Does scorpion bite lead to development of resistance to the effect of local anaesthetics?
A 65-year-old multiparous female with grade IV procedentia, cystocele, rectocele and enterocele was admitted for vaginal hysterectomy and pelvic floor repair. On pre-operative evaluation, she gave history of hypertension, controlled with Tab. Amlodipine 2.5 mg once a day. Her general physical examination was normal and she was Mallampati grade II. All the laboratory investigations, chest X-ray, ECG and two-dimensional echo cardiography were within normal limits. She was accepted for vaginal hysterectomy and pelvic floor repair as ASA grade II.\nInside the operation room, intravenous infusion of 5% Dextrose in normal saline was started with a 20 gauge indwelling intravenous cannula. Three-parametric monitoring including ECG, oxygen saturation (SpO2) and non-invasive blood pressure (NIBP) was started. Under all aseptic precautions, lumbar puncture was performed at the level of the L3-4 interspace with a 26 gauge Quincke's needle in sitting position. After confirming the free flow of cerebrospinal fluid (CSF) on aspiration, 3.5 mL 0.5% of hyperbaric bupivacaine was injected into the subarachnoid space. Thereafter, the patient was made supine with 10 degrees head down tilt. In spite of waiting for 20 min, the patient did not show any signs or symptoms of sensory block, as confirmed by pinprick method or of motor block, as confirmed by movements of lower limbs or toes.\nThe patient was made to sit up again and spinal anaesthesia was repeated. This time, it was given by a senior consultant with >25 years of professional experience at L2-3 interspace. Again, 3.5 mL of 0.5% hyperbaric bupivacaine of a different batch and brand was injected after confirming the free flow of CSF on aspiration. The patient was made supine and 20 degree head down tilt was given. To our dismay, this time also, there was no sensory or motor block in spite of waiting for 30 min. The patient also did not show any signs of autonomic block, i.e. hypotension, bradycardia or even tachycardia. Motor power in both the lower limbs was grade IV and there was no sensory block at any dermatomal level.\nAt this point, after very specific inquiry into past history, the patient gave history of scorpion bite twice; first, at the age of 17 years, she had scorpion bite on her right foot and the second time, she had scorpion bites on her face, neck, right arm and forearm about 8 months back (this happened when she was sleeping on the floor in her farmhouse).\nThereafter, it was decided to give standard balanced general anaesthesia for the procedure. The patient was given Inj. Glycopyrrolate 0.2 mg IV, followed by Inj. Butorphanol 1 mg IV. Induction was done with Inj. Propofol and Inj. Rocuronium and, after intubation, anaesthesia was maintained with oxygen and nitrous mixture, isoflurane and controlled ventilation. The surgery lasted for 105 min, and was uneventful. After the end of surgery, residual paralysis was reversed with Inj. Neostigmine and Glycopyrrolate and the patient was extubated after adequate recovery of respiration, laryngeal and pharyngeal reflexes. In the immediate post-operative period, after recovery of consciousness and orientation, she did not show signs of any residual/delayed neuraxial block. The patient was followed up in the post-operative period for the next 48 h, which was uneventful.\nOn the eighth post-operative day, the patient was called to the operation theatre accompanied by her daughter and a gynaecology resident. After explaining them about her possible special condition (? Resistance to local anaesthetic agents) and obtaining informed consent, the patient was administered peripheral nerve blocks of left median, ulnar and anterior interosseous branch of radial nerves at the level of wrist (wrist block) using 0.5% bupivacaine (total volume 12 mL). Also, local infiltration of the skin near the anatomical snuff box of the left arm using 2% xylocaine with adrenaline (total volume 3 mL) was carried out. Confirming our suspicion, there was neither sensory nor motor block after these injections. Even the infiltration did not produce any perceptible sensory loss. The patient was observed in the recovery room for the next 2 h and then sent back to the ward.\nOn the 10th post-operative day, after satisfactory recovery from the surgical procedure, she was discharged from the hospital.