What could be the reason for insect biting like sensation of the index finger?

Hello,

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Depending upon your description of the problem it seems most likely that your father is having some neurologically related problem regarding the affected area. Most commonly the nerves in the wrist might be the culprit especially a nerve known as a median nerve.

There could be a problem associated with nerve impingement at the level of the spine as well. An MRI of cervical spine would help to rule that out.

The depression in the right side of the chest needs to be confirmed that it is not related to a cardiac thing. Hence, doing an ECG should rule it out.

On other routine evaluation, we need to be sure that his blood pressure and blood sugars are within normal limits. So, please check those out. Hope this helps. Take care.