Anesthesia Tutorial of the Week Quiz

1) The incidence of Peripheral Nerve Injuries has reduced since the advent of ultrasound.

2) The perineurium is more permeable than the epineurium.

3) The peripheral nerves receive their vascular supply from 2 sources: a capillary network known as the vasa nervorum, and 2) via arterioles, veins and capillaries in the epineurium.   

4) On Seddons’ classification, a neurotmesis is the most severe injury, with a poor prognosis.

5) With Sunderland’s classification, a type 2 injury equates to axonal injury with endoneurium disruption.

6) Potential risk of PNI includes malpositioning of the insensate limb post-surgery. 

7) The popliteal sciatic nerve has a relatively higher neural to connective tissue ratio compared with the brachial plexus in the interscalene region.

8) Using an adrenaline adjunct for PNB can potentially cause localised ischaemia.

9) A short bevelled needle is more likely to penetrate perineurium than a long bevelled needle, but injury tends to be less severe. 

10) Increased needle diameter is associated with increased severity of injury.

11) When using a peripheral nerve stimulator, you can proceed with injection having elicited a response at 0.6mA, but no response at 0.4mA.

12) Research so far suggests that injection pressure monitoring is a specific but not sensitive method of avoiding PNI.

13) Being able to differentiate between intra- and extraneural needle tip placement is a key safety feature of ultrasound.

14) Around 95% of PNIs will self-resolve within 6 weeks. 

15) Nerve fibres are grouped together into fascicles surrounded by epineurium.

16) There is no association between the number of needle passes and risk of PNI.

17) Following an interscalene PNB, a patient who recovers with ipsilateral eyelid droop and miosis has most likely had a CVA.

18) A raised contralateral hemidiaphragm on preoperative X-ray is a relative contraindication to interscalene PNB.

19) Severe pain on initial injection of local anaesthetic doesn’t suggest a risk of nerve injury if it subsides with further injection

20) A patient with an apparently working sciatic block for ankle ORIF who postoperatively complains of excruciating calf pain may need intracompartmental pressure measurement.