Table 1 Sample demographics, study design, tumor type, treatment type, method and timing of data collection of the selected papers

Study design

Case report

Retrospective study

Case Report

Retrospective study (1998–2005)

How information was obtained

• Clinical and MRI assessment.

• Review of clinical and MRI records.

• Clinical and MRI assessment.

• Review of clinical and MRI records.

Population

• N = 1

• N = 5 (only 3 had MRI)

• N = 1

• N = 35

Characteristics

• Sex: F

• Sex: 4 M, 1 F.

• Sex: M

• Sex: 30 M, 5 F.

Mean age

• Age: 9 years.

• Age: mean 54 years, range 17 to 74.

• Age: 57 years.

• Age: mean 51 years, range 35 to 75.

Tumor type

• Rhabdomyosarcoma

• Squamous cell carcinoma.

• Squamous cell carcinoma.

• Nasopharyngeal carcinoma

• Adenocarcinoma.

• Mucoepidermoid and oncocytic carcinomas of parotid.

Treatment type

• Radiotherapy

• Radiotherapy

• Radiotherapy

• Radiotherapy

• Chemotherapy

• Chemotherapy

Tumor site

Right auricular region

Soft palate

Nasopharynx

Nasopharynx

Nasopharynx

Submandibular and parotid glands

Time between radiotherapy completion and MRI assessment

• 18 months

• Mean 4.4 years (range 1 to 8 years)

• 8 months

• Mean 6.7 years (range 1.3 to 15.2 years)

Radiation dose

• 50 Gy

• 60 to 69 Gy

• 75.8 Gy

• Not reported

MRI findings

○ (T1-W):

○ (T1-W, T2-W, contrast-enhanced):

○ (T1-W, T2-W, contrast-enhanced):

○ (T1-W, T2-W, contrast-enhanced):

Pre-radiotherapy:

• Ipsilateral masseter muscle atrophy.

• Bone marrow of involved portion of mandible showed homogenous low signal intensity in T1-W, high signal intensity in T2-W, and diffuse intense enhancement with contrast medium.

• Tumor mass in left nasal cavity.

• 19 patients had abnormal increase in signal intensity of masseter, temporalis, lateral & medial pterygoid muscles

• Ipsilateral condylar head flattening.

• All patients had cortical disruption of the mandible.

• Ipsilateral size reduction in the masseter, lateral & medial pterygoid muscles.

.• 16 patients had only mild signal intensity changes in masticatory muscles. However, they had different abnormalities such as (nerve injury, TMJ deformity, osteoradionecrosis, fibrosis & inflammation).

• Contralateral condylar head osteophyte.

• 3 patients had ipsilateral increase of signal intensity of masseter, lateral and medial pterygoid muscles adjacent to the osseous abnormalities.

• T1-W revealed increase in signal intensity of the lateral pterygoid muscle due to fatty infiltration.

• Bilateral normal TMJ articular disc morphology.

• 2 patients had prominent mass-like thickening of masseter, lateral and medial pterygoid muscles.

• T2-W revealed increase of signal intensity of the masseter, lateral & medial pterygoid, temporalis and mylohyoid muscles.

• Bilateral normal signal intensity of the TMJ articular surfaces & mandibular ramus.

• Contrast enhanced image showed tumor invasion along the mandibular division of trigeminal nerve.

Post- radiotherapy:

• Remarkable increase in the (T2-W) signal intensity of the lateral pterygoid muscle.

Radiographic findings

○ Panoramic radiograph:

○ CT with IV administration of contrast medium:

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• Normal TMJ articular disc morphology.

• All patients had ipsilateral abnormal enhancement of the masseter, lateral and medial pterygoid muscles adjacent to the osseous abnormalities.

• Root development stopped at ipsilateral molars and premolars.

• 4 patients had prominent mass-like thickening of masseter, lateral and medial pterygoid muscles.

• Ipsilateral shorter ramus and larger gonial angle.

• All patients had mandibular osseous abnormality, disorganization & loss of trabeculation of the spongiosa of the mandible.

• 1 patient suffered ipsilateral mandibular fistula.

• 1 patient suffered ipsilateral mandibular pathologic fracture.

Clinical findings

• Tenderness of ipsilateral TMJ capsule, masseter, lateral & medial pterygoid and posterior digastric muscles.

• All patient suffered ipsilateral facial pain and swilling.

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• Restricted vertical mouth opening range (3–25 mm).

• Restricted vertical mouth opening (23mm).

• 1 patient suffered ipsilateral numbness, tingling & dysesthesia a long the inferior alveolar nerve.

• Normal lateral mouth movement.

• 3 patients suffered trismus.

• Higher EMG activity of ipsilateral masseter & temporalis muscles in all movements.

• All patients suffered osteoradionecrosis (4 ipsilateral &1 contralateral).

• Normal salivary flow.

• 1 patient suffered ipsilateral mandibular fistula.

• Ipsilateral superficial dental decay, heavy plaque accumulation and gingivitis.

• 1 patient suffered ipsilateral mandibular pathologic fracture.