Clinical relevance of negative initial angiogram in spontaneous subarachnoid hemorrhage

We aimed to compare the presentation, management, and clinical course in patients with perimesencephalic and nonperimesencephalic (aneurysmal) bleeding patterns on noncontrast CT, but negative initial 4-vessel digital subtraction angiography (DSA).

We retrospectively reviewed clinical and imaging data for 280 patients presenting with spontaneous SAH admitted between 2005 and 2011. We identified 56 patients (20%) with SAH diagnosed on high resolution head CT performed within 48 hours of admission, and negative initial DSA, and divided them into perimesencephalic and non-perimesencephalic groups based on hemorrhage patterns. Patients with traumatic subarachnoid bleeding and those with initial positive DSA were excluded from this analysis.

Perimesencephalic SAH was seen in 25 patients (45%); non-perimesencephalic bleeding patterns were seen in 31 (55%). All patients with perimesencephalic SAH presented with Hunt and Hess (HH) I, versus 45% HH I and 55% HH II-IV in those with non-perimecenphalic SAH. All patients with perimesencephalic SAH achieved modified Rankin score (mRS) 0 at discharge and 6-month follow-up, compared with 45% mRS 0 at discharge and 68% at 6-month follow-up in non-perimesencephalic SAH. Patients with perimesencephalic SAH presented a uniformly uncomplicated clinical course. Among non-perimesencephalic SAH patients there were 19 neurological/neurosurgical and 10 medical complications, two small aneurysms diagnosed at follow-up DSA, and one death.

In this series, perimesencephalic SAH was associated with good clinical grades, consistently negative initial and follow-up angiograms, and an excellent prognosis. In contrast, non-perimesencephalic SAH was associated with a worse clinical presentation, higher complication rates, higher rates of true aneurysm detection on follow-up angiogram, and a poorer outcome.