Fluoroscopy-guided lumbar puncture: decreased frequency of traumatic tap and implications for the assessment of CT-negative acute subarachnoid hemorrhage.

BACKGROUND AND PURPOSE In patients with suspected subarachnoid hemorrhage (SAH) and negative CT findings, the iatrogenic introduction of RBCs into the CSF during lumbar puncture may lead to a misdiagnosis. We tested the hypothesis that the risk of traumatic lumbar puncture is lower with the fluoroscopy-guided technique than with the standard bedside technique. METHODS Data were collected retrospectively from two populations: adult inpatients undergoing standard bedside lumbar puncture for any reason and adult patients undergoing fluoroscopy-guided lumbar puncture for myelography. Patients with SAH and CSF samples with significant abnormalities other than erythrocytosis (ie, CSF leukocytosis, xanthochromia, or elevated protein) were excluded. In all, 1489 bedside procedures and 723 fluoroscopy-guided procedures met the criteria. RESULTS We found a significant difference in the level of iatrogenic CSF erythrocytosis produced by the two procedures. Using a cutoff of 1000 cells/mm(3), the frequency of traumatic lumbar puncture was 10.1% for bedside lumbar puncture and 3.5% for fluoroscopy-guided lumbar puncture. With fluoroscopic guidance, the frequency of a traumatic tap varied significantly with the operator, ranging from 0% to 24%. CONCLUSION The use of fluoroscopy-guided lumbar puncture in patients with suspected SAH and negative CT findings should reduce the frequency of false-positive diagnoses of acute SAH as well as the number of unnecessary angiograms for patients with suspected SAH but no underlying intracranial vascular malformation.