Can repeated scorpion bite lead to development of resistance to the effect of local anesthetics? Maybe it does!

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 postoperative 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.