An FDA advisory panel ruled unanimously today that Biogen Idec’s multiple sclerosis drug Tysabri should return to the market with safeguards to monitor patient complications.The FDA advisory panel voted 12-0 that Tysabri sales could resume if Biogen creates a patient registry to track side effects and imposes other controls.  “Most people in (Tysabri) studies did not have a relapse and did not have disability progression,” Dr. Karl Kieburtz, the panel chairman, told Reuters. The panel also voted 7-5 that Tysabri could be considered as a first choice treatment for some MS patients. The FDA will make the final decision however usually follows the advice of its advisory panels.Tysabri marketers Biogen Idec and Elan pulled the drug in February 2005 after two patients developed progressive multifocal leukoencephalopathy, or PML, a rare and often fatal brain infection. A third patient was later discovered to have PML. Two of the three patients died.