The Neuro-Ophthalmology of Cerebrovascular Disease* JOHN W. HARBISON, M.D. Associate Professor, Department of Neurology, Medical College of Virginia, Health Sciences Division of Virginia Commonwealth University, Richmond The neuro-ophthalmology of cerebrovascular however, are important pieces to the puzzle the disease is a vast plain of neuro-ophthalmic vistas, patient may present. A wide variety of afflictions encompassing virtually all areas of disturbances of of the eye occur by virtue of its arterial dependence the eye-brain mechanism. This paper will be re­ on the internal carotid artery. It is also logical to stricted to those areas of the neuro-ophthalmology assume that changes in the distribution of the of cerebrovascular disease which one might con­ ophthalmic artery may reflect changes taking place sider advances in its clinical diagnosis and treatment. in other channels of the internal carotid artery­ Most practitioners of medical and surgical neu­ the middle cerebral, the anterior cerebral, and de­ rology give little thought to that aspect of medicine pending upon anatomic variations, the posterior generally accepted as the ideal approach to any cerebral artery. This paper will discuss these afflic­ disease-prevention. Usually when one is presented tions, those common as well as rare, those well with an illness of the central nervous system, it recognized, and those frequently overlooked. seems to be a fait accompli. Although prevention Historically, the recognition of the eye as an is by no means new, certain aspects of it qualify index of cerebrovascular disease presents an inter­ as advances. There is one advance in cerebrovascu­ rupted course. Virchow is credited with the first lar disease in which prevention plays a significant autopsy correlation of ipsilateral blindness with role. This is the recognition and surgical correction carotid thrombosis; Gowers in 1875 demonstrated of atherosclerotic lesions of the extracranial carotid embolization as a source of central retinal artery system which threaten the patient with that bane and middle cerebral artery occlusion, resulting in of antiquity-the "stroke." monocular blindness and contralateral hemiplegia; Neuro-ophthalmology, largely by virtue of the Chiari followed in 1905 with his identification of carotid origin of the ophthalmic artery, plays a the carotid bifurcation as a common source of valuable role in the recognition, evaluation, therapy, atheromatous emboli to the cerebral circulation; in and prognosis of disease of the extracranial internal 1914 Ramsey Hunt emphasized the significance of carotid artery. Even this markedly restricted aspect transient symptoms involving the ipsilateral eye and of the neuro-ophthalmology of cerebrovascular dis­ contralateral extremities as strong evidence of ease is far too extensive to review adequately in ischemia. Thus by the turn of the century, the this paper. I have therefore selected for discussion stage was set for incrimination of the extracranial certain aspects of our neuro-ophthalmic approach internal carotid artery as a major source of "strokes." to extracranial carotid disease. Some of these are Embolization was known as a basis for ipsilateral well known; others are less obvious and frequently eye and contralateral extremity symptoms and overlooked in our evaluation of patients. They all, signs; the carotid bifurcation was known as a source of emboli; and transient symptoms were recognized * Presented by Dr. Harbison at the 27th Annual as reflections of ischemia-a stroke prodrome or Stoneburner Lecture Series, February 7, 1974, at the Medi­ warning was discovered. Yet it was for Fisher in cal College of Virginia, Richmond. 1951 to rekindle interest in extracranial carotid 114 MCV QUARTERLY 10(3): 114-117, 1974 HARBISON: NEURO-OPHTHALMOLOGY OF CEREBROVASCULAR DISEASE 115 disease with his emphasis on transient ipsilateral one and one-half to two or three minutes despite visual and contralateral extremity symptoms as pre­ the patient's initial claim of five, ten minutes, or cursors of future strokes. It is this reawakening longer of impairment. A watch second hand or stop which has led directly to the current advances in watch could also be used; however, the vocal metro­ the medical and surgical neurologic care of extra­ nome seems helpful. cranial internal carotid disease. Although emphasis has been placed on the Amaurosis fugax, "fleeting blindness," has be­ association of ipsilateral eye and contralateral ex­ come a household phrase of those involved in the tremity signs and symptoms, it should be recognized diagnosis and care of patients with carotid disease. that their actual temporal association is unnecessary The clinical picture of amaurosis fugax is reasonably diagnostically and infrequent clinically. The eye straightforward. It consists of transient monocular symptoms and signs in isolation as evidence of painless visual loss. Much has been made of the cervical internal carotid disease are, in all likelihood, character, duration, mode of onset, and resolution far more common than many practitioners realize. of the visual loss. Perhaps too much emphasis has The work of Lubow and associates at Ohio State been placed on such characteristic patterns as the regarding "retinal strokes" underlines this concept. window shade or picket fence effect. As a result, On rare occasions, transient homonymous visual we find that many patients we see have already been impairment may be a reflection of internal carotid "well educated" by housestaff. The potential patterns disease by virtue of a carotid origin of the posterior of visual loss are many. They include 1) an upper cerebral artery. Correct diagnosis will depend upon altitudinal loss of vision, "the window shade"; 2) a associated symptoms and signs. lower altitudinal loss of vision, "the picket fence"; The precise pathophysiology of these brief 3) a generalized peripheral loss of vision; 4) a total alterations of visual function continues to excite blackout of vision; and 5) a central blurring of some debate. It seems certain that most are based vision. The onset is most frequently abrupt; the upon emboli of either platelet aggregates or athero­ curtain seldom drops or rises slowly. Occasionally, sclerotic debris. The exact point at which the em­ the event is associated with photopsia-crude visual bolus works its evil is less certain. As will be hallucinations, usually in the form of showers or discussed, visible emboli in central retinal arterioles flecks of light but suggestions of geometric character must play a role; whether they are the sole inciting will sometimes be seen. The key factors differentiat­ force is less certain. Emboli to the choroid, not ing this photopsia from occipital disease and mi­ apparent clinically, may be important. The role of graine are its clear unilaterality, the patient's age, dynamic reduction of blood flow in the production and a detailed analysis of the history, which excludes of visual symptoms of carotid disease is probably migraine as a consideration and supports amaurosis small. It does, however, in selected but infrequent fugax. The event need not be simply a blackout; instances, probably play a significant role. Total dimming with a sensation of color may occur with carotid occlusions obviously cause some transient green and yellow having popularity. In my experi­ visual symptoms; generally, the symptoms cease ences, color sensation has been uncommon. following the stabilization occurring postocclusiori. The duration is generally brief, lasting two Our diagnostic evaluation of patients with or three minutes, or rarely, five-to-ten minutes. We symptoms of transient visual loss consists of the have found a common tendency for patients to careful analysis and integration of the specific physi­ misjudge the time sequence with frequent exaggera­ cal signs with the presenting and elicited symptoms. tion of the period of visual loss. As this tendency Although we have defined amaurosis fugax as to misjudge the duration of visual handicap may transient painless monocular visual loss, occasionally, be bothersome diagnostically, we have adopted a residual deficits of vision remain. In addition, a simple time confirmation method. It consists of number of patients with cervical internal carotid instructing the patient that you are going to begin to disease present not with transient ipsilateral eye count and he is to assume that this is the onset symptoms but with fixed deficits. of his visual symptomatology. We encourage the Needless to say, the diagnostic evaluation of patient to "relive" the experience and with the use all patients with eye symptoms and signs suggesting of our verbal clock, determine the average duration ipsilateral carotid disease must begin with docu­ of visual loss. The rule is to find a duration of from mentation of visual function-this includes best 116 HARBISON: NEURO-OPHTHALMOLOGY OF CEREBROVASCULAR DISEASE corrected visual acuity, pupillary reactivity, and tery. Ophthalmodynamometry plays a definite, quantitative visual field evaluation. Although we though limited, role in the diagnosis of atheroscle­ palpate neck vessels, much less than total absence rotic cervical internal carotid disease. With the value of vessel pulsation is lightly regarded. Auscultation of ODM's in perspective, we continue to use them is considered an important adjunct, with realiza­ routinely. tion that bruits at sites other than the suspected A discussion of amaurosis fugax is not com­ symptomatic area may be significant.