Transient ischemic attacks (TIAs) are transient attacks of loss of function of one part of the brain coming suddenly and lasting for variable period of time ranging from minutes to hours. Since arteries supplying the brain are end arteries so any pathology which produces obstruction to the flow of that vessel shall produce symptoms in the distribution of that blood vessel.
Internal carotid artery is one of the commonest cerebral vessel which is involved by atherosclerosis and patient complains of transient disturbances due to localized cortical ischemia in the form of confusion contralteral hemiparesis and sensory loss. There may be aphasia (if lesion on left side) and hemianopic visual loss. Most commonly occlusion is in the common carotid artery and one may be able to appreciate diminished pulsation in the vessel in the neck. When obstruction is severe a bruise may be auscultated at the site.
Obstruction of other arteries like anterior cerebral artery, middle cerebral artery and posterior cerebral artery produce picture almost like above except for little variations depending on the occlusion site. On the other hand involvement of posterior circulation (basilar artery, vertebral artery, post inferior cerebellar artery) produces a picture of crossed hemiplegia, hemisensory loss and hemianopic visual loss.
In addition patient has impairment of consciousness, small fixed pupils, pseudobulbar palsy and quadriplegia seen mainly in basilar artery lesions while cases with posterior inferior cerebellar artery involvement are associated with severe vertigo, vomiting, dysphasia and diplopia. In addition there is some degree of cerebellar deficiency with hypotonia and in coordination on the side of lesion, analgesia and thermo anesthesia on the face on the side of lesion and on the trunk and limbs on opposite side. Again neurological deficits shall be depending on which branch of the vessel is involved.
Diagnosis of Transient ischemic attacks (TIAs) is based upon the previous history of such transient episodes of neurological deficit coming suddenly and lasting for a short time. In some these attacks are very transient and may have to be differentiated from other causes of transient loss of function like focal epilepsy. In cases of Transient ischemic attacks (TIAs), there is presence of diseases like diabetes, hypertension etc. Person generally is in the age group where atherosclerosis is common.
Confirmation of the diagnosis is made by carotid angiography when transient ischemia or narrowing of vessel is seen. Doppler echo flow studies are also important for assessing the blood flow and presence of any narrowing in the vessels.
Management of ischemic stroke
A case of ischemic stroke requires careful management since patient is in the twilight zone of cerebral ischemia and stroke. When the attack has lasted for sometime it is better to use decongestant therapy in the form of Mannitol, infusion and Injection Dexamethasone 4 mg I/M 6 hourly. After the acute stage is over orally Glycerol 15 ml three times a day is given.
‘When a patient is having repeated attacks of ischemic stroke or stroke in evolution use of anticoagulants is considered though it is risky and there is danger of cerebral leak or hemorrhage. Usually Injection Heparin 5000 units I/M six hourly is given for first few days. Dosage is monitored by keeping control of levels which should not exceed one and half to two times the pre-treatment values.
Once results have been obtained, patient is switched on oral anticoagulants (Table Dindevan 50 mg). Dosage has to be adjusted individually keeping a watch on bleding tendency.
Anti platelet drugs are of use in prevention of thrombotic or Transient ischemic attacks (TIAs). A daily dose of Aspirin (Dispirin) 75 mg is effective in inhibiting platelet aggregation. MI coexisting disease like hypertension and diabetes must be treated and controlled properly. Hypertension is no contraindication to the use of anticoagulants though in such case caution has to be employed.
Check the video below on Transient ischemic attacks: