1. Complications of peripheral nerve blocks
Dr. S. Parthasarathy
MD., DA., DNB, MD (Acu), Dip. Diab. DCA, Dip. Software statistics-
PhD ( physiology), IDRA

2. General complications
Peripheral nerve injury
Hematoma
Failure and rescue blocks
Infection
LAST
General complications
Not individual blocks

3. Peripheral nerve injury
Definition of an injury ?
More than one year
Incidence ? 0.4 %
Transient paresthesia – may be upto 8 %
Permanent damage ? 1.5 / 10,000
7000 peripheral nerve and plexus blocks performed with US- 30 were referred for neuro injury but three met criteria = 0.04 %
Shoulder arthroplasty - ? 4 % in one study
but under GA ??

4. Anatomy

5. Perineurium is difficult to penetrate What is intra neural
Breach the epineurium
Intra neural may be Intrafascicular or extra fascicular
Pressure less means intra neural or more means intra neural ??
Both can happen
Extra fascicular intra neural
Intraneural intra fascicular

6. “sweet spot of the nerve,”
For closed academic purpose only

7. Possible theories Second block Three months Laceration Pressure
Preexisting neuro illness
Double crush
Chemical ( local, additives , conc, betadine)
Laceration
Pressure
Ischemia
Long bevel needles ??
Vascular
Compression (entrapment)
Stretch ( 24 hours )

8. Syrinx
Fascicular arrangement – divides and groups but nerve maintain the same group – clean cut injuries better to suture

9. Can happen after a week or after complete recovery
What is it ??
Danger
Can happen after a week or after complete recovery

10. Danger signs Paresthesia on injection Pain on injection
In clinical practice, however, it can be difficult to discern when pain paresthesia on injection is “normal” and when it is the ominous sign of an intraneural injection

11. Stimulation
stimulation at currents higher than 0.5 mA may result in block failure because the needle tip is distant from the nerve,
whereas stimulation at currents lower than 0.2 mA theoretically may pose a risk of intraneuronal injection
Seems logical but studies ?
Neither nerve stimulators nor paresthesia appear to predict the proximity of the nerve and the needle

12. Abnormal resistance
? Intra neural
Anesthetists felt a change of resistance
The difference of 40 psi
Hence Ok but ??
Intra neural extra fascicular injection does not cause nerve injury
Anesthetized patients ??

13. Needle size and bevels
Long beveled needle - 15 degrees more likely to traumatize than short beveled needles 45 0
But short beveled needles the penetration of fascicle is less likely but after penetration the likelihood of injury is more with short beveled needles

14. Benzylpenicillin, diazepam, and paraldehyde
Other antibiotics and analgesics ?
Label the catheter
No similar tubing
educate nurses
Does betadine as a coupler go in to cause ?
Ischemia , adrenaline , hematoma and compression
Local anesthetics ?

15. Local anesthetics ? Bupivacaine – BP – 150 mg Ropivacaine BP – 190
Celiac – 100
Epidural 150
Lignocaine – 400 mg for all
Ropivacaine
BP – 190
Intercostal – 150
epidural – 150
Levo bupi -
Epidural – 75
BP – 250

16. Some other clinical pearls
Nerve blocks performed near bone have been associated with a high incidence of nerve dysfunction.
Round nerves are less likely to be impaled because the needle moves to the side during needle advancement
Nerve can regenerate
Factors that influence regenerative capacity of peripheral nerves include diabetes, preexisting neuropathy, age

17. Some other clinical pearls
Stretch the nerve ??
Cytotoxic potential tetra < bupi < ligno
But systemic toxicity – reverse
Nerve damage can start 48 hours after recession of block
Lumbar plexus block – highest incidence of complications – hematoma here - can cause hypovolumia

18. Ballooning is OK in plexus blocks but not with individual nerves

20. In summary, peripheral nerve injury associated with regional anesthesia is likely caused by a combination of insults to the nerve's internal milieu

21. What to do ?
Examine for deficits Sensory ( more chances of recovery) or motor USG and MRI Treatable cause – hematoma – evacuate Electro diagnostic studies
Reassurance

22. When and why ? Nerve conduction study Electromyography
High frequency ultrasound
MRI
Detect a nerve lesion – 1 – 2 days
Locate a lesion
2 -4 weeks
Morphology of nerve like swelling rupture and hematoma
Earliest – nerve anatomy within 24 hrs

23. A lot of protocols Wait for 3- 4 weeks – mostly recover
6 – 9 months – physiotherapy and go ahead with nerve grafts or other surgeries
Think of surgical causes
Non anesthesia related inflammation of the nerve (parsonage turner syndrome )
Drugs – no – so far
A lot of protocols

24. Always neurological injuries are not due to anesthesia factors

25. Failure

26. 3- 10 %
Definition of failure ??? Upto 30 %
Rescue blocks
Multiple injection points
Soak time
Sedoanalgesia
Reverse axis blocks !!

27. Hematoma EJV injury in interscalene— Lumbar plexus block
Aspirin, warfarin, heparin
Clopidogrel –
increase chances -Careful
USG and wait
Academic purpose only

28. Less than 1.5 INR – ok

29. Myotoxicity Local into the muscle – may cause inflammation
Edema necrosis and apoptosis reported
Femoral nerve catheter and myonecrosis reported
Normal recovery without residue – normal

30. Infection Extremely rare - aureus Aseptic precautions
Normal flora – staph epidermidis
Only one case of severe necrotizing fascitis reported after axillary block ( single shot)
Bupivacaine and clonidine have some antibacterial activity ? Less incidence

31. Risk of infection is more
Catheter
Catheter more than two days
ICU
No antibiotics
Femoral site

32. Recommendations for infection control
Grade A
Hand washing
Skin clean
with alcohol
Sterile gloves
Grade B
Face mask
Remove jewelry
Antiseptic to dry
Grade D
Gowns ,
Minimise disconnections during top up
Grade C – antibiotic prophylaxis

33. Summary
Nerve injury
Prevention
Treatment
Others