CerebroVascular Accidents (CVA) are of two main types - arterial blockage (ischemic stroke) and hemorrhage. Blockage is commonly the result of the same atherosclerosis which causes most heart-attacks and impaired circulation to the legs. Less often it is due to the lodging of fragments of fatty material, clot or infection which originate in distant blood-vessels or from the heart. In these embolic types, preventive surgery such as endarterectomy may head off future disaster.
The ratio of risks to benefits for generalised thrombolysis (clot-busting) has proved disappointing .
However, localised delivery of fibrinolysin through an intra-arterial catheter to the clot within 6 hours is more promising [1a], though its efficacy too remains unproven. In particular, bleeding into the brain or skull, resulting in permanent brain damage, is a relatively common complication of intra-arterial thrombolysis [1b], [1c].
Stroke caused by blockage of the vertebro-basilar arteries has a significantly worse prognosis than carotid artery ischemic stroke, and the results of intra-arterial thrombolysis are similarly more disappointing[1d].
Initial enthusiasm for early removal of blood clot has been dampened by poor results: mortality has been reduced in some studies, but quality of survivors is not significantly improved[1e], , . Nor does operating within 24 hours result in advantage over waiting a few days.
Animal experiments have provided some explanation: the area of surrounding brain tissue irreversibly damaged by acute compression is many times larger than the area of bleeding.
Indications for surgery are now based on size of bleed as reflected in distortions of anatomy, severity of neurological malfunctioning and depression of consciousness. Evacuation of the blood clot may also be needed for adequate control of acutely raised blood pressure resulting from the bleeding.
If spontaneous bleeding into the brain was treated neurosurgically, it is not likely that delay in referral altered the outcome.
Because of disappointing surgical results, less invasive methods of removing hemorrhage are being tried. There are encouraging initial results from simple suctioning or dissolving clot with the enzyme urokinase through a catheter.
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