Postinjection paresthesia with articaine: a case report

 

Michael J. Wahl, DDS* and Patrick T. Wahl, DMD#

*Corresponding author
Private practice
1601 Concord Pike
Wilmington, DE 19803

#Department of Oral and Maxillofacial Surgery
School of Dental Medicine
Temple University
Philadelphia, PA

Abstract. Local anesthesia has revolutionized dental practice allowing for dental procedures to be performed relatively painlessly, but like any drugs, local anesthetics are associated with possible side-effects, including postinjection prolonged paresthesia. We report a case of postinjection paresthesia after an inferior alveolar injection with articaine. Dentists should weigh the advantages and disadvantages of an anesthetic before choosing one for a particular procedure. When comparing articaine 4% with epinephrine and lidocaine 2% with epinephrine for inferior alveolar block injections, clinicians should be aware of articaine’s higher, allowing for less anesthetic volume to be administered before reaching the maximum recommended dose. Articaine 4% with epinephrine also seems to have a greater association with postinjection paresthesia than lidocaine 2% with epinephrine.

Keywords: articaine, paresthesia, local anesthetics, lidocaine

Ever since its discovery in the 1880s, local anesthesia has revolutionized the practice of dentistry, allowing both simple and complex dental procedures to be accomplished relatively painlessly. Although its benefits are numerous, local anesthesia is also associated with potential unwanted side-effects, rarely including prolonged paresthesia, defined by Malamed as an alteration in sensation lasting more than 24 hours postinjection.1 We present a case of prolonged paresthesia after an articaine anesthetic injection.

A 59-year-old male patient with no significant medical history presented on 8/23/07 for root canal therapy of #29 by one of the authors (PTW), which was vital but painful. After administering two cartridges of articaine hydrochloride 2% with 1:200,000 epinephrine (Septocaine, Septodont), the patient was not profoundly numb. A third injection was therefore administered. While this injection was being administered, the patient reported feeling a “jolt” and an “electric sensation,” but profound anesthesia was finally achieved.

Root canal therapy was completed uneventfully, and the canals were filled within the radiographic apices. When contacted the next morning, the patient reported that he was fine, but that his right lower lip and tongue were still numb. We remained in contact with him weekly, but there was no improvement until four weeks after the injection, when the patient reported some improvement, but that his right lip and tongue were still profoundly numb. On 10/23/08, two months after the injection, the patient reported no further improvement.

On 11/20/08, three months after the injection, the patient was not certain, but there may have been very slight improvement. On 12/14/07, approximately four months after the injection, the patient reported no change. We mailed the patient a copy of Malamed’s article about transient paresthesias a few days later.

On 1/10/08, the patient noted he had some slight improvement but he was still numb. He mentioned that the article we mailed described his situation well. On 1/21/08, the patient reported that he was about the same and that only the tongue was still affected but not as profoundly as before.

On 3/4/08, a little more than six months after the paresthesia began, the patient reported to be doing a little better. On 3/21/08, the patient reported to be completely healed and has remained fully recovered as of 11/15/08, 16 months after the initial paresthesia.

Discussion. Most patients dislike the feeling of numbness for just several hours after a dental procedure, but it is difficult to imagine feeling profoundly numb for months afterward. Our patient reported that for the first month after the paresthesia, he was uncomfortable due to the fact that the right side was totally numb and that he was not used to that. He repeatedly bit his tongue while eating and could not fully taste his food. His speech was impaired, and he stated that as a result, many people with whom he came into contact thought he was drunk. He stated that it was difficult to concentrate for the first month, and as a truck driver who happened to be on leave of absence for other reasons, he thinks it would have been difficult to drive his truck under the circumstances.

Athough our patient was not pleased with his paresthesia, he was grateful that we were concerned with his condition enough to see him and call him frequently and to send him information until his paresthesia was better. He was also somewhat comforted to read (in the article we sent him) that his condition was not so rare as to be unreported in the literature. Finally, he was pleased that we advised watchful waiting as the most prudent course after explaining to him that most paresthesias get bet better on their own without the risks and costs of additional surgery.

In this case, the paresthesia after the dental procedure seemed to be related to the anesthetic injection and not the root canal treatment itself. Of the three injections given, it seems probable that the third injection was the one associated with the postinjection paresthesia. First, since the inferior alveolar nerve was not anesthetized after either of the two injections, it would follow that paresthesia from such unsuccessful injections would not result. In other words, if anesthesia was not achieved in the first place, then paresthesia or “prolonged anesthesia” could not result from it. Second, the patient experienced an “electric” jolt during the otherwise successful articaine injection, which immediately anesthetized the lip on that side. This jolt leads us to believe that this injection probably played a role in the subsequent anesthesia – either from the mechanical trauma of the needle, the articaine anesthetic, or a combination of the two. The root canal instrumentation and obturation were completed within the apices of the tooth. While post-procedure paresthesia is sometimes associated with root canal therapy, the paresthesia association with the root canal therapy in this case can be ruled out since the area of paresthesia included the tongue.

Articaine 4% has been shown to be more effective for anesthesia than lidocaine 2%, but the difference has been slight, and in most studies the difference did not even reach statistical significance. However, two recent studies have shown a more statistically significant difference. A prospective, randomized, double-blind clinical study of 1129 patients showed that articaine was slightly more effective than lidocaine for first-dose anesthesia and overall the difference was statistically significant. Another smaller study of 73 patients showed that inferior alveolar nerve anesthesia with articaine was significantly more successful than with lidocaine.

One disadvantage of articaine 4% versus lidocaine 2% is that only half as many cartridges of articaine may safely be administered before reaching the maximum recommended dose. The maximum recommended doses of articaine and lidocaine are the same (500 mg in a 70 kg adult or 3.2 mg/lb), but articaine 4% is twice as concentrated as lidocaine 2%. As a result, only 7.4 (1.7 ml) cartridges of articaine 4% may be administered to a 154 pound adult versus 13.9 (1.8 ml) cartridges of lidocaine 2% before reaching maximum doses. Also, although it is controversial, articaine has been associated with a higher incidence of paresthesia than lidocaine. Exactly why articaine is associated with more paresthesia is unknown, but perhaps articaine’s formulation is more neurotoxic than other formulations, perhaps because with a 4% formulation, articaine is twice as concentrated as lidocaine’s 2% formulation. When choosing an anesthetic for inferior alveolar block injections, clinicians must weigh the advantages of articaine including a slightly greater efficacy in achieving anesthesia versus the disadvantages including lower maximum recommended dose and greater association with postinjection paresthesia.

Conclusion. We report a case of paresthesia after an articaine inferior alveolar block injection lasting a little more than six months. Before choosing an anesthetic for inferior alveolar block injection, clinicians should weigh the advantages and disadvantages of articaine and other anesthetics. When comparing articaine with lidcocaine for inferior alveolar block injections, clinicians should be aware of articaine’s lower maximum recommended dose and greater association with postinjection paresthesia.

 

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First Published November 2009

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