IPHREHAB : Transient Ischemic Attacks(TIA) & CEREBRAL THROMBOSIS

IPHREHAB

1.Transient Ischemic Attacks(TIA)
Current opinion holds that TIAs are brief, reversible episodes of focal, nonconvulsive ischaemic neurologic disturbance, Consensus has been that their duration should be less than 24 h.

Clinical picture
Transient Ischaemic Attacks can reflect the involvement of any cerebral artery. The loss of function entirely depends on the influenced artery. It may last  a  few seconds or up to 12 to 24 h, Most of them last 2 to 15 min. There are only a few attacks or several hundred. Between attacks, the neurologic examination may disclose no abnormalities. A stroke may occur after numerous attacks have occurred over a period of weeks or months.

Differential diagnosis of TIAs

Transient episodes, indistinguishable from TIAs, are known to occur in patients with Seizure,Migraine,Transient global amnesia,and occasionally in patients with multiple sclerosis, meningioma, glioblastoma ,metastatic brain tumors situated in or near the cortex ,and even with subdural hematoma.

2. Cerebral thrombosis

Most cerebrovascular disease can be attributed to atheroscleroses and chronic hypertension; until ways are found to prevent or control them, vascular disease of the brain will continue to be a major cause of morbidity.

Pathogenesis

Pathogenesis of Ischemic neuronal death

   Ischemia

       ↓ 

   Excitatory amino acid receptors

       ↓ 

   Borderzone or penumbra    ↓

   Programmed cell death

Clinical picture  

In general, evolution of the clinical phenomena in relation to cerebral thrombosis is more variable than that of embolism and hemorrhage. The loss of function that the patient notices, and which may be apparent on examination, entirely depends on the area of brain tissue involved in the ischaemic process.

Clinical picture

In more than half of  patients, the main part of the stroke is preceded by minor signs or one or more transient attacks of focal neurologic dysfunction. The final stroke may be preceded by one or two attacks or a hundred or more brief TIAs, and stroke may follow the onset of the attacks by hours, weeks, or, rarely, months.

The most occurrence of the thrombotic stroke is during sleep.The patient awakens paralyzed. Either during the night or in the morning.

Unaware of any difficulty, he may arise and fall helplessly to the floor with the first step.

Clinical picture

Associated symptoms

Seizures accompany the onset of stroke in a small number of cases (10-50%); in other instances, they follow the stroke by weeks to years. The presence of seizures does not definitively distinguish embolic from thrombotic strokes, but seizure at the onset of  stroke may be more common with embolus.

Headache  occurs in about 25% of patients with ischaemic stroke, possibly because of the acute dilation of collateral vessels.

Laboratory Findings

• CT Scan or MRI: A CT scan or MRI  should be obtained routinely to distinguish between infarction and hemorrhage as the cause of stroke, to exclude other lesions (eg, tumor, abscess) that can mimic stroke, and to localize the lesion. CT is usually preferred for initial diagnosis because it is widely available and rapid and can readily make the critical distinction between ischaemia and hemorrhage.
• Lumbar Puncture: This should be performed in selected cases to exclude subarachnoid hemorrhage.
• Cerebral Angiography: Intra-arterial angiography is used to identify operable extracranial carotid lesions in patients with anterior circulation TIAs who are good surgical candidates. It also can be used for intra-arterial thrombolysis ( r-tPA)
• Magnetic resonance  Angiography (MRA) may detect stenosis of large cerebral arteries, aneurysms, and other vascular lesion, but its sensitivity is generally inferior to that of conventional angiography.