Expert: Dr Ian Jackson - please note UK based - 5/28/2008

Question
QUESTION: Hello, I recently went to my dentist for root canal treatment. I have had it on a couple of teeth before with no problem. This time, I had the usual injection and he cleared to of the canals, but on entering the third I felt like I was about to faint. My head started swimming and my chest fluttered badly. After sitting up, I felt old and shaky. I can only describe it as if my body had reacted severe pain, although I couldn't feel any pain. I went back 3 weeks later to try again. All was going fine until he hit exactly the same spot again and I had the same reaction and we had to stop again. He confirmed that it was exactly the same spot again and he does not think it was a voluntary or anxiety related reaction now.

Is it possible for your body to react to pain even if you cannot sense it? For instance, I know you can still feel pressure during dental procedures. Could this cause this kind of reaction?

I have a small abscess under that tooth and his guess was that pushing into the canal somehow transfered the pressure through the canal, through the abscess, and onto another nerve in the lower jaw. The tooth was second from back on the lower left (my left) if that makes any difference.

I apologise if this is not your field, but seeing as my dentist is at a loss for explanations, I thought your skills may be able to shed some light.

Could my body have a similar effect under general?

Thankyou

ANSWER: Hi Neil
Now that is an interesting one. especially as it has happened twice. I don't really buy the pushing on another nerve bit as if it did it would most likely cause pain as well as the reaction you felt. If there is an abscess above the tooth then perhaps when pressure is applied small amounts of 'pus' from the abscess gets into your bloodstream and that makes you feel ill.
There are other nerve fibres from what is called the autonomic nervous system that might not be blocked that could lead to a reaction but not very likely and also the symptoms would be more likely to be that of a faint rather than as you have described. Your despcirption fits with an intravascular injection of local anaesthetic and adrenaline but that must have been given sometime before he actually started the treatment.
So I am also at a loss but would tend more towards the release of pus and nasty products that your body creates inside abscesses being released into your circulation as a cause.
Sorry can't shed more light on this.
Dr Ian Jackson

---------- FOLLOW-UP ----------

QUESTION: Thankyou very much for the response. I appreciate your time.

I am curious about what you said about the autonomic nervous system. If pressure was being put on these fibres/nerves in my jaw, what would the effect be? For instance, would I feel pain, or just the faint approach. Why would my body react like that? If it was just the faint then that could certainly fit in with what I experienced, as the chest flutter could very well have been me panicking at the faint setting in (possibly?).

A little more history is that my dentist has struggled to find certain nerves in my mouth before when numbing teeth to the rear of the mouth and 1 molar tooth 3 visits to numb. Now he has the spot in his notes, he gets it every time.

One other slightly strange thing (I'm really not a complainer, so please don't put me down as a hypochondriac :-) ) is that I often don't react as well to local anesthetics on one side of my body. I have experienced this in a toe operation (one of each foot. One side was fine, the other was loaded up with so much local that they couldn't squeeze more in and it was still painful) and vasectomy (once again, far more local on one side and I could still feel the cut and pressure).

Is this common?

Finally, and I apologise for asking so much here, Do you also think it would be possible for my body to react so instantly to pus entering the blood stream?

Thankyou for you so much for your time.

best regards

Neil

Answer
Wow, that is a lot of ground to cover.
Last bit first - it is very possible for your body to react very quickly to anything released in your bloodstream. The contents of an abscess (the pus) is made up from bacteria and white blood cells that have been trying to deal with the infection. The white blood cells release all sorts of neurohumeral factors (substances that can have an effect on the nervous system and other parts of the body - a bit like hormones). This is complex and not something anyone can get their head round easily - however it is not usually a problem especially from a small abscess)
Now the difference between left and right side of your body. The insertion of local anaesthetic is not a perfect art - indeed it is an art. For the local anaesthetic to work it needs to be injected close to (but not in) the nerve, This is where we sometimes have problems. Everyone is different and nerves can take slightly different routes - hence your dentist has had problems doing specific blocks in yopur mouth. Your problems between one side and another are almost certainly (99.9%) down to chance ie if you were to have 100 procedures on 2 sides then it would balance out with similar number of failures on each side. Notice I didn't say 100% as I never totally discount anything but it would be difficult to explain how you might have nerves with different susceptability to local anaesthetics on different sides of your body.
The toe thing happened to my wife and many colleagues have struggled a bit with the LA for vasectomy in certain patients - this is not helped by the understandable anxiety the procedure causes in patients.
Autonomic nervous system.
Certain areas of the body are well innervated by this system - famous areas being the eyes, the cervix and the anus. Operations on these areas can cause profound stimulation of this system and lead to sudden profound bradycardia i.e. slowing of the heart rate (not flutter or palpitations) to the extent the heart can actually stop. The eyes in particular are famous for this - called oculo-cardiac reflex.
Flutter and palpitations are more associated with excess of adrenaline, nicotine, caffeine and various stimulant drugs. Hence I mentioned it as dentists tend to use a mixture of local anaesthetic plus a vasoconstrictor (which is a stimulant like adrenaline).
At the end I cannot give you a diagnosis - just some other ideas and background stuff. I suspect you will never know exactly what has been happening.
Kind regards
Dr Ian Jackson