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Re: Safety of Articaine in subarachnoid space
- Helena Kallio, Martina Bachmann, Pertti Pere, Pekka Kairaluoma, Per H. Rosenberg (16 December 2008)
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Safety of Articaine in subarachnoid space
- Muhammad Rahim Kayani (5 December 2008)
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Helena Kallio , Martina Bachmann, Pertti Pere, Pekka Kairaluoma, Per H. Rosenberg
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Editor - We appreciate very much the considerate comment by Dr. Krucheck and Dr. Kayani regarding the suspicion of neurotoxicity of articaine in dental nerve blocks. This has been discussed vividly in the literature during the last few years in particular in Canada1 and Denmark.2 The mechanism of sensory deficits after dental nerve blocks, the mandibular nerve block in particular, has often remained unclear and such disturbances seem to have followed even when there was no paraesthesia from the injection needle. It cannot be denied that high concentrations of any local anaesthetic can be neurotoxic when the solution is deposited in the immediate vicinity of the nerve, or even into a nerve (by mistake), or as in the case of the mandibular nerve block, into a narrow bony canal encasing the nerve. What is often missing in the discussions about neurotoxicity of local anaesthetics in peripheral nerve blocks are the methods of diagnosis and verification of an intraneural block, which may happen even without clearly experienced paraesthesia, the risk of which in many regional anaesthetic blocks has diminished in recent times due to the use of ultrasound-directed techniques. Another aspect often missing in the discussion about mechanisms of nerve damage is the role of adrenaline in the local anaesthetic solution. Adrenaline injected into a nerve may worsen the damage caused by the needle3 and, in addition, it induces vasoconstriction with reduction of the blood perfusion of the nerve. In spinal anaesthesia, articaine is deposited into the lumbar cerebrospinal fluid where it is immediately diluted, and it is further diluted in the diffusion process. Therefore, the risk that the spinal nerves are exposed to very high concentrations is very low. In theory this could occur if the patient would remain in an anti-Trendelenburg position for some time after the injection of a hyperbaric solution. Adrenaline is not added to articaine in spinal anaesthesia, but the influence of a small adrenaline addition on spinal blood flow has anyway been regarded as negligible, or very minimal.4 We conclude that all local anaesthetics are toxic when applied at high concentrations and the risk of nerve damage rises if the solution is applied directly on (or in) the nerve, which is not the case in spinal anaesthesia. In any respect, more studies on the toxicity of articaine, and other local anaesthetics are needed, and some new are already under way. 1. Smith MH, Lung KE. Nerve injuries after dental injection: a review of the literature. J Can Dent Assoc 2006; 72: 559-64 2. Hillerup S, Jensen R. Nerve injury caused by mandibular block analgesia. Int J Oral Maxillofac Surg 2006; 35: 437-43 3. Selander D, Brattsand R, Lundborg G, Nordborg C, Olsson Y. Local anesthetics: importance of mode of application, concentration and adrenaline for the appearance of nerve lesions. An experimental study of axonal degeneration and barrier damage after intrafascicular injection or topical application of bupivacaine (Marcain). Acta Anaesthesiol Scand 1979; 23: 127-36 4. Neal JM. Effects of epinephrine in local anesthetics on the central and peripheral nervous systems: neurotoxicity and neural blood flow. Reg Anesth Pain Med 2003; 28: 124-34 Conflict of Interest:None declared |
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Muhammad Rahim Kayani
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Dear Sirs We read with interest the article “Comparison of hyperbaric and plain articaine in spinal anaesthesia for open inguinal hernia repair” and feel a comment on the safety of this drug in the confines of the sub arachnoid space should be made. The authors statement about the safety of articaine as an appropriate local anaesthetic agent for spinal anaesthesia includes the phrase. “It has been found safe in preclinical toxicology testing and (its) low degree of toxicity has been verified to result from ester hydrolysis of a sidechain on the molecule.” However, in 2005, the Danish Medicines Agency was compelled to initiate a study of the local anaesthetic articaine, which is used in dental care in Denmark and other parts of Europe . The reason was that the Danish Medicines Agency had received information about occurrences of sensory impairment (paraesthesia, nerve damage) in patients who had been given local anaesthesia in the lower part of the mouth or the lower jaw (mandibular block) with articaine. The suspicion is based on: • an increased number of damages reported to the Danish Dental Association’s Patient Insurance Scheme • adverse reaction reports submitted to the Danish Medicines Agency • a number of open observation studies carried out in Denmark • notifications in the literature about the result of relatively retrospective statements about patients, as well as experimental animal studies. This information raised a suspicion that articaine might cause nerve damage and that the risk of using articaine (at least in Dentistry) is greater than the risk of using alternatives (mepivacaine, prilocaine, lidocaine). The Danish Medicines Agency believes that further studies are required. It is necessary to make animal trials with a view to examining whether/to what extent articaine may cause nerve damage. Furthermore, it is necessary to examine a large number of patients in prospective blinded and randomised studies. The Danish Medicines Agency was going to urge the marketing authorisation holder to perform such studies. Further the article qualifies the choice of articaine as a spinal agent from 2000 published cases since 1976. We ask the authors in view of an unresolved controversy surrounding Articaine and the apparent lack of published experience of this drug in spinal anaesthesia to justify an unrestricted use of this drug in the subarachnoid space. Dr. D. Krucheck F.R.C.A Dr. M.R.M.Kayani M.R.C.A Ashford & St Peter's Hospitals NHS Trust Conflict of Interest:None declared |
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