our knowledge, have not been previously described. The role of ultrasonography in the diagnosis of suspected optic nerve head avulsion has been high-lighted.

Ocular motor abnormalities from head trauma

Head injuries cause the hospitalization of 200-300 persons per 100,000 population per year. Ophthalmologists provide diagnostic and therapeutic care to those trauma victims with damage to the globe, optic nerve, orbit, and ocular motor system. Eye movements can be affected by damage at any level of the central nervous system or peripheral motor unit. Comprehensive ocular motor assessment of the trauma patient can substantially contribute to the understanding of the patient's injury, recovery, and rehabilitation. This review examines all aspects of head and face trauma that can lead to ocular motility disturbances.

Surgical treatment of progressive visual loss in traumatic optic neuropathy. Report of two cases

In two patients with traumatic optic neuropathy progressive visual loss was reversed by surgical decompression of the optic nerve sheath. The first patient with hemorrhage beneath the optic nerve sheath had progressive loss of vision from counting fingers to no light perception within 24 hours after the injury. Surgical evacuation of the hematoma improved visual acuity to 8/30. The second patient had progressive visual loss from 20/20 to 20/400 within the 1st week after injury. Drainage of an arachnoid cyst of the optic nerve sheath improved visual acuity to 20/25. Computerized axial tomography disclosed the hemorrhage in the first case and enlargement of the optic nerve sheath in the second. While the management of traumatic optic neuropathy is controversial, surgical intervention for an arachnoid cyst and hematoma involving the optic nerve is clearly beneficial.

Complete evulsion of the optic nerve

Evulsion of the optic nerve is an uncommon traumatic event, probably because the intraorbital portion of the optic nerve is mobile and surrounded by sheaths. The present paper reports a case of complete evulsion of the optic nerve with retinal detachment and discusses the possible patho mechanisms involved. Fluorescein angiography showed no retinal circulation.

Evulsion of the retina associated with optic nerve evulsion

We examined two patients with optic nerve evulsion as well as nasal peripapillary retinal and retinal pigment epithelial evulsion after ocular trauma. Fluorescein angiography demonstrated an intact peripapillary choriocapillaris, loss of peripapillary retina and retinal pigment epithelium, and complete disruption of retinal perfusion. We have postulated a mechanism for traumatic peripapillary retinal evulsion involving severe anterior displacement and abduction of the globe that may explain how the disruptive force was transmitted to the nasal retinal nerve fiber layer. We have provided a clinical correlation with magnetic resonance imaging of the optic nerve and globe of a normal individual.