Background
Fascial spaces are the spaces between the various layers of muscles, filled with loose connective tissue [
1]. In the orofacial area, major fascial spaces include submandibular, sublingual, infratemporal, canine, buccal, and masticator spaces. Among those, masticator spaces are divided into masseteric, pterygoid, and temporal space. Fascial spaces are effective barriers, but they also act as the pathway for progressing infection. In the orofacial area, the most common source of infection is an odontogenic infection, which accounts for about 78% of space abscesses [
2]. Other possible sources of infection include trauma, sinus disease, and invasive treatment of the orofacial area [
3]. Common symptoms of fascial space infection and abscess in the orofacial area include limited mouth opening, neck stiffness, dyspnea, dysphagia, fever, swelling and redness [
4]. If the diagnosis and treatments of fascial space abscess in the orofacial area are delayed, the abscess can spread into more critical structures including neck, airway, orbital septum, and even brain, leading to grave consequences [
5,
6].
Although early detection and treatment are necessary to prevent the progress of infection, diagnosis of fascial space abscess in the orofacial area is often challenging. Conventional images, such as panoramic images, have limitations in detecting an infectious state of soft tissues. Although clinical examinations might help identify typical symptoms of fascial space abscesses, early fascial abscesses are often disguised as other diseases due to their ambiguous symptoms. One of the diseases that clinicians might confuse with orofacial fascial space abscess is temporomandibular disorder (TMD), especially when only limited mouth opening and pain are observed [
7]. TMD is a multidisciplinary disorder and related to multiple causes such as psychology, general health, or spinal disorders, and thus it is common for any other orofacial disease including fascial space abscess to mimic TMD [
8]. Since TMD and space abscess treatments are quite different, clinicians need to differentiate TMD and space abscess as early as possible. We herein report three cases in which patients were diagnosed with TMD at first visit but finally proven to have fascial space abscess by additional symptoms and further diagnosis.
Discussion and conclusions
In these cases, we could identify patients initially diagnosed with TMD but finally proven to have fascial space abscesses. All patients complained of severely limited mouth opening with the pain of TMJ or masticatory muscles, similar to TMD symptoms. Like other infections, clinical signs and symptoms of orofacial fascial space are broad depending on the degree of infection. If there are only a few common symptoms, such as pain in the facial area and limited mouth opening, clinicians might neglect the possibility of space abscess.
Previous case series have reported the possibilities of fascial space abscess in the orofacial area (Table
5) [
3,
9‐
27]. Of the 24 cases, 9 (37.5%) reported that distinct facial swelling was not observed at the first visit. Thus, patients were initially diagnosed with other diseases rather than space abscess: TMD, parotitis, headache and otitis media [
3,
9,
13,
14,
18,
21,
26]. What made clinicians realize the possibility of a fascial space abscess were clinical symptoms, symptoms that were aggravated or not responded to treatment, and, additionally, symptoms such as facial swelling that strongly suggest a fascial space abscess.
Table 5
Summary of previous case reports of orofacial fascial space abscess
| 62/M | Facial swelling, trismus, pain | Parotitis (at another clinic) | Enhanced CT, MRI, blood test | Masticator | #17; dental caries | Masseter muscle dissection, I&D, antibiotics | 3 years | Immediate | 3 years |
| 69/M | Facial swelling, dysphagia, pain, fever, tachypnea, tachycardia | Space abscess | CT, blood test | Masticator, submandibular, parapharyngeal, peritonsillar | #37; dental caries, periapical abscess | I&D, tracheotomy, antibiotics | Un-known | Immediate | Unknown |
| 51/M | Facial swelling, trismus, pain, fever | Space abscess | Panoramic view, ultrasound scan, blood test, urea test | Masticator | #38; pericoronitis | Needle aspiration, I&D, antibiotics | 2 days | Immediate | 2 days |
| 21/M | Facial swelling, dysphagia, trismus, lymphadenopathy | Space abscess | Panoramic view, ultrasound scan, blood test, urea test | Masticator | #38; pericoronitis | Needle aspiration, I&D, antibiotics | Unknown | Immediate | Unknown |
| 25/M | Facial swelling, pain, intra-oral fistula | Space abscess | Enhanced CT, CT, dual-isotope scan | Masticator, subdural | Right molars; dental caries, periapical abscess | I&D, antibiotics, neuro-surgical drainage | 5 days | Immediate | 5 days |
| 62/F | Trismus, pain | TMD (ADD without reduction) | MRI, blood test | Masticator | #17; periodontitis | I&D, antibiotics | 1 week | 5 days | 12 days |
| 68/F | Trismus, pain | TMD (at another clinic) | Enhanced CT, MRI, blood test | Masticator | #37; dental caries, #38; pericoronitis | I&D, antibiotics | Unknown | Immediate | Unknown |
| 61/M | Headache, dysphagia, fever / Facial swelling, trismus | Headache | CT, blood test | Masticator, parapharyngeal, intra-orbital, intra-cranial | #26–27 | I&D, bur hole drainage, antibiotics | 1 week | 5 days | 12 days |
| 49/M | Facial swelling, trismus, pain, visual disturbance | Space abscess, thrombosis | CT, MRI, blood test | Masticator, parapharyngeal, cavernous sinus | #16,18,48; dental caries | I&D, antibiotics | 5 days | Immediate | 5 days |
| 50/F | Facial swelling, trismus, pain, fever, dyspnea, dysphagia, foreign sensation of neck | Space abscess | Panoramic view, CT, blood test | Masticator, submandibular, cervical | #45–47; dental caries | I&D, cervicotomy, antibiotics | 10 days | Immediate | 10 days |
| 28/F | Facial swelling, trismus, pain | Space abscess | CT | Masticator | #38; dental caries | I&D, antibiotics | 1 week | Immediate | 1 week |
| 6/M | Trismus, ear pain, fever, vomiting, neck stiffness | Otitis media (at another clinic) | CT, blood test | Masticator, TMJ space | Unknown | Arthrocentesis, antibiotics | 1 week | Immediate | 1 week |
| 18/F | Trismus, pain / Facial swelling | TMD (at another clinic) | Enhanced CT, blood test | Masticator, deep temporal, skull base, TMJ space | Left wisdom teeth | I&D, antibiotics, arthrocentesis | 3 weeks | 4 days | 25 days |
| 14/F | Facial swelling, sinus congestion, gray drainage | Allergic fungal sinusitis | CT, MRI | Infratemporal, maxillary sinus, middle cranial | Sinus infection | Abscess drainage, craniotomy, antibiotics | 1 year | Immediate | 1 year |
| 75/M | Trismus, tonsillar swelling, pain / Facial swelling | Peritonsil abscess | CT, blood test | Masticator, submandibular, parapharyngeal | Peritonsilar abscess | I&D, antibiotics | 5 days | 2 days | 1 week |
| 90/F | Facial swelling, trismus, pain | Peritonsil abscess | Enhanced CT, blood test | Masticator, parapharyngeal | Peritonsilar abscess | I&D, antibiotics | 3 days | 4 days | 1 week |
| 56/F | TMJ area swelling, trismus, pain, fever | TMD (at another clinic) | Ultrasound, MRI, blood test | Masticator, intracranial | Unknown | Antibiotics | 1 week | Immediate | 1 week |
| 66/M | Pain / Trismus | TMD | Enhanced CT, blood test | Masticator | Facial acupressure massage | I&D, antibiotics | 3 days | 1 week | 10 days |
| 79/F | Facial swelling, trismus, pain | Space abscess | Enhanced CT | Masticator, parapharyngeal | Unknown | I&D, antibiotics | 1 week | Immediate | 1 week |
| 38 | Facial swelling, pain, headache, oral ulcer | Space abscess | CT, MRI, blood test | Masticator, epidural | Lung infection | Burr hole drainage, antibiotics | 3 weeks | Immediate | 3 weeks |
| 53/M | Facial swelling, pain, fever | Space abscess | CT, MRI, blood test | Masticator | #38; pericoronitis | I&D, antibiotics | 10 days | Immediate | 10 days |
| 53/M | Facial swelling, pain, trismus, pain, speaking problem | Space abscess | Enhanced CT, blood test | Masticator, buccal, sphenoid bone, whole brain | #37; periodontitis | Neuro-surgical drainage, antibiotics | 2 weeks | Immediate | 2 weeks |
| 50s/M | Trismus, pain / Facial swelling, dysphagia | TMD (at another clinic) | Enhanced CT, blood test | Masticator, parotid, submandibular, parapharyngeal | Intra-muscular stimulation | I&D, antibiotics | 4 weeks | Immediate | 4 weeks |
| 84/F | Facial swelling, trismus, pain | Space abscess | CT | Masticator, infratemporal, extra-cranial | Unknown | I&D, antibiotics | 2 days | Immediate | 2 days |
Meanwhile, 20 cases reported suspicious sources of infection (Table
5). In 14 cases (70%), the source of infection was odontogenic origin: pericoronitis, periodontitis, dental caries, and periapical lesion [
9‐
18,
24,
25]. Among the odontogenic origins, maxillary molars were in 6 cases, and mandibular molars were in 11 cases. In 4 cases (20%), the source of infection was the spread of infection from other sites: sinus infection and peritonsillar abscess [
19,
20,
23]. In 2 cases (10%), the infection source was invasive facial area treatments such as acupressure massage and intra-muscular stimulation [
3,
26]. Once space abscess was suspicious, all cases used blood tests and additional imaging techniques to evaluate soft tissue, such as enhanced CT, MRI, or ultrasound, to confirm space abscess.
The clinical key to distinguishing hidden fascial space abscesses is to catch the possibility of infection. If distinct symptoms such as facial swelling, redness or fever are observed, it is reasonable to suspect a fascial space abscess. However, facial swelling or fever alone represents a non-specific symptom and cannot solely serve as a clear basis for diagnosing a fascial space abscess. Some fascial space abscesses can exist without evident facial swelling, and various diseases within the orofacial area, such as giant cell arteritis or autoimmune disorders like systemic lupus erythematosus, can mimic the symptoms of a fascial space abscess [
28,
29]. From this perspective, clinical symptoms to suspect fascial space abscess should be severe mouth opening limitation, considering that limited mouth opening was observed in all 24 cases of fascial space abscess. Limited mouth opening in the orofacial fascial space abscess is because the inflammatory state of masticatory muscles and fascia induced the weakness and limited functions of masticatory muscles [
30]; thus, limited mouth opening can represent the possibility of fascial space abscess in the orofacial area. Alongside limitations in vertical mouth opening, suspicion of orofacial fascial space abscess can arise when the mandibular movement during lateral excursion is less than 5 mm, as demonstrated in this case series.
If clinicians realize the possibility of a fascial space abscess, the next step is to search for possible sources of infections, which include recent infections of other regions, trauma, surgical treatment, or intravenous drug use [
1,
31]. There might be systemic risk factors such as diabetes mellitus, steroid therapy, chemotherapy, and immune dysfunction. However, the most common cause of orofacial fascial space abscess is still odontogenic infection. Common origins of orofacial infection include dental caries, periapical lesions, inappropriate fillings, inadequate root canal treatment, pericoronitis, and periodontal disease [
32]. As the treatment of odontogenic infection is delayed, the risk of spreading infection increases. Delayed treatment can result from diagnostic errors, patient disagreement with treatment, or socioeconomic factors among patients. In a recent study, individuals with a lower socioeconomic status exhibited a higher prevalence of untreated dental caries and poorer oral hygiene [
33]. In case 1, the patient, a recipient of a medical aid program, took 60 days from the onset of symptoms to the first hospital visit. It was the longest duration among the three cases, and her socio-economic status might explain the reason behind this delay.
When the origins of orofacial infections are maxillary molars, infections mainly spread through the thin maxillary buccal plates, involving temporalis, lateral pterygoid, and masseter muscles [
32,
34]. Since maxillary infections are less prone to spread downward, fascial space abscess with maxillary infection usually involves masticator, buccal, and parapharyngeal space. On the other hand, orofacial infections from mandibular molars show different patterns. Mandibular molar infections frequently spread into the masseter and medial pterygoid muscles and can involve lateral pterygoid or temporalis less frequently [
34]. Eventually, mandibular infections mostly progress to masticator space abscesses and spread downward to form submandibular and sublingual space abscesses [
7].
Among the possible infection pathways of odontogenic infections, isolated lateral pterygoid and parapharyngeal space abscesses are relatively uncommon but have been reported steadily, such as case 3 in this report [
35]. The common pathway of parapharyngeal space abscess due to odontogenic infection is through masticator space; thus, maxillary and mandibular molars are both responsible for abscess formation [
36]. However, when a parapharyngeal space abscess originates solely from an infection in the pterygoid space due to odontogenic causes, distinct facial swelling might not be observed [
13,
37]. In cases of isolated pterygoid and parapharyngeal space abscess, odontogenic infection is more likely to stem from maxillary molars than mandibular molars.
Once clinicians suspect fascial space abscess by clinical symptoms and search for possible sources of infection, additional examinations are needed to confirm the abscess. A blood test is a simple but surely effective measurement to detect and estimate infectious lesions. Especially, some blood markers have been reported to show high sensitivity to infection. CRP is a broadly used blood marker, and it can effectively reflect the severity of infections, including fascial space abscesses [
38,
39]. Since CRP decreases corresponding to the cure of infections, it can also help to evaluate the treatment efficacy and adjust the treatment plan efficiently. Meanwhile, hs-CRP is commonly used to evaluate cardiovascular disease, but it can also be used to detect fascial space abscesses, considering that hs-CRP reflects the inflammatory state of muscles and vessels [
40,
41]. Compared with CRP, hs-CRP shows high sensitivity and can detect levels as low as 0.1 mg/dL; thus, it can more sensitively evaluate minor risk factors and course of treatment. Another useful biomarker is the neutrophil-to-lymphocyte ratio (NLR). Increased NLR is a state of increased neutrophils and decreased lymphocytes, which reflects an inflammatory state [
42]. NLR is a simple biomarker that can be calculated from conventional differential counts, but it can evaluate not only the inflammatory state but also host immunity, which can determine the prognosis of fascial space abscess.
Imaging techniques are also needed to confirm the location and extent of abscess. Since fascial space abscess is a soft tissue disease, conventional imaging, such as panoramic images, cannot effectively detect fascial space abscess. Broadly used imaging techniques are enhanced CT and MRI. Both can reflect the actual state of abscess precisely and can identify the pathway of infection [
7,
43]. Also, ultrasonography can be used to diagnose fascial space abscesses. In ultrasonography, an abscess shows a typical anechoic area, whereas inflammatory structures show a hyperechoic area [
4]. Ultrasonography is a minimally invasive diagnostic tool known for its effectiveness in diagnosing soft tissue structures. Additionally, it can enhance the precision of invasive treatments like muscle injections or arthrocentesis [
44]. Compared to MRI or enhanced CT, ultrasonography is slightly inferior in detecting the extent of fascial space infections, and it cannot detect deep space abscesses such as parapharyngeal abscesses [
4,
45]. However, the key advantage of ultrasonography in diagnosing abscesses lies in its ability to assess the real-time condition of the abscess promptly, facilitating the swift formulation of additional diagnostic plans.
Once a fascial space abscess is definitively diagnosed, treatment should prioritize infection control. Alongside conventional methods like antibiotics or incision and drainage (I&D), several studies have introduced novel approaches. A local chemotherapeutic approach involves delivering antibiotics directly to the infection site, minimizing systemic complications. Specifically, in odontogenic infections, membrane or gel-type polymers—such as cellulose or polysaccharides—containing dental drugs can be targeted to specific areas in the oral cavity, such as periodontal tissues with significant pocket depth and alveolar bone loss [
46,
47]. As a more conservative therapy, low-level laser therapy has been suggested for its potential anti-inflammatory effects in focal lesions. However, its efficacy in infection control has not yet been established [
48].
When dealing with an orofacial fascial space abscess, early recognition of the potential for a space abscess is crucial. This can be attained by recognizing clinical symptoms such as restricted mouth opening accompanied by facial pain, including discomfort in the TMJ or masticatory muscles, particularly when these symptoms have recently emerged. In this case series, limitations were noted in both the vertical movement and lateral excursion of the mandible when compared to the normal range. When assessing mandibular motion in units of millimeters (mm), restriction is indicated in the side-to-side lateral excursion when it measures less than 7 mm, while the mouth opening is < 35 mm [
49,
50]. The presence of limitations in vertical and side-to-side mouth opening is important in discerning orofacial fascial space abscess. However, clinicians must recognize that various conditions can mimic both TMD and orofacial fascial space abscess. Therefore, the next crucial step in diagnosing orofacial fascial space abscess should involve investigating potential sources of infection. Since the delayed intervention of orofacial fascial space abscess can cause increased morbidity and mortality, clinicians must also consider the possibility of fascial space abscess in TMD patients to prevent unexpected progress of orofacial abscess.
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