During treatment, you will have a complete physical exam and brain and spinal exam (performed by checking your coordination and strength by looking at how you walk and pull objects), which will be done every one cycle if you are in Phase I and every 2 cycles if you are in Phase II. On Day 1 of every cycle you will discuss birth control methods. You will have blood drawn (about 2 teaspoons each time) for routine tests once a week during Cycle 1 and then every 2 weeks in further cycles. You will have blood drawn (about 2 teaspoons each time) for routine tests on Day 15 of Cycle 1 and then on Day 1 in further cycles (every one cycle if you are in Phase I and every 2 cycles if you are in Phase II). You will also have a dynamic MRI scan done every 2 cycles after completion of Cycle 2. For all women who are able to have children: You will have a pregnancy test performed by your doctor within 10 - 14 days and 24 hours prior to starting lenalidomide therapy, even if you have not had any menses due to treatment of your disease or had as little as one menstrual period in the past 24 months. If you have regular or no menstrual cycles, you will have pregnancy tests every week for the first 28 days, then every 28 days while taking lenalidomide, when you stop taking lenalidomide, then 28 days after you have stopped taking lenalidomide. If you have irregular menstrual cycles, you will have pregnancy tests every week for the first 28 days, then every 14 days while taking lenalidomide, again when you have been taken off of lenalidomide therapy, and then 14 days and 28 days after you have stopped taking lenalidomide.