Clinical spectrum, underlying etiologies and radiological characteristics of cortical superficial siderosis

Cortical superficial siderosis (cSS) is an increasingly recognized MR-imaging marker most probably caused by focal convexity subarachnoid hemorrhage (SAH). There is accumulating evidence that cSS represents an important risk factor for subsequent intracranial hemorrhages. Here, we aimed to determine clinical symptoms, underlying etiologies, and radiological characteristics of cSS in a large patient cohort. We performed an electronic database search on all patients who presented between 2002 and 2013 to the university hospital Munich with non-traumatic and non-aneurysmal cSS. T2*-weighted gradient-echo sequences were analyzed regarding localization and extent of cSS as well as of acute SAH, intracerebral hemorrhages (ICH) and microbleeds. Besides, all available clinical, laboratory, imaging and histological data were analyzed. 113 subjects matched the inclusion criteria. The following etiologies for cSS were identified: definite (n = 6; 5 %), probable (n = 75; 66 %), and possible (n = 28; 25 %) cerebral amyloid angiopathy (CAA); reversible cerebral vasoconstriction syndrome: 2 (2 %); central nervous system vasculitis: 1; and hyperperfusion syndrome: 1. Acute ICH was evident in 55 (49 %) cases. Other clinical manifestations were: transient focal neurological episodes (TFNE): 38 (34 %); cognitive impairment: 14 (12 %); generalized seizure: 4 (4 %); and headache: 2 (2 %). Adjusting for age and gender, cognitive impairment was more frequent in disseminated cSS, while TFNE was more often found in focal cSS (p = 0.042). Our data indicate CAA to be the most common etiology of cSS. In absence of symptomatic ICH, patients with focal cSS frequently present with TFNE, while those with disseminated cSS commonly manifest with cognitive impairment.