THE INSULIN TOLERANCE-TEST AND OVINE CORTICOTROPIN-RELEASING-HORMONE TEST IN EPISODIC CLUSTER HEADACHE-II - COMPARISON WITH LOW-BACK-PAIN PATIENTS

Hypothalamic involvement has been invoked to explain the periodicity o f the cluster periods and rhythmicity of the pain attacks in cluster h eadache. To-explore this hypothesis the ovine corticotrophin-releasing hormone (o-CRH) and the insulin tolerance test were administered to a group of episodic cluster headache sufferers during both cluster peri od and remission. A group of low back pain patients and healthy subjec ts comprised the control populations. For the o-CRH test, 7 healthy su bjects, 7 low back pain patients, 6 cluster headache patients in remis sion, and IZ in cluster period were studied. Five healthy subjects, 7 low back pain patients, 6 cluster headache patients in remission, and 9 in cluster period were administered the insulin tolerance test. Sign ificantly increased basal cortisol levels were found in duster headach e patients in both illness phases (p < 0.0001), but not in low back pa in patients. Significantly reduced cortisol response to the o-CRH test was observed in cluster headache patients in both phases compared to healthy controls (p < 0.02). A blunted ACTH and cortisol response (p < 0.0001 and p < 0.003 respectively) to the insulin tolerance test was present in cluster headache patients in both phases of the illness com pared to healthy subjects and low back pain patients. On the contrary, the ACTH surge after insulin induced hypoglycemia was significantly i ncreased in the low back pain patient group (p = 0.02). These results suggest that the altered hypothalamic-pituitary-adrenal axis responsiv eness in cluster headache patients is not a consequence of the pain, a nd point to a central, probably hypothalamic derangement in this patho logy.