Review of anesthesia in maxillofacial trauma

Introduction

Maxillofacial trauma presents complex and multifaceted challenges in the realm of anesthesia. The intricate nature of the anatomical structures involved, coupled with the potential for concurrent injuries to the airway, vasculature, and nervous system, necessitates a nuanced and specialized approach to optimize patient outcomes. This literature review endeavors to provide a comprehensive account of the diverse array of anesthesia strategies employed in the management of maxillofacial trauma. It is intended for anesthesia providers, surgeons, and other healthcare professionals involved in the care of patients with head and neck trauma.

To construct this review, a comprehensive search of the literature was conducted with specific search terms pertinent to each subsection. Selected sources include randomized controlled trials, retrospective and prospective studies, review articles, case reports, and textbooks. No constraints were imposed on publication timelines or publication language, thereby ensuring a broad and inclusive scope.

The review will begin by exploring the epidemiology, etiology and anatomy relevant to facial trauma in order to establish a foundation for understanding the prevalence, patterns and severity of these injuries. We will then provide an overview of the clinical considerations for the assessment of the patient presenting with maxillofacial trauma as it relates to the practice of anesthesia. This will include Advanced Trauma Life Support (ATLS) principles, as well as an overview of anatomical factors and imaging modalities. Finally, we will delve into the management of this patient population, including approaches to the airway, pharmacological strategies, hemorrhage control, and local and regional anesthetic techniques.

Our goal is that this review will enhance the understanding of anesthesia considerations in challenging clinical scenarios where the patient presents with maxillofacial trauma. We hope that the reader will take away practical applications to increase proficiency in the field of anesthesia, leading to improved clinical outcomes and patient safety.

Epidemiology and etiology of maxillofacial trauma

Maxillofacial trauma accounts for a substantial proportion of emergency department visits and hospital admissions globally, and its incidence exhibits variability across demographic factors, including age, gender, and socioeconomic status.

There have been numerous epidemiological studies investigating trends in maxillofacial trauma at high-volume trauma centers in the United States. From 1993 to 2010, it was estimated that 2.23 million facial fractures were admitted to hospitals across the country (1). The most common injuries were mandible (26%), nasal bone (24%), malar/maxillary (20%) and orbital floor (14%) fractures. During this period, there has been a decline in morbidity associated with motor vehicle collisions (MVC), which has been attributed to the increase in compliance with seat belt laws, as well as with improved vehicle construction and technologies such as air bags.

Recently, a report from an urban level 1 center showed that assaults were the prevalent mechanism of injury (44%), followed by MVC (22%) and falls (11%) (2). The average age was 37 years, and the injuries predominantly affected men at a ratio of 4.3 to 1. In another recent study looking at a level 1 center in a rural setting, the most common etiology was falls (37%), followed by assault (30%) and MVC (14%) (3). In this rural population, injuries occurred on average at an older age (41 years) and the male to female ratio was more even (1.6 to 1) than in the urban setting.

Outside of the United States, a multicenter study across multiple European countries revealed that assaults are the leading cause of facial trauma (39%), followed by falls (31%), sports (11%), and road traffic accidents (11%) (4). This contrasts with a similar worldwide study (excluding North America) that showed road traffic accidents are the most common mechanism (45%), ahead of falls (22%) and assaults (21%) (5). In both samples, midface fractures were the most common, accounting for more than half of injuries, followed by mandible fractures at approximately 40%.

In pediatric patients, the most common etiologies for facial trauma include MVC (55%), assaults (15%), and falls (9%) (6). In contrast to adults, younger children are more likely to fracture cranial rather than facial bones, owing to their relative sizes and increased elasticity during growth of the facial skeleton (7).

In the geriatric population, facial trauma is most commonly associated with falls and predominantly involves fractures of the midface and orbits (8). Elderly patients are more likely to have concurrent non-facial injuries, such as long bone and pelvic fractures, cervical spine injuries, and intracranial hemorrhages. Additionally, geriatric trauma patients tend to have longer hospital stays, require intensive care unit (ICU) admission, and have higher mortality.

Sports injuries vary widely across the world (9). For example, in Europe soccer is the leading sports-related cause of facial trauma, accounting for 59% of maxillofacial fractures in Germany and 42% in Italy. Boxing and martial arts are undoubtedly sports with a propensity for injuries to the head and face. Other sports associated with a high risk of facial trauma include hockey, basketball, rugby, and lacrosse.

Combat trauma to the maxillofacial complex presents an entirely different spectrum of injuries. Recent data from theaters of operations in Iraq and Afghanistan between 2011 and 2016 tallied over 5,300 face and neck injuries among 922 American service members, sustained from either penetrating (53%) or blunt (47%) trauma (10). Approximately three quarters were soft tissue injuries, while the rest were fractures, most often orbital fractures (26%), followed by midface (25%), teeth (16%), nose (15%), and mandible (12%). While the incidence of mandibular fracture was lower than in civilian settings, high-velocity mechanisms and penetrating injuries resulted in over 75% of fractures being open and 31% involving a segmental defect.

These epidemiological trends have recently been recognized by large language models and the use of artificial intelligence in the management of maxillofacial trauma is an area that is showing a lot of potential, particularly when it comes to patient triage (11).

Evaluation of the patient with maxillofacial trauma

ATLS principles

Since its inception in 1976, ATLS has evolved over its many iterations but has been instrumental in reducing morbidity and mortality resulting from traumatic injuries. Currently in its 10th edition (12), the ATLS course aims to educate healthcare providers on the recognition and management of critical injuries in the acute setting. During the primary survey, the acronym ABCDE helps identify and treat life-threatening conditions (Table 1).

Maxillofacial injuries on their own are rarely life-threatening, aside from potential compromise of the airway and severe hemorrhage. They can occur alone but often present in conjunction with other injuries in the multiply injured patient. Regardless, the critically ill patient must be stabilized with the use of the ATLS principles prior to planning definitive repair of maxillofacial injuries.

In the secondary survey, a head-to-toe exam is conducted to identify occult injuries and rule out additional morbidity. Additional information such as the patient’s medical history and details on the mechanism of injury are sought. When evaluating the patient with maxillofacial trauma, the head and neck surgeon must follow the same principles and maintain a high degree of suspicion for critical injuries (13).

Facial fractures

Fractures of the facial bones can be broadly classified into lower face, mid face and upper face (14,15). In the lower face, mandibular fractures are classified by the site of the fracture. This can involve the symphysis, parasymphysis, body, angle, ramus, and condyle. Of significance for the anesthesiologist, bilateral mandibular fractures will be unstable and can lead to considerable edema around the airway. Open mandibular fractures are often associated with occlusal step-offs and intraoral hemorrhage. Significantly displaced fractures can also result in a sublingual hematoma, which can be a threat to airway security in severe cases.

Midface fractures involve the maxilla, nasal and ethmoid bones, orbital floor and walls, and zygoma including the zygomatic arch. The LeFort classification system is commonly used to communicate the extent of the midface fracture (Figure 1). LeFort I fractures are the most common and result in a horizontal separation of the maxillary dentition from the rest of the maxilla. The LeFort II fracture pattern is pyramidal in shape extending through the orbits to the nasal bridge, while a LeFort III is a complete craniofacial disjunction above the zygomas. In reality, multiple LeFort levels can present concurrently, and asymmetry is common. Of note for anesthesia, midface fractures can significantly alter airway anatomy and may present a higher risk of concomitant base of skull fractures and traumatic brain injuries.

Figure 1 LeFort fracture patterns of the midface: (A) LeFort I, (B) LeFort II, and (C) LeFort III.

Upper face fractures are less common, referring to fractures of the superior orbital rim, frontal bone and frontal sinus. As with midface fractures, one must be vigilant for skull base fractures, which may manifest as cerebrospinal fluid leak.

Dentoalveolar trauma can manifest as a tooth fracture, luxation or avulsion, and as a dentoalveolar fracture where the alveolar bone is fractured resulting in mobility of a segment of teeth (16). During the pre-anesthesia assessment, the dentition must be examined for any loose, broken or missing teeth. Avulsed teeth or tooth fragments that cannot be accounted for raise the possibility of aspiration, which must be ruled out with a chest radiograph.

Vascular injuries

The face is a highly vascular part of the body and contains a great amount of redundancy. The primary blood supply is via branches of the external carotid artery including the lingual, facial, maxillary and superficial temporal arteries, and branches of the internal carotid artery including the ophthalmic, supraorbital, supratrochlear and dorsal nasal arteries. These vessels are quite superficial and are therefore prone to injury by penetrating trauma (17).

Blunt mechanisms can lead to more sinister injuries such as arterial dissections, pseudoaneurysms, extra-axial hematomas, arteriovenous fistulas, and carotid-cavernous fistulas (17). Vascular injuries from blunt trauma are more likely to occur with high-velocity mechanisms or rapid deceleration, such as assault with blunt objects or MVC with airbag deployment.

The most common cause of shock in trauma patients is hemorrhage, which is a type of hypovolemic shock (12). The American College of Surgeons categorizes blood loss in four classes and monitoring vital signs aids in determining the severity of the hemorrhage (Table 2) (12). One in ten people with maxillofacial trauma need resuscitation secondary to hemorrhage, and twenty percent of those will succumb to blood loss (18).

Occult bleeding into the pharynx, especially in the obtunded or sedated patient, may lead to airway compromise. Injuries to the highly vascular nasal mucosa can result in significant epistaxis, which is likely to gravitate to the pharynx if the patient is supine. The tongue is also very vascular and lacerations are frequently associated with excessive bleeding into the oral cavity (Figure 2). Patients in distress will often adopt the tripod position by sitting upright with their head in the forward position, in order to maintain a patent airway.

Figure 2 Large avulsive laceration to the tongue associated with excessive bleeding into the oral cavity. This patient presented in the tripod position and could not tolerate lying supine.

Intraoral bleeding can also be the result of displaced fractures of the mandibular body, which can injure the inferior alveolar artery. This injury can also bleed into the sublingual space and may rapidly constrict or obstruct the airway. A raised tongue and ecchymotic floor of the mouth is pathognomonic for a developing sublingual hematoma (Figure 3). The patient must be frequently reassessed for the need to establish a secure airway.

Figure 3 Intraoral injuries may present with an expanding sublingual hematoma. Ecchymosis of the floor of the mouth and a raised tongue are concerning for sudden compromise of the airway.

Nerve injuries

The facial nerve is injured in approximately 7–10% of temporal bone fractures, usually from blunt trauma as a result of an MVC, fall or assault (19). Therefore, trauma patients presenting with hemifacial paresis must be assessed for cranial fractures and associated injuries. Penetrating injuries such as lacerations, gunshot wounds and animal bites to the lateral face and temple can also result in weakness of the associated facial muscles (20).

Anesthesia or paraesthesia in the distribution of the trigeminal nerve is highly suggestive of fractures causing impingement of the nerve (21). For example, patients with orbital floor fractures involving the V2 distribution will often complain of numbness of the cheek, while those with mandible fractures may have a numb lower lip resulting from injury to the V3 branch. In most cases, the paraesthesia will resolve over time after repair of the fractures, and long term trigeminal nerve neuropathy is less commonly associated with facial trauma. In a case series of 63 patients suffering from trigeminal neuropathy, the vast majority of injuries were iatrogenic secondary to dental surgical procedures while only two were the result of facial trauma (22).

The trigeminocardiac reflex (TCR) is a nerve reflex triggered by a pressure stimulus to any part of the face innervated by the trigeminal nerve, resulting in bradycardia via the vagus nerve (23). It is most often observed in younger patients, likely due to increased vagal tone. One type of TCR more frequently encountered in maxillofacial trauma and surgery is the oculocardiac reflex (OCR), which is specific to the ophthalmic branch of the trigeminal nerve (24). The OCR sometimes manifests in patients with midface trauma and during surgery for the repair of globe injuries and orbital fractures. In the presence of hypoxemia, hypercarbia and light planes of anesthesia, the TCR can progress to ectopic beats, heart block, ventricular bigeminy, multifocal premature ventricular beats, ventricular tachycardia, and asystole (25). The management of TCR involves removal of the pressure stimulus and administering 0.01 to 0.4 mg/kg intravenous (IV) atropine.

Imaging

The patient with maxillofacial injuries must undergo diagnostic imaging on arrival to a facility with the appropriate capabilities. The gold standard is computed tomography (CT) of the maxillofacial bones (26). Radiographic studies should be examined systematically in all available views to identify injuries. It is important to emphasize that the radiographic examination should not guide the physical examination, but rather should supplement it.

In addition to identifying facial fractures, a CT will also provide valuable information about the soft tissues which may influence the anesthesia plan. For example, the airway can be assessed for injuries, narrowing or lateralization. Hematomas and surgical emphysema can be identified on CT. Depending on the extent, they can travel quite far via the fascial spaces of the head and neck (Figure 4). An expanding facial or cervical hematoma requires prompt recognition and management, particularly when it is located in the floor of the mouth or in the spaces adjacent to the airway (Figure 5). A stable patient may be subjected to a repeat imaging study to reassess for airway patency, but a deteriorating patient with a rapidly progressing hematoma may require emergent intubation for airway security.

Figure 4 Axial slice of a CTA of a patient who sustained a left zygomatic arch fracture. Two days after the injury, there was a clinical concern for ongoing bleeding due to rapid and severe facial swelling. Thus, this CTA was taken which confirmed active extravasation from the transverse facial artery (red arrow). CTA, computed tomography angiogram.

Figure 5 Same patient and study as in Figure 4. This axial slice of the CTA at the level of the mandible shows significant airway deviation to the right resulting from the facial hematoma which extended to the neck. CTA, computed tomography angiogram.

When vascular injuries are suspected, CT angiography can assist in identifying active extravasations and help guide management (15). Deep vascular injuries may require consultation with interventional radiology for possible embolization.

Lacerations of the skin can sometimes be identified on imaging. This can be particularly useful on the posterior scalp in patients with thick hair and those with a cervical collar. However, this should not replace a thorough physical examination. Lastly, radiopaque foreign bodies, such as metal, glass and stone, can be detected using CT imaging.

Airway techniques

For reasons identified above, trauma patients may require a definitive airway either on scene by emergency medical technicians or on arrival to the hospital emergency department. Often, this comes in the form of endotracheal intubation. Rapid sequence induction (RSI), where bag-mask ventilation is not done prior to intubation, is often used in emergency situations for several reasons (27). First, the emergency patient’s nil per os (NPO) status is often unknown, and the potential for the presence of stomach contents increases the risk of aspiration. Additionally, patients with soft tissue injuries around the mouth and nose may be difficult to bag-mask ventilate and applying positive airway pressure may result in subcutaneous emphysema. Given these considerations, a significant disadvantage of RSI is the lack of pre-oxygenation, which may lead to devastating consequences in patients with a difficult airway.

In stable and non-intubated patients with maxillofacial trauma who need surgery, there will be more time for the anesthesia and surgical teams to develop a plan. Table 3 lists the available intubation techniques and their considerations.

The surgical procedure itself may dictate the type of endotracheal tube (ETT) selected. If the patient will require maxillomandibular fixation (MMF) during or at the conclusion of the procedure, then a nasal tube will likely be indicated. Several types of tubes are available, including right angle endotracheal (RAE) tubes, which minimize visual obstructions into the surgical field.

Intubation of the patient with maxillofacial trauma can be complicated by several factors (Table 4). Firstly, bleeding from recent injuries can quickly obscure the field, and thus it is imperative to proceed with a gentle technique to reduce hemorrhage and to have adequate suction available to clear away blood. The use of hemostatic agents such as oxymetazoline, cocaine or epinephrine can help. Secondly, it is important to recognize that injuries to the mouth and adjacent structures can distort the anatomical landmarks which are normally used during intubation. Moreover, care should be taken to avoid avulsing teeth with a laryngoscope if there has been trauma to the dentition. Additionally, patients with cervical spine injuries who are placed in a cervical collar must remain in a neutral spine position, and therefore cannot be placed in the sniffing position, making intubation more difficult. Nasal intubation can sometimes be challenging under normal circumstances, but in the patient with facial trauma this difficulty can quickly be amplified. For all these reasons, adjunct equipment like flexible tracheal tube introducers (e.g., Bougie), videolaryngoscopes, and flexible fiberoptic bronchoscopes should be available in the room to assist the anesthesiologist with intubation and avoid complications (28).

When there are extensive injuries to the midface and nose, the patient should ideally be orally intubated to avoid further traumatizing the area. Although rare, complications such as retropharyngeal dissection during intubation have been described (29). Similarly, patients with base of skull fractures should not be nasally intubated to avoid accidental instrumentation into the cranial cavity or displacement of the fractures.

If the surgical plan calls for the application of MMF, and nasal intubation is not possible or contraindicated, the patient may still be intubated orally and one of the following alternative techniques will allow the surgery to proceed. The first technique is retromolar placement of an ETT. With this approach, an oral ETT is passed behind the last molars, between the mandibular ramus and the maxillary tuberosity, to allow the teeth to come together into MMF. A wire-reinforced tube is recommended to prevent kinking and constriction of the tube. Most dentate adults can accommodate a wire-reinforced tube size 7.0 or smaller (30). However, each patient must be evaluated on a case-by-case basis as the presence of erupted third molars, supra-erupted maxillary molars, or malpositioned teeth may prevent successful retromolar passage of the tube.

Another alternative technique is the submental intubation. Many variations of this technique have been described in the literature (31), but the concept basically remains the same. The patient is first orally intubated using a wire-reinforced ETT. The surgeons will proceed to make a floor of mouth incision, taking care to avoid injury to the salivary gland orifices. Blunt dissection is carried to the submental skin, which is then sharply incised. The balloon and pilot tube are carefully passed through the newly created tract, followed by the ETT without the connector (loosening this piece prior to intubation will help save valuable time during the critical steps). After reestablishing ventilation, the tube may be secured to the skin with silk sutures. At the conclusion of the procedure the process is reversed, and the incisions are repaired with sutures.

Lastly, no discussion of airway techniques would be complete without mentioning surgical airways. The cricothyrotomy is usually done emergently as a life-saving measure, while the tracheostomy is normally done in a more controlled fashion by trained surgeons. In patients with extensive head and neck trauma who are about to be intubated, the threshold to plan for a tracheostomy as a backup technique should be low. The necessary tracheostomy instruments and equipment must be available in the room, and trained personnel should remain vigilant and follow the instructions provided by the anesthesiologist.

Pharmacologic strategies

The trauma patient’s hemodynamic stability, neurologic status, and airway security are all important considerations when choosing the appropriate perioperative pharmacologic agents, and the anesthetic plan may need to be altered from the standard regimen.

Propofol is the most commonly used induction medication due to its rapid onset and short duration of action making it suitable for RSI, but causes dose-dependent hypotension and respiratory depression (32). In acute trauma with hemodynamically unstable patients, etomidate is sometimes preferred due to its minimal myocardial depression and vasodilation (33). Dexmedetomidine is less often used in trauma due to its relatively slower onset and recovery compared with propofol, but can be considered as a sedative agent for awake fiberoptic intubation if needed (34). Ketamine is a potent sedative with bronchodilating effects and minimal respiratory depression. While early studies suggested it had a detrimental effect on trauma patients due to an increase in intracranial pressure, a growing number of studies point to its safety profile and potential benefits even in patients with traumatic brain injuries (35-37).

Succinylcholine is a suitable paralytic for RSI due to rapid onset and short duration. The use of non-depolarizing neuromuscular blockers such as rocuronium has become widespread, but their duration of action far exceeds that of succinylcholine (38). If the surgeon requires intraoperative nerve monitoring, as is often the case with procedures near the major branches of the facial nerve, this should be communicated with the anesthesia team prior to induction so that succinylcholine can be used instead. Alternatively, sugammadex can be used to predictably reverse non-depolarizing neuromuscular blockers.

Midazolam is commonly used as an adjunct during induction of anesthesia. Longer-acting benzodiazepines such as diazepam and lorazepam should be avoided in the perioperative period for trauma patients, because their prolonged sedating effects can negatively impact the postoperative neurological exam (39). Similarly for narcotics, those with a shorter duration of action should be favored in acute trauma. Fentanyl is commonly used during induction medication and the ultra-short acting remifentanil can be used as a continuous infusion without negative impacts on cerebrovascular haemodynamics and intracranial pressure (40,41).

After induction, the maintenance of anesthesia can be accomplished with inhalational or intravenous agents, or a combination of both. One study found that the most severely injured patients are more frequently maintained without the use of volatile agents (42). This choice is likely due to the fact that volatile agents will lead to respiratory and myocardial depression at higher minimal alveolar concentrations (MAC), therefore a balanced approach is warranted. When used at a low dose (MAC of less than 0.6), there is no significant difference in the rate of morbidity and mortality between sevoflurane, isoflurane, and desflurane (42). Furthermore, volatile anesthetics can modulate immune function through the inhibition of neutrophil response to improve ischemia-reperfusion injuries, which may be protective in trauma surgery and septic patients (43).

Management of hemorrhage

Timely and thorough assessment of a patient experiencing hemorrhagic shock is crucial to limit life-threatening blood loss and avoid airway complications (12). By correlating the mechanism of injury with clinical exam findings such as the extent of wounds and vital signs, providers can estimate the severity of hemorrhagic shock (Table 2). Hemorrhage can lead to airway complications in several ways, including airway constriction from hematomas and edema, direct aspiration of blood, and emesis of ingested blood (13,44). Therefore, maintaining a patent airway or intubating for airway security should be a priority in accordance with the ATLS primary survey. Suction must be available to clear blood and identify its source. Epistaxis can be addressed with the use of resorbable packing materials or inflatable balloons to prevent bleeding posteriorly into the pharynx.

Significant bleeding from facial lacerations needs to be addressed to reduce blood loss. In the stable patient, timely and definitive laceration repair with sutures is indicated. When other more threatening injuries are present, facial hemorrhage may be quickly controlled and revisited after the patient has been stabilized. With consideration of local anatomy and the source of the bleed, options to control bleeding include pressure packing, electrocautery, tacking sutures, balloon tamponade, direct vessel ligation, and transarterial embolization (45). Patients with displaced fractures in the dentate portion of the mandible may benefit from bridle wiring in order to reduce and stabilize the fracture and alleviate bleeding and pain.

In addition to achieving hemostasis, a concurrent goal in managing maxillofacial hemorrhage is to replenish lost volume. According to the latest ATLS guidelines, initial fluid resuscitation should be administered as a bolus of crystalloids of 1 liter for adults and 20 mL/kg for children under 40 kg (12). Large volume fluid resuscitation can dilute clotting factors and lead to trauma-associated coagulopathy, therefore the patient should be transfused with blood products per institutional protocols as soon as they are available (18). The early administration of plasma, platelets and red blood cells at a ratio of 1:1:1 has been demonstrated to be equally as effective as a ratio of 1:1:2 in reducing overall mortality, but resulted in more rapid hemostasis and fewer exsanguination events (46). Moreover, there were no differences in the rates of inflammatory-mediated complications between the two groups, such as acute respiratory distress syndrome, multiple organ failure, venous thromboembolism, and sepsis.

Trauma-induced coagulopathy is associated with three major factors frequently seen in trauma: hemodilution, hypothermia, and acidemia (47). Resulting in decreased clot strength and increased fibrinolysis, the condition is mediated by the activation of protein C, the depletion of fibrinogen and by platelet dysfunction. Hemodilution must be limited by avoiding overly aggressive crystalloid resuscitation or an inappropriate transfusion ratio of blood products. It is also important to maintain normothermia and a normal blood pH. Continuous monitoring for the adequacy of resuscitation should include trends in vital signs, urine output, and laboratory studies including blood gas and complete blood count. Another strategy for anesthesia providers is the practice of permissive hypotensive by maintaining lower mean arterial blood pressures in order to limit blood loss in the actively hemorrhaging patient. Tranexamic acid (TXA) is an antifibrinolytic agent that has been shown to significantly increase survival in bleeding trauma patients if given in the first three hours post-injury (48). It is administered intravenously as a loading dose of 1 gram given over 10 minutes followed by an infusion of 1 gram over 8 hours. Finally, diagnostic aids such as thromboelastography (TEG) and rotational thromboelastometry (ROTEM) can help identify coagulopathies and guide targeted management to correct the specific deficiency (49).

Local and regional anesthetic techniques

Soft tissue trauma to the maxillofacial region will often require debridement of wounds and repair of lacerations to prevent infection and optimize wound healing. In the awake patient, the administration of local anesthesia will help improve clinical outcomes and patient comfort. Knowledge of the anatomy is crucial in achieving adequate anesthesia, and appropriate techniques are also paramount in avoiding complications. With an abundant neurovascular supply, the face is most appropriately anesthetized using epinephrine-containing amide local anesthetics (50). Extravascular administration of local anesthetics must be confirmed by negative aspiration prior to injection, particularly in highly vascular areas. The practitioner must be cognizant of the doses of anesthetic being administered and be aware of the signs of local anesthetic systemic toxicity (LAST). Care must be taken when injecting in sites with end-arterial blood supply, such as the nose and ear, where there is a risk of ischemia and necrosis with the use of vasoconstrictor-containing local anesthetics.

Most small wounds can be successfully anesthetized by local infiltration, with the added benefit of helping with hemostasis when epinephrine is used. Alternatively, nerve blocks can be more efficient because they stop afferent nerve conduction over a large area using a relatively low volume of local anesthetic. This section will provide a brief overview of the various nerve blocks for the face (51), which are illustrated in Figure 6.

Figure 6 Injection site and approximate nerve distribution of various facial nerve blocks: a, supraorbital nerve; b, supratrochlear nerve; c, infratrochlear nerve; d, external nasal branch of the anterior ethmoid nerve; e, infraorbital nerve; f, zygomaticofacial nerve; and g, mental nerve (administered intraorally).

The upper eyelids, brows and forehead can be anesthetized by performing a supraorbital nerve block, which is administered above the superior orbital rim in line with the medial limbus of the eye. The supraorbital foramen or notch can often be palpated. Just medial to this point, the supratrochlear nerve can also be blocked, which will anesthetize the medial forehead. When performing any of the periorbital injections, the needle should be angled away from the globe to prevent inadvertent injury and no more than 1 mL of anesthetic should be deposited per location at least 0.5 cm from the rim to avoid diffusion into the orbit.

The dorsal nose is innervated by the infratrochlear nerve and the nasal tip by the external nasal branch of the anterior ethmoid nerve. For the former, the nasal bones are palpated, and 1 mL of anesthetic is injected 6–10 mm lateral to the midline. The latter is located at a similar distance from the midline and situated approximately 2 cm inferiorly.

The infraorbital nerve block will achieve anesthesia of the cheek from the lower eyelid to the upper lip, and from the ala of the nose to 1 cm lateral to the oral commissure. Similar to the supraorbital nerve block, the foramen can often be palpated, and local anesthetic is administered in line with the medial limbus. Alternatively, an intraoral injection can be performed high in the maxillary vestibule. Innervation to the lateral cheek is from the zygomaticofacial nerve which is found approximately 1 centimeter outside the inferolateral corner of the orbit.

The lower lip and chin can be anesthetized by blocking the mental nerve, which is most easily accomplished intraorally using 1–2 mL of local anesthetic. The mental foramen is submucosal near the apex of the first and second mandibular premolars, approximately 15–20 mm inferior to the crowns of teeth. Other intraoral blocks to anesthetize the dentition are beyond the scope of this publication and should be administered by dental professionals.

Innervation to the external ear can be variable; the anterosuperior portion of the ear as well as the temple are innervated by the auriculotemporal nerve, the inferior part of the ear is innervated by the great auricular nerve, while the posterosuperior part is innervated by the lesser occipital nerve. To anesthetize the external ear, a common approach is the so-called diamond block (Figure 7). A long needle is inserted above the ear and tracked subcutaneously at an angle to reach a point anterior to the acoustic meatus, then 1–2 mL of anesthetic is deposited as the needle is retracted back to the insertion point. The process is repeated posterior to the ear, then twice inferiorly until a diamond-shaped track of local anesthetic has been administered.

Figure 7 The diamond block is used to anesthetize the external ear via two injection points to deposit four tracks of local anesthetic solution surrounding the ear.

Conclusions

Patients presenting with maxillofacial trauma can be challenging to manage in the perioperative period. The adherence to proven treatment principles, such as ATLS, is essential to maintain good patient outcomes. A thorough clinical and radiographic examination is necessary to establish an adequate anesthetic plan. The provider must be able to quickly recognize signs of clinical deterioration and intervene appropriately. We hope that this review was able to provide the reader with a thorough overview of anesthesia considerations for the patient presenting with facial trauma.

Acknowledgments

Funding: None.

Footnote

Peer Review File: Available at https://joma.amegroups.com/article/view/10.21037/joma-24-10/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://joma.amegroups.com/article/view/10.21037/joma-24-10/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All clinical procedures described in this study were performed in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient for the publication of this article and accompanying images.

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