====== Subarachnoid hemorrhage clinical features ======

Sudden [[headache]] is the cardinal feature, but patients might not report the mode of onset, usually with [[vomiting]], [[syncope]] (apoplexy), [[neck pain]] (meningismus), and [[photophobia]]. If there is LOC, patient may subsequently recover [[consciousness]]. Focal [[cranial nerve]] deficits may occur (e.g. [[third nerve palsy]] from aneurysmal compression, causing [[diplopia]] and/or [[ptosis]]), [[Low back pain]] may develope due to irritation of lumbar [[nerve root]]s by dependent blood.

[[Loss of consciousness]] (LOC) is a common presenting symptom of [[subarachnoid hemorrhage]] (SAH) that is presumed to result from transient intracranial circulatory arrest.

In patients with a normal level of [[consciousness]] without [[focal neurological deficit]]s the presence of [[neck stiffness]] is helpful but not pathognomic for the diagnosis of SAH. Moreover, the absence of neck stiffness does not rule out SAH, especially when evaluated ≤6h after symptom onset
((Backes D, Rinkel GJ, Sturkenboom AJ, Vergouwen MD. Time-dependent test
characteristics of neck stiffness in patients suspected of nontraumatic
subarachnoid haemorrhage. J Neurol Sci. 2015 Jun 10. pii: S0022-510X(15)00357-3. 
doi: 10.1016/j.jns.2015.06.016. [Epub ahead of print] PubMed PMID: 26115913.
)).


Focal cranial nerve deficits may occur (e.g. third nerve palsy from aneurysmal compression, causing diplopia and/or ptosis). 

Low back pain may develop due to irritation of lumbar nerve roots by dependent blood.

===== Subarachnoid hemorrhage headache =====

see [[Subarachnoid hemorrhage headache]].