Table 1 Overview of CGRP levels (pmol/l) in external jugular vein during cluster headache [15–17]

Thirteen patients with spontaneous cluster headache attacks [19]

110 ± 7

38 ±_- 6^a

Controls

41 ± 6

Twelve NTG induced cluster headache attacks [20]

46 ± 3

Baseline^b: 20 ± 2

22 ± 2 (after spontaneous resolution)

Six NTG induced cluster headache attacks [20]

50 ± 4

Baseline^b: 18 ± 2

22 ± 2^c

NTG induced cluster headache in 11 patients [21]

52 ± 7

Baseline^b: 19 ± 2

22 ± 2^c