Table 2.

Differentiation between cSS and iSS.

Items	cSS	iSS
Classification of type	Focal type (≤3 sulci involvement); Disseminated type (>3 sulci involvement)	Type 1 (classical); Type 2 (secondary)
Most common cause	CAA	Dural tear
Clinical presentation	TFNEs, cognitive impairment	Progressive hearing loss, ataxia and myelopathy
Imaging on MRI	Linear hypointensity on T2-WI was restricted to the supratentorial	Linear hypointensity on T2-WI involved at least two sites (brain stem, cerebellum, spinal cord), with or without supratentorial
CSF studies	Red cells	Red cells
Treatment	Surgical removal of the source of bleeding; deferiprone	Surgical removal of the source of bleeding; deferiprone
Differential diagnosis	TIA, migraine with aura, epilepsy, et al.	Spinocerebellar ataxia, et al.

cSS, cortical superficial siderosis; iSS, infratentorial superficial siderosis; CAA, cerebral amyloid angiopathy; TFNEs, transient focal neurologic symptoms; TIA, transient ischemic attack.