Should local anesthetics be banned during treatment of palmar hyperhidrosis with botulinum toxin A?
Antranik Benohanian MD
Dermatology Online Journal 13 (3): 33

Montreal University Hospital Center, Hôpital Saint-Luc, Montreal, Quebec. info@benohanian.com

I read with great interest the comments by Lim and Seet on the possible long-term effects of prolonged and repeated injections of local anesthetics and the permanent neurotoxicity that may result [1, 2].

Paracelsus, one of the pioneers of toxicological science, about 400 years ago, stated that there are no toxic materials, there are only toxic doses. The average lidocaine volume per spurt delivered through the needle free injector Med-Jet® MBX (manufactured by MIT Canada, a subsidiary of Medical International Technology USA) prior to the injection of botulinum toxin type A (BTX-A) with needle is 0.02 mL per site [3, 4, 5]. Assuming that 40-50 such sites are to be injected per hand, the total volume will hardly exceed 1 ml. This is in agreement with the recommendations brought up by the authors of the referenced article by Lim and Seet as follows: "other than using the lowest possible concentration and dosage of local anesthetics, no other option is currently available to prevent local-anesthetic induced direct neurotoxicity" [1]. Further, this volume of 1 ml of lidocaine is much less than that used in a traditional nerve block, the latter being 5 to 6 times more.

Although not recommended by the manufacturer, reconstitution of BTX-A in lidocaine, originally published by Gassner [6], started to gain popularity when two other studies confirmed that toxin potency is not affected [7, 8]. Based on the results of their study, Vadoud-Seyedi and Simonart concluded that reconstitution of BTX-An in lidocaine jeopardizes neither the short-term nor the long-term results achieved with BTX-A in the treatment of axillary hyperhidrosis (HH) [7]. Moreover, they even recommend that the procedure be evaluated for patients with palmar and plantar HH to eventually replace peripheral nerve blockade [7]. However, the authors did not elaborate how they would deliver the diluted BTX-A through the densely innervated dermis of the palm where eutectic mixtures of local anesthetics such as Emla® fail to control the pain caused by the needle prick during BTX-A injection. One valid option would be through needle free lidocaine injection (jet anesthesia). The injectate, delivered through the MED-JET® is directed through a small orifice about four times smaller than a 30 G needle. As most of the pain occurs during the piercing of the skin itself, the smaller the orifice the better the pain control will be. The high speed penetration during jet anesthesia is another factor contributing to the reduction of pain. The amount of pain generated by jet anesthesia is no more than that induced by an elastic band snapped against the palmar skin. Conversely, lidocaine injected with a needle will not be of any help to relieve the pain during the needle prick itself.

Similarly, Alam et al. found that the use of preservative-containing saline to reconstitute BTX-A can significantly decrease patient discomfort on injection [9]. The preservative used was benzyl alcohol, which, besides having anesthetic properties, may also prolong the stability of the product with refrigeration for 5 weeks. Their work was based on facial skin.

In my practice, I have found that BTX-A injections, topical aluminum chloride formulations [10] and iontophoresis, when used in combination, may act synergistically to (a) reduce the BTX-A dose and (b) extend the interval between BTX-A injections beyond the 3-month period mentioned by Lim and Seet [2]. Low BTX-A doses together with longer intervals between their injections not only lower the treatment cost but may also prevent antibody formation that neutralizes the effect of BTX-A [11].

Even though cryo-analgesia is considered by many to be a useful technique to inject BTX-A for palmar HH, difficulty is encountered when the diluted BTX-A is injected into frozen tissues [12], this will need a wait of 2-3 seconds per site in order that the tissue warms up before injecting the drug. This is not an issue with jet anesthesia, which, when delivered through an appropriate device, remains one of the convenient ways to treat palmar HH. The technique can be viewed at http://www.benohanian.com/multimedia/AVSEQ02_1.wmv.

Dimache et al. reported that jet injectors can be safely used in the medical practice if they are protected by the sterile anticontaminant disposable device [13]. The Med Jet MBX is now equipped with a sterile disposable anticontaminant nozzle, easily replaced within a few seconds, that may allow treatment of more than one patient without necessarily undergoing a thorough sterilization of the equipment.

There is no perfect, completely painless and risk-free treatment for palmar hyperhidrosis. Luckily, as a recent article in Therapy shows [10], there are now more options available than in the last century. It is important to constantly review what scientific information is available on each approach to ensure the most appropriate choice in each case.

References

1. Lirk P, Haller I, Myers RR, Klimaschewski L, Kau YC, Hung YC, Gerner P. Mitigation of direct neurotoxic effects of lidocaine and amitriptyline by inhibition of p38 mitogen-activated protein kinase in vitro and in vivo. Anesthesiology. 2006 Jun;104(6):1266-73.

2. Lim EC, Seet RC. Another injection-free method to effect analgesia when injecting botulinum toxin for palmar hyperhidrosis: cryoanalgesia. Dermatol Online J. 2007 May 1;13(2):25.

3. Benohanian A. Palmar hyperhidrosis. Needle-free anesthesia as an alternative to Bier's block and peripheral nerve blockade for botulinum toxin therapy. Dermatol Online J. 2006 Oct 31;12(6):26.

4. Benohanian A. Needle free anaesthesia prior to botulinum toxin type-A injection treatment of palmar and plantar hyperhidrosis. Br J Dermatol. 2007;156 (3), 593–596.

5. Benohanian A. Needle-free anesthesia: A promising technique for the treatment of palmoplantar hyperhidrosis with botulinum toxin A. Therapy 2006. 3;5:591-596

6. Gassner HG, Sherris DA. Addition of an anesthetic agent to enhance the predictability of the effects of botulinum toxin type A injections: a randomized controlled study. Mayo Clin Proc 2000;75:701-4.

7. Vadoud-Seyedi J, Simonart T. Treatment of axillary hyperhidrosis with botulinum toxin type A reconstituted in lidocaine or in normal saline: a randomized, side-by-side, double-blind study. Br J Dermatol. 2007 May;156(5):986-9.

8. Gorgu M, Silistreli OK, Karantinaci B, Ayhan M, Ozdemirkiran T, Celebisoy M. Interaction of botulinum toxin type A with local anesthetic agents: an experimental study with rabbits. Aesthetic Plast Surg. 2006 Jan-Feb;30(1):59-64.

9. Alam M, Dover JS, Arndt KA. Pain associated with injection of botulinum A exotoxin reconstituted using isotonic sodium chloride with and without preservative: a double-blind, randomized controlled trial. Arch Dermatol. 2002 Apr;138(4):510-4.

10. Benohanian A, Boudjikanian A, Paylan Y. Palmar and plantar hyperhidrosis: a practical management algorithm. Therapy 2007;4(3):279-283.

11. Dressler D. [Pharmacological aspects of therapeutic botulinum toxin preparations.] Nervenarzt. 2006 Aug;77(8):912-921.

12. Kontochristopoulos G, Gregoriou S, Zakopoulou N, Rigopoulos D. Cryoanalgesia with Dichlorotetrafluoroethane Spray Versus Ice Packs in Patients Treated with Botulinum Toxin-A for Palmar Hyperhidrosis: Self-Controlled Study. Dermatol Surg 2006;32:873-874.

13. Dimache G, Croitoru M, Balteanu M, Butur D, Negut A, Dimache A, Paul F, Barbu A, Velea L, Alexandrescu V, Isacu F. .A clinical, epidemiological and laboratory study on avoiding the risk of transmitting viral hepatitis during vaccinations with the Dermojet protected by an anticontaminant disposable device. Vaccine. 1997 Jun;15(9):1010-3.

© 2007 Dermatology Online Journal

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Title:

Should local anesthetics be banned during treatment of palmar hyperhidrosis with botulinum toxin A?

Journal Issue:

Dermatology Online Journal, 13(3)

Author:

Benohanian, Antranik

Publication Date:

2007

Publication Info:

Dermatology Online Journal, UC Davis

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