Differential diagnosis key to treatment of pale optic nerve

Buffalo, NY-In the absence of optic nerve swelling, the clinician may be faced with a difficult diagnosis in a patient with a pale optic nerve, according to Norah S. Lincoff-Cohen, MD. A comprehensive differential diagnosis needs to be made to rule out disorders that may require immediate treatment.

"The first thing I worry about is the different diagnoses that could be acutely damaging the optic nerve," said Dr. Lincoff-Cohen, associate clinical professor of neuro-ophthalmology, Jacob's Neurologic Institute, Buffalo, NY. "Could it be ischemia, inflammatory disease, or compression? What could be acutely making the nerve pale? These possible disease states can cause permanent, rapid damage to the affected eye as well as to the fellow eye if not treated immediately. One shouldn't even wait a couple of days before considering this so-called Friday afternoon differential."

Dr. Lincoff-Cohen pointed out some key clinical factors to consider.

"Second, giant cell arteritis is a potential diagnosis that cannot be ignored on a Friday," Dr. Lincoff-Cohen said. This diagnosis should be considered in an elderly patient with a pale optic nerve whether or not the nerve is swollen.

These patients may have suffered from ischemic disease from giant cell arteritis in the past, and their fellow eye may still be at risk, she continued. In an elderly patient with normal optic nerve morphology and poor vision, a choroidal infarction may have occurred and should be ruled out by a fluorescein angiogram.

"Third, be aware that there are a number of different types of optic neuritis," she said. She warned against thinking of only demyelinating disease when the patient with a pale optic nerve complains of new or recurrent pain on eye movement. A different inflammatory disease state such as lupus erythematosus or sarcoid are also possibilities.

Diagnoses to consider

When considering ischemia, the patient's age should be taken into account. Giant cell arteritis presents in patients as young as 50 years. In patients younger than 50, a pale optic nerve may indicate cardiac valvular disease, a hypercoagulable state, or vasculitis.

She cautioned that patients with autoimmune disease such as lupus erythematosus require immediate treatment. These patients need to be differentiated from patients with optic neuritis due to demyelinating disease, which does not necessarily necessitate treatment (a finding of the Optic Neuritis Treatment Trial).

The presence of intraocular vitreal inflammation should be assessed by slit-lamp examination. Inflammation can damage the optic nerve as well as cause orbital inflammatory syndromes, which often present with other clinical signs such as proptosis or chemosis and redness, she said.

The most common tumors associated with a pale optic nerve are pituitary tumors, meningioma, and glioma. When the tumor involves the orbital portion of the optic nerve, the optic nerve is likely to be very congested and pale; there is usually no cupping because of the chronic congestive state.

However, when the chiasm is compressed, temporal atrophy is generally apparent. When temporal atrophy is observed bilaterally, Dr. Lincoff-Cohen advised ordering a scan and avoiding first settling on a diagnosis of glaucoma.