What Causes Feeling Of Numbness Inside Head?
No brain lesion is suspected.
Detailed Answer:
I read your query and I understand your concern.
It is very useful of you to have checked and reported the lack of headache, normal strength and speech.
The brain itself has no sensations, so there are no objective causes to originate any numbness on the inside as you are describing. When there are lesions in the brain the stretching of the surrounding structures would be sensed as pain, but you say that she has no headache either.
So unless there are other symptoms, like a newly manifested disorder of balance, problems with vision, sudden changes in behavior there is no need to suspect a brain lesion. When isolated, such reportings such as brain numbness are usually subjective sensations of a psychological origin, common in the elderly.
Of course you should be careful about other physical manifestations like fever, blood pressure, breathing issues etc. If she's not had a recent check-up, routine blood count, blood sugar, kidney and liver tests, electrolytes, urine test are recommended as especially in the elderly infections or alterations in other organs which can be perceived as fogginess or generalized numbness are common.
I hope to have been of help.