Updated from 4:29 p.m. ESTA Food and Drug Administration advisory panel has unanimously decided to recommend that the FDA allow the multiple sclerosis drug Tysabri to return to the market. The 12-member panel of medical experts completed a two-day meeting on Tysabri Wednesday. The drug is marketed by Biogen Idec ( BIIB) and Elan ( ELN), and it was pulled in February 2005 after being linked to a rare brain illness that can be deadly. Panel members had to discuss what conditions should be met before Tysabri is given to individual patients and how it should be used. Committee members voted 7-to-5 to suggest doctors be permitted to prescribe Tysabri as the first treatment choice for MS patients. Many Wall Street analysts expected that Tysabri would again be available for sale, but with certain conditions attached. The FDA isn't required to follow the decisions of its advisory panels, but it usually does. The panel concluded that additional clinical trials weren't necessary for the drug's return. However, if the FDA were to allow re-entry, the drug should be limited to a certain subgroup of MS patients under strict guidelines, the panel said. Also, according to the advisory committee's suggestions, patients should be tracked by regular surveys given prior to monthly Tysabri infusions. Patients' receipt of the drug would be contingent on Biogen getting the safety reports, which would include any side effects and allergic reactions. Shares of Elan were halted during the meeting but opened just before the close of regular New York Stock Exchange trading. When they did, the buying was fast and furious, as the stock jumped $3.11, or 24.5%, to $15.81. More than 17 million shares changed hands in just under 30 minutes of trading, compared with average volume of 10.7 million shares for a full session during the last three months.