Fig. 1From: Pneumocephalus and headache following craniotomy during the immediate postoperative periodScatter plot showing Spearman positive correlation of intracranial air volume and intravenous analgesic consumption a within 24 h after surgery (r = 0.699, p < 0.001), b within 48 h after surgery (r = 0.687, p < 0.001) and, c within 72 h after surgery (r = 0.726, p < 0.001)Back to article page