The Scorpion Block—A Sting operation

J. Sivagurunathan1, S. Khaja Mohideen2, K. Senthil Kumar3

1Consultant, Department of Anaesthesiology, Kauvery Hospitals, Trichy

2Senior Consultant Department of Anaesthesiology, Kauvery Hospitals, Trichy

3Senior Consultant & Head Department of Anaesthesiology, Kauvery Hospitals, Trichy

Abstract

Subarachnoid block is the preferred technique of anaesthesia for lower abdominal and lower limb surgeries. Resistance or failure to achieve the block with local anaesthetic agent by various routes is an uncommon but known phenomenon. Various factors have been attributed to this, one of them being scorpion venom. Here we report one such case of failed spinal anaesthesia in a patient with history of scorpion sting.

Key Words: Resistance to local anaesthesia; Failed spinal anaesthesia; Scorpion venom

Case Presentation

A 13 year old boy weighing 38kg, was posted for wound debridement of right foot. He had no comorbid illness. His blood investigations were normal and hence assessed under ASA-PS IE for spinal anaesthesia. Under strict aseptic precautions with patient in sitting position, spinal anaesthesia was given at L3-L4 inter vertebral space using 27G Whitacre spinal needle in single attempt with 2.5ml of 0.5% hyperbaric Bupivacaine. The drug (2.5ml of 0.5% hyperbaric bupivacaine) was injected into sub arachnoid space after confirming free flow of CSF on aspiration. The patient was then made to lie supine. Even after waiting for 20 min patient did not develop sensory or motor block. His haemodynamics were also stable. The spinal drug and its shelf life was once again verified and was found to be appropriate. Once again spinal anaesthesia was repeated with 2ml of 0.5% hyperbaric Bupivacaine using the same size needle at L2-L3 inter vertebral space. Inspite of waiting for nearly 30 min, patient did not develop sensory or motor block. On enquiring the patient once again, he remembered and gave history of scorpion sting 8-10 months back. Resistance to local anaesthetic action was considered. Hence the procedure was carried out under general anaesthesia. The surgical duration was about 90 minutes and uneventful. Patient did not develop any sensory or motor blockade in the postoperative period also.

Discussion

Spinal anaesthesia is a blind procedure that is performed by identifying the anatomical landmarks. Causes of failed spinal anaesthesia are

  • Successfully injected drugs that are mal-distributed relative to the needs of the planned surgery.
  • Unrecognized failed injection of drugs.
  • Technical failure to enter the subarachnoid space with no drug injection.
  • Drug errors i.e., expired drugs and in-appropriate additives.
  • Local anaesthetic resistance.
  • Pseudo block failure due to excessive expectations for speed of block onset.
  • Subdural injection of drug.

Local anaesthetic agents act by binding with sodium channel in closed, open or inactivated state. Sodium channel have three subunits eg; alpha, beta-1 and beta-2 subunits. The alpha subunit has further four homologous domains (I-IV) and each domain is made up of six Trans membrane segments (S1-S6). Mechanism of action of local anaesthetics is believed to be due to interaction with S6 of domain four of alpha subunit (IV-S6).

Hottentotta tamulus– the Indian red scorpion, belongs to the family Buthidae, and is commonly found in India. Scorpions use their venom to defend against predators and to capture prey.

The composition of scorpion venom is highly complex and heterogeneous. Up until now, small scorpion venom peptides are the most studied compounds mainly due to their diversity and broad pharmacological properties. Accordingly to their structure, these small peptides are classified into three large super families: peptides containing cysteine-stabilized (CS) α/β motifs, calcins, and non-disulfide bridged peptides (NDBPs). However, enzymes (larger proteins), mixtures of inorganic salts, free amino acids, nucleotides, amines, and lipids are also found in scorpion venom.

The venom of some species can cause prolonged depolarization by causing incomplete inactivation of sodium channels resulting in a slow influx of sodium. This influx then leads to membrane hyper excitability and unregulated axon firing by inhibiting the inactivation of an action potential. The neurotoxins also cause the excessive release of acetylcholine from parasympathetic ganglia as well as the release of epinephrine and norepinephrine from sympathetic ganglia and the adrenal glands. In turn, envenomation can produce cholinergic as well as sympathetic stimulation. Typical cholinergic symptoms include diaphoresis, priapism, lacrimation, vomiting, diarrhea, and bradycardia. Typical sympathetic symptoms include hypertension, tachycardia, and restlessness.

Alpha and Beta toxins act on sodium channels. Scyllatoxin, charybdotoxin and tityus toxin inhibits calcium dependent potassium channels and also causes opening of sodium channels at presynaptic nerve terminals.

Scorpion venom and local anaesthetic agents have common site of binding i.e., the S6 of domain four of alpha subunit (IV-S6). The proposed hypothesis for this local anaesthetic resistance is the elicitation of strong immunological response by the antigenicity of scorpion venom. This leads to the development of antibodies against the binding site. As the binding site is same for local anaesthetic, later on in life when these sensitized persons are exposed to local anaesthetic agents, the drugs are unable to bind with the receptor because of the competitive antagonism by the antibodies formed.

The resistance may manifest as inadequate block or block failure requiring conversion to general anaesthesia. Studies show that, in patient with recent history of scorpion sting (<6 months) there is complete failure of spinal anaesthesia. Whereas in patients with history of scorpion bite > 6months and >1 year had delayed onset of sensory or motor block and adequate level of blockade respectively.

Conclusion

Previous single/multiple scorpion sting can cause development of resistance to the effect of local anaesthetic agents administered via various routes. Number of sting and more recent the sting, more the chances of failure or inadequate block or delayed onset of action. Hence attention should be paid in eliciting previous history of scorpion sting and duration since last sting. Regional anaesthesia should be avoided in patients with recent (6–8months) history of scorpion sting.

References

  • Mridul M Panditrao, et al. Development of resistance to the effect of local anaesthetic agents administered via various routes due to single or multiple previous scorpion bites. J Anesth crit care open Access 3(5): 00110. DOI:10.15406/jaccoa.2015.03.00110
  • V Sunilkumar, et al. Effect of previous scorpion bite(s) on the action of intrathecal bupivacaine: A case control study. Indian J Anaesth 57(3): 236-240. DOI 10.4103/0019-5049.115593
  • Kosam D, et al. Effect of previous scorpion sting on the efficacy of spinal anaesthesia- A case control study. Int J Med Res Rev 2015;3(8):826-831.
  • Ahmadi S, Knerr JM, Argemi L, Bordon KCF, Pucca MB, Cerni FA, Arantes EC, Çalışkan F, Laustsen AH. Scorpion Venom: Detriments and Benefits. Biomedicines. 2020 May 12;8(5):118. doi: 10.3390/biomedicines8050118.
  • Shamoon Z, Peterfy RJ, Hammoud S, et al. Scorpion Toxicity. [Updated 2023 Aug 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan.

Dr. J. Sivagurunathan
Consultant, Department of Anaesthesiology

Dr. S. Khaja Mohideen

Dr. S. Khaja Mohideen
Senior Consultant – Anesthesiologist

Dr K Senthil kumar
Dr. K. Senthil Kumar
Senior Consultant and HOD of Anaesthesiology

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