Abstract
Background: NASAH constitute 10-20 % of all spontaneous subarachnoid haemorrhages (SAH) as no structural causes for the haemorrhage were detected despite extensive neuroimaging investigations. The optimal diagnostic pathway is still open to question.

Objective: To evaluate the diagnostic yield and the utilization rate of Magnetic Resonance Imaging (MRI) for spinal column routinely used in identifying a structural lesion in patient with NASAH.

Methods: In this retrospective study, adult patients admitted to the Walton Centre/Liverpool/UK between the 1/2009 and 05/2018 with spontaneous NASAH were surveyed. A multidisciplinary team examined the utilization rate, mean time, and the diagnostic yield of the following imaging tests: Computed Scan, Computed Tomography Angiography, Digital Subtraction Angiogram, cervical and whole spine MRI. The assessment was during hospital admission and for long term follow-up (6-24 months).

Results: During that period, 450 patients with spontaneous NASAH were treated in the hospital. In 76 patients (17%), an entire spinal axis by standard T1- and T2-weighted MR-imaging was done. While cervical T1- and T2-weighted MR-imaging was conducted in 156 patients (24.5 %). In all the 232 patients (51.5%), MR-imaging for the spinal axis did not identify any underlying spinal anomaly that contributing to the SAH formation.

Conclusion: In spontaneous NASAH patients, traditional use of spinal axis MR-image has a very low diagnostic yield. Therefore, MRI for possible causes of NASAH is not routinely recommended unless there are focal neurological deficits to suggest a cranial or spinal pathology.

Key words: Subarachnoid haemorrhage. Non-aneurysmal subarachnoid haemorrhage Cerebrovascular diseases. Magnetic resonance imaging. Spinal cord vascular anomaly. Spinal cord imaging