Risk Stratification
Several studies have identified risk factors for stroke after TIA, which may be useful in making initial management decisions. Three very similar formal prediction rules have been developed and cross-validated in northern California and Oxfordshire. The California score and the ABCD score both predict short-term risk of stroke well in independent populations of patients presenting acutely after a TIA. The newer ABCD² score was derived to provide a more robust prediction standard and incorporates elements from both prior scores. Patients with TIA score points (indicated in parentheses) for each of the following factors: age ≥60 years (1); blood pressure ≥140/90 mm Hg on first evaluation (1); clinical symptoms of focal weakness with the spell (2) or speech impairment without weakness (1); duration ≥60 minutes (2) or 10 to 59 minutes (1); and diabetes (1). In combined validation cohorts, the 2-day risk of stroke was 0% for scores of 0 or 1, 1.3% for 2 or 3, 4.1% for 4 or 5, and 8.1% for 6 or 7.

These prediction rules do not incorporate imaging findings, which have been shown to have prognostic value. The presence of a new infarct on brain imaging, which was consistent with the classic definition of TIA but would now lead to a diagnosis of stroke, is associated with an {approx}2- to 15-fold increase in subsequent short-term risk of stroke. Evidence of vessel occlusion on acute brain MRA also has been associated with a 4-fold increased short-term risk of stroke. MRI changes have been associated with the clinical factors identified in prior prediction rules, so it is unclear how much they will add to validated prediction rules such as ABCD.

Hospitalization

Hospitalization rates after TIA vary widely among practitioners, hospitals, and regions. A study from the National Hospital Ambulatory Medical Care Survey found that 54% of patients with TIA were admitted to the hospital, with rates varying from 68% in the northwest United States to 41% in the west.

Close observation during hospitalization has the potential to allow more rapid and frequent administration of tissue plasminogen activator should a stroke occur. A cost-utility analysis demonstrated that hospitalization was cost-effective for patients with 24-hour risk of stroke >4% solely on this basis. Prospective studies are required on the efficacy and safety of the use of tissue plasminogen activator in patients with recent prior clinical symptoms lasting < 24 hours associated with small DWI lesions. In the past, these patients were diagnosed as having TIA, which did not contraindicate lytic therapy. Now, these patients will be classified as minor cerebral infarction patients. However, it is likely that the risk of bleeding with lytic therapy is much lower in these patients than in patients with large recent prior cerebral infarcts. Hospitalization may have other benefits as well. It permits cardiac monitoring and facilitates rapid diagnostic evaluation. Rates of adherence to secondary prevention interventions may also be greater after hospitalization. No randomized trial has evaluated the benefit of hospitalization or the utility of the ABCD² score in assisting with triage decisions.

References
1. Albers GW, Caplan LR, Easton JD, Fayad PB, Mohr JP, Saver JL, Sherman DG, for the TIA Working Group. Transient ischemic attack: proposal for a new definition. N Engl J Med.  2002; 347: 1713–1716.

2. Albucher JF, Martel P, Mas JL. Clinical practice guidelines: diagnosis and immediate management of transient ischemic attacks in adults. Cerebrovasc Dis. 2005; 20: 220–225.

3. Adams HP Jr, del Zoppo G, Alberts MJ, Bhatt DL, Brass L, Furlan A, Grubb RL, Higashida RT, Jauch EC, Kidwell C, Lyden PD, Morgenstern LB, Qureshi AI, Rosenwasser RH, Scott PA, Wijdicks EF. Guidelines for the early management of adults with ischemic stroke: a guideline from the American Heart Association/American Stroke Association Stroke Council, Clinical Cardiology Council, Cardiovascular Radiology and Intervention Council, and the Atherosclerotic Peripheral Vascular Disease and Quality of Care Outcomes in Research Interdisciplinary Working Groups: the American Academy of Neurology affirms the value of this guideline as an educational tool for neurologists. Stroke. 2007; 38: 1655–1711.

4. Johnston SC. Clinical practice: transient ischemic attack. N Engl J Med. 2002; 347: 1687–1692.

5. Johnston SC, Fayad PB, Gorelick PB, Hanley DF, Shwayder P, van Husen D, Weiskopf T. Prevalence and knowledge of transient ischemic attack among US adults. Neurology. 2003; 60: 1429–1434.

6. Edlow JA, Kim S, Pelletier AJ, Camargo CA Jr. National study on emergency department visits for transient ischemic attack, 1992–2001. Acad Emerg Med. 2006; 13: 666–672.

7. Kleindorfer D, Panagos P, Pancioli A, Khoury J, Kissela B, Woo D, Schneider A, Alwell K, Jauch E, Miller R, Moomaw C, Shukla R, Broderick JP. Incidence and short-term prognosis of transient ischemic attack in a population-based study. Stroke. 2005; 36: 720–723.

8. Correia M, Silva MR, Magalhaes R, Guimaraes L, Silva MC. Transient ischemic attacks in rural and urban northern Portugal: incidence and short-term prognosis. Stroke. 2006; 37: 50–55.

9. Rothwell PM, Coull AJ, Giles MF, Howard SC, Silver LE, Bull LM, Gutnikov SA, Edwards P, Mant D, Sackley CM, Farmer A, Sandercock PA, Dennis MS, Warlow CP, Bamford JM, Anslow P, for the Oxford Vascular Study. Change in stroke incidence, mortality, case-fatality, severity, and risk factors in Oxfordshire, UK from 1981 to 2004 (Oxford Vascular Study). Lancet. 2004; 363: 1925–1933.

A Scientific Statement for Healthcare Professionals From the American Heart Association/American Stroke Association Stroke Council; Council on Cardiovascular Surgery and Anesthesia; Council on Cardiovascular Radiology and Intervention; Council on Cardiovascular Nursing; and the Interdisciplinary Council on Peripheral Vascular Disease: The American Academy of Neurology affirms the value of this statement as an educational tool for neurologists.

J. Donald Easton, MD, FAHA, Chair; Jeffrey L. Saver, MD, FAHA, Vice-Chair; Gregory W. Albers, MD; Mark J. Alberts, MD, FAHA; Seemant Chaturvedi, MD, FAHA, FAAN; Edward Feldmann, MD, FAHA; Thomas S. Hatsukami, MD; Randall T. Higashida, MD, FAHA; S. Claiborne Johnston, MD, PhD; Chelsea S. Kidwell, MD, FAHA; Helmi L. Lutsep, MD; Elaine Miller, DNS, RN, CRRN, FAHA Ralph L. Sacco, MD, MS, FAAN, FAHA