A transient ischemic attack (TIA) is a medical emergency. It is defined as a transient episode of neurologic dysfunction due to the focal brain, spinal cord, or retinal ischemia, without acute infarction or tissue injury. The definition of a TIA has moved from time-based to tissue-based. A TIA typically lasts less than an hour, more often minutes. TIA can be considered as a serious warning for an impending ischemic stroke; the risk is highest in the first 48 hours following a transient ischemic attack. Differentiating transient ischemic attack from other mimicking conditions is important. Transient ischemic attacks are usually associated with a focal neurologic deficit and/or speech disturbance in a vascular territory due to underlying cerebrovascular disease. It is always sudden in onset. Evaluation of TIA should be done urgently with imaging and laboratory studies to decrease the risk of subsequent strokes. The subsequent risk of TIA or ischemic stroke can be stratified with a simple clinical measure. Immediate multimodality therapeutic interventions should be initiated. These will include aggressive treatment of blood pressure, high dose statin, antiplatelet therapy, blood sugar control, diet, and exercises. Specific underlying etiology needs to be managed accordingly. This treatment scheme may substantially reduce the risk of recurrent strokes or future TIA by at least 80%.
TIA subtypes, classified according to the pathophysiological mechanisms are similar to ischemic stroke subtypes. They include large artery atherothrombosis, cardiac embolism, small vessel (lacunar), cryptogenic, and uncommon subtypes such as vascular dissection, vasculitis, etc. The common risk factors for all TIA include diabetes, hypertension, age, smoking, obesity, alcoholism, unhealthy diet, psychosocial stress, and lack of regular physical activity. A previous history of stroke or TIA will increase substantially the subsequent risk of recurrent stroke or TIA. Among all risk factors, hypertension is the most important one for an individual as well as in a population.
TIA incidence in a population is difficult to estimate due to other mimicking disorders, but TIA incidence in the United States could be around half a million per year, and estimates are about 1.1 per 1000 in the United States population. The estimated overall prevalence of TIA among adults in the United States is approximately 2%. It has been shown that previous stroke history increases the prevalence of TIA. Few studies have shown that the majority of people who presented with initial stroke had prior TIA symptoms.
The pathophysiology of TIA depends on the subtype as follows. The common issue is the transient interruption of arterial blood flow to an area of the brain supplied by that particular artery.
TIA symptoms have often resolved by the time the patients presented to her doctor or emergency department. The history of present illness should include onset, duration, timing, complete neurological symptoms, associated symptoms, and any aggravating or relieving factors. The clinician should also try to identify the associated risk factors such as coronary artery disease, smoking, drug abuse, obesity, diabetes mellitus, dyslipidemia, and hypertension, as well as personal or family history of hypercoagulability disorders, stroke, or TIA. The history should include etiological clues such as a history of atrial fibrillation, recent myocardial infarction to suggest a cardioembolic source, transient loss of vision like a curtain rising or descending will suggest an internal carotid artery problem. The presence of any cortical symptoms such as language disturbance or visual field loss will point to a cortical TIA rather than a lacunar syndrome.
Physical examination should focus on identifying focal neurological deficits and speech disturbances which are the most common presenting symptoms in patients with TIA. Cranial nerve examination can yield findings of monocular blindness, disconjugate gaze, facial droop, hemianopia, diplopia, abnormal tongue movement, difficulty swallowing, and auditory dysfunction. Some of the motor findings include unilateral weakness in the upper or lower extremities, face, and tongue, increased tone, clonus, rigidity and also abnormal reflexes that could occur with TIA. Cardiac examination and carotid auscultation for a carotid bruit are very important. Fundoscopy is important to look for any fundoscopic evidence of vascular changes as a result of hypertension or diabetes. It may also show a Hollenhurst plague which will indicate an underlying internal carotid artery disease.
The goals of evaluation of TIA are
The 2009 AHA/ASA guidelines include "neuroimaging within 24 hours of symptom onset and further recommend MRI and diffusion-weighted MR imaging as preferred modalities." A head CT preferably with a CT angiogram is recommended if an MRI cannot be performed. Brain MRI with diffusion-weighted imaging has a greater sensitivity than CT for detecting small infarcts in patients with TIA. The practitioner should assess the patient's cervicocephalic vasculature for atherosclerotic lesions using carotid ultrasonography/transcranial Doppler ultrasonography, magnetic resonance angiography, or CT angiography. These lesions are treatable. In candidates for carotid endarterectomy, carotid imaging should be performed within 1 week of the onset of symptoms. Cardiac assessment should be done with ECG, Echocardiogram/TEE to find a cardioembolic source and the presence of patent foramen ovale, valvular disease, cardiac thrombus, and atherosclerosis. Holter monitor or more prolonged cardiac rhythm monitor in the outpatient setting is reasonable for patients with cortical infarct without any clear source of emboli, primarily to evaluate for paroxysmal atrial fibrillation. Routine blood tests including complete blood count (CBC), PT/INR, CMP, FBS, lipid panel, urine drug screen, and ESR should be considered..
National Stroke Association has established guidelines for TIA evaluation as follows in 2006:
CBC = complete blood count
CEA = carotid endarterectomy
TCD = transcranial Doppler
TEE = transesophageal echocardiogram
TTE = transthoracic echocardiogram
The ABCD2 score is very important for predicting subsequent risks of TIA or stroke. The ABCD2 score was derived from providing a more robust prediction standard. The ABCD2 score includes factors including age, blood pressure, clinical symptoms, duration, and diabetes.
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. Most stroke centers will admit patients with TIA to the hospital for expedited management and observation if the score is 4 or 5 or higher. For those patients who have a lower score, expedited evaluation and management is still warranted. This expedited approach has been proven to improve the outcome. 
The main aim of treatment of TIA is to decrease the risk of subsequent stroke or TIA. Early treatment after a TIA can significantly reduce the risk of early stroke. Post TIA, the risk of stroke within 3 months has been reported to be around 20%, with approximately 50% of these strokes occurring within the first 2 days after the initial presentation. It is extremely important to evaluate the vessel status and look for atrial fibrillation when a patient comes with TIA. This will significantly reduce future strokes. Management of TIAs should focus on treating underlying etiologies.
Studies in the new millennium already confirmed the importance of expedited evaluation and treatment plus the polytherapy approach. The EXPRESS study in the UK has shown the importance of early intervention versus regular treatment by reducing 80% of the stroke risk.  Hackam et al did a meta-analysis in 2007 showing that combination of diet, exercise, antiplatelet, statin and antihypertensive therapy may reduce the subsequent stroke by 80-90%.
More recent studies in China (CHANCE trial) and the multinational POINTE trail also confirmed dual antiplatelet with aspirin and clopidogrel for 3 weeks to 1 month followed by a single antiplatelet agent is the best scheme for antiplatelet therapy. 
The other part of the treatment will depend on the underlying etiology of the TIA. Revascularization is recommended for symptomatic cervical internal carotid artery stenosis of 70% or higher. Carotid endarterectomy may have a slight benefit to risk ratio compared with endovascular intervention and stenting. Whether to operate on patients with 50-69% stenosis will depend more on the surgeon's complication rates given the vast improvement in the efficacy of aggressive medical therapy. SAPPRIS trial showed that endovascular Wingspan stenting of intracranial major arterial stenosis of 70-99% stenosis is not better than aggressive medical therapy alone. 
Oral anticoagulation is indicated for patients with atrial fibrillation or other sources of cardioembolic sources of TIA.
Risk Stratification Scores
To help physicians manage patients with a TIA, several risk stratification scores have been developed. One widely used score is the ABCD2 score:
A= Age more than 60 years / Score 1
B= SBP> 140 or DBP> 90 / Score 1
C= Clinical features:
Speech impairment without weakness / Score 1
Weakness with/without speech impairment / Score 2
More than 60 mins / Score 2
Between 10-59 mins / Score 1
D= Diabetes / Score 1
Patients with an ABCD2 score of 6-7 have an 8% risk of stroke within 48 hours
Patients with an ABCD2 score of less than 4 have a 1% risk of stroke within 48 hours
Even though scales are important in the evaluation of TIA, be aware that patients with critical carotid artery stenosis may some times present with a very low ABCD2 score.
Differentiating other potential causes that mimic TIA is important since diagnosing and treating TIA early can potentially help in preventing a future stroke. Differential diagnosis of TIA includes but is not limited to vertigo, dizziness, seizures, headaches, bells palsy, drug withdrawal, dementia, electrolyte disorders, acute infections, syncope, and alcoholism.
Patients with a TIA often present to the emergency department or the primary caregiver. Because there is a real risk of a severe stroke, it is important that these patients are managed with an interprofessional team of healthcare workers. The triage nurse must be familiar with the symptoms of a TIA and when to call the neurologist. The early risk of stroke varies from 4-9% within 90 days and without treatment, the risk of a stroke within five years varies from 20-30%. At the same time, these patients also have the same risk factors for adverse cardiac events. Once a TIA has been diagnosed, the patient must be referred to a neurologist. At the same time, the patient should be educated about the importance of blood pressure control, discontinuing smoking and eating a healthy diet. Finally, the patient should be educated about the symptoms of a stroke and when to seek immediate medical assistance. (Level V)
|||Gennai S,Giordano-Orsini G,Lefour S,Cuisenier P, [Transient Ischemic Attack: Limits and challenges of early management]. Presse medicale (Paris, France : 1983). 2018 Oct 18 [PubMed PMID: 30343830]|
|||Yousufuddin M,Young N,Shultz J,Doyle T,Fuerstenberg KM,Jensen K,Arumaithurai K,Murad MH, Predictors of Recurrent Hospitalizations and the Importance of These Hospitalizations for Subsequent Mortality After Incident Transient Ischemic Attack. Journal of stroke and cerebrovascular diseases : the official journal of National Stroke Association. 2018 Oct 16 [PubMed PMID: 30340936]|
|||Kim J,Thrift AG, A Promising Skills-Based Intervention to Reduce Blood Pressure in Individuals With Stroke and Transient Ischemic Attack. JAMA neurology. 2018 Oct 8 [PubMed PMID: 30304354]|
|||Navis A,Garcia-Santibanez R,Skliut M, Epidemiology and Outcomes of Ischemic Stroke and Transient Ischemic Attack in the Adult and Geriatric Population. Journal of stroke and cerebrovascular diseases : the official journal of National Stroke Association. 2018 Oct 6 [PubMed PMID: 30297169]|
|||Cereda CW,Olivot JM, Emergency Department (ED) Triage for Transient Ischemic Attack (TIA). Current atherosclerosis reports. 2018 Sep 25 [PubMed PMID: 30251027]|
|||Liu L,Ding J,Leng X,Pu Y,Huang LA,Xu A,Wong KSL,Wang X,Wang Y, Guidelines for evaluation and management of cerebral collateral circulation in ischaemic stroke 2017. Stroke and vascular neurology. 2018 Sep [PubMed PMID: 30294467]|
|||Bibok MB,Votova K,Balshaw RF,Penn M,Lesperance ML,Harris DR,Sedgwick C,Nealis M,Farrell B,Mathieson JR,Penn AM, Retrospective evaluation of a clinical decision support tool for effective computed tomography angiography utilization in urgent brain imaging of suspected TIA/minor stroke in the emergency department. CJEM. 2018 Oct 2 [PubMed PMID: 30277176]|
|||Johnston SC,Nguyen-Huynh MN,Schwarz ME,Fuller K,Williams CE,Josephson SA,Hankey GJ,Hart RG,Levine SR,Biller J,Brown RD Jr,Sacco RL,Kappelle LJ,Koudstaal PJ,Bogousslavsky J,Caplan LR,van Gijn J,Algra A,Rothwell PM,Adams HP,Albers GW, National Stroke Association guidelines for the management of transient ischemic attacks. Annals of neurology. 2006 Sep; [PubMed PMID: 16912978]|
|||Cutting S,Regan E,Lee VH,Prabhakaran S, High ABCD2 Scores and In-Hospital Interventions following Transient Ischemic Attack. Cerebrovascular diseases extra. 2016; [PubMed PMID: 27721312]|
|||Bath PM,Woodhouse LJ,Appleton JP,Beridze M,Christensen H,Dineen RA,Flaherty K,Duley L,England TJ,Havard D,Heptinstall S,James M,Kasonde C,Krishnan K,Markus HS,Montgomery AA,Pocock S,Randall M,Ranta A,Robinson TG,Scutt P,Venables GS,Sprigg N, Triple versus guideline antiplatelet therapy to prevent recurrence after acute ischaemic stroke or transient ischaemic attack: the TARDIS RCT. Health technology assessment (Winchester, England). 2018 Aug [PubMed PMID: 30179153]|
|||Boulanger JM,Lindsay MP,Gubitz G,Smith EE,Stotts G,Foley N,Bhogal S,Boyle K,Braun L,Goddard T,Heran M,Kanya-Forster N,Lang E,Lavoie P,McClelland M,O'Kelly C,Pageau P,Pettersen J,Purvis H,Shamy M,Tampieri D,vanAdel B,Verbeek R,Blacquiere D,Casaubon L,Ferguson D,Hegedus Y,Jacquin GJ,Kelly M,Kamal N,Linkewich B,Lum C,Mann B,Milot G,Newcommon N,Poirier P,Simpkin W,Snieder E,Trivedi A,Whelan R,Eustace M,Smitko E,Butcher K, Canadian Stroke Best Practice Recommendations for Acute Stroke Management: Prehospital, Emergency Department, and Acute Inpatient Stroke Care, 6th Edition, Update 2018. International journal of stroke : official journal of the International Stroke Society. 2018 Jan 1 [PubMed PMID: 30021503]|
|||Ranta A,Dovey S,Gommans J,Tilyard M,Weatherall M, Impact of General Practitioner Transient Ischemic Attack Training on 90-Day Stroke Outcomes: Secondary Analysis of a Cluster Randomized Controlled Trial. Journal of stroke and cerebrovascular diseases : the official journal of National Stroke Association. 2018 Jul [PubMed PMID: 29610038]|
|||Rothwell PM,Giles MF,Chandratheva A,Marquardt L,Geraghty O,Redgrave JN,Lovelock CE,Binney LE,Bull LM,Cuthbertson FC,Welch SJ,Bosch S,Alexander FC,Silver LE,Gutnikov SA,Mehta Z, Effect of urgent treatment of transient ischaemic attack and minor stroke on early recurrent stroke (EXPRESS study): a prospective population-based sequential comparison. Lancet (London, England). 2007 Oct 20; [PubMed PMID: 17928046]|
|||Hackam DG,Spence JD, Combining multiple approaches for the secondary prevention of vascular events after stroke: a quantitative modeling study. Stroke. 2007 Jun; [PubMed PMID: 17431209]|
|||Wang Y,Johnston SC,Wang Y, Clopidogrel with aspirin in minor stroke or transient ischemic attack. The New England journal of medicine. 2013 Oct 3; [PubMed PMID: 24088101]|
|||Johnston SC,Easton JD,Farrant M,Barsan W,Conwit RA,Elm JJ,Kim AS,Lindblad AS,Palesch YY, Clopidogrel and Aspirin in Acute Ischemic Stroke and High-Risk TIA. The New England journal of medicine. 2018 Jul 19; [PubMed PMID: 29766750]|
|||Chimowitz MI,Lynn MJ,Derdeyn CP,Turan TN,Fiorella D,Lane BF,Janis LS,Lutsep HL,Barnwell SL,Waters MF,Hoh BL,Hourihane JM,Levy EI,Alexandrov AV,Harrigan MR,Chiu D,Klucznik RP,Clark JM,McDougall CG,Johnson MD,Pride GL Jr,Torbey MT,Zaidat OO,Rumboldt Z,Cloft HJ, Stenting versus aggressive medical therapy for intracranial arterial stenosis. The New England journal of medicine. 2011 Sep 15; [PubMed PMID: 21899409]|
|||Clare CS, Role of the nurse in stroke rehabilitation. Nursing standard (Royal College of Nursing (Great Britain) : 1987). 2018 Oct 1 [PubMed PMID: 30132306]|
|||Basaraba JE,Picard M,George-Phillips K,Mysak T, Pharmacists as Care Providers for Stroke Patients: A Systematic Review. The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques. 2018 Jan [PubMed PMID: 28929979]|