Leptomeningeal carcinomatosis (LMC) is a rare but devastating complication of systemic malignancy, characterized by tumor spread to the pia and arachnoid mater. ^{Reference Malani, Bhatia, Warner and Yang1} It occurs in various solid tumors, including lung, breast, melanoma, gastrointestinal, genitourinary and primary central nervous system cancers. ^{Reference Malani, Bhatia, Warner and Yang1} LMC can lead to visual loss either from direct optic nerve invasion or indirectly through impaired CSF drainage, causing elevated intracranial pressure (ICP) and papilledema. ^{Reference Malani, Bhatia, Warner and Yang1}

Medical management of papilledema includes agents that reduce CSF production, such as acetazolamide, though systemic side effects and limited efficacy in rapidly progressive cases often necessitate surgical intervention. ^{Reference Xie, Donaldson and Margolin2} Optic nerve sheath fenestration (ONSF) offers rapid decompression of the optic nerve to prevent irreversible visual loss. ^{Reference Xie, Donaldson and Margolin2} However, due to the rarity and poor prognosis of LMC, outcomes of ONSF in this context are sparsely reported.

We describe a case of bilateral ONSF performed for progressive vision loss due to papilledema in a patient with LMC secondary to metastatic lung adenocarcinoma and review the literature on medical and surgical management of papilledema in LMC.

A 54-year-old woman, a non-smoker, presented with several months of progressive right-sided numbness, hearing impairment, imbalance, blurred vision, headaches and intermittent diplopia. Initial examination revealed best-corrected visual acuity (BCVA) of 20/20 OD and 20/25 OS, normal color vision, no relative afferent pupillary defect (RAPD) and bilateral Grade 3 optic disc edema. 30-2 Humphrey visual fields showed superior more than inferior defects OU. MRI brain with contrast showed communicating hydrocephalus, leptomeningeal enhancement with foci in the left thalamus and superficial locations involving the cortex of bilateral cerebral hemispheres (Figure 1). MRI showed prominent optic nerve sheaths but no enhancement of optic nerve/chiasm/tract. No specific MR venography was completed, but on review of post-contrast imaging, there was bilateral transverse sinus stenosis. CT chest identified a left upper lobe mass.

Figure 1. MRI brain with axial and sagittal post-contrast fat-saturated images of a patient with non-small cell lung cancer presenting with multifocal leptomeningeal enhancement suggestive of leptomeningeal carcinomatosis. Note multiple enhancing foci in superficial locations involving the cortex of bilateral cerebral hemispheres, but without enhancement of the optic nerve or optic nerve sheath.

Acetazolamide 250 mg PO BID was started, leading to subjective improvement in vision and diplopia. Biopsy confirmed stage IV epidermal growth factor receptor (EGFR)-positive non-small cell lung carcinoma (NSCLC) with leptomeningeal and bone metastases. The patient was started on osimertinib and dexamethasone. Her course was complicated by focal seizures, deep vein thrombosis and pulmonary embolism. Acetazolamide was discontinued due to metabolic acidosis.

Two weeks after acetazolamide cessation, her BCVA remained stable, and headaches improved despite persistence of Grade 3 optic disc edema OU. However, three months later, her vision deteriorated with a new + 1 RAPD OD and visual field loss. Acetazolamide was restarted and titrated to 750 mg PO BID but discontinued again due to severe fatigue and imbalance. MRI brain remained stable, but lumbar puncture revealed an opening pressure of 43.5 cm H₂O. Her optic disc edema also worsened during this time (Grade 5 OD and Grade 4 OS). Furosemide 40 mg PO BID provided minimal benefit, and vision declined to 20/100 OD and 20/200 OS.

Given rapid visual deterioration, bilateral ONSF was performed. Eight days postoperatively, BCVA improved to 20/40 OU with reduced optic disc edema (Grade 4 OD, Grade 3 OS). MRI brain remained stable, though CT chest demonstrated cancer progression. By 6 weeks, optic disc edema had resolved with visual field improvement sustained for 13 weeks (Figure 2). Fourteen weeks post-ONSF, the patient succumbed to respiratory failure secondary to disease progression, 16 months after cancer diagnosis.

Figure 2. The evolution of papilledema is demonstrated in rows A–E. The first column shows the infrared image of the optic disc; the green circle highlights the region where the OCT RNFL scan was captured. The second column shows the OCT RNFL thickness along the different regions around the optic disc: TMP = temporal; SUP = superior; NAS = nasal; INF = inferior. The black line within the green region indicates that the RNFL thickness is in the normal range, while the yellow and red regions represent thin RNFL. Anything above the green region indicates a thickened RNFL (e.g., optic disc swelling). The third column shows the visual fields (24-2 Humphrey visual fields). The last column provides the timeline and highlights the key clinical exam findings and intervention. BCVA = best-corrected visual acuity; OCT = optical coherence tomography; ONSF = optic nerve sheath fenestration; RAPD = relative afferent pupillary defect; RNFL = retinal nerve fiber layer.

LMC occurs in 3–5% of NSCLC cases (1). Tumor infiltration elevates ICP via obstruction of CSF reabsorption or ventricles, increased CSF protein causing outflow resistance or disruption of the blood-brain barrier leading to cerebral edema. Resultant headaches, papilledema and visual loss significantly affect quality of life, yet optimal management strategies remain undefined.

We performed a structured PubMed search from 1996 to October 2025 using combinations of keywords: (optic nerve sheath fenestration OR optic nerve sheath decompression) AND (papilledema OR intracranial hypertension OR pseudotumor cerebri) AND (leptomeningeal carcinomatosis OR neoplastic meningitis OR malignant meningitis). Abstracts of articles and reference lists were reviewed to identify any additional articles. A total of five published cases were identified addressing the management of papilledema in LMC (Table 1). ^{Reference Ahmed and Halmagyi3–Reference Takagi, Oku, Kida, Akioka and Ikeda7} Medical management with acetazolamide was most common and often provided transient symptom relief. Takagi et al. reported resolution of papilledema in primary leptomeningeal lymphoma after acetazolamide, though symptoms recurred following discontinuation due to nephrolithiasis. ^{Reference Takagi, Oku, Kida, Akioka and Ikeda7} Our case similarly demonstrated transient improvement followed by recurrence after stopping therapy, underscoring the challenge of sustaining benefit amid systemic toxicity. Alternatives such as topiramate or furosemide may be considered, though evidence is limited. ^{Reference Xie, Donaldson and Margolin2}

Table 1. Review of cases published on elevated intracranial pressure due to leptomeningeal carcinomatosis causing papilledema

ONSF = optic nerve sheath fenestration; VP = ventriculoperitoneal.

Surgical intervention is indicated when medical therapy fails or is not tolerated. It is important to consider multiple mechanisms of optic disc edema before considering a patient to have failed medical therapy for papilledema. Patients with metastatic cancer can develop infiltrative optic neuropathy, which classically causes decreased visual acuity, color vision deficits or central scotomas. ^{Reference Sun and Ma8} Based on our patient’s initial visual field defect, it is possible that there was also concurrently an aspect of bilateral infiltrative optic neuropathy, which would not improve with lowering of ICP. However, the initial relative preservation of central visual acuity and color vision despite significant edema and clinical improvements with both acetazolamide and ONSF argue for a significant component of papilledema. ONSF allows localized CSF drainage from the optic nerve sheath into the orbit, alleviating mechanical pressure on the optic nerve head. ^{Reference Ahmed, King and Gibson4} The procedure has proven efficacy in idiopathic intracranial hypertension (IIH) and cerebral venous sinus thrombosis but remains underreported in LMC. Only four prior cases of ONSF in LMC were identified, showing variable outcomes. ^{Reference Ahmed and Halmagyi3–Reference Manusow, Lee-Wing, Rahman and Mis6} Ahmed et al. demonstrated stabilization of vision for 10 weeks after ONSF in metastatic signet-ring adenocarcinoma. ^{Reference Ahmed and Halmagyi3} Manusow et al. and Ala et al. reported progressive decline despite surgery. ^{Reference Ala, Yener and Özer5,Reference Manusow, Lee-Wing, Rahman and Mis6} In our patient, ONSF achieved a rapid reduction in optic disc edema and sustained visual improvement until systemic disease progression.

ONSF success rates in IIH and related conditions range from 56–77% for visual improvement, 13–28% for stabilization and 10–15% for continued decline at approximately one year. ^{Reference Yaqub, Mehboob and Islam9} Visual prognosis correlates negatively with duration of preoperative visual symptoms, suggesting that earlier intervention may optimize outcomes. ^{Reference Yaqub, Mehboob and Islam9}

Complications of ONSF include diplopia, anisocoria, ptosis, corneal dellen or disc hemorrhage. Severe vision loss is rare but can occur due to ischemic or hemorrhagic events. While there are no known cases reported in the literature, theoretically, ONSF could allow seeding of cancer cells into orbits. For patients with residual or recurrent papilledema post-ONSF, CSF shunting may be considered. CSF diversion procedures, including ventriculoperitoneal shunts, are more often performed for refractory headaches, with or without visual compromise. In patients with systemic malignancy and immunosuppression, shunt infection or peritoneal seeding of tumor cells pose substantial risks, making ONSF a preferable first-line surgical option when vision is threatened.

While the overall prognosis of LMC remains poor, with a median survival of under six months for most solid tumors, ONSF can provide meaningful palliation by preserving functional vision. In our case, ONSF restored visual acuity and stabilized fields, significantly improving the patient’s quality of life during her remaining months.

LMC-related papilledema represents a rare yet vision-threatening manifestation of metastatic cancer. Medical management with acetazolamide may offer a transient benefit but is often limited by side effects or refractory disease. ONSF provides rapid decompression of the optic nerve and can preserve or restore vision when timely performed. Although outcomes in LMC are variable, this case supports ONSF as a viable therapeutic option to prevent irreversible vision loss and enhance quality of life in select patients. Further studies and case aggregation are warranted to clarify predictors of surgical success and develop evidence-based treatment algorithms for managing papilledema in LMC.