Spinal Subarachnoid Hemorrhage¶

Definition¶

Spinal subarachnoid hemorrhage (SAH) is bleeding into the subarachnoid space surrounding the spinal cord and cauda equina. It can result from trauma, vascular malformations, tumors, coagulopathy, or extension from intracranial SAH. Spinal SAH is much less common than intracranial SAH.

Etiology¶

Extension from intracranial SAH — Most common cause of spinal SAH
Spinal vascular malformations — AVMs, perimedullary AVFs
Tumors — Hemorrhagic spinal tumors (ependymoma, hemangioblastoma)
Trauma
Coagulopathy
Spinal artery aneurysm — Rare

Imaging Findings¶

MRI¶

T1-weighted — High signal in the subarachnoid space (subacute blood — methemoglobin) replacing the normal dark CSF signal
T2-weighted/FLAIR — Variable signal depending on the age of the hemorrhage
GRE/SWI — Susceptibility artifact (blooming) from blood products in the subarachnoid space; hemosiderin staining of the cord surface (superficial siderosis) in chronic cases
Superficial siderosis — Chronic hemosiderin deposition on the cord and brain surface, appearing as a thin rim of low T2 signal coating the cord — a clue to chronic or recurrent SAH

CT¶

Hyperdense material in the spinal subarachnoid space (acute blood)
CT angiography may identify the source

Clinical Pearl

Superficial siderosis — a thin rim of low T2/GRE signal coating the cord surface — indicates chronic or recurrent subarachnoid hemorrhage. When you see superficial siderosis of the spinal cord, evaluate for a source of bleeding: myxopapillary ependymoma of the filum terminale, cavernous malformation, or vascular malformation. Brain MRI should also be obtained, as intracranial sources can cause spinal siderosis.

Key Points¶

Most common cause is extension from intracranial SAH
MRI shows high T1 signal and GRE blooming in the subarachnoid space
Superficial siderosis indicates chronic/recurrent hemorrhage — search for the source
Spinal vascular malformations and ependymomas are important causes
CT detects acute hemorrhage; MRI is more sensitive for subacute and chronic blood

References¶

Pierce JL, Donahue JH, Nacey NC, et al. Spinal Hematomas: What a Radiologist Needs to Know. RadioGraphics. 2018;38(5):1516-1535. https://pubs.rsna.org/doi/abs/10.1148/rg.2018180099
Kumar N. Neuroimaging in Superficial Siderosis: An In-Depth Look. AJNR Am J Neuroradiol. 2010;31(1):5-14. https://www.ajnr.org/content/31/1/5
Massand MG, Wallace RC, Gonzalez LF, Zabramski JM, Spetzler RF. Subarachnoid Hemorrhage Due to Isolated Spinal Artery Aneurysm in Four Patients. AJNR Am J Neuroradiol. 2005;26(9):2415-2419. https://www.ajnr.org/content/26/9/2415
Sankarappan K, Doucet D, Daly SR, et al. Exploring Spinal Subarachnoid Hemorrhage: A Neurosurgical Case Series. Cureus. 2023;15(9):e45627. https://pmc.ncbi.nlm.nih.gov/articles/PMC10588961/
Ziu E, Khan Suheb MZ, Mesfin FB. Subarachnoid Hemorrhage. In: StatPearls. Treasure Island (FL): StatPearls Publishing; updated 2023 Jun 1. https://www.ncbi.nlm.nih.gov/books/NBK441958/
Hoskin J, Kaneko K, Munakomi S, Fife T. Superficial Siderosis. In: StatPearls. Treasure Island (FL): StatPearls Publishing; updated 2024 Apr 30. https://www.ncbi.nlm.nih.gov/books/NBK603744/
Spinal subarachnoid haemorrhage. Radiopaedia.org. https://radiopaedia.org/articles/spinal-subarachnoid-haemorrhage