TABLE 1:

Patients with negative head CT findings and aneurysms on angiography

Patient	Time from Symptom Onset to Head CT	Time from Head CT to LP	Tube 1 (RBCs/mm³)	CSF Description	Tube 4 (RBCs/mm³)	CSF Description	% Change from Tube 1 to 4	Angiographic Result
1	4 days	5 hours	3550	Cloudy	2550	Slightly bloody	−28.2	Basilar artery dissecting aneurysm
2	3 days	5 hours	24,686	Cloudy	17,842	Bloody	−27.7	Right posterior communicating artery aneurysm
3	8 days	2 hours before CT	14,325	Xanthochromic	11,207	Xanthochromic	−21.8	Anterior communicating artery aneurysm
4	7 days	1 hour	2249	Cloudy	2129	Bloody	−5.3	Left vertebral artery dissection
5	3 hours	3 hours	29,710	Cloudy	33,700	Bloody	13.4	Anterior communicating artery aneurysm
6	2 days	6 hours before CT	69	Clear	100	Clear	45	Right middle cerebral artery aneurysm
7	24 days	2 hours	192	Clear	1150	Slightly bloody	499	Anterior communicating artery aneurysm
8	3 hours	9 hours	80	Clear	6225	Slightly bloody	7700	Right anterior communicating artery aneurysm