The former England captain has been suffering all week from the back problem which has plagued him for most of his career, and he could miss their penultimate Championship match with Nottinghamshire.
Atherton missed the AXA League games against Hampshire and Nottinghamshire this week, but was due to link up with the squad in Nottingham today after having treatment at Old Trafford.
Northamptonshire have moved a step closer to a possible points deduction after the English Cricket Board decided to convene a panel to inspect the pitch for their Championship match against Sussex.
Harry Brind, the Board's pitches inspector, examined the strip before the start of the second day's play yesterday, and then watched as Sussex were skittled out for 72 in reply to the home side's 178.
The panel, which includes the former England captain, Mike Denness, and the ECB's Director of Cricket Operations John Carr, was expected to look at the pitch at close of play yesterday, but no decision will not be announced until the match is over.