Superficial siderosis of the central nervous system is a sporadic finding in magnetic resonance imaging, resulting from recurrent bleedings into the subarachnoid space. This study aimed to determine the frequency of spinal dural cerebrospinal fluid (CSF)-leaks among patients with a symmetric infratentorial siderosis pattern.
We screened 97.733 magnetic resonance images performed between 2007 and 2018 in our neurocenter by a keyword search for “hemosiderosis” and “superficial siderosis”. Siderosis patterns on brain imaging were classified according to a previously published algorithm. Potential causative intracranial bleeding events were also assessed. Patients with a symmetric infratentorial siderosis pattern but without causative intracranial bleeding events in history were prospectively evaluated for spinal pathologies.
We identified forty-two patients with isolated supratentorial siderosis, 30 with symmetric infratentorial siderosis, and 21 with limited (non-symmetric) infratentorial siderosis. Amyloid angiopathy and subarachnoid hemorrhage were causes for isolated supratentorial siderosis. In all 4 patients with a symmetric infratentorial siderosis pattern but without a causative intracranial bleeding event in history, spinal dural abnormalities were detected. We searched for dural leaks in patients with symmetric infratentorial siderosis and a history of intracranial bleeding event without known bleeding etiology, considering that spinal dural CSF-leaks themselves may also cause intracranial hemorrhage e.g. by inducing venous thrombosis due to low cerebrospinal fluid pressure. Thereby, one additional spinal dural leak was detected.
Persisting spinal dural CSF-leaks can frequently be identified in patients with a symmetric infratentorial siderosis pattern. Diagnostic work-up in these cases should include magnetic resonance imaging of the whole spine.

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