@feruze-- Do you remember what other symptoms your grandmother had?
My dad had a stroke last year which damaged his left parietal lobe. We knew something was wrong when he couldn't name his index finger and he couldn't add small numbers together. He wasn't able to do dress himself either, but my mom thought that he just wanted to be taken care of and so she was doing everything for him.
When we took him to the neurologist, he did some simple tests and also noticed that my dad couldn't follow his directions and had also developed dyslexia. The doctor had him get an MRI for diagnosis although he knew that it was an injury to the left perietal lobe. All the symptoms were pointing in that direction.
My dad is now in rehabilitation. He is better on some days than others.