Association of Infraorbital Nerve Injury with Zygomaticomaxillary Complex Fractures at a Tertiary Care Hospital, Karachi

By Qasim Saleem¹, Tanzeela Shaikh², Tarique Hussain Shaikh³, Ume-Habiba⁴, Farah Irshad⁵, Hamza A. Bajwa⁶

DOI: https://doi.org/10.36283/PJMD13-2/008

How to cite: Saleem Q, Shaikh T, Shaikh TH, Habiba U, Irshad F, Bajwa HA. Association of Infraorbital Nerve Injury with Zygomaticomaxillary Complex Fractures at a Tertiary Care Hospital, Karachi. Pak J Med Dent. 2024;13(2): 48-54. Doi: 10.36283/PJMD13-2/008

Background: The zygomatic region stands out as the most prominent facial portion, and zygomatic complex fractures (ZMC) are the second most prevalent facial fractures in the lateral mid-face area. This study investigated the associations between fractures in the ZMC and injuries to the infraorbital nerve at a tertiary care hospital.

Methods: This cross-sectional study was conducted among 72 patients from September 2021 to March 2022, at the Oral and Maxillofacial Surgery Department, Jinnah Post Graduate Medical Centre, Karachi. Patients aged between 16 to 65 years, recently diagnosed with zygomatic bone fractures, were included in the study through consecutive non-probability sampling. Comprehensive patient histories, including demographic information, gender, age and residential status, obesity, and the identification of infraorbital nerve injuries diagnosed through clinical examinations and radiographic assessments. SPSS vr20 was used and the Chi-Square test was utilized to explore associations between categorical variables.

Results: Among the 72 cases, 45(62.5%) were male, while 27(37.5%) were females. The average age was 37.43 ± 11.04 years, with ages ranging from 16 to 65 years. Within this cohort, 47(65.3%) individuals were residents of urban areas, whereas 25(34.7%) hailed from rural regions. Notably, positive infraorbital nerve injuries were detected in 54 patients (p=0.02), constituting 75.0% of the total injuries. Among those with ZMC fractures, 25(34.7%) (p=0.02) also had infraorbital injuries, while 20(27.8%) (p=0.03) did not exhibited such injuries.

Conclusion: our study highlights a noteworthy correlation between ZMC fractures and infraorbital injuries. These results underscore the reciprocal relevance of assessing infraorbital injuries in ZMC fracture cases and vice versa, enhancing the comprehensive understanding and management of such injuries in clinical practice.

Keywords: Zygomatic Fractures, Nerve Injuries, Oral Surgical Procedures.

Concerning the definition of the Zygomaticomaxillary Complex (ZMC), we outlined its anatomy, specifying that the central portion forms the malar prominence. Originating from the central part of the malar prominence, four attachments connect it to the skull: superiorly, it links to the frontal bone through a frontal zygomatic suture line; laterally, there’s a connection to the temporal bone via the zygomaticotemporal suture line¹. Medially, it attaches to the maxillary bone through the zygomaticomaxillary suture line and deeply connects to the greater sphenoid bone through the zygomaticosphenoidal suture². The diagnosis of ZMC fractures relied on clinical and radiographic assessments³. The Zygomaticomaxillary Complex (ZMC) constitutes a significant segment of the facial skeleton, contributing to 45% of mid-facial fractures and 25% of all facial fractures.^4,5 Disruptions at the zygomaticomaxillary and zygomatico-sphenoidal sutures involve crucial anatomical structures like the infraorbital foramen, infraorbital canal, and inferior orbital fissure leading to unintended injury to the infraorbital nerve^6,7. The incidence of infraorbital nerve injury after ZMC fractures ranges from 80% to 90%. Infraorbital nerve damage can result in neurosensory disturbances, affecting various facial structures⁷.

ZMC fractures are notably influenced by road traffic accidents (RTAs), prevalent in developing nations, and interpersonal violence, more common in the Western world. Indicative symptoms include depression of the affected side, pain, subconjunctival hemorrhage, periorbital ecchymosis, and restricted mouth opening. Infraorbital nerve injuries often accompany ZMC fractures, causing sensory disruptions^8.9. Traumatic infraorbital nerve injury may result from compression, edema, ischemia, or laceration of the neural bundle. In 95% of ZMC fractures, the fracture line involves the infraorbital fissure or infraorbital canal, with reported incidence rates of infraorbital nerve injury ranging from 18% to 83%¹⁰. Notably, sensory disturbances along the Infraorbital Nerve (ION) distribution were identified through patient-reported complaints and clinical manifestations, highlighting the importance of addressing infraorbital nerve injuries in the treatment of facial fractures^11,12.

This study aimed to highlight the relationship between infraorbital nerve injuries and the prevalent occurrence of Zygomaticomaxillary Complex fractures in our region. The findings will inform enhancements in resources and staff capabilities for more effective management. The purpose of our study is to examine the frequency and correlation between infraorbital nerve injuries and zygomatic complex fractures in our specific area. It seeks to stress the importance of addressing infraorbital nerve injuries alongside zygomaticomaxillary complex fractures, often overlooked in comprehensive facial fracture treatment. By clarifying this relationship and emphasizing its significance, this study in which the identification of the association of ZMC fractures with infraorbital nerve injury has been observed aims to improve resources, staff skills, and patient care in managing such cases, ultimately aiming for better outcomes and overall well-being in facial trauma management.

This cross-sectional study, involving 72 cases, took place within the Department of Oral and Maxillofacial Surgery at Jinnah Post Graduate Medical Centre in Karachi. The study duration spanned six months, from September 24, 2021, to March 23, 2022. The sample size of 72 was determined using OpenEpi software, with a 95% confidence interval, 7% margin, and an 89.77% proportion for infraorbital nerve injury in Zygomatic Complex (ZMC) fractures derived from a prior study. Employing non-probability consecutive sampling, individuals newly diagnosed with all zygomatic bone fractures, aged 16 to 65 years, were eligible for inclusion. Exclusion criteria comprised those with only maxillary and Lefort III fractures, a history of prior infraorbital nerve sensory disturbances, diabetes, and neurological disorders. After the approval from the Review Board Committee of JPMC obtaining no. 39562/JPMC, all the eligible outpatients presented with ZMC fractures and meeting inclusion criteria were enrolled after providing informed consent.

Thorough histories and pertinent clinical examinations were conducted to gather baseline information regarding gender, age groups, residential status, and obesity. BMI, or Body Mass Index, was used as a screening tool to estimate body fat levels by dividing weight in kilograms by the square of height in meters (kg/m²). The formula involves multiplying weight in pounds by 703, then dividing by height in inches squared. BMI, a widely used indicator of health, categorizes a BMI of 30.0 or higher as obesity according to the CDC. Radiological assessments, including water submentovertex and occipitomental views, as well as computed tomography scans, were utilized to assess the presence of fractures. The majority of cases exhibited distinctive features such as cheek flattening or Malar eminence, circumorbital ecchymosis, subconjunctival hemorrhage, trismus, and infraorbital nerve paresthesia, alongside radiological evidence revealing fracture lines extending through the zygomatico-maxillary and frontozygomatic sutures. Data collection was supervised by a senior consultant, a fellow of the College of Physicians and Surgeons Pakistan (CPSP), and meticulously documented using a pre-designed proforma.

The Data analysis involved the use of SPSS version 20.0, which computed frequencies and percentages for categorical variables such as gender, residential status, infraorbital nerve injury, and the specific type of nerve injury. Mean and standard deviation were provided for age, with stratification applied to account for effect modifiers such as age, gender, and residential status. To evaluate the association between categorical variables, the Chi-Square test was employed, with statistical significance set at p<0.05.

In our investigation, a comprehensive total of 72 patients, meeting the predefined inclusion criteria, participated. Within this cohort, 45 individuals (62.5%) were male, and 27 (37.5%) were female (refer to Table No. 1). The mean age of the study subjects was 37.43 ± 11.04 years, with males having a mean age of 40.44 ± 10.62 years, while females had a mean age of 32.40 ± 10.02 years. A significant proportion of the study cases, 51 (70.8%), belonged to the age group over 30 years. Regarding the residential distribution, 47 (65.3%) of the study cases hailed from urban areas, while 25 (34.7%) resided in rural regions. The mean body mass index (BMI) of the study participants was recorded at 24.77 ± 3.0 kg/m2, with 37 cases (51.4%) falling under the classification of obesity. (Table 1)

Table 1: Demographic characteristics of study participants (n=72)

In Table 2A, the correlation between zygomatic complex fractures (ZMC) and demographic variables using Chi-square tests has been explored. The analysis revealed significant associations: ZMC fractures were more prevalent among males 35 (48.6%) compared to females 19 (26.4%) (p = 0.001), older individuals 40 (55.6%) compared to those <30 years 14 (19.4%) (p = 0.00), urban residents 33 (45.8%) compared to rural residents 21 (29.2%) (p = 0.001), and obese individuals 37 (51.4%) compared to non-obese 35 (48.6%) (p = 0.001). This suggests that males, older adults, urban dwellers, and obese individuals are at a higher risk of ZMC fractures.

Table 2B outlines the distribution of infraorbital nerve injuries among study cases, classified by demographic factors. Males comprised 33 (73.3%) of cases, with a significantly higher occurrence of nerve injuries compared to females 17 (63%) (p = 0.023). Older participants 38 (74.5%) exhibited a trend of increased injuries compared to younger ones 13 (59.1%). Infraorbital nerve injuries were prevalent among obese individuals 37 (51.4%) compared to non-obese individuals 35 (48.6%). Urban residents had a significantly higher prevalence of nerve injuries 32 (68.08%) compared to rural residents 20 (80%)

Table 2A: Stratification of ZMC fracture among the study cases (n=72)

Table 3A presents the association between zygomatic complex (ZMC) fractures and infraorbital injuries among the study participants (n=72). Among individuals diagnosed with ZMC fractures, 25 (34.7%) also had infraorbital injuries, while 20 (27.8%) of those without ZMC fractures exhibited infraorbital injuries. The p-value for this comparison is 0.021, indicating a statistically significant association between ZMC fractures and infraorbital injuries.

Conversely, among participants without ZMC fractures, 15 (20.8%) had infraorbital injuries, whereas 12 (16.7%) did not. The p-value for this comparison is 0.035, also indicating a statistically significant association between the absence of ZMC fractures and the absence of infraorbital injuries.

Table 3A: Association between ZMC fracture and Infraorbital Injury (n=72)

Table 3B: Association of Infraorbital Nerve Injury with ZMC Fractures.

Table 3B delves into the relationship between infraorbital nerve injuries and zygomatic complex (ZMC) fractures, categorized by age, gender, and obesity status. For participants <30 years old, 15 out of 18 cases with ZMC fractures also had infraorbital injuries, showing a significant association (p = 0.032). Similarly, among those >31yrs., 15 out of 20 ZMC fracture cases exhibited infraorbital injuries (p = 0.027). Males demonstrated a higher incidence of infraorbital injuries among ZMC fracture cases (22 cases) compared to females (13 cases), with significant p-values of 0.011 and 0.039, respectively. Among obese individuals with ZMC fractures, 17 had infraorbital injuries (p = 0.023), while among non-obese individuals, 18 showed infraorbital injuries (p = 0.017). These findings emphasize significant associations between infraorbital nerve injuries and ZMC fractures across different demographic factors, as determined by chi-squared tests.

The zygomatic bone, a critical component of the facial skeleton, assumes a pivotal role in maintaining structural integrity by serving as a vital link between the cranium and the maxilla¹³. Beyond its structural importance, the zygomatic bone significantly contributes to facial aesthetics and function. It shapes the natural contours of the cheeks, acts as a separator for orbital contents, and acts as a protective barrier between the maxillary sinus and the temporal fossa^14,15. However, owing to its convex structure and protrusion, the zygomatic bone is susceptible to fractures, ranking as the second most common facial fracture following nasal bone fractures¹⁶. Particularly in developing countries, road traffic accidents (RTAs) emerge as a primary cause of maxillofacial injuries, fueled by factors such as speeding, non-compliance with traffic rules, and vehicle-related incidents¹⁷.

In orbitozygomatic fractures, sensory disruptions along the distribution of the infraorbital nerve are frequently observed. The incidence of posttraumatic neurosensory deficiency in the infraorbital nerve varies, influenced by factors such as the type and energy of impact, fracture displacement, timing of surgical intervention, and the chosen treatment method^18,19,20. Our comprehensive study, encompassing 72 patients meeting specific inclusion criteria, revealed a demographic profile where 45 (62.5%) were male, 27 (37.5%) were female, and the majority were over <31 years old. Urban areas accounted for 47 (65.3%) with rural areas constituting 25 (34.7%). The mean age was 37.43 ± 11.04 years, and the mean BMI was 24.77 ± 3.0 kg/m2, with 19.4% classified as obese.

In our study, infraorbital nerve injury was identified in 75.0% of Zygomaticomaxillary Complex (ZMC) fracture patients, with paresthesia emerging as the most prevalent type of disturbance (59.7%). Hypoesthesia, dysesthesia, and complete anesthesia were also observed. These findings align with existing studies, pointing to a high incidence of infraorbital nerve injuries following ZMC fractures. The results contribute valuable insights into the demographic and clinical characteristics of patients with zygomatic complex fractures, enriching our understanding and management of these injuries.

Damage to the infraorbital nerve can result in a spectrum of neurosensory disturbances, including hyperaesthesia, hypoaesthesia, paraesthesia, or anesthesia in various innervated structures such as the lower eyelid, cheek, skin of the lateral wall of the nose, upper lip, and intraorally^21,22. This encompasses the mucous membrane of the upper lip, cheek, and anterior as well as posterior teeth on the affected side. The resolution of these neurosensory issues occurs gradually, with mild injuries recovering within two months and moderate injuries within a year. Notably, the loss of static light touch/tactile sensation is a common feature of infraorbital nerve deficits post ZMC fractures, primarily attributed to damage to large myelinated Aβ fibers²³.

In terms of treatment modalities, Open Reduction Internal Fixation (ORIF) emerges as the preferred option for mild to moderately displaced Zygomaticomaxillary Complex (ZMC) fractures^6,14,20. This approach not only yields favorable functional and cosmetic outcomes but also facilitates an early return to work post-surgery^24,25. Research by De Man and Bax reported a 77.9% complete nerve recovery rate after ORIF, specifically at the fronto-zygomatic suture and/or zygomaticomaxillary buttress region. Notably, their findings cautioned against exploring the infraorbital region during surgery, as it could potentially lead to additional nerve damage, hindering the recovery process. This highlights the importance of careful surgical considerations to optimize patient outcomes in the management of Zygomaticomaxillary Complex fractures.

Our study demonstrates that infraorbital nerve injury is common in most cases of zygomatic complex fractures we examined. This correlation sheds light on the need to focus on infraorbital nerve injuries alongside zygomaticomaxillary complex fractures in our region. Our findings lay a crucial foundation for improving resources and staff capabilities to manage these cases effectively. Addressing infraorbital nerve injuries is vital in treating facial fractures comprehensively. This awareness enables clinicians to enhance patient care, leading to improved outcomes and overall well-being in facial trauma management.

The authors extend their appreciation to the Jinnah Postgraduate Medical Centre for their facilitation of the study.

The authors have no conflict of interest.

The ethical approval was taken from the Ethics Committee of Jinnah Post Graduate Medical Centre Karachi, with reference number F.2-81/2020-GENL/39562/JPMC.

Participants were briefed on the procedure steps, and consent was appropriately obtained.

The authors made distinct contributions to the study. QS played a pivotal role in conceptualizing the study design. TS, the corresponding author, took on responsibilities encompassing writing, proofreading, and the overall write-up. THS conducted meticulous data collection, while UH skillfully performed data analysis. FI contributed her expertise to the interpretation of the gathered data. Finally, HAB was actively involved in the writing process. Together, their varied roles and expertise enriched the comprehensive development of the study.

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