Hi, Cerebral and cerebellar atrophy is loss of nerve cells (neurones) and connections between nerve cells, thus affecting the functional performance of brain. It may be result of many conditions like stroke, post traumatic and certain neurological conditions like dementia, Alzheimer, Pick s disease etc. It may be a normal aging process also. Also, in some cases, the atrophy may be result of some unknown medical conditions as well as vice versa. In the case of your husband, the chronic tubercular infection, prior to diagnosis and / or some silent strokes due to any Known or unknown medical accompanying conditions may be also a cause. Usually, this type of atrophy is not a sudden process, rather it is a gradual increasing process. However, in its earlier stage, it may not be diagnosed by MRI. This may be only reason for the finding of atrophy being negative in earlier MRI, while being Positive in current MRIs. The treatment of the accompanying disease, a good healthy diet and regular exercises may stop or slow the progression of disease. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Satnarain Bansal, General & Family Physician