The critical stage of pinealectomy surgery after which scoliosis is produced in young chickens

STUDY DESIGN: Stages of the surgical procedure for pinealectomy in chickens were identified. Groups of chickens were selected for each stage. Scoliosis development was identified from radiographs. OBJECTIVES: To determine the critical stage of surgery for pinealectomy after which scoliosis develops in young chickens. SUMMARY OF BACKGROUND DATA: Pinealectomy in young chickens consistently produces scoliosis in young chickens that has many characteristics similar to those seen in patients with adolescent idiopathic scoliosis. The mechanism behind this phenomenon remains unknown. METHODS: Five distinct stages in the pinealectomy surgery were identified. Groups of chickens were selected to undergo surgery to represent these five stages. Scoliosis was determined from weekly radiographs. RESULTS: Cutting the pineal stalk was identified as the critical stage in the surgery after which scoliosis developed. The incidence of scoliosis did not increase after more extensive surgery in which the pineal bulb was removed from the skull. This stage was also correlated with a significant reduction of serum melatonin levels. CONCLUSIONS: Cutting the pineal stalk was identified as the critical stage of pinealectomy surgery after which scoliosis may develop. This stage was also correlated with the significant reduction of average serum melatonin levels. These results allow the focus of attention into the mechanism behind this phenomenon to center on the consequences of cutting the pineal stalk rather than total removal of the pineal gland.