Evaluation of Efficacy of Ultrasonography as an Additional Diagnostic Tool for Deciding Management Protocol of Odontogenic Superficial Fascial Space Infections: A Prospective Clinical Study

Abstract

Objective

To explore the efficacy of ultrasonography as an additional diagnostic tool in superficial odontogenic fascial space infections of maxillofacial region and modifying the treatment plan when needed.

Materials and Methods

Forty patients with superficial fascial space infections underwent a detailed clinical, plain radiological and ultrasonographic examination. Based on the ultrasonographic findings, final diagnosis was made and compared with clinical findings. Patients diagnosed with cellulitis were given medical line of treatment, and those with abscess were subjected to incision and drainage along with standard general supportive care and removal of etiologic agent.

Results

In this study, out of 40 patients (male = 22, female = 18), clinical diagnosis of cellulitis was made in 26 cases (65%) and abscess in 14 (35.0%). On USG examination, cellulitis was present in 21 cases (52.5%), while abscess in 19 (47.5%). Final diagnosis of cellulitis was made in 13 (59.1%) males and 12(66.7%) females, while abscess was confirmed in 9 (40.9%) male and 6 (33.3%) female patients. The results showed that sensitivity of the clinical examination alone was 64% with 33% specificity, and for USG, sensitivity was 84% with specificity of 100%.

Conclusion

The adjuvant role of ultrasonography in the diagnosis and timely management of superficial fascial space infections is promising owing to its accessibility, relative safety, repeatability and cost-effectiveness.

Introduction

Odontogenic infections signify a noteworthy amount of dental problems that present to any dental hospital. Pulp necrosis caused by caries, trauma, periodontal infections, pericoronitis or any of these may lead to most odontogenic infections in healthy patients [1]. The direction of the infection's spread depends on the overlying bone thickness and the relation of the site of bone perforation to the muscle attachments of the jaw [2]. Superficial to deep neck infections after entering into the tissues may either resolve, become localized or can spread [3]. The course and severity of the infection process can differ depending upon the virulence of organisms, host resistance and anatomy of the involved area. Once the infection extends beyond the dentoalveolar apparatus into the surrounding soft tissues, inflammatory edema occurs and the area becomes swollen, leading to cellulitis. Subsequently, suppuration occurs and the infection localizes to form an abscess. Occasionally, an abscess may arise directly, without passing through the preceding stage of cellulitis [4].

To deal with the dilemma of whether an acute odontogenic infection is an abscess or cellulitis exclusively by clinical examination may be difficult but is very important as both may require different treatment plans [5, 6]. Frequently, the two conditions coexist, as an abscess often begins as cellulitis. In many cases, fascial space infections are difficult to determine just by clinical examinations as the anatomy of head and neck structure is complex [7]. Failure to diagnose correctly leads to unnecessary invasive procedures and delayed inappropriate therapy which, in turn, may lead to medical emergencies, additional emergency department visits and high costs [5].

There are numerous diagnostic modalities available that can minimize such a therapeutic dilemma for oral surgeons [8]. Plain radiographs can show the causative agent, but it does not provide a good definition of soft tissues. While magnetic resonance imaging (MRI) and computed tomography (CT) are precious diagnostic aids in imaging odontogenic infections, they have certain limitations of their own. MRI is expensive and can cause discomfort with the procedure, especially with claustrophobic patients. CT is not readily available in many dental clinics, is costly, time-consuming and causes exposure of large doses of radiation to patients [6].

Ultrasonography (USG) visualizes deep structures of the body by directing ultrasonic waves into the tissues and then recording their reflections (echoes). The role of ultrasonography as a diagnostic tool in the field of oral and maxillofacial surgery is enduring [9].

This study aimed to evaluate the efficacy of ultrasonography as an additional diagnostic tool in odontogenic superficial fascial space infections and its predictability in detecting the stage of infection, and thereby modifying the management protocol if required.

Materials and Methods

In this study, 40 patients having odontogenic superficial fascial space infection of the maxillofacial region in the age range of 18–60 years, categorized under ASA–I classification system and reported to the Department of Oral and Maxillofacial Surgery at Ahmedabad Municipal Corporation-Medical Education Trust Dental College and Hospital, Ahmedabad, from December 2016 to November 2018 were included.

However, patients having deep facial space infections or having any infection other than odontogenic etiology or patients with non-inflammatory soft/hard tissue swellings, any infected cyst, tumors, developmental anomalies or presence of frank pus discharge (intraoral/extraoral) were excluded. Prior ethical clearance was obtained for the study.

Methodology

The complete protocol comprised of:

A. Patient assessment.

B. Ultrasonography examination.

C. Treatment plan.

A. Patient Assessment

The clinical examination of patients was performed, and the detailed history was taken. If the swelling was firm, warm and no visible fluid movement was found, then the provisional diagnosis of cellulitis was made. Fluid movement present under the tissue led to the diagnosis of an abscess. Patients were prescribed IOPA (intra-oral periapical radiograph) or OPG (orthopantomogram) to confirm the clinical findings which were then recorded. After the admission of a patient to the ward, a single dose of empirical antibiotic therapy was given and the patient was sent for an ultrasonography examination.

B. Ultrasonography Examination

USG examination of the suspected area was done using the diagnostic ultrasound machine, which had an ultrasonic probe and various high-definition and multifrequency features. The ultrasound probe was covered with an ultrasound gel to eliminate air bubbles. Then, it was positioned against the skin of the involved area and then was moved several times to obtain a sufficient number of transverse (axial) planes for defining the extent of the lesion.

All the spaces involved were measured in 3 planes (i.e., anteroposterior, superoinferior, mesiodistal). The analysis of the grayscale ultrasound images was done, and onscreen calipers were used to measure focal lesions. The ultrasound echogenicities were described in comparison with the adjacent tissues as hyperechoic (brighter) or isoechoic (equal) or hypoechoic (darker) or anechoic (no internal echoes) or mixed signals. These observations were the key to staging the infections from the acute phase to a complete abscess formation. The information which was obtained from USG (like the site of swelling/infection, edge definition, internal echo-pattern and intensity, dimension of abscess cavity or swelling, depth from the skin surface, amount of pus/liquid, final diagnosis) was recorded, and the treatment plan was decided accordingly.

Routine blood and preoperative investigations were also done.

C. Treatment Plan

In all cases, removal of the odontogenic cause was done the next day. All the patients were prescribed a standard dose of empirical therapy of intravenous antibiotics (amoxicillin and clavulanic acid, metronidazole) along with analgesic diclofenac and antacid pantoprazole for 5 days, if required, which were extended based on patient’s improvement or till complete resolution of all the sign and symptoms of space infection was attained. In a few cases, traditional incision and drainage was performed under local anesthesia or conscious sedation using propofol and culture and antibiotic sensitivity tests were done whenever there was an abscess. The modification of antibiotics was done based on its results.

Results

In this study, total of 40 patients (Sample size N = CHISQAURE/W^2, where W = 0.5, CHISQUARE = 7.5, DF = 1; Categorical data using Chi Square test at 5% level of significance by SPSS 20.0) were included. Out of 40 patients of odontogenic superficial facial space infections, 22 were male and 18 were female. The M/F ratio was 1.2:1.

Out of all spaces, buccal space was the most common space involved (n = 11, 27.5%) followed by submandibular space (n = 6, 15.0%). The most common combination of spaces involved in both sexes was buccal and submandibular (n = 9, 22.5%; for males: n = 6, 27.3%; for females: n = 3, 16.7%). In males, the most frequently involved space was buccal space (n = 7, 31.8%), while in females, it was submandibular space (n = 5, 27.8%). The analysis was done according to the Pearson Chi-square test, but results were insignificant (Table 1).

Table 1.

Distribution of spaces involved based on gender

Sex	Spaces involved
		Buccal space	Submandibular space	Submental space	Infraorbital space	Canine space	Parotitis
Male	Count	7	1	1	2	1	2
	%	31.8	4.5	4.5	9.1	4.5	9.1
Female	Count	4	5	0	2	0	2
	%	22.2	27.8	0.0	11.1	0.0	11.1
Total	Count	11	6	1	4	1	4
	%	27.5	15.0	2.5	10.0	2.5	10.0

Sex		Buccal and submandibular	Submental and submandibular	Canine and buccal space	Buccal and sublingual	Buccal and infraorbital	Total
Male	Count	6	1	0	1	0	22
	%	27.3	4.5	0.0	4.5	0.0	100.0
Female	Count	3	0	1	0	1	18
	%	16.7	0.0	5.6	0.0	5.6	100.0
Total	Count	9	1	1	1	1	40
	%	22.5	2.5	2.5	2.5	2.5	100.0

The most commonly affected tooth was mandibular first molar both in males (n = 14) and in females (n = 12).

The most common side affected was the left side (n = 25, 62.5%). In males, the left side (n = 16, 72.7%) was commonly affected, while in females both sides were equally affected (n = 9, 50%) (Table 2) .

Table 2.

Affected side in both genders

		Side affected		Total
Sex		Right	Left
Male	Count	6	16	22
	%	27.3	72.7	100.0
Female	Count	9	9	18
	%	50.0	50.0	100.0
Total	Count	15	25	40
	%	37.5	62.5	100.0

In a total of 40 cases, clinical diagnosis of cellulitis was made in 26 cases (65%) and that of abscess in 14 patients (35.0%). In both sexes, cellulitis (males: n = 16, 72.7%; females: n = 10, 55.6%) was the most common clinical diagnosis (Fig. 1 Clinical diagnosis of all patients).

Fig. 1.

Clinical diagnosis of all patients

All patients were subjected to the USG examination in which cellulitis was diagnosed in 21 cases (52.5%) and abscess in 19 cases (47.5%) (Fig. 2 USG diagnosis of all patients).

Fig. 2.

Ultrasonographic diagnosis of all patients

On clinical examination, 14 cases were diagnosed as abscesses, while on ultrasonography examination, 19 cases were found as abscesses. Thus, ultrasound was more superior to clinical examination in detecting abscess because of its real-time processing.

On final diagnosis, among male patients 13 (59.1%) had cellulitis and 9 (40.9%) had an abscess. In females, 12 (66.7%) patients had cellulitis and 6 (33.3%) had an abscess. In the whole study, out of 40 patients, 25 patients had cellulitis (62.5%), while abscess was seen in 15 patients (37.5%) (Fig. 3 Final diagnosis of all patients).

Fig. 3.

Final diagnosis of all patients

Both clinical and USG examination showed 12 patients with a diagnosis of cellulitis and 5 patients having an abscess. The dissimilar diagnosis was seen in rest of other cases where the clinical diagnosis was an abscess and USG diagnosis was cellulitis (n = 9), while in 14 cases clinical diagnosis as cellulitis and USG diagnosis as abscess were observed.

In a total of 40 patients, 20 patients underwent conservative treatment only by intravenous medications along with general supportive therapy, while remaining were primarily treated by surgical incision and drainage under antibiotic coverage. In both situations, the removal of offending tooth/teeth was done simultaneously.

The results showed that the sensitivity of the clinical examination alone was 64% with 33% specificity and for USG, sensitivity was 84% with the specificity of 100% (Table 3).

Table 3.

Sensitivity and specificity of clinical and ultrasonography findings for diagnosing cellulitis and abscess

		Clinical findings		USG findings
		Cellulitis	Abscess	Cellulitis	Abscess
Final diagnosis	Cellulitis	16	9	21	4
	Abscess	10	5	0	15
Sensitivity		0.640		0.840
Specificity		0.333		1.000

Thus, ultrasonography was found to be a valuable adjunct to clinical diagnosis in determining the state of infection, i.e., cellulitis or abscess and treatment to be performed, i.e., conservative therapy or incision and drainage. However, the experience of the clinician would definitely affect the ultimate management.

Discussion

Odontogenic infections are among the most often encountered and one of the key causes of fascial space infections in the region of head and neck [2]. The usual cause of odontogenic infections is pulpal necrosis of tooth, which follows bacterial invasion to the deeper tissues [10]. The course and severity of the infection process can differ on the basis of anatomy of the involved area, on the virulence of organisms and host resistance [4]. The spaces involved in odontogenic infections can be classified as primary maxillary and mandibular spaces plus secondary fascial spaces which comprises cervical spaces. Poorly managed primary odontogenic infections can spread posteriorly to involve secondary and cervical spaces where it becomes more difficult to treat and complications such as Ludwig' angina, mediastinitis, intracranial abscess, and parapharyngeal spread with airway obstruction and morbidity arise [4, 11, 12]. To prevent devastating results, aggressive surgical and medical care is vital [10].

In this study, the most frequently involved space was buccal space followed by submandibular space, that is in accordance with some studies [2, 10] while in contrast to few [12–14].

Odontogenic infections have been primarily treated surgically for centuries and will continue to be so. Offending tooth extraction, abscess drainage and release of pressure are basic in the management of these infections. Antibiotics are used as adjunctive therapy for more rapid and complete resolution. Numerous factors play a role in the resolution of these infections like the level of host defenses, correct antibiotic therapy, the seriousness of primary infection and extensiveness of surgical exploration [10].

Clinical examination of inflammatory facial swelling is largely restricted to visual and tactile sensation. However, as the anatomic structure of the head and neck is complex, it becomes challenging to determine it by clinical examinations alone. In severe cellulitis, the induration of skin over the swelling may mask the actual clinical diagnosis of underlying abscess formation, stage of infection and its exact anatomic location [10, 15], whereas relatively blind exploration of abscesses on the basis of clinical diagnosis alone may sometimes end up in excessive tissue trauma, unnecessary extensive incisions, long duration, pain and failure to locate and evacuate the abscess cavity [16].

Imaging studies are useful when the clinical diagnosis is in question for maxillofacial diseases. Various modalities like conventional radiography, computed tomography (CT), magnetic resonance imaging (MRI), ultrasonography (USG), etc., can be utilized to detect the infection spread in the head and neck region [17].

The plain radiograph is a primary radiographic diagnostic tool, easily available, cost-effective, gives exact idea of the etiologic agent; however, it often provides limited soft tissue definition.

However, CT and MRI are associated with certain disadvantages. CT scan is expensive, possesses potential risks of high radiation doses, and is hazardous for pregnant women and infants, and to distinguish different pathologic processes from adjacent normal soft tissues, administration of an intravascular contrast medium is needed, while in the case of MRI, though it provides excellent tissue contrast, it is expensive, takes relatively prolonged time for image acquisition, tends to be claustrophobic and is contraindicated in people with cardiac pacemakers, cochlear implants or neurostimulator units [11, 18].

The advantages of USG over other modalities are its wide availability, ease of usage, it is harmless and painless, utilizes nonionizing radiation, is non-radio-invasive, economical and unaltered by metal artifacts such as dental restorations, can be done without heavy sedation, can be repeated on follow-up examinations, creates no health issues and can frequently be used in pregnant women where routine radiography is contraindicated.

Ultrasonographic picture in the case of cellulitis shows ill-defined edges with heterogeneous pattern and hypoechoic intensity with an increase in the thickness of involved muscle and subcutaneous tissue, while in the case of an abscess, the edges are well defined with the homogenous pattern and hypoechoic intensity, with posterior acoustic enhancement suggestive of some collection [19]. In our study, we followed the same criteria, when USG examination of fascial space infections showed no collection, subcutaneous tissue thickness and increased muscle involvement, then the diagnosis of cellulitis was made, and when the presence of fluid was detected, the provisional diagnosis was made as an abscess.

The USG picture of any fascial spaces is similar depending on the contents and the boundaries of a particular space. Hence, it is also helpful in cases of space infection involving multiple spaces, because the radiographic picture depends on the anatomic area scanned and the stage of infection, rather than the number of spaces involved. However, if the infection tends to spread in deeper spaces, then the assistance of other radiological modalities is required. Thus, overall USG picture of different superficial fascial spaces can evaluate the stage and type of infection depending on the region studied.

Ultrasonography can determine the relation of the abscess to the overlying skin. It can precisely gauge the dimensions of an abscess cavity and its depth below the surface of the skin [20]. Abscess cavity dimension, quantity of collected pus and depth of the center of the abscess cavity from the skin surface were also calculated in our study [15].

In our study, a high male-to-female ratio (M/F = 1.2:1) was seen. The number of males (n = 22) having superficial fascial space infections was more than that of females (n = 18) which is in accordance with most of the prior studies [1, 18, 21, 22]. This can be explained by the fact that women manage to have better oral health and seek out for oral health care more often [14]. Studies showed that women are significantly more affected by pain, have a lower acceptance of pain, a greater fear of pain, have significantly lower thresholds for the detection and tolerance of pain and avoid pain more than males [22, 23].

The left side was more commonly involved in our study (n = 25, 62.5%) which is in contrast to study done by Poweski et al. [18] (Table 2).

The results of our study found the sensitivity and specificity of the clinical examination alone to be 64% and 33.3%, respectively, while sensitivity and specificity of USG imaging were high, 84% and 100%, respectively, which is almost parallel to study carried out by Khemaleelakul S et al. [24] (Table 3).

Our study indicates that USG is a very reliable additional diagnostic tool for diagnosing a collection and providing proof that the resolution of small pus collections without surgical drainage can be done. Similar findings were reported by Nawaz et al. [15].

Literature reports have also shown ultrasound to be very specific and sensitive in detecting abscess cavity, except one. Elias et al. [23] in their study found that, in 5 patients, in whom initially ultrasonography had not suggested abscess, after few hours when they were subjected to surgical procedures, there was a drainage of purulent material. A gradual transition from cellulitis to an abscess a few hours after examination might be the probable reason for not detecting abscess formation.

In total of 40 patients, 20 patients underwent conservative treatment only by intravenous medications along with general supportive therapy and removal of causative agent, while remaining were principally treated by incision and drainage under antibiotic coverage. In our study, antibiotics were started as per protocol immediately once the diagnosis of the odontogenic infection was made. In some of the cases where the patient does not show improvement clinically even after surgical intervention and removal of etiological agent, course of antibiotics was changed based on culture and sensitivity results.

In some settings, due to a lack of facilities and high cost to the patient, routine culture and sensitivity testing is difficult. In such cases, this testing can be delayed, unless specified by a failure in clinical response. There is an absolute lack of definite agreement regarding standard antibiotic protocol because of the absence of proven data to support one regimen over the other in terms of well-designed clinical trials [14].

The role of USG is twofold and also can be efficacious in cases of superficial neck abscess. Its diagnostic aspect, due to the availability of high-frequency ultrasonography probes, can be considered the best initial investigation tool for the evaluation of neck abscesses [9]. The management of abscesses of head and neck by USG guided surgical drainage with the combined help of grey-scale and color Doppler ultrasonography is found particularly useful in cases that were difficult to locate by physical examination [25].

In addition, technical advances in recent years, including higher resolution, color Doppler sonography, USG-guided FNAC, contrast-enhanced ultrasound, elastography, and tissue harmonics, have expanded the usefulness of ultrasonography by making an improvement in diagnostic accuracy of sonography [21].

The major drawback of application of USG is that deep fascial space infections like parapharyngeal, retropharyngeal, masticator, pterygomandibular, infratemporal and sublingual space could not be precisely identified. Inhibition of transmission of ultrasound signals through the mandibular body and ramus region might be the probable cause for this drawback [3]. However, in the submasseteric space infection, which is one of three spaces that make up the main masticator space, role of USG seems to be important. It is effective in diagnosis of submasseteric space abscess as well as its role in treatment of abscesses of odontogenic origin by the means of USG-guided surgical drainage without incision and drainage is valuable [26].

Therefore, USG cannot be solely used as a diagnostic aid in assessment of all odontogenic fascial space infections but can definitely be very useful as an adjunct to clinical diagnosis and thereby in deciding management protocol for the same.

Conclusion

Ultrasonography can be recommended as a promising adjunct to clinical examination and plain radiography for diagnosis and management of superficial fascial space infections. It also plays a significant role in deciding a timely treatment protocol for the same. USG provides some of the advantages like portability, possibilities of repeated examinations and low cost which is a boon for developing countries like India, especially at smaller rural centers and many small peripheral local hospitals, where the cost of health care can be inexpensive and people do not have to visit higher centers for mere imaging of odontogenic infections. However, with newer USG techniques, advanced research designs and clinical trials with a greater number of cases can be undertaken to prove additional advantages of ultrasonography.

Funding

None

Declarations

Conflict of interest

The authors declare that they have no conflict of interest.