Intracranial vessels lie in the subarachnoid space and give off small perforating branches to the brain tissue. Bleeding from these vessels or from an associated aneurysm occurs primarily into this space. Some intra-cranial aneurysms are imbedded within the brain tissue and their rupture causes intracerebral bleeding with or without sub-arachnoid haemorrhage.
Occasionally the arachnoid layer gives way and a subdural haematoma results. INCIDENCE
Subarachnoid haemorrhage occurs in approximately 10-15 per 100 000 per year. CAUSE
Cerebral aneurysms are the most frequent cause of subarachnoid haemorrhage, with arteriovenous malformations accounting for 6%.
In some patients detailed investigation fails to reveal a source of the haemorrhage. Hypertension may account for some. Cryptic arteriovenous malformations or small thrombosed aneurysms may contribute to the remainder.
CAUSES OF SAH
A-V malformations Bleeding diathesis Anticoagulants Tumours Vasculitis
SYMPTOMS AND SIGNS
The severity of the symptoms is related to the severity of the bleed.
Usually the headache is severe and the onset instantaneous (often described as a 'blow to the head'). A transient or prolonged loss of consciousness or epileptic seizure may immediately follow. Nausea and vomiting commonly occur. Symptoms continue for many days.
Occasionally, the headache is mild (although still instantaneous) and may represent a 'warning leak' of blood before a major bleed.
Signs of meningism develop after 3-12 hours Neck stiffness is present on passive neck flexion.
Was this article helpful?
This guide will help millions of people understand this condition so that they can take control of their lives and make informed decisions. The ebook covers information on a vast number of different types of neuropathy. In addition, it will be a useful resource for their families, caregivers, and health care providers.