Serum Galactomannan as a Minimally Invasive Diagnostic Tool for Fungal Skull Base Osteomyelitis

Multidrug resistant strains and fungi add to treatment conundrums in skull base osteomyelitis (SBO). Deep tissue culture in these patients is challenging due to their advanced age and co-morbidities. Besides, fungal culture positivity is seen only in 60% of invasive aspergillosis. To determine the efficacy of a minimally invasive test—Serum Galactomannan (sGM)–for diagnosing fungal SBO. Prospective observational study. Thirty- three patients, clinically diagnosed with SBO were included in this study. Baseline ESR (Erythrocyte Sedimentation Rate), CRP (C- Reactive Protein), pain score, and sGM were noted for all patients. Antifungal Voriconazole was initiated on patients if the sGM values were more than 0.8. At the 12th week of treatment, all parameters were repeated and compared with the baseline values. A significant reduction was noted in ESR, CRP, and pain scores at the 12th week of treatment compared to the baseline values in patients with raised sGM values who were started on Voriconazole. For a culture-proven fungal skull base osteomyelitis with a cut-off value of sGM > / = 0.8, the obtained sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were 81.82, 36.36, 39.13, 80 and 51.52% respectively. At a cut-off value of sGM > / = 01.6, the values of sensitivity/specificity, PPV, NPV and accuracy were 81.82/72.73%, 60%, 88.89% and 75.76%. Culture-negative patients in SBO with sGM value > 0.8 were more likely to be fungal SBO. An sGM cut-off of 1.6 was observed to give maximum accuracy for diagnosing fungal SBO.