Difference Between Cortical Blindness And Blind Sight Book

Difference between cortical blindness and blind sight book

In this study, we present a case of abrupt cortical blindness after exposure to contrast media during diagnostic coronary angiography; to our knowledge, this is the 1st report in the medical literature that describes transient cortical blindness after iobitridol use. Transient cortical blindness is an infrequent complication of cerebral and vertebral angiography, with occurrence rates of 0.

This, to our knowledge, is the 1st such report in the literature.

Difference between cortical blindness and blind sight book

In January , a year-old woman who had angina on exertion was admitted to our clinic for coronary angiography. She had a history of hypertension of 20 years' duration, of diabetes mellitus, and of hypercholesterolemia. Selective angiography of her native coronary arteries and a left ventriculogram were completed without difficulty by use of the Judkins technique from the right femoral artery. The procedure was performed without complications.

Transient Cortical Blindness after Cardiac Catheterization with Iobitridol

Two hours later, the patient experienced visual loss, headache, and confusion, with retrograde amnesia and disorientation. Neurologic findings were normal: extraocular movements were preserved and pupillary reflex was normal.

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Ophthalmic examination of the fundi also yielded normal results; however, bilateral cortical blindness was diagnosed. A cranial computed tomographic CT scan was performed 3 hours after coronary angiography.

Difference between cortical blindness and blind sight book

No additional contrast material was used during the procedure. The CT scan showed marked bilateral contrast enhancement in the occipital lobes and no evidence of cerebral hemorrhage Fig.

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The patient remained confused and amnesic for 24 hours after visual loss. Then her vision gradually improved, progressing to complete recovery within 72 hours. Cranial CT scanning—repeated at 36 hours after visual loss—showed clearing of the contrast media Fig. She was discharged 4 days after admission with no residual blindness or neurologic deficit.

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Subsequently, the patient was well at her 6-month and 1-year visits. There is no contrast enhancement in the cranium. The accumulation of contrast media shows no relationship to avascularity, which argues against an embolic event as the pathogenesis. The mechanism of cerebral injury that causes cortical blindness remains speculative. Some previous studies 3 have suggested that cortical blindness may be related to contrast-induced hypotension during the angiographic procedure, to the presence of hypertensive vascular disease, or to the osmolality and total amount of contrast material injected.

Hinchey and colleagues 8 have suggested that there might be a relationship between cortical blindness and hypertensive encephalopathy—a clinical syndrome that can include visual disturbances.

Difference between cortical blindness and blind sight book

Our patient had a long history of hypertension and had a documented acute rise in blood pressure after the procedure. Most of the patients in previous reports also had chronic hypertension, although the details of pressure changes during angiography have not usually been reported.

What is Cortical Blindness: Types, Causes, Symptoms,Treatment, Prevention, Diagnosis

Hypertensive encephalopathy is thought to result from sudden elevation of systemic blood pressure that exceeds the autoregulatory capacity of the cerebral vessels, thereby producing regions of vasodilation and vasoconstriction, with a breakdown of the blood—brain barrier and focal transudation of fluid.

Reversible edema, localized mainly in the occipital lobes, is a prominent feature. Edema secondary to disturbance of autoregulation of the posterior cerebral vessels is another possible mechanism for transient cortical blindness. Experimentally, the blood—brain barrier can be disrupted with the introduction of hyperosmolar solutions into the spinal cord or blood.

Whether disruption is causally related to the hypertonicity of the contrast agent or to the volume of the dose is not yet clear. Various investigators 1—7 have reported using from 80 to mL of contrast agent we used only 75 mL.

Difference between cortical blindness and blind sight book

Although non-ionic agents are less toxic than their ionic counterparts, several cases of transient cortical blindness have now been reported with use of these low-osmolality agents. Most of the patients in whom transient cortical blindness has been reported have undergone angiography of bypass grafts. It is likely, in these patients, that direct injection into the vertebral artery occurs during angiography of the internal mammary artery conduit. The patients' prolonged supine posture might also play a role in the intracranial enhancement of the contrast solution in the occipital region.

It is known that certain patients are more prone than others to idiosyncratic reactions after contrast injection. Direct idiosyncratic neurotoxicity still appears to be the most reasonable explanation to account for transi ent blindness after coronary angiography, although the exact mechanism is not known.

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There is no specific measure to be taken for protection against this unusual and alarming complication. Prompt neurologic consultation and MRI or CT scanning of the brain are indicated to confirm the diagnosis. Forced diuresis to remove the offending agent has not been shown to be beneficial, but the blood pressure must be controlled.

The cerebral reaction is not patient specific. When the contrast medium has been excreted— which takes an average of 3 days range, 15 minutes to 3 weeks —normal vision returns as the normal protective function of the blood—brain barrier returns. In most cases, the return of vision is gradual, proceeding from light and motion perception to a final return of color vision.

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E-mail: moc. National Center for Biotechnology Information , U. Tex Heart Inst J. Author information Copyright and License information Disclaimer. Department of Cardiology Drs.

This article has been cited by other articles in PMC. Case Report In January , a year-old woman who had angina on exertion was admitted to our clinic for coronary angiography. Open in a separate window.

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Discussion The mechanism of cerebral injury that causes cortical blindness remains speculative. References 1. Horwitz NH, Wener L.

Temporary cortical blindness following angiography.

Blindsight

J Neurosurg ;—6. Cortical blindness after cerebral angiography.

Difference between cortical blindness and blind sight book

Case report. J Neurosurg ;—4.

Case Report

Cortical blindness after coronary angiography: a rare but reversible complication. Cathet Cardiovasc Diagn ;—9. Transient cortical blindness. An unusual complication of coronary angiography. Neurology ;—5. Cortical blindness after left internal mammary artery to left anterior descending coronary artery graft angiography.

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Cortical blindness after cardiac catheterization: effect of rechallenge with dye. Cathet Cardiovasc Diagn ;— Transient bilateral cortical blindness after coronary angiography. Lancet ; A reversible posterior leukoencephalopathy syndrome. N Engl J Med ;— Transient cortical blindness related to coronary angiography and graft study.

Med J Aust ; 43—4. Johansson BB. Hypertension and the blood-brain barrier.

Difference between cortical blindness and blind sight book

In: Neuwelt EA, editor. Implications of the blood-brain barrier and its manipulation. Vol 2. New York: Plenum Press; MRI findings in a case of transient cortical blindness after cardiac catheterization.

What is Cortical Blindness?

Catheter Cardiovasc Interv ;—9. Results of the safety and efficacy of iobitridol in more than 61, patients. Eur Radiol ;— Support Center Support Center. External link. Please review our privacy policy.