Types of individuals included | Number with serious abnormality/number scanned | % (95% CI) |
---|---|---|
*To improve clarity, these results are summarised here in a simpler format than that used in the guidelines. | ||
†No abnormal neurological findings on examination. | ||
‡Only those studies which definitely excluded patients with acute headache are included here. | ||
¶ A study of the incidental findings on brain MR scans of 1000 asymptomatic volunteers who participated as control subjects in various research projects and whose median age was similar to the individuals included in the studies of headache patients summarised in the guidelines. | ||
CI, confidence interval. | ||
Migraine†2–12 | 2/1086 | 0.2 (0.02 to 0.7) |
Tension type headache†2,7 | 0/83 | 0 (0 to 4.4) |
Chronic headache (not further defined)†‡13–17 | 7/1445 | 0.5 (0.2 to 1.0) |
Asymptomatic volunteers¶18 | 4/1000 | 0.4 (0.1 to 0.8) |