A 60-year-old male judge with hypertension and diabetes describes a single episode of monocular transient visual loss OD. A dark curtain descended from superior to inferior OD, lasted 10 minutes and then spontaneously resolved. The patient was seen by an outside ophthalmologist and a diagnosis of “retinal migraine” was made. The next day the patient suffers two more episodes of similar visual loss and calls the ophthalmologist back and is given a referral for a two week appointment to neurology for “migraine”. That night the patient suffers a hemispheric stroke with hemiparesis and aphasia. A carotid study shows near occlusion of the right internal carotid artery.\nThe diagnosis of “retinal migraine” is one of exclusion. In elderly patients the diagnosis should be made with caution in the absence of headache history, prior attacks without residual or sequelae, and in patients who have vasculopathic risk factors. The International Headache Society (IHS) criteria for the diagnosis include: “≥ 2 attacks of “fully reversible” monocular visual loss with migraine headache”. The presumptive vasospasm mechanism for migraine headache and visual aura has fallen out of favor and spreading depression of cortical neuronal activity is a more plausible explanation for the visual symptoms in migraine. Unfortunately there is no diagnostic test for the migraine aura and a convincing history is required for the diagnosis. The role of the ophthalmologist is to exclude permanent visual loss after the event by performing formal visual field, documenting that there is no permanent residual loss, and ruling out alternative etiologies or eye markers for ischemic disease (e.g., central or branch retinal artery occlusion, Hollenhorst plaque). The most characteristic historical features for migraine are positive (e.g., scintillation or fortification scotoma) rather than negative (e.g., a black curtain) visual phenomenon; march and build up across the visual field in a nonvascular distribution, stereotyped quality with repeated events without permanent sequelae; and preferably the headache follows the aura after a few minutes duration. The most worrisome historical features for ischemia as the cause for amaurosis fugax include older aged, vasculopathic patient with first onset of an altitudinal (e.g., curtain over my vision) onset and disappearance, duration of minutes (1-10”), and seconds in onset. I would consider ordering a work up in transient monocular visual loss for patients with altitudinal history (e.g., curtain of visual loss), visible embolus, residual visual field defect, vasculopathic risk factors, and an ischemic time course. I would expedite the evaluation if the course was one of an increasing crescendo of events. On the other hand, I often defer work up for visual loss symptoms which have been present for years (e.g., hundreds of events with no residual loss) or have longer duration (e.g., 1-2 hours to days); are non-altitudinal events, the patient has no vasculopathic risk factors, or gives only a vague history of blurring. The clinician should also try to elicit a history suggestive of fluctuating rather than transient visual loss that might suggest the more common benign etiologies like ocular surface disorders or dry eyes. I will give these latter patients a pinhole to try during the events and if it alleviates the problem then it can be safely assumed to be ocular surface or refractive in nature. I also ask the patients to keep a diary of their events to establish some of the historical details above and I often give an empiric artificial tear trial.
A 25-year-old woman presents with chronic and unresolved loss of vision OD that occurred acutely two months prior to presentation. There is a right RAPD, a central scotoma OD on visual field testing, and a normal optic disc. Computed tomography (CT) scan of the head in the emergency room was normal. A diagnosis of chronic optic neuritis” is made.\nChronic “optic neuritis” is a real diagnosis but the clinician should be careful to insure that the patient has a confirmed diagnosis of multiple sclerosis and no alternative etiology for the optic neuropathy. Typical optic neuritis resolves (20/40 or better vision) in over 90% of cases and lack of improvement should be a big “red flag” that the diagnosis is incorrect. In my experience patients with chronic”“optic neuritis” due to demyelinating disease often have a systemic MS course that mirrors the course of their optic neuropathy (i.e., primary or secondary progressive rather than relapsing-remitting course). One should also be cautious of using the term “optic neuritis” when one truly means optic neuropathy. Misusing or mixing terms (e.g., papilledema) or creating neologisms (e.g., “ischemic optic neuritis”) also is potentially misleading to your colleagues. The bottom line is that typical optic neuritis usually gets better over time and patients with an atypical course (e.g., “chronic optic neuritis”) should have evaluation for alternative etiologies for their optic neuropathy including neuroimaging. There are potentially dangerous conditions that could mimic the presentation of acute painful optic neuropathy and suggest a diagnosis of demyelinating optic neuritis (e.g., pituitary apoplexy or ophthalmic artery aneurysm). In addition there are subsets of variants of demyelinating optic neuropathy that may not have as favorable a rate of recovery and therefore might suggest alternative diagnoses (e.g., neuromyelitis optica). Finally, some patients with the mitochondrial disorder, Leber hereditary optic neuropathy (bilateral acute visual loss with cecocentral scotomas in a young male) can be associated with MS like illness. Although rare, I would accept the diagnosis of “chronic optic neuritis” as a diagnosis of exclusion if a high quality MR scan of the head and orbit with gadolinium has excluded a compressive lesion, the patient has clear diagnosis of prior multiple sclerosis, and alternative MS mimics have been considered and adequately excluded. I typically will inform the treating neurologist of the findings and my concerns and if there is any history of transverse myelitis or if the optic neuropathy is bilateral then I would consider evaluation for neuromyelitis optica (NMO) including NMO antibody testing. I would also consider ordering the mitochondrial genetic testing for Leber hereditary optic neuropathy if the patient has bilateral central or cecocentral scotomas especially in a young man.