Methods and devices are disclosed herein that allow for infusion and aspiration through a single device. The device can be used to treat a stroke by delivering the device to the site of a blood clot and simultaneously or sequentially infusing a thrombolytic or other drug into the clot and aspirating the dissolving clot from the patient. The methods and devices can advantageously permit more efficient thrombolytic infusion and clot aspiration. Modular systems are also disclosed, as are methods of treating subdural hematoma or other conditions.