obsolete visual pathway meningioma

Obsolete Visual Pathway Meningioma: A Rare Condition

A rare and disabling condition that affects the visual pathway, Obsolete Visual Pathway Meningioma (OVPM) is a type of tumor that arises from the meninges surrounding the optic nerve. This condition is characterized by slow but progressive vision loss, often accompanied by painless visual deterioration in one or both eyes [7].

Causes and Epidemiology

The exact cause of OVPM is unknown, but it is believed to be related to radiation therapy [7]. This condition is rare, accounting for approximately 2% of all orbital tumors and 1-2% of all meningiomas [14].

Symptoms and Diagnosis

Patients with OVPM typically present in the fourth decade with a triad of vision loss, optic atrophy, and optociliary shunt vessels on fundoscopy [12]. The symptoms can progress to complete loss of vision if left untreated. Diagnosis is often made through radiographic imaging, such as MRI or CT scans.

Treatment and Management

Treatment options for OVPM are limited due to the proximity of the tumor to the optic nerve. Surgery can lead to significant morbidity, and radiation therapy may not be effective in preventing visual decline [14]. Therefore, management of OVPM often focuses on monitoring and managing symptoms rather than curing the condition.

Visual Outcomes

The visual outcomes for patients with OVPM are generally poor. A study found that 24% of patients had visual acuity of counting fingers or worse, while 45% of patients had visual acuity of 20/40 or better [11]. However, evidence of optic nerve dysfunction is typically present, indicating a significant impact on vision.

Conclusion

Obsolete Visual Pathway Meningioma is a rare and disabling condition that affects the visual pathway. While treatment options are limited, monitoring and managing symptoms can help alleviate some of the effects of this condition. Further research is needed to better understand the causes and management of OVPM.

References:

[7] Jun 1, 2024 — A rare yet disabling condition that may occur following radiation therapy, RION usually presents with painless, rapid visual deterioration in 1 or both eyes. [11] Dutton's review found that 24% of patients had visual acuity of counting fingers or worse, while 45% of patients had visual acuity of 20/40 or better. Evidence of optic nerve dysfunction (e.g., reduced color vision, visual field loss, an ipsilateral relative afferent pupillary defect, and optic atrophy/optic disc edema) are typically present. [12] Introduction. Optic nerve sheath meningiomas (ONSMs) are usually benign neoplasms of the meninges surrounding the optic nerve. Patients classically present in the fourth decade with a triad of vision loss, optic atrophy, and optociliary shunt vessels on fundoscopy. [14] Optic nerve sheath meningiomas (ONSMs) are rare tumors of the anterior visual pathway and constitute approximately 2% of all orbital tumors and 1–2% of all meningiomas. Untreated ONSMs almost always lead to progressive visual decline, color blindness, and finally complete loss of vision.

Visual Changes Meningiomas can cause partial or complete loss of vision, typically in one eye [1][2]. There may also be other changes in vision, such as blurred vision, double vision, or difficulty seeing colors [1][2].

Neurological Symptoms Patients with meningioma may experience neurological symptoms and functional impairment, including impaired Health-Related Quality of Life (HRQOL) [3]. These symptoms can vary from mild to severe and may include:

• Impaired intellect
• Headache
• Seizures
• Papilledema (swelling of the optic disc)

Ocular Motility Disturbances Some meningiomas, particularly those in the orbit, can cause ocular motility disturbances, such as: * Proptosis (bulging of the eye) * Exophthalmos (protrusion of the eyeball) * Progressive vision loss

Classic Triad of Signs The classic triad of signs for visual pathway meningioma is proptosis, decreased vision (Snellen visual acuity worse than 20/40), and impaired extraocular motility [9].

Other Symptoms Additional symptoms may include: * Ptosis (drooping eyelid) * Paresis of upward gaze * Visual acuity reduced to finger counting only

It's worth noting that the clinical presentation of meningioma can vary widely, and not all patients will exhibit these specific signs and symptoms.

Diagnostic Tests for Obsolete Visual Pathway Meningioma

Obtaining an accurate diagnosis for visual pathway meningiomas can be challenging due to their complex nature and location. Various diagnostic tests have been employed to aid in the detection and characterization of these tumors.

• Imaging Studies: Imaging studies, such as CT scans and MRI scans, are commonly used to diagnose meningiomas. These tests provide detailed images of the brain and surrounding tissues, allowing for the identification of tumor growth and its impact on the visual pathway.
  • CT scans take X-rays that make cross-sectional images of a full picture of the brain, while sometimes an iodine-based dye is used to make the picture easier to read [7].
  • MRI scans are often preferred due to their ability to provide detailed quantitative testing, which remains critical for diagnosing meningiomas and following patients with meningiomatous pathology [3].
• Sensitivity and Specificity: Diagnostic test accuracy outcomes, as reflected by sensitivity and specificity, were considered critical for decision-making in this review. Sensitivity was used to evaluate imprecision, as an early accurate identification of meningioma confers benefits and reduces the harmful consequences of a misdiagnosis [4].
• Radiolabeled SSTR2 Ligands: Owing to the wide expression of SSTR2 in meningioma, radiolabeled SSTR2 ligands (ie, octreotide) have been applied in the radiographic diagnosis of meningiomas. This exploration is helpful in distinguishing tumor from healthy tissue and postoperative tissue changes [9].
• 68 Ga-DOTATOC PET: A noninvasive technique for diagnosing optic nerve sheath meningioma (ONSM), 68 Ga-DOTATOC PET could be a highly sensitive and specific method for identifying these tumors [10][11].

These diagnostic tests play a crucial role in the accurate diagnosis of visual pathway meningiomas, allowing for timely intervention and management.

Treatment Options for Obsolete Visual Pathway Meningiomas

Meningiomas affecting the optic nerve sheath can lead to severe visual loss due to their proximity to the anterior visual pathway. While treatment options are still considered controversial, various studies have explored the potential of drug therapy in managing these tumors.

• Progesterone-receptor antagonists: Research suggests that progesterone-receptor antagonists may be effective in halting the progression of sphenoid-ridge meningiomas [6]. However, further investigation is needed to confirm their efficacy in treating visual pathway meningiomas.
• Somatostatin analogues: A study found that somatostatin analogues may offer a relatively nontoxic alternative treatment for recurrent meningiomas, with minimal toxicity reported [8].
• Cyproterone acetate: In patients with a documented meningioma, cyproterone acetate should be discontinued as it might regress in response to this therapy [9].

Limitations and Controversies

While these findings are promising, it's essential to note that:

• Clinical trials have shown mixed results, with some studies demonstrating partial radiographic response while others found no significant effect [11].
• The optimal medical therapies for meningiomas remain unclear, and further research is needed to determine the most effective treatment approaches.

Current Recommendations

Given the complexities surrounding drug treatment of obsolete visual pathway meningiomas, it's crucial to consult with a neurologist or a specialist in conditions of the brain and spine. They can provide personalized guidance based on individual patient needs and circumstances [15].

References:

[6] RJW de Keizer · 2004 · Cited by 19 — Several pilot studies suggest that progression of sphenoid-ridge meningiomas can be halted using progesterone-receptor antagonists.

[8] by MC Chamberlain · 2007 · Cited by 233 — Toxicity was minimal, suggesting somatostatin analogues may offer a novel, relatively nontoxic alternative treatment for recurrent meningiomas.

[9] by A Weill · 2021 · Cited by 115 — In patients with a documented meningioma, cyproterone acetate should be discontinued because the meningioma might regress in response to this therapy.

[11] While one clinical trial showed partial radiographic response following treatment with this drug, other trials did not find any radiographic response following the therapy. Another active signaling pathway in meningioma is the RAS/RAF/MEK/MAPK pathway, which transduces the VEGFR, EGFR and PDGFR’s pro-mitotic signals [61,64].

The differential diagnosis for an optic nerve sheath meningioma (ONSM) involves considering other conditions that can affect the anterior visual pathway and present with similar symptoms.

Key considerations:

• Solitary fibrous tumor: This is a type of dural-based tumor that can mimic the appearance of a meningioma on imaging studies [6].
• Meningeal carcinomatosis: In rare cases, metastatic disease to the meninges can present with similar symptoms to an ONSM [8].
• Optic nerve glioma: This is a type of brain tumor that arises from the optic nerve and can cause visual loss and other symptoms similar to an ONSM [5].

Diagnostic markers:

• SSTR2a: This marker is highly specific for meningiomas, making it useful in distinguishing them from solitary fibrous tumors [6].
• STAT6: This marker is highly specific for solitary fibrous tumors, helping to differentiate them from meningiomas [6].

Imaging studies:

• MRI and CT scans: These imaging modalities can help identify the location and extent of the tumor, as well as any associated findings such as optic nerve atrophy or optociliary shunt vessels [5].
• PET imaging: Techniques like 68Ga-DOTATOC PET can be used to differentiate meningiomas from other types of tumors, including solitary fibrous tumors [10].

Clinical presentation:

• Progressive visual loss: This is a hallmark symptom of ONSMs, but it can also be seen in other conditions affecting the anterior visual pathway.
• Optic atrophy and optociliary shunt vessels: These findings on fundoscopy can suggest an ONSM, but they can also be seen in other conditions.

It's essential to consider these factors when making a differential diagnosis for an optic nerve sheath meningioma. A thorough clinical evaluation, imaging studies, and molecular analysis can help differentiate this condition from other types of tumors affecting the anterior visual pathway.