In-Reply-To: <[log in to unmask]> Ah! You have given the all-important clue. This was in all probability opiate rigidity. This is well-recognised, particularly with the synthetics such as fentanyl and alfentanil, but can occur with a high molar concentration of any of the opiates. I would be much more inclined to that diagnosis than serotonin syndrome. Best wishes, Rowley Cottingham [log in to unmask] In God we trust. All others get a spine board. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%