Learning objectives
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Post Ischaemic stroke disorder of cell function leads to the development of cytotoxic oedema usually accompanies infarction and is seen in lesions after about 24 hrs and tends to peak at the 48-72 hr period.
Oedema is usually cytotoxic and is due to a failure of cellular pumps due to ischaemia. Later oedema can be vasogenic due to break down in normal vascular blood brain barrier and it is this that causes raised ICP.
It is cytotoxic oedema that we see on DWI causing restricted diffusion. Oedema is often a transient phenomenon but becomes more malign when a stroke involves a large volume of the brain causing a significant rise in intracranial pressure usually due to a
large vessel occlusion - MCA or Internal carotid. There is no role for steroids. Vasogenic oedema is seen with tumours and does respond to steroids. As ICP rises patients may require
decompressive surgery such as hemicraniectomy for large lobar strokes and to reduce pressure and prevent coning or with suboccipital decompression for malignant cerebellar infarcts.
Patients with oedema are given isotonic fluids, e.g. N-Saline rather than Dextrose to try to reduce excess free water and oedema. Fluid restriction may even be considered in this period however there are concerns that this may be prothrombotic or reduce cerebral perfusion in those with stenotic lesions.
Cerebral oedema can also be managed medically often as a bridge to surgery using either IV Mannitol or Hypertonic saline or Barbiturates or elevated head position at 30-45 degrees.
There are several types of cerebral oedema seen in stroke disease. Oedema can be a dramatic and life ending phenomena such as with a malignant MCA syndrome. Significant and progressive oedema usually happens day 2 to 4 of the stroke course. The oedema can cause swelling and increased ICP and compression of midline structures and uncal herniation.
There are two major types of cerebral oedema which are cytotoxic (intracellular) and vasogenic (extracellular) oedema.
Perilesional haemorrhagic stroke oedema may be seen with ICH. It tends to develop and peak later than the above. Again, it can add to pressure effects and cause clinical worsening. The causes can involve and inflammatory reaction to blood products, complement, thrombin and other factors.
Causes of Cerebral oedema
Cerebral oedema
Cerebral Oedema with Ischaemic stroke
Cerebral Oedema with Haemorrhagic stroke
Management