CXCL8 and trigeminal neuralgia: CSF interleukin-8 (IL-8) was elevated in 7/7 (100%; 6 × B/SC subgroup) CSF samples from 7 patients in group I, based on a cut-off of 40 pg/ml derived from a German cohort of patients with normal pressure hydrocephalus (21.40 ± 7.96 pg/ml) [26] (which is in good accordance with the upper reference range found in a recent Chinese healthy control cohort [23.86 ± 17.74 pg/ml] [27] and a cohort of European patients with trigeminal neuralgia [23.1–33.9 pg/ml] [28]).