Diagnostic value of the RCVS features at onset.
| Feature | Sensitivity, % | Specificity, % | PPV, % | NPV, % |
|---|---|---|---|---|
| Headaches | 100 | 27 | 62 | 100 |
| Thunderclap headaches | 77 | 82 | 83 | 75 |
| No focal deficit | 46 | 100 | 100 | 61 |
| Normal vigilance | 85 | 54 | 69 | 75 |
| Rankin < 3 | 73 | 77 | 73 | 77 |
| Normal brain MRI | 23 | 100 | 100 | 52 |
| Cortical subarachnoid hemorrhage | 54 | 100 | 100 | 67 |
| String of beads appearance | 100 | 54 | 72 | 100 |
PPV: positive predictive value; NPV: negative predictive value; RCVS: reversible cerebral vasoconstriction syndrome; MRI: magnetic resonance imaging.