Sensory aphasia (also known as Wernicke's aphasia, fluent aphasia, or receptive aphasia) is a condition of the brain where the patient loses the ability to comprehend language, either written or oral. They do, however, retain the ability to form words and sentences with proper grammar, syntax, and emphasis without those words or sentences actually making sense. This is due to their inability to comprehend their own speech. Like many acquired language disorders, symptoms will present throughout a spectrum ranging from minor language problems to complete disability. Interestingly, patients who use sign language also experience the same expressive deficits as speaking patients. This problem is caused by brain damage to the part of the brain known as Wernicke's area and can be caused by injury or stroke.