title: Subarachnoid hemorrhage with negative baseline digital subtraction angiography: is repeat digital subtraction angiography necessary?
abstract: BACKGROUND
  Patients with negative initial digital subtraction angiography (DSA) are at significant risk for re-bleeding, which can lead to severe disability and death. The purpose of this study was to evaluate the necessity of repeat DSA in subgroups of patients with subarachnoid hemorrhage (SAH) with negative initial DSA.
  
  
  METHODS
  A total of 904 spontaneous SAH patients were admitted to our department between May 2005 and May 2012. Twenty eight patients were selected for inclusion in this study because repeated DSA performed due to the etiology of the SAH could not be demonstrated on the initial DSA. According to the SAH pattern on initial computed tomography scans, patients were divided into perimesencephalic nonaneurysmal SAH (PN-SAH) and non PN-SAH (NPN-SAH) groups. Repeat DSA was performed in all patients, and two of these patients underwent a third DSA.
  
  
  RESULTS
  Of the 904 patients, 28 patients (3.1%) had no vascular abnormality on initial DSA. Sixteen PN-SAH patients underwent a repeat DSA; however, no aneurysms were found. In contrast, 12 patients with NPN-SAH underwent repeat DSA, with detection of two cerebral aneurysms. Overall, the false-negative rate of the initial DSA was 7.1% (2/28 patients). No significant differences in false-negative results on initial DSA were observed between the PN-SAH and NPN-SAH groups.
  
  
  CONCLUSIONS
  In the line with the results of the current study, we should be highly suspicious of patients with a nonaneurysmal SAH, especially those with a NPN-SAH pattern. In order to reduce the morbidity and mortality resulting from a misdiagnosis, repeat DSA is necessary, and exclusion of an aneurysm is important.
authors.affiliation: Department of Neurosurgery, College of Medicine, Yeungnam University, Daegu, Korea.
authors.forename: Dong-Woo
authors.initials: DW
authors.lastname: Yu
authors.forename: Young-Jin
authors.initials: YJ
authors.lastname: Jung
authors.forename: Byung-Yon
authors.initials: BY
authors.lastname: Choi
authors.forename: Chul-Hoon
authors.initials: CH
authors.lastname: Chang