Professor Minnu M. Panditrao gives her award winning (SAARC Bengaluru 2011) and recently published paper in Inidan Journal of Anaesthesia 56, 6 Nov.dec 2012, 575-78, paper where she explains the peculear responswe seen by herself and her team, about the developement of resistance to the local anaesthetic agents given via various routes, inpatients who give history of old single/ or usually multiple scorpion bites.

1. Does Scorpion Bite Lead to
Development of Resistance to
Effect of Local Anaesthetics?
: A Case Report

2. Dr. MINNU MRIDUL PANDITRAO
DEPARTMENT OF ANAESTHESIOLOGY &
INTENSIVE CARE
PUBLIC HOSPITAL AUTHORITY’S RAND
MEMORIAL HOSPITAL
FREEPORT, BAHAMAS

3. THIS CASE REPORT WAS AWRDED
“ THE BEST PAPER AWARD”
IN
9TH CINGRESS OF SAAARC
ASSOCIATION OF
ANAESTHESIOLOGISTS
CONFERENCE, BENGALURU
26TH – 28TH August 2011

4. THIS CASE REPORT HAS BEEN RECENTLY
PUBLISHED IN:
INDIAN JOURNAL OF ANAESTHESIA,
issue 56, volume 6, Nov-Dec 2012, page
no.s 575-578.

5. Introduction
• Failure of Local Anesthetic Block” : via various routes is
a rare but a known phenomenon !
• Various factors/causes have been considered to be
responsible for this i. e. technical difficulties, drug
errors etc.
• Even genetic factors like being a Redhead, i.e. carrying a
variants of the melanocortin-1 receptor (MC1R) gene, may
lead to resistance to not only local anaesthetics like
novocaine, lidocaine, but may make them resistant to
effects of inhalational anaesthetic agents like desflurane

6. • Can happen even in „ expert/ skillful‟ hands
• May be misinterpreted as a “technical or
Skill‟s failure”, causing embarrassment,
Low morale, wastage of time and resources
(needing G.A.)
• Unexplainable factors responsible for
this failure

7. Case Report
• 65 years old multi-para female
• Grade IV procedentia, cystocele,
rectocele and enterocele
• Posted for vaginal hysterectomy and
pelvic floor repair

8. Case Report ( contd.)
• Pre-op. evaluation:
H/O Hypertension, controlled with
Amlodipine 2.5 mg o.d.
G. P. E. Normal
M. P. C. grade II
Lab. Inv., X-ray, E.C.G., ECHO, were W. N. L.
• A.S.A. Grade II.
• Planned subarachnoid Block

9. Case Report ( contd.)
• Operative Procedure :
Infusion of D.N.S. with 20 Gz. I.V. cannula
Monitoring of E.C.G., SPO2 and NIBP
Aseptic Precautions , Lumbar Puncture
26 Gz. Quincke‟s needle at L3-L4 interspace
Sitting position
3.5 ml of 0.5% hyperbaric Bupivacaine
injected after free flow of CSF
Patient turned supine, with head down tilt
10o

10. Case Report ( contd.)
• No „Sensory or Motor Blockade‟ observed
• Waited for 10 minutes
• Increased Head down Tilt
• Waited another 10 minutes
• Still „No effect‟
• No changes in the vitals (PR, BP) observed

11. Case Report ( contd.)
• Decision to repeat „Spinal Block‟
• Performed by a Sr. Consultant at L2-3 Interspace
• Again 3.5 ml 0.5% Hyperbaric Bupivacaine of
different batch/ brand administered
• Patient made supine and 20o Head down tilt
• „ No Sensory/ Motor Block even after 30 min.
• No signs of „autonomic block‟ seen

12. Case Report ( contd.)
• On specific inquiry into past history
• Gave history of “Scorpion Bite” Two
times
• First at 17 years on right foot
• Second time, 8 months back on face,
right arm and forearm
• Decided to abandon the spinal block and
to give G.A.

13. Case Report ( contd.)
• Standard balanced G.A.
• Injs. Glycopyrrolate, Butorphanol
• Injs. Propofol, Rocuronium
• Intubation, O2, N2O and Isoflurane, IPPV
• Surgery lasted 105 min., uneventful
• Reversed with glycopyrrolate + neostigmine, extubated
• After recovery no signs of residual/delayed spinal block
• Follow up for 48 hours, uneventful.

14. Case Report ( contd.)
• Patient called in the O.T. on 8th post op. day
• Condition explained
• Informed consent obtained
• Peripheral Nerve Blocks of Median, Ulnar and Anterior
interosseous br. of Radial nerve given at the level of
left wrist with 0.5% bupivacaine
• Local infiltration of the skin of the left forearm was
done with 3 ml. of 2% xylocaine with adrenaline

23. Case Report ( contd.)
• Confirming our suspicion, there was neither any
sensory nor motor block observed
• Even the local infiltration did not produce any
perceptible sensory loss
• Patient observed for 2 hours in PACU and then
sent back to the ward
• Discharged on 10th Post operative day after
uneventful stay

24. Discussion
• Spinal anesthesia is not a 100% certain successful
technique.
• Failure rates of 0.72% to 16.0% have been reported
• Causes of failed spinal anesthesia can be classified as
1. Technical Failure to enter the subarachnoid space: no drug injection
2. Successfully injected drug may be maldistributed relative to
the need of the planned surgery
3. Un-recognized failed injection of the drug: partial or total
4. Drug errors : wrong drugs, inappropriate doses/ additives

25. Discussion
5. Pseudo block failure: excessive expectation for speed of block
onset
6. Subdural injection of the spinal dose: possible cause, but never
reported
7. Central neuroplasticity in Phantom limb pain and Human model of
tachyphylaxis
8. Local Anaesthetic Resistance: Genetic or acquired;
these are mystifying circumstances, as in our case, when there
is failure of spinal block, despite apparent technically correct
injection of the correct dose of drug

26. Discussion
• Mechanism of Local Anaesthetic Resistance:
 Receptor Mutation with Na+ Channel abnormalities
Resulting from variation in the amino acid sequence
within the Na+ Channel
Na+ Channel consists of α, β1, β2 subunits
α subunit has 4 domains (I-IV), each made of
6 segments (S1-S6)
• L.A. action is due to their interaction with S6-IV D
of α subunit (sites of Ph ala and Tyr A.A.residues)
• Variation/alteration at this site, can cause LAA
resistance

27. Structure of a Na+ channel α‐subunit

28. Discussion
• Scorpion Bites
• Common Phenomenon in Tropical/ subtropical Countries
• Scorpion venom neurotoxins possess general ability
to depolarise the excitable membranes due to an
increase in Na+ permeabilty of the resting membrane
and reduction in the rate and amount of Na
inactivation
• It may also modify Na pumping mechanism and
passive / active Na permeability systems

29. Discussion
• In acute phase : Pain, inflammation, N.M.
intoxication is due to venom acting on exposed
nerve or muscle fibers or N.M. Junction
• Muscular twitching/ fibrillations due to release
of neuro-transmitter/neurotoxins.
• Not much importance given to the past history of
scorpion bite by patients or anaesthesiologists

30. Discussion
• We had similar type of presentation- failed spinal in some
patients in the past, but did not give significant importance to it
• Inability to block the peripheral nerves as well as failure of local
infiltration, high lights the possibility of resistance to local
anaesthetics as the most plausible explanation in this case
• Since the patient was bitten by scorpion twice and at multiple
sites, it could have caused development of antibodies against
the scorpion venom leading to competitive antagonism at the
receptor site ( S6-D IV of α subunit of Na channel) where
LAAs are supposed to act

31. Observation
With h/o scorpion bite
• 2 cases of failed supraclavicular
brachial block, where local infiltration
was also ineffective
• 3 cases of failed spinal
• 7 cases of delayed effect of spinal
block
• We are making it our practice to elicit
the history, routinely

32. Conclusion
• We are convinced about the hypothesis:
 ‘Scorpion Bites ( especially repeated
bites) may cause development of
resistance to the action of local
anaesthetics used to achieve blocks
by various routes!’