NMS Q&A Family Medicine

58 NMS Q&A Family MedicineExamination Answers1. The answer is E. The one choice among the five givenas an exclusion criterion for cerebral thrombolysis is amajor surgical operation within 14 days of the onset ofthe stroke. The list of exclusion criteria includes no previousstroke within 3 months, small stroke in terms of neurologicalsigns, recent major surgery (2 weeks), SBP 185/110, blood sugar 50 mg/dL. Given the stringentcriteria, only 4% to 5% will qualify. The procedure resultsin a 30% decrease in disability at the 3 months point andno change in mortality at 1 year. Negative sequelae ofthrombolysis to reverse stroke include a 10% increase insymptomatic intracerebral hemorrhage as complication.2. The answer is E. Regarding the TIA described in thisvignette, a carotid duplex scan is indicated. The chances of astroke in a TIA by the newest definition (neurological symptomsthat last less than 1 hour) is 15% within 3 months, thegreatest risk being within 48 hours. By the older definition,if neurological symptoms resolve in less than 24hours , 50% will manifest infarction on MRI, and if symptomspersist for more than 1 hour, only 14% will recovercompletely. Thus, this distinction is significant; the olderdefinition appears to overlook a strong possibility of completedstroke, albeit with minimal or no clinical evidence.Anticoagulation therapy, begun in timely fashion andafter appropriate study, reduces the chances of stroke afterTIA by the new definition (15% as stated) will be reducedby 80%. However, anticoagulation should not proceeduntil after a CT or MRI scan has ruAled out hemorrhagicstroke or certain other conditions been ruled out. Involvementof the upper extremity indicates middle cerebralartery pathology, as does involvement of the face. Anteriorcerebral artery occlusion or TIA tends to result inneurological symptoms in the legs.3. The answer is B. Testing for protein S should beaccomplished but not until two months after the strokeonset. In fact, due to the suppression of clotting factorsthat occurs during the acute phase after stroke, proteins Cand S as well as antithrombin III and the presence of prothrombingene mutation, all of which are relevant forstudy in the presence of cerebrovascular disease, shouldawait testing until 2 months have passed after the incidenceof stroke.4. The answer is B. Protonix (pantoprozole), protonpump inhibitor, reduces the effectiveness of clopidogrel.Apparently this is not true of other PPIs. NSAIDs such asibuprofen and naproxen multiply the antiplatelet effectsand can lead to bleeding problems when taken at the sametime as clopidogrel and other antiplatelet preparations.Warfarin anticoagulation therapy is a contraindication toantiplatelet drugs because of enhancing the danger ofhemorrhage.5. The answer is E. Hypertension is the most prevalent ofmodifiable risk factors for stroke, as it is present in 25% to40% of patients who have suffered stroke and confers arelative risk (RR) of three to five times the risk of stroke inthe population at large. The second most prevalent riskfactor in stroke patients is hypercholesterolemia, whichoccurs in 6% to 40% and confers a RR of 1.8 to 2.6.6. The answer is C. Smoking cessation is the most powerfultool in secondary stroke reduction (33% RR reduction).Aspirin antiplatelet aggregation therapy is moreeffective than the more expensive thienopyridine class ofdrugs, which are designed also as antiplatelet therapy(28% reduction in RR vs. 13%). Antihypertensive therapyis the most powerful modality in risk reduction for primaryprevention of stroke (42%). However, it reduces RRby 28% in secondary prevention, similar to aspirin therapy.Statin therapy for hypercholesterolemia (and necessarilyfor the subgroups of dyslipidemia, i.e., elevatedLDL-C and inadequate levels of HDL-C) reduces RR onan average of 25%. Warfarin therapy, although the strongesttool in secondary prevention of thromboembolicstroke caused by atrial fibrillation (66% secondary strokeRR reduction), is less effective than aspirin for thrombotic–ischemicstroke. Another special circumstance is thatof secondary prevention of cerebrovascular disease after aTIA in a patient with moderate or severe carotid arterystenosis. Preemptive carotid endarterectomy reduces RRfor recurrent stroke by 44% to 50% according to theAmerican Carotid Artery study. Although it is useful toknow the rank order of risk factors and of treatmentthereof, it goes without saying that all known risk factorsshould be aggressively addressed in secondary preventionof stroke.7. The answer is C. When all risk and demographic categoriesare thrown together, the overall risk of stroke inuntreated nonvalvular atrial fibrillation is 5% per year.When the categories are broken down, patients youngerthan 65 years without risk factors (“low risk”) have a 1%chance of stroke per year; those 65 to 75 years (“low moderaterisk”), 1.5% per year; those 65 to 75 years who havediabetes or diagnosed coronary artery disease (“highmoderate risk”), 2.5% per year; those of any age youngerthan 75 years with hypertension or left ventricular dysfunctionbut no other risk factors (“high risk”), 6% peryear; and, finally, those 75 years with hypertension, left