Optic nerve sheath fenestration for visual impairment in cerebral venous diseases

Abstract

Objective: Visual impairment is the most common clinical feature of cerebral venous sinus occlusion or cerebral venous thrombosis-induced intracranial hypertension, which can result in optic atrophy, leading to irreversible vision loss, visual field defections, and finally, permanent blindness. Papilledema is a typical early pathophysiological alteration in visual impairment. Optic nerve sheath fenestration (ONSF) has become increasingly accepted as an option to prevent or halt progressive visual loss owing to its low risk and complications. The objective of this study is to review the latest research progress on ONSF for the treatment of visual impairment related to cerebral venous diseases.

Methods: Study were searched following PRISMA guidelines based on three electronic databases (Pubmed, Embase and Medline-Ovid). We used the following keywords and variations as keywords to identify studies: "optic nerve sheath fenestration, papilledema, cerebral venous diseases, cerebral venous stenosis, cerebral venous thrombosis, idiopathic intracranial hypertension". The publication date of studies was restricted between 1,872.1.1 and 2,021.12.31. The application of ONSF in papilledema due to cerebral venous diseases is reviewed. Additionally, the common surgical approaches as well as advantages and disadvantages are also described graphically.

Results: With the improvement of specific details of the ONSF procedure and surgical instruments, complications of ONSF have reduced and its safety has been significantly improved, although the number of clinically investigated cases in the literature remains low.

Conclusion: We recommend that ONSF should be considered as an imperative alternative to reduce or delay the visual morbidity of cerebral venous diseases, although there is yet no consensus on the optimal surgical timing.

Keywords: cerebral venous diseases; cerebral venous stenosis; cerebral venous thrombosis; optic nerve sheath fenestration; papilledema.

Figure 1

Schematic diagram for the proposed management algorithm of visual impairment caused by intracranial hypertension due to CVT/CVSS. CVT, cerebral venous thrombosis; CVSS, cerebral venous sinus stenosis; MRI, magnetic resonance imaging; MRV, magnetic resonance venography; CT, computed tomography; CTA, computed tomographic angiography; ONSF, optic nerve sheath fenestration; OCT, optical coherence tomography; DAVF, dural arteriovenous fistula; EVT, endovascular therapy; ICP, intracranial pressure.

Figure 2

The medial conjunctival approach: (a) Incise the bulbar conjunctiva along the nasal limbus, bluntly separate the bulbar conjunctiva and fascial tissue; (b) expose and separate the medial rectus muscle; (c) immobilize the internal rectus muscle; (d) expose the optic nerve sheath and make an incision.

Figure 3

Transepithelial medial eyelid approach: (a) Incise the skin; (b) incise orbicularis oculi muscle; (c) bluntly separate the medial fat in the upper eyelid; (d) expose the optic nerve sheath; (e, f) incise and drain.

Figure 4

Transcanthal incision approach: (a) Incise a 1 cm lateral canthal incision; (b) use sutures to secure the lateral rectus muscle; (c) separate the overlying periosteum superiorly and inferiorly; (d) expose the eyeball, lift the deep lacrimal gland; (e) expose the optic nerve sheath and make an incision.

Figure 5

Nasoendoscopic transsphenoidal route: (a) Use nasendoscopy to pass through the nostril, resects part of the middle turbinatet, exposes the uncinate process and ethmoid bullae of maxillary sinus, and incises the lower 1/3 of the maxillary sinus to expose the maxillary sinus. (b) Resect the ethmoid and sphenoid sinuses, reveal the sphenoid plateau and sellar base, identify the optic nerve carotid crypts as well as the optic nerve bulging. (c) Chisel the medial and superior wall of optic nerve canal and make an incision from medial to lateral.

Figure 6

Transcranial route: (A) Make a frontotemporal pterygium craniotomy via Dolenc route. (B) cut the scalp and temporalis muscle. (C) Grind off the anterior bed and the sphenoid bone and decompress the optic nerve at 270 degrees from superior, medial, and inferolateral.