Does magnetic resonance imaging produce further benefit for detecting a bleeding source in subarachnoid hemorrhage of unknown origin?

BACKGROUND

Spontaneous subarachnoid hemorrhage (SAH) without evidence of a bleeding source on the first digital subtraction angiogram (DSA) - also called SAH of unknown origin - is observed in up to 27% of all cases. Depending on the bleeding pattern on CT scanning, SAH can be differentiated into perimesencephalic (PM-SAH) and non-perimesencephalic SAH (NON-PM-SAH). The aim of our study was to investigate the effectiveness of magnetic resonance imaging (MRI) for detecting a bleeding source in SAH of unknown origin.

METHODS

We retrospectively reviewed 1,226 patients with spontaneous SAH between January 1991 and December 2008 in our department. DSA was performed in 1,068 patients, with negative results in 179 patients.

RESULTS

Forty-seven patients were categorized as having PM-SAH and 132 patients as having NON-PM-SAH. MRI of the brain and the craniocervical region was performed within 72 h after diagnosis of SAH and demonstrated no bleeding sources in any of the PM-SAH and NON-PM-SAH patients (100% negative).

CONCLUSIONS

In our experience MRI did not produce any additional benefit for detecting a bleeding source after SAH with a negative angiogram. The costs of this examination exceeded the clinical value. Despite our results MRI should be discussed on a case-by-case basis because rare bleeding sources are periodically diagnosed in cases of NON-PM-SAH.