masticator space infections
Epidemiology
- The majority of masticator space infections are secondary to odontogenic infections.
- These patients are typically adolescents or adults with poor oral h ygiene. Occasionally, masticator space infection is secondary to malignant otitis externa often seen in diabetics or immunologically compromised patients.
Clinical Findings
- Patients with masticator space abscess typically present with pain, fever, and trismus.
- The diagnosis of dental abscess or malignant otitis externa is usually evident from the clinical history and associated signs and symptoms.
- Trismus associated with masticator space infection often hampers the examination of the oral cavity or oropharynx.
- In addition, malignant otitis externa with temporomandibular joint extension may further aggravate trismus
Pathology
- The vast majority of masticator space abscesses due to odontogenic disease consist of mixed infection.
- Masticator space abscess may also be due to malignant otitis externa with the most common organism being Pseudomona
Treatment
- The treatment for masticator space infection involves controlling the infection of the primary site.
- Spreading cellulitis requires only antibiotic therapy, and surgery is indicated only when pus formation ensues.
- If mandibular or external auditory canal osteomyelitis is present, subperiosteal drainage will be required.
- Multiple abscesses in multiple spaces may necessitate complex drainage procedures.
Imaging Findings
CT
- Inflammation of the masticator space causes swelling of one or a combination of the following muscles: medial and lateral pterygoids and temporalis and masseter muscles.
- There is usually moderate to good contrast enhancement.
- Mandibular or temporal bone erosion is best seen on CT images acquired with bone algorithm.
- A masticator space abscess is characterized by a well-defined low attenuation mass that may have an enhancing rim
MR
- On fat suppressed, contrast-enhanced MR images, there is strong contrast enhancement of the involved muscles.
- A diagnosis of abscess formation is made when a mass with areas of no enhancement is noted.
- T2-weighted MR images typically show high signal intensities
Imaging Pearls
• Bone algorithms need to be evaluated for evidence of odontogenic disease in all cases of abscesses involving the masticator space .
• When a masticator space abscess is secondary to malignant otitis externa, it is important to document the full extent of the skull base and temporal bone involvement.
- This may require thin sections in both axial and coronal planes using bone algorithms.
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