An 80 years old, bronchial
asthmatic, male was posted for left cataract extraction with intra ocular lens
implantation. He was administered peribulbar block/left facial nerve block.
There was no sensory or motor block. Thereafter peribulbar block was
repeated. Only partial akinesia was achieved, so under intermittent intra venous
sedation, the surgery continued for 40 minutes. In the post-operative period,
no signs of any residual/delayed block were noted. On specific enquiry, patient
gave history of scorpion bite thrice, at the age of 27 years on his right
foot, about 8-9 years back and again about 6-7 months back on his right hand.
On 4th post-operative day after obtaining informed consent, local infiltration
of the skin on the ventral aspect of the forearm, using, 6 mL, 2% lignocaine
with adrenaline, was carried out. Confirming the suspicion, there was no
sensory block after the injection, confirmed by pin prick method. Peribulbar
block produces adequate intra-operative analgesia for cataract extraction. The
cause of the failures may be due to technical inability to achieve block.
However failure that occurs despite of technically correct injection of the
correct drug can be mystifying. As the scorpion venom
is known to affect the pumping mechanism of sodium channels in the nerve
fibres, which are involved in the mechanism of action of local anaesthetic
drugs, it may be responsible for the development of “resistance” to the action
of local anaesthetic agents.