Survival analyses for MSI Pattern A. (A) Overall survival, (B) local relapse-free survival, (C) metastasis-free survival and (D) disease-free survival for different groups of MSI in pattern A. MSI, masticator space involvement. Classification pattern A: grade 0 converted to PA0, grade 1 converted to PA1, grade 2 converted to PA2, grade 3 converted to PA3. Grades of masticator space involvement. Grade 0: without MSI; Grade 1: with medial pterygoid muscle involvement but without lateral pterygoid muscle involvement or infratemporal fossa involvement; Grade 2: with medial and/or lateral pterygoid muscle but without infratemporal fossa involvement; Grade 3: with infratemporal fossa involvement.