I recently attended an awake brain surgery for deep brain stimulation and it seemed to me that only the skin surrounding the drilled hole got local anaesthesia. I know that the brain itself does not have nociceptors, but what about the skull? And how does this compare to other bones in the body? Would you feel a hole being drilled in your skull? Would you feel your leg being chopped off if the surrounding tissue was numbed?
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3 Answers
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Yes, bones can be innervated. I say "can be" because although I'm not certain that ALL are, I know that most are. "Innervation" is your key word to learning more about the presence or absence of nerves reaching to any body part. Googling "are bones innervated" yields plentiful results, but the short answer is yes.
If you were to chop your leg off with surrounding tissue numbed, you would still feel it for this same reason.
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$\begingroup$ Can you put in some references please $\endgroup$ Commented Jul 17, 2014 at 8:39
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$\begingroup$ Sure thing: mananatomy.com/basic-anatomy/nerve-supply-bones and ncbi.nlm.nih.gov/m/pubmed/12123694/as well as ncbi.nlm.nih.gov/m/pubmed/19425099 $\endgroup$– yelxCommented Jul 17, 2014 at 17:03
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Thanks for your answer Alexandria,
As you didn't seem entirely confident about the innervation in the skull bone, I ended up asking the neurosurgeon, and she indeed only anaesthetises the skin surrounding the drill hole and the subcutaneous tissue as the bone does not have nociceptive innervation in that area. So you are right for the leg: if chopped off, you would still feel the pain from the nerves in the bone. In the case of deep brain stimulation however, the skull does not have nociceptive innervation in the area where the holes are drilled.
This leaves the question of why there are some exceptions to bone innervation, but that's a problem for another day.
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Sharp acute pain in response to acute physical breach comes mainly from the superficial periosteal innervation, and not much from internal bone innervation.
I am an orthopedic surgery internee. It's in our routine to drill ~3-5mm dia rods (steinmann pins) through bones of lower limb including femur, tibia and calcaneum. We too only inject anesthetic deeply into the skin, but that probably covers the perisoteal innervation too. At the end, when we doo the drilling, despite the great width of these aforementioned bones in comparision with the skull, patient seems calm while we transit through bone, and is only uneasy when the two skin ends are breached.
