Learning Objectives
- A TIA is a loss of neurological function lasting for less than 24 hours
- It is caused by a process identical to that which causes ischemic stroke
- A TIA is not treated, it is prevented by modifying vascular risk factors
History
A 76 year old right handed woman comes to the ER after she has weakness of the right arm. The symptoms started during breakfast, during which she could not pick up a spoon or a cup of coffee. She called her doctor’s office, they asked her to go to the ER. She called 911. When she arrived at the hospital, she thought the symptoms had improved. The duration of the symptoms was 15 minutes. She had no trouble talking and she denied numbness during this time.
She takes no medications and she has no allergies to medications.
She has a past medical history of eczema.
She has a family history of lung cancer (father) and colon cancer (mother). She has no siblings.
She smoked cigarettes for 3 years and she quit 56 years ago. She does not drink alcohol. She is a retired postal clerk.
Review of systems: she denies chest pain or palpitations, she denies coughing, she denies weight changes or fevers, she denies joint pain or rash, she denies trouble with the bowels or the bladder, she denies bruising and bleeding, she denies changes in her vision, trouble sleeping, or mood changes.
Examination
Her temperature is 97.7 F, her blood pressure is 179/94, and her pulse is 78. She is an alert, healthy woman, sitting comfortably on a gurney in the ER. She has normal cardiac and carotid artery sounds. Her orientation and speech are normal. Her pupils are reactive to direct and indirect light. Her eye motions are conjugate and full in all directions. She has normal sensation on both sides of the face. Her smile, forced eye closure and facial grimace are normal. The tongue protrudes straight. The shoulder shrug is normal. There is no weakness in the arms or legs on either side. Deep tendon reflexes are normal. The toes are down going. She has normal sensation on both sides. She has normal finger nose finger movements and she has a normal gait.
Localization and Neuroanatomy
This is a 76 year old with transient weakness in the right arm. There are no exam findings. Right arm weakness localizes to the brain and the brain stem, either in the left motor cortex, the left basal ganglia, or the corticospinal tract within the left cerebrum, midbrain, or anterior pons. Facial weakness symptoms may also occur with lesions in these locations. It is conceivable that carpal tunnel syndrome, apraxia or incoordination was the cause of her symptoms- these would alter the localization. If we take her history at face value, we cannot be confident of these other sites.
Diagnosis
A sudden loss of function in an older person, especially an older person with high blood pressure and a history of smoking, is a vascular disease process until proven otherwise. A TIA, ischemic stroke, or hemorrhagic stroke fit these conditions best. A TIA is a condition that lasts less than 24 hours. Otherwise, it has the same pathophysiology and preventive medicine interventions as an ischemic stroke. Unlike an ischemic stroke, CT and MRI scans of a brain with a TIA are normal.
At times the diagnosis of TIA is applied to symptoms that are otherwise not explained. Dizziness, facial weakness or numbness lasting for seconds, visual disturbances and falling are often diagnosed as TIA. These are soft definitions of TIA, and the causes of these symptoms may be indeterminable. In most cases, TIA lasts for several minutes or hours, not seconds. TIAs rarely cause pain, positive visual symptoms (e.g. sparkles) or tingling, and the symptoms should be consistent with a lesion of the human CNS.
The patient in our case should have a noncontrast CT scan of the head. Although it is not likely that she has had a hemorrhagic stroke, it is important to verify this before any other treatment decisions are made. This is standard protocol for evaluating patients with TIA and stroke.
After the CT scan, it is less urgent to obtain an EKG, echocardiogram, and carotid imaging study to determine if there are lingering causes of these symptoms, such as atrial fibrillation, valvular heart disease, or carotid artery stenosis. A lipid profile and a serum glucose measurement are also helpful.
Treatment
Patients with TIAs recover quickly by definition. Since treatment of a TIA is irrelevant, attention is placed on preventing future attacks. The risk of ischemic stroke 90 days after a TIA is about 10%- whatever therapy can be done to lower this risk is well-deserved. The following interventions should be recommended to all patients with a TIA.
Daily aspirin- aspirin 81 mg taken daily has been shown to be an effective preventer of ischemic stroke and TIA. Unless anticoagulation is indicated, aspirin should be part of the therapy strategy.
Blood pressure therapy- High blood pressure correlates with an increased risk of ischemic stroke and heart disease. When either of these conditions is identified, treatment is indicated to lower the average blood pressure to about 120/80. In the setting of acute stroke symptoms, blood pressure is not treated unless it is safe to do so. This may be decided on a case by case basis.
Lipid-lowering therapy- For most patients, reducing LDL-C to 100 (or in some cases 70) mg/dL or lower prevents future risk of TIA and stroke.
Anticoagulation when appropriate- patients who have atrial fibrillation or flutter will have optimal ischemic stroke prevention with anticoagulation. This should be used in place of aspirin in such cases. Choices for anticoagulation include warfarin, dabigatran and rivaroxaban.
Carotid surgery when appropriate- patients with greater than70% carotid artery stenosis on the symptomatic side are a candidate for either a carotid artery stent or carotid endarterectomy. Although these procedures come with some risk, five-year mortality is lower for patients treated with these interventions than for patients who are treated with medical therapy alone. Patients with severe diseases affecting other organ systems may best be treated medically however.
Blood glucose treatment when appropriate- hyperglycemia correlates with stroke and TIA risk also. Modifying serum glucose peaks and the average burden of glycosylation are appropriate goals in stroke prevention.
Smoking cessation- smoking cessation is beneficial to the prevention of both cerebrovascular and cardiovascular disease.
Dietary changes may be helpful- dietary behavior practices such as the DASH diet (Dietary Approaches to Stop Hypertension) have been shown to prevent stroke independent of other medical interventions.
A long-lasting TIA may appear identical to an ischemic stroke. It is assumed that some TIAs are treated with IV TPA. This is not intended. TIAs should not be treated with TPA. TPA is contraindicated in the setting of a rapidly improving neurological exam.
Review Questions
- By definition, the duration of a TIA is:
a. 30-90 seconds
b. 2-60 minutes to hours
c. less than 24 hours
d. 2 hours to 2 days
e. the symptoms are transient, and they resolve within a short amount of time - Which of these symptoms best represents a TIA, based on a single lesion affecting the brain?
a. numbness and tingling of the lips on both sides
b. loss of vision in the upper half of the left eye, and the lower half of the right eye
c. numbness and tingling in the first three fingers of the left hand
d. numbness affecting the left face and left arm
e. falling while walking - A TIA that has resolved should be treated with
a. IV TPA
b. aspirin 325 mg one time
c. daily prevention including aspirin, lipid-lowering therapy, and blood pressure treatment, if applicable
d. oral anticoagulation
e. none of the above