Authors: Shettar V et al
Cureus 17(5): e84966. doi:10.7759/cureus.84966
Abstract
Unusual complications have been associated with the inferior alveolar nerve (IAN) block. In this study, we aimed to review and analyze the cases of rarely occurring unusual complications following the administration of the IAN block.
A systematic search of PubMed, Google Scholar, and Science Direct was conducted for articles on rarely occurring unusual complications following the administration of the inferior alveolar nerve block until September 2024, and articles documented in English were included. Based on inclusion and exclusion criteria, a total of 29 articles were selected, of which six articles could not be retrieved. A total of 23 articles were analyzed.
Various rare and unusual complications have been reported, which include Horner’s syndrome, blanching of the face, self-inflicted injury, hoarseness, convulsions, headache, intracranial air embolism, glossopharyngeal nerve palsy, bleeding in the external auditory meatus, and herpes zoster infection. Treatment ranged from monitoring in mild cases to hospital admission in severe cases.
Awareness of these complications can help in better patient management. Precautions can be taken by dentists while administering the IAN block to avoid complications. These include the use of proper technique and management of patient anxiety. Rare, unusual complications must be considered when administering the IAN block.
Introduction & Background
The inferior alveolar nerve (IAN) block is the most commonly performed block in dentistry to anesthetize the lower teeth to perform various dental procedures. When administering the IAN block, the local anesthesia is deposited just before the nerve enters the mandibular foramen [1]. Anatomical variation and improper technique are some of the common causes for IAN block failure [2]. The position of the mandibular foramen can vary among individuals. This can result in the failure of the IAN block occasionally [3]. Various methods were tried to increase the anesthetic efficacy of the IAN block, e.g., patient position and needle bevel orientation. The pulpal anesthesia for premolars improved with the supine position. Anesthesia success remained unchanged with supine or upright position for molars and anterior teeth, with needle orientation toward or away from the mandibular ramus [4,5].
In 15.3% of cases of IAN block, the aspiration was positive [6]. Accidental intravascular injection of local anesthesia with vasoconstrictor can lead to complications [6].
Transient facial nerve palsy, hematoma, trismus, and ocular complications are some of the most common complications noted with IAN block [2,7-10].
The incidence of facial nerve palsy following the administration of IAN block is around 0.3% [11]. Difficulty in facial expression, inability to close the eyes, and drooping of the corner of the mouth on the affected side are noted in facial nerve palsy. Immediate or delayed type of facial nerve palsy has been reported. Immediate type is seen soon after the administration of local anesthesia. When the IAN block is administered posteriorly, the spread of the local anesthesia into the parotid gland, which incorporates the facial nerve, can lead to facial nerve palsy. This is transient in nature, and the condition reverses in a few hours [12]. Different theories have been proposed related to delayed-type facial nerve palsy. Delayed-type facial nerve palsy can result from a sympathetic vascular reflex due to ischemic paralysis at the entry of the stylomastoid foramen region. Other theories include stretching of the facial nerve due to prolonged mouth opening and reactivation of latent viral infections, such as herpes simplex virus or varicella zoster virus, due to trauma. The alcohols that form from the breakdown of local anesthesia may result in prolonged nerve damage. Pressure due to the backward flow of local anesthesia solution during intra-arterial injection can cause the solution to flow in different anatomical pathways; this could be another reason for delayed-type facial nerve palsy. The treatment of late facial nerve palsy involves steroids, eye protection by eye patch, and eye lubricant [13].
Damage to the blood vessel and subsequent bleeding in the surrounding tissues leads to a hematoma. Inferior alveolar artery damage during IAN block can result in a hematoma. If a hematoma occurs, the IAN block must be stopped immediately. Cold application, antibiotics, and analgesics must be administered, and the patient must be kept on follow-up for further management [7,14].
Repeated intramuscular injection, intramuscular hematoma due to inferior alveolar artery or vein injury, and needle track infection can lead to trismus on the administration of IAN block. Trismus resolves over weeks, and treatment involves a soft diet, muscle relaxants, etc. [15].
Needle breakage, another complication, was most commonly associated with the IAN block. Following the proper technique, advising patients to avoid sudden movements during the procedure, and avoiding needle bending or multiple injections can help prevent needle breakage during the administration of the IAN block. Early removal of a broken needle can help avoid complications. Some clinicians also suggested that a broken needle can be treated as a small, non-infected root tip, which can be left behind, and scar tissue will form around it; this prevents further complications. When needle breakage occurs, patients must be informed, and the event must be documented. Patients can be referred to higher centers. Proper investigations must be carried out to locate the needle, and treatment can be done accordingly [16].
Ocular complications, although rare, can occur while administering an IAN block. Ocular complications such as diplopia, amaurosis, and blurred vision have been reported. Most of these complications usually manifest immediately after the administration of local anesthesia. The majority of these are self-limiting, requiring only monitoring; in a few cases, additional treatment is required [8,9].
Unusual complications such as blanching, neurological complications, laryngeal complications, glossopharyngeal nerve palsy, and complications related to the external auditory meatus, although rare, have been reported in the literature following the administration of IAN block. The occurrence of an unexpected event during the administration of IAN block can make the dentist and patient anxious. Knowledge of the same can help dentists initiate the necessary measures to prevent a further sequence of serious events. Gathering all information related to unusual complications can lead to earlier diagnosis and management. Any pattern noted in the occurrence of complications in relation to patients with a particular medical history or any particular local anesthetic used could help in drawing inferences and conducting further studies.
In this study, we aimed to review and analyze cases of rare and unusual complications. Due to the rarity of the occurrence of unusual complications following the administration of IAN block, prospective studies are not feasible; hence, they are reported as case reports or case series.
Review
Methods
Information Sources
A systematic search of PubMed, Google Scholar, and Science Direct was conducted for articles on rare and unusual complications following the administration of the IAN block. The last search was performed until September 2024.
Search Strategy
Search strategy was developed using keywords and MeSH terms related to “inferior alveolar nerve block”, “complications”, “unusual complications”, “rare complications”, “blanching”, “neurological symptoms”, and “glossopharyngeal nerve palsy”, searched through the above databases.
PubMed Search Strategy
PubMed search strategy included ((inferior alveolar nerve block) AND (complication)) OR (unusual complication), ((“mandibular nerve”[MeSH Terms] OR (“mandibular”[All Fields] AND “nerve”[All Fields])) OR “mandibular nerve”[All Fields] OR (“inferior”[All Fields] AND “alveolar”[All Fields] AND “nerve”[All Fields]) OR “inferior alveolar nerve”[All Fields]) AND (“block”[All Fields] OR “blocked”[All Fields] OR “blocking”[All Fields] OR “blockings”[All Fields] OR “blocks”[All Fields]) AND (“complicances”[All Fields] OR “complicate”[All Fields] OR “complicated”[All Fields] OR “complicates”[All Fields] OR “complicating”[All Fields] OR “complication”[All Fields] OR “complication s”[All Fields] OR “complications”[MeSH Subheading] OR “complications”[All Fields])) OR ((“unusual”[All Fields] OR “unusually”[All Fields]) AND (“complicances”[All Fields] OR “complicate”[All Fields] OR “complicated”[All Fields] OR “complicates”[All Fields] OR “complicating”[All Fields] OR “complication”[All Fields] OR “complication s”[All Fields] OR “complications”[MeSH Subheading] OR “complications”[All Fields]).
Eligibility Criteria
Articles that described rare and unusual complications (other than trismus, hematoma, facial nerve paralysis, and ocular complications) following the administration of IAN block documented in English were included. Unusual complications following the administration of local anesthesia using the Gow-Gates technique, the Vazirani-Akinosi technique, and techniques other than IAN block were excluded. All studies published until September 2024 fulfilling the inclusion criteria were included.
Population, Intervention, Comparison, and Outcome (PICO) Framework
The PICO framework was used in this study. For the population, we included patients of any age group who developed unusual complications during the administration of the IAN block. The intervention used was the IAN block. There was no comparison group. The outcome is the resolution of complications.
Selection Process
For the initial selection of studies, the title and abstract of the case reports and case series were reviewed based on the inclusion and exclusion criteria. Then, the full texts of case reports and case series were viewed by all authors.
Data Collection Process
A standardized data extraction form was prepared in Microsoft Excel (Microsoft Corp., Redmond, WA); 3-4 entries were made in Excel and reviewed by an expert. Any disagreement between the authors was resolved by discussion. The following data were extracted: demographics of the study population (age and gender), tooth requiring treatment, medical history, local anesthesia, aspiration, and details of unusual complications.
Results
A comprehensive search for related articles was done. Duplicates were removed. Titles and abstracts were assessed for the initial selection of articles. Based on inclusion and exclusion criteria, a total of 29 articles were selected, of which six could not be retrieved (Figure 1) [5]. The 23 articles were analyzed (Table 1).
The patients presented with various conditions such as Horner’s syndrome, herpes zoster infection, blanching of the face, self-inflicted injury, hoarseness, convulsions, headache, intracranial air embolism, glossopharyngeal nerve palsy, and bleeding in the external auditory meatus. The most common local anesthetics used were lignocaine and articaine. Treatment ranged from monitoring in mild cases to hospital admission in severe cases.
Risk of Bias Assessment
The Joanna Briggs Institute (JBI) Critical Appraisal Checklist for Case Reports was used to assess the case reports [43]. The case reports are of moderate to high quality. Although most of the information was reported in the cases, some information related to either the patient’s medical history, technique (aspiration and needle size), or whether the treatment was done at the same appointment was missing. Information related to medical history and technique can help in assessing if there is any correlation between these factors and complications reported, so necessary precautions can be taken to prevent these complications.
Discussion
The IAN block is a commonly performed dental nerve block to anesthetize the lower teeth and soft tissues in the hemimandible region. Anatomical variations and technical failures can lead to complications when IAN block is performed. Although rare, unusual complications have been noted during the administration of IAN block. These complications were noted in patients irrespective of age, gender, and specific medical history. In a few cases, pre-existing medical conditions/previous history of trauma and anxiety were predisposing factors for complications that occurred during IAN block administration [36,42]. Awareness of the rarely occurring complications can help dentists in diagnosing, reassuring patients, and planning further treatment. Although most of the complications are benign in nature, they can make the patient anxious. Monitoring, referral to higher centers, and hospital admissions are the various treatment protocols followed in the management of these rare complications.
Various theories have been proposed in relation to the complications of administering IAN block. These include drug overdose leading to systemic toxicity, inadvertent intravascular injection (either intra-arterial or intravenous), or injection in the vicinity of the central nervous system (CNS), leading to neurological complications [19,31-33,36-38].
Vasoconstriction of blood vessels, such as the maxillary artery, results in skin and mucosa blanching. It occurs due to the action of epinephrine on α-adrenergic receptors in the periphery of the skin and mucosa. Sympathetic vasoconstrictor fiber stimulation can lead to the contraction of blood vessels, resulting in facial ischemia [21,23,24,26,29,30,33-35,39].
Accidental injection of local anesthesia directly into the carotid sheath or subperineural spread of local anesthesia results in cervical sympathetic block or stroke-like symptoms [18,42]. The effect of local anesthesia at the ipsilateral brachial plexus via retromandibular vein, external jugular vein, and plexus of veins around the vertebral artery leads to symptoms that are similar to a stroke, where patients complain of ipsilateral upper extremity paralysis and paresthesia [42].
A high IAN block can lead to the spread of local anesthetics toward the glossopharyngeal nerve, leading to uvular paralysis. When the block is injected at a higher level, the mandibular nerve and supply to the tensor veli palatini can be affected, leading to uvular paralysis [10]. Diffusion of local anesthesia close to the glossopharyngeal nerve in the carotid triangle through the parapharyngeal space can lead to this complication [40].
Numbness in the auricle could be the result of auriculotemporal nerve anesthesia during the administration of IAN block, which rarely happens. Anatomical variations such as the origin of the auriculotemporal nerve at a lower level, connecting branch with IAN, and spread of local anesthesia through the masticatory space to reach the superior location are the various causes mentioned [25,29]. Laceration and ear bleeding result from the superior movement of the needle in the parotid gland vicinity during the administration of IAN block [41].
A self-inflicted injury in the area of the lip was noted. These kinds of injuries are usually noted in children. These injuries are usually self-resolving and heal with palliative care, unless they get infected secondarily [27].
Individual anatomical variation of the sympathetic nerve may allow the anesthetic solution to be delivered to ectopic sites, leading to temporary complications. These complications subside once the local anesthesia wears off [28].
Activation of a latent virus can lead to herpes zoster infection during the administration of IAN block. Stress and dental surgical treatment can lead to reactivation of these viruses. Treatment involves the administration of antivirals and steroids [20].
It is advocated that aspiration must be performed during the administration of IAN block. Intravascular injection can lead to failure of anesthesia. Administration of local anesthesia in blood vessels has been associated with undesirable systemic effects. Hemodynamic effects, especially in patients with medical conditions such as cardiovascular diseases, must be considered. A greater concentration of vasoconstrictor and rapid deposition of local anesthesia increase these possibilities. Studies have shown that the percentage of positive aspiration varies, which can be as high as 20% [44]. In some of the cases above, complications occurred even when aspiration was negative. Even when the initial aspiration is negative, slight tilting of the needle due to patient movement during the final administration of IAN block could lead to intravascular injection.
Lidocaine and articaine are the most commonly used local anesthetics in the above cases. Lidocaine has been a commonly used local anesthetic in dentistry and has been found to be effective and safe. In recent times, local anesthetics, such as articaine, have gained popularity. Because of its effectiveness and safety levels, it is used for routine dental procedures [45].
Precautions must be taken by dentists while administering IAN block to avoid unusual complications. Medical history must be considered, and stress must be managed during dental procedures. The dentist must have thorough knowledge of anatomy, and the correct technique and guidelines must be considered during the administration of the block. Aspiration and slow administration of the solution are recommended. These measures lessen the amount of solution that reaches the systemic circulation, hence minimizing the risk of complications [34].
Patients should always be informed about the unusual complications that can occur due to the administration of IAN block. In case an event occurs, the dentist must be knowledgeable of the differential diagnosis and must effectively manage patients. The dentist must reassure the patient.
All dental procedures must be terminated in case any complication occurs following the administration of IAN block. The condition must be diagnosed, and the patient must be monitored. If the patient is calm and the condition is stable, dental treatment can be performed after obtaining patient consent. In some cases, additional treatment, such as hospital admission, must be initiated depending on the complication. If the complaint does not subside, postponing the treatment can be considered [36].
Limitations
This systematic review includes only case reports and case series.
Conclusions
Although rare, unusual complications can occur following the administration of the IAN block. Patients should always be informed about the same before the start of the same treatment. The dentist must be knowledgeable about the complications. Precautions must be taken to avoid them. In case complications occur, the condition must be diagnosed immediately. Patients must be informed about the same and reassured so that they remain calm. Although most complications resolve and dental treatment can be completed at the same appointment with patient consent, referral to medical centers may be necessary in certain cases. Rare complications must always be considered when administering an inferior alveolar nerve block.
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