Jpgm_jan_mar_06_new.pmd

Transient global amnesia followingcoronary angiography Sir, Transient global amnesia (TGA) is a memory disorder, which is characterized by an episode of amnesia and bewilderment lasting for several hours. A few cases have been reported in literature following coronary angiography. In this paper, we present the findings of a case and briefly discuss the various etiologies which are responsible for TGA. A 32-year-old man was admitted for coronary angiography, having experienced an acute anteroseptal myocardial infarc­tion 3 days earlier. He had a history of diabetes mellitus and was on regular treatment with oral glipizide. He was also re­ceiving atenolol, aspirin, and sorbitrate. There was no past or family history of transient ischemic attack, epilepsy, migraine, or stroke. Physical examination was unremarkable. The elec­trocardiogram showed a qs pattern in the anteroseptal leads. His left ventricular ejection fraction was 35% on the echocardiogram. He complained of class III angina (Canadian classification) for which coronary angiography was performed. No sedation was used and 15cc of 1% lignocaine was infiltrated in the groin. The left ventriculogram was not performed. His blood pressure and arterial oxygen saturation was 170/90 mmHg and 95%, respectively, and his blood glucose was 153 mg/dl. The coronary angiogram revealed a recanalized left anterior descending artery and the other arteries were normal. A total of approximately 30 ml of omnipaque [Iohexol 350 mg iodine per ml] was used. As the artery had recanalized, no angioplasty was performed. Three hours later, the patient complained of headache and started retching. He was talking irrelevantly and enquiring about his whereabouts. He had total disorientation in space and time. A neurology opinion was sought which did not re­veal any clinical focal deficit. A CT scan of the brain done immediately (without contrast injection) was normal. Nine hours later the patient's orientation was normal, however, he had retrograde amnesia. He had no recollection about the pro­cedure he had undergone. Electroencephalogram done on the next day was normal. His blood sugar during the episode was 172 mg/dl. He was discharged on the third day without any neurological deficit. TGA is the name applied by Fisher to a particular type of memory disorder, which is characterized by amnesia and memory disorder lasting for several hours.[1] Transient dysfunction of the medial temporal lobe and the J Postgrad Med March 2006 Vol 52 Issue 1 hippocampus may be responsible for the TGA.[2] This may be caused by direct toxic effect of the contrast medium or by slug­gish flow in the cerebral circulation. The sluggish flow may be caused by platelet dysfunction owing to emotional stress of angiography and the contrast agent. The emotional stress of coronary angiography releases epinephrine which causes acti­vation of platelets which slows the cerebral circulation. Thus, some TGA attacks may involve emotional reaction as an un­derlying pathophysiological mechanism.[3] It is also known that omnipaque, which was used, has less in­herent anticoagulant property than the ionic agents.[4] This may be responsible for the sluggish flow in the cerebral circu­lation and dysfunction of the medial temporal lobe causing TGA. TGA is a dramatic event which occurs without warning. It is necessary for the cardiologist to recognize TGA as a dramatic complication of coronary angiography, but one which is tran­sient and completely reversible. Udyavar AR, D'souza RC,
Gadkar N, Rajani RM
Department of Cardiology, P. D. Hinduja National Hospital & Medical Research Centre, Veer Savarkar Marg, Mahim, Fisher CM. Transient global amnesia. Precipitating activities & other observa­tions. Arch Neurol 1982;39:605-8. Tong DC, Grossman M. What causes transient global amnesia? New insights from DWI. Neurology 2004;62:2154-5. Hirabayashi H, Shimizu M, Kohara S, Shinohara Y. Activated platelets in tran­sient global amnesia & TIA. Neurology 2004;63:736-8. Stormorken H, Skalpe IO, Testart MC. Effect of various contrast media on coagulation, fibrinolysis and platelet function: An in vitro and in vivo study. Invest Radiol 1986;21:348-54.

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