Vision loss in patients with malignancy may be misdiagnosed

Chicago-A careful history followed by a complete workup may be key to understanding and treating the cause of vision loss in patients with malignancy, explained Nicholas J. Volpe, MD.

He outlined the possible yet relatively rare conditions associated with unexplained vision loss in cancer patients during the neuro-ophthalmology subspecialty day meeting at the American Academy of Ophthalmology.

The direct effects of malignancy can be seen with metastatic disease to the eye, optic nerve, and meninges. The indirect effects known as paraneoplastic processes are not as common and are rarely encountered.

Metastatic disease

Breast and lung cancers are the most common metastatic diseases seen in these patients. More common conditions like ischemic optic neuropathy can be mimicked by metatstatic tumors or radiation-induced optic nerve damage.

"Radiation optic neuropathy and optic nerve involvement by cancer can cause a pattern similar to ischemic optic neuropathy," Dr. Volpe explained. "If you think it is ischemic optic neuropathy and it is getting worse, a workup is indicated."

The clinician should work closely with the entire medical team if malignancy is suspected. Proceed with high-quality, specifically directed imaging; lumbar puncture; and consultation with a neurologist, he suggested.

"Between 15% and 40% of patients with carcinomatous meningitis will ultimately develop an optic neuropathy by one of several different mechanisms," Dr. Volpe said. "Certainly the combination of a normal disc with vision loss in an older patient with cancer should raise, first and foremost, the consideration of an ischemic process and always brings into consideration either temporal arteritis or cancer affecting the optic nerve."

Metastases to the optic nerve can be detected after careful examination of MRI study of the optic nerve sheath and repeated analysis of spinal fluid to pinpoint the cancer.

"You can occasionally capture thickening of the optic nerve sheath with imaging," Dr. Volpe said. "Alternatively, when disc edema develops it may just be papilledema from elevated intracranial pressure."

Dr. Volpe said that metastases to the optic nerve are uncommon. In fact, he noted that Jerry A. Shields, MD, documented only 30 cases of optic nerve metastases throughout his career.

"These are very rare, often recognized by massive swelling of the optic disc, often with a component of uveal involvement. In Shields' series, breast, lung, and bowel cancers were the most common," Dr. Volpe said. "These can mimic anything, initially look like ischemic optic neuropathy or any of the other optic neuropathies that produce disc swelling."

Treatment options for patients with optic nerve metastases are corticosteroids, radiation, and chemotherapy, he said.

Optic nerve involvement has also been seen in patients with lymphoma or leukemia, although this is rare. In these patients, isolated optic nerve involvement can occur before the involvement of other cranial nerves.

"A unilateral optic neuropathy and/or a unilateral cranial nerve palsy in a patient with a history of lymphoma or leukemia is particularly concerning," Dr. Volpe said. "A similar situation can develop with lymphomatous meningitis." In these patients, radiation is the treatment of choice, he said.

Orbital metastases can occur in patients with malignancy. Patients present with acute or subacute orbital syndrome, similar to an orbital tumor or orbital inflammatory disease with impaired motility, he said.

"Vision loss mechanisms include optic nerve involvement, choroidal folds, and elevation of intracranial pressure. In a small segment of patients, it will be recognized by the rapidity of progression," Dr. Volpe noted. He showed a case of a man with lung cancer that had metastasized to the orbit. The man presented with proptosis, a corneal ulcer, and neurotrophic keratitis.