Uper Molar Extraction & Trismus

[rasmallai]

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OK, here's the scenario; patient has upper molar extraction, medial pterygoid muscle is pierced, and consequently develops trismus. How?

wat i think....'cos its a upper molar, most liely to hav used posterior superior alveolar nerve block (or is it?!)......if needle travels too far posteriorly, enters infratemporal fossa, pierces medial pterygoid muscle and vessel: causes bleeding...reflex contraction of jaw, leading to trismus

or am i barking up the wrong tree.......? is the pterygoid venous plexus likely to be involved, how close is it to medial pterygoid?

 

[dentaldoc]

There r lots of reasons for trismuss...we can only assume "can be becos of it"...but examining the pt clinically might help us to analyse the etiology....

Hope this helps...

 

[organic]

rasmallai

I could be totally wrong, but I believe that needles could possibly penetrate into Med. pterygoid muscles only in Inferior alveolar nerve block or other mandibular nerve block technqieus.

Thnk about the position and direction of Med. Pterygoid muscle. This muscle runs from pterygoid fossa and medial surface of lateral pterygoid plates to the medial side of mandibular ramus. Imagine that if you insert the needle correctly ( direction wise) for post. sup. alveolar nerve block, it is not possible to touch this muscle.

trismus in this situation could be caused by:

1. irritation to the muscle or tissues caused by local anesthetic (LA) solution

2. LA has slight myotoxic properties and could cause necrosis to exposed muscle fibers

3. hemorrhage-- as you said, there is the important pterygoid venous plexus around this area. Hematoma from penetration could cause trismus and swelling in this area. Sometimes you can even see purplish color through the skin in the area

4. Infection inonculated from needle ( not the extraction site)-- low-grade ( no fever) or high-grade ( with fever) -- usually appear after 24 hours

5. too large amount of LA solution deposisted at one time

6. extremely long procedures, patient's jaw muscles got spastic and exhausted

7. psychological factors

I would think that LA techniques used for upper 3rd molar extraction are not likely to cause penetration of muscles. If I have to guess, I'd say hematoma is the most likely possibility, if the technique is applied properly ( direction, amount, sterilization...)

please correct me if I am wrong
thank you

 

[rasmallai]

Wat you have said is completely true, but our anatomy tutors are being really awkward by stating the trismus was caused by an upper molar extraction. Thanx for the input, the presentation's 2mrw, wish me luck!

 

[organic]

It can be caused by upper 3rd molar extraction, but not due to piercing into med. Pterygoid muscle

 

[KAJALKIRAN]

hemorrhage-- as you said, there is the important pterygoid venous plexus around this area. Hematoma from penetration could cause trismus and swelling in this area.

It can be caused by upper 3rd molar extraction, but not due to piercing into med. Pterygoid muscle

i would go with this explanation, as an infected hematoma is a more likely cause of trismus, and hematoma formation is quite easy in the psan block