Journal of Neuro-Ophthalmology, June 1993, Volume 13, Issue 2

Metastatic lesion of the optic nerve.

Metastatic disease to the optic nerve is uncommon. Optic nerve involvement has been described as an extension from choroidal, retinal, orbital, or central nervous system metastatic foci. Isolated optic nerve metastatic disease is extremely rare. We present the case of an isolated circumscribed metastatic lesion to the retrobulbar portion of the optic nerve detected radiographically.

Journal of Clinical Neuro-ophthalmology 13(2): 102-104, 1993. Metastatic Lesion of the Optic Nerve A. M, Mansour, M,D., Kevin Dinowitz, M.D., Gregory Chaljub, M,D" and Faustino C. Guinto, M.D. © 1993 Raven Press, Ltd., New York Metastatic disease to the optic nerve is uncommon (1-8). Optic nerve involvement has been described as an ex­tension from choroidal, retinal, orbital, or central ner­vous system metastatic foci. Isolated optic nerve meta­static disease is extremely rare. We present the case of an isolated circumscribed metastatic lesion to the retrobul­bar portion of the optic nerve detected radiographically. Key Words: Metastatic disease-Optic nerve-Radio­graphy. CASE REPORT A 41-year-old woman presented with a 2-week history of progressive visual loss in the left eye. She underwent a left simple mastectomy in 1985 and a modified radical right mastectomy in 1989 with postoperative radiotherapy and chemother­apy for bilateral primary infiltrating ductal adeno­carcinoma. Metastatic brain disease was diagnosed in February 1992 and was controlled by surgical resection of a left frontal mass and by radiation therapy to the whole brain (3,000 cGy dosage in 10 sessions ending in March 1992). Upon presenta­tion in early September 1992, ophthalmic evalua­tion of the left eye revealed a visual acuity of hand motion, marked afferent pupillary defect, and mild disc pallor. The right eye had mild background diabetic retinopathy and normal Goldmann visual fields. Computed tomography of the optic nerves revealed mild fusiform enlargement of the left op­tic nerve adjacent to the optic canal (Fig. 1). The differential diagnosis included carcinomatous lep­tomeningitis and infectious neuritis. Cerebrospinal fluid was negative for malignant cells. Cerebrospi­nal fluid cultures (including fungal and mycobac- From the Departments of Ophthalmology (A.M.M., K.D.), and Radiology (G.c., F.C.G.), University of Texas Medical Branch, Galveston, Texas, U.S.A. Address correspondence and reprint request to Dr. A. Mansour, Department of Ophthalmology, American University of Beirut-Medical Center, Beirut, Lebanon. 102 terial) were negative. Visual acuity of the left eye dropped to light perception 3 days later. Magnetic resonance imaging then revealed an enhancing 3­to 4-mm intraparenchymal lesion of the left optic nerve just before the optic chiasm, on gadolinium enhanced Tl-weighted images (Figs. 2-5). Multi­ple l-cm metastatic lesions were present in the pa­rietal and the temporal lobes. The visual acuity did not improve following prompt initiation of radio­therapy (total dose of 1,400 cGy in 7 sessions). The visual status was unchanged after 1 month of fol­low- up. New metastases were found in the right parietal lobe and the femur in November 1992. DISCUSSION This is the first radiographic report of an isolated optic nerve metastatic lesion without retinal, cho­roidal, or optic nerve head involvement. The le­sion was suspected by CT scan and was well de­lineated by magnetic resonance imaging. Due to its multiplanar capabilities, excellent soft tissue con­trast, and no-beam hardening artifact from adja­cent bone, magnetic resonance imaging is the im­aging modality of choice over CT in prechiasmatic optic nerve pathology. Reports of retrobulbar optic nerve metastases (3,5,7-10) have usually dealt with involvement of the optic nerve sheaths. In­traparenchymal metastasis as in the present case (focal lesion, normal cerebrospinal fluid, normal cranial nerves besides the left optic nerve) needs to be differentiated from the more common men­ingeal carcinomatosis (or carcinomatous optic neu­ropathy (10). In meningeal carcinomatosis, the ce­rebrospinal fluid is positive for malignant cells, and the patient often demonstrates signs of low­grade meningitis, as well as signs of damage to one or several cranial nerves. There is usually diffuse tumor infiltration of the leptomeninges around the optic nerves resulting in compression and second- METASTATIC LESION OF OPTIC NERVE 103 FIG. 1. Axial postcontrast CT shows thickened optic nerve adjacent to the optic canal. ary compromise of blood supply leading to visual loss. Metastatic optic nerve disease manifested ophthalmoscopically in the majority of reported cases as a visible mass occupying the optic nerve head (3). Metastatic retrobulbar optic nerve disease may manifest as a retrobulbar neuritis (3,9). Visual loss can be progressive as the metastatic focus en­larges or can be sudden from complications such as central retinal vein occlusion (3). Most primary sites arise from the breast or the lung. Radiation FIG. 2. Parasagittal T1-weighted magnetic resonance image without contrast shows prechiasmatic enlarge­ment of the optic nerve (arrow). FIG. 3. Parasagittal T1-weighted magnetic resonance imaging with gadolinium showing an enhancing 3-4 mm lesion (arrow) of the optic nerve before the optic chiasm. therapy and chemotherapy may preserve vision if the intervention is performed early in the course of the disease. Other differential diagnoses in the present case include radiation neuritis (11,12). Ra­diation neuritis usually occur in patients with FIG. 4. Coronal post-gadolinium T1-weighted image shows an enlarged left prechiasmatic optic nerve (ar­row) with intraparenchymal enhancement. The right optic nerve (hollow arrow) is normal in size. I Clill Neuro·ophthalmol. Vol. 13. No.2. 1993 104 A. M. MANSOUR ET AI. FIG. 5. Axial post-gadolinium T1-weighted image with fat suppression shows an enhancing nodule (arrow) within a thickened prechiasmatic optic nerve (the nodule was not apparent on axial noncontrast T2­weighted image). higher radiation doses (above 5,000 cGy), with ra­diation focused around the periorbital region (as in pituitary fossa tumors), and with a longer interval time between the radiation and the neuropathy (6 months interval in the present case). Infectious neuritis [bacterial, sarcoid (13), tuberculous (14), toxoplasmic (15), and syphilitic (16)] is added to the differential diagnosis. I ell" NClInH,/,htlllll"1<lI, Vol. 13, No.2, 1993 REFERENCES 1. Garrity JA, Herman DC, Dinapoli RP, et al. Isolated me­tastasis to the optic nerve from medulloblastoma. Ophthal­mology 1989;96:207-10. 2. Takagi T, Yamaguchi T, Mizoguchi T, Amemiya T. A case of metastatic optic nerve head and retinal carcinoma with vitreous seeds. Ophthalmologica 1989;199:123-6. 3. Arnold AC, Hepler RS, Foos RY. 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