What Can Be Done To Address The Numbness In My Father S Upper Lip And Left Cheek After Nerve Damage From Endoscopic Surgery?

Hi, My father had a endoscopy surgery for removing fungus from orbital region near optic near and brain ,Doctors have removed maximum fugus but they could not touch the fungus which is formed near to optic nerve . After the surgery he is suffering from numbness in the region of above left upper lip and particular area of left cheek .Doctors told ,it would be because of nerve damage during endoscopic surgery and they prescribed some tablets for nerve weakness. What is the remediation for this numbness problem