Table 2.

Clinical, Laboratory, Imaging and Histopathologic Characteristics Useful to Distinguish RVCS from PACNS

	RVCS	PACNS
Clinical data
age	20-40 years	40-60 years
gender	primarily women	more frequent in men
trigger (drugs, postpartum etc)	frequently identified	absent
headache	acute and severe	insidious
cognitive impairment	unusual	frequent
CSF	Normal or minimal protein increase	Abnormal (increased protein concentration and mild pleocytosis)
MRI	Normal (>70%) *	Abnormal in 90%. Small infarcts in grey and white matter in multiple vascular territories, diffuse white matter lesions, mass lesions
Angiography	Abnormal:diffuse areas of multiple stenoses and dilatations **	May be normalSingle or multiple abnormalities(cut-offs, lumen irregularities, avascular mass lesion)
CNS / leptomeningeal biopsy	Normal	Vasculitis

^*Except when complicated by stroke, intraparenchymal or cortical subarachnoid hemorrhage or posterior reversible leukoencephalopathy.

^**Angiographic abnormalities are required for diagnosis but must be reversible in 6-12 weeks.