shock pain from molars to back head

Hi! people I want suggestions at medical condition of my father. Which is>>>>

He started feeling a pain in about 2004. The pain is unbearable it is a shock which rises from upper right molars and follows through the right side of his head till backside of head.

We contacted a neurosurgeon and he said it is two veins which touch each-other causing this terrible shock pain. He said the solution was an operation in which he'd cut the veins which are causing disturbance; but also he said it is not guaranteed that the pain will never arise again also there could come some other problem too like paralysis of some body-parts.

Due to risk we didn't go for operation but we found a dentist who injected alcohol type injection in the molars (dad got his upper right molar removed a long time ago) of my dad and then dad didn't feel the pain for about one year. But after a year again he started feeling the same pain once again we went for the injection and again it worked for about one year and the same thing happened three to four times but about four to five months ago once again he started feeling the pain severe and once again we went for injection but it didn't work this time for a year and a week or two weeks ago once again my dad started feeling the same pain and once again we got him injected the same but this time the injection would work no more and pain won't go away.

Now the only option we are left with is operation which is a too high risk, anything could happen.
So what do we do now? the injections don't work now.
Should we go for operation or is there another way?

Please tell me with whatever good you can.
Thanks in anticipation.

[Maddy_MadHelp]

on receive e-mail that I have received a reply but here it is zero comment

[teddybears4ever2]

As we are not doctors here we can't really tell you how it will turn out.  Even if we could everyone is different.  With any surgery there are risks and what I would do is make out a list of pros and cons with your dad.  
If you are anything like me you really love your dad and would do anything for him.  If the pain is really bad I might go for it, but then again I don't know how hard the pain is to control for your dad.  I'm sorry the alternative treatment does't work for your dad anymore.  Maybe he developed an immunity to it.  I wish you and your family luck in making this decision.  Please come back and keep us posted.

[Maddy_MadHelp]

Thankyou very much teddybears4ever2