Skull base osteomyelitis: Comprehensive analysis and a new clinicoradiological classification system.

OBJECTIVE: Skull baseosteomyelitis (SBO) is a rare phenomenon that typically occurs in diabetic or immunocompromised patients, causing significant morbidity and mortality. This study aimed to analyze a single institution's treatment results in SBO patients and propose anew integrated clinicoradiological classification system.

METHODS: The medical records of 32 SBO patients that were treated at a tertiary care center between 2006 and 2017 were retrospectively reviewed. A scoring system based on anatomical involvement according to MRI was created. Subsequently, the scoring system was integrated with cranial nerve dysfunction status and a clinical grading system (CGS) was proposed.

RESULTS: Among the 32 patients, 78.1% were diabetic and 63% had cranial nerve dysfunction at presentation. Bone erosion based on CT was greater in the patients without regression (P = 0.046). The regression rate decreased from clinical grade (CG)1 to CG3 (P = 0.029). Duration of hospitalization increased as CG increased (P = 0.047). Surgery had no effect on regression status at the time of discharge (P = 0.41). The 1-year, 2-year, and 5-year overall survival rates were 82.2%, 70.8%, and 45.8%, respectively. CG was significantly correlated with overall survival but not with disease-specific survival (log-rank; P = 0.017, P = 0.362, respectively).

CONCLUSION: SBO continues to pose a challenge to clinicians, and causes significant morbidity and mortality. The proposed new classification system can be an option for grouping SBO patients according to clinical and radiological findings, helping clinicians estimate prognosis.