G44.02Non-Billable (Header)Chronic cluster headacheChild CodesG44.021Chronic cluster headache, intractableG44.029Chronic cluster headache, not intractableCode Hierarchy└G44Other headache syndromes└G44.0Cluster headaches and other trigeminal autonomic cephalgias (TAC)└G44.02Chronic cluster headache└G44.02Chronic cluster headache