Mike Neal, former executive chairman, left the company in late December and was reassigned to look after ITV's interests in its global cinema ad business Screenvision.
Trevor Davies, formerly chief operating officer, has replaced Neal, with the new title of managing director. A senior TV industry source said that CSA's restructuring is in part due to a need to renegotiate key sales contracts aimed at preparing the firm for a possible sale by ITV.
The source said: "Neal's role with the business hasn't worked out very well. He's gone because the business was not sorted out as it should have been and CSA is now in the position where it is having to renegotiate its contracts with key exhibitors."
ITV refused to comment.
Media Week understands CSA is currently in talks to renegotiate contracts with Cineworld, Odeon, Showcase and Empire.
Commercial director Nicolette Homes is leaving this month to become commercial director of events company Nova International, while Adam Mills has been promoted from sales director to sales and commercial director.
Fleur Castell adds research responsibilities to her role as marketing controller, and David Ives joins as finance director after several freelance contracts. His last permanent position was at now-defunct Highbury House.