What is the procedure that enters the brain through the eye socket?

From the Guidelines

The procedure that enters the brain through the eye socket is not a recommended or commonly used technique in modern medicine, and the most recent evidence suggests that alternative approaches, such as needle biopsy or open biopsy via craniotomy, are preferred for diagnosing and treating brain lesions. When considering a procedure that involves entering the brain, it is crucial to prioritize techniques that minimize risk and maximize diagnostic accuracy and therapeutic efficacy. According to the most recent study 1, needle biopsy offers advantages such as small incision size, reduced anesthesia time, and the ability to target lesions in critical or difficult-to-access locations. However, it also has limitations, including the potential for sampling error due to the lack of direct visualization of the needle tip and inaccuracies inherent to frameless neuronavigation systems.

Some key considerations for any procedure that involves entering the brain include:

• The use of high-resolution MR or CT images for preoperative planning and image guidance
• Careful trajectory planning to avoid transiting blood vessels, sulci, and eloquent or deep brain regions
• Targeting specific regions of the lesion, such as areas of confluent or nodular enhancement, to maximize the amount of viable, diagnostic tumor tissue
• Avoiding necrotic or cystic regions of the lesion to minimize the risk of sampling error

In cases where open biopsy via craniotomy is necessary, the procedure offers advantages such as direct visualization of the tissue being obtained, the ability to perform anatomical functional mapping of speech and motor cortices, and the potential for adjunctive tumor debulking or resection for local disease control and symptom relief 1. However, this approach also carries risks associated with the more invasive nature of the procedure, including larger incision size, removal and replacement of the bone flap, and theoretical increased anesthesia time. Ultimately, the choice of procedure depends on the individual patient's needs and circumstances, and should be guided by the most recent and highest-quality evidence available.

From the Research

Procedure Overview

• The procedure that enters the brain through the eye socket is known as Optic Nerve Sheath Fenestration (ONSF) 2, 3, 4, 5, 6.
• ONSF is a surgical technique used to relieve visual loss due to various optic disc pathologic conditions, such as pseudotumor cerebri or idiopathic intracranial hypertension.

Surgical Approaches

• There are several surgical approaches to ONSF, including:
  • Medial approach with disinsertion of the medial rectus muscle 2
  • Lateral approach with removal of the lateral orbital rim 2
  • Lateral canthotomy incision without removal of bone or disinsertion of an extraocular muscle 2
  • Superomedial lid crease incision 3, 6
• Each approach has its advantages and disadvantages, and the choice of approach depends on the surgeon's preference and the individual patient's needs.

Technique and Outcomes

• The technique involves making an incision in the eye socket to access the optic nerve, and then creating a fenestration (window) in the optic nerve sheath to relieve pressure on the optic nerve 2, 3, 4, 5, 6.
• The procedure can be performed under local anesthesia, such as subtenon's local anesthesia, which provides excellent anesthesia and maximal patient comfort 4.
• While ONSF is generally a safe and effective procedure, there are potential risks and complications, including unilateral blindness, bilateral vision loss, and metastatic disease involving the optic chiasm and optic nerve sheath 5.