思案に余る
しあんにあまる to be at wit's end to be at a loss for what to do

思案に暮れる
しあんにくれる to be lost in thought

思案を凝らす
しあんをこらす to rack one's brains (i.e. for a solution)

思案投げ首
しあんなげくび at one's wits end

思案投首
しあんなげくび be at one's wit's end