A diagnostic dilemma of central skull base osteomyelitis mimicking neoplasia in a diabetic patient

Microbial spectrum, management challenges, and outcome in patients with otogenic skull base osteomyelitis

Objectives

The study aimed to explore the spectrum and trend of causative microbial agents and to identify management challenges and the risk factors for poor outcomes in patients with confirmed otogenic skull base osteomyelitis.

Methods

A retrospective observational study was conducted at a tertiary-care academic center from 1999 through 2019 and included 28 adult patients with confirmed otogenic skull base osteomyelitis. Relevant data was extracted from electronic and hard patient medical files. The microbial spectrum of involved microbes was identified and correlated to management options. Deterioration risk factors were investigated using suitable statistical analysis tests.

Results

Twenty-eight patients with confirmed skull base osteomyelitis were included; most were males (78.6%) and Saudis (78.6%). All patients were ≥50 years of age (mean ± SD is 69.0±10.2.4). Of 41 identified microbial isolates, 56% were bacterial, 44% were fungal. 32.1% of patients had polymicrobial infections, most patients (92.8%) had received ≥2 systemic antibiotics, 57.1% received systemic antibiotic combinations, and 32.1% underwent surgical interventions. The mean antibiotic and antifungal therapy duration was 58.3 and 45.8 days, respectively. The identified risk factors of deterioration were advanced age and concomitant cardiac failure, with P-values of .006 and .034, respectively.

Conclusions

The study findings highlight the microbiological spectrum and trend of otogenic skull base osteomyelitis-causative microbes over two decades, present the management challenges, identify deterioration risk factors, and suggest tissue biopsy as the golden standard for accurately identifying causative microbes.

[Current diagnosis and treatment of skull base osteomyelitis]

Skull base osteomyelitis is a rare, refractory, and potentially fatal disease primarily caused by otogenic and sino rhinogenic infections. At times, it can mimic neoplasia complicating the diagnosis. With the use of antibiotics, advancements in diagnostic methods, and skull base surgical techniques, the mortality rate has significantly improved. However, the successful diagnosis and treatment of the disease is still challenging due to delayed diagnosis, lengthy treatment course, a tendency for relapse and lack of guidelines. Therefore, this article aims to review the progress in the diagnosis and treatment of skull base osteomyelitis.

Dynamic Contrast-Enhanced MRI Parameters and Normalized ADC Values Could Aid Differentiation of Skull Base Osteomyelitis from Nasopharyngeal Cancer

BACKGROUND AND PURPOSE

The skull base osteomyelitis sometimes can be difficult to distinguish from nasopharyngeal cancer. This study aimed to investigate the differences between skull base osteomyelitis and nasopharyngeal cancer using dynamic contrast-enhanced MR imaging and normalized ADC values.

MATERIALS AND METHODS

This study included 8 and 12 patients with skull base osteomyelitis and nasopharyngeal cancer, respectively, who underwent dynamic contrast-enhanced MR imaging and DWI before primary treatment. Quantitative dynamic contrast-enhanced MR imaging parameters and ADC values of the ROIs were analyzed. Normalized ADC parameters were calculated by dividing the ROIs of the lesion by that of the spinal cord.

RESULTS

The rate transfer constant between extravascular extracellular space and blood plasma per minute (Kep) was significantly lower in patients with skull base osteomyelitis than in those with nasopharyngeal cancer (median, 0.43 versus 0.57; P = .04). The optimal cutoff value of Kep was 0.48 (area under the curve, 0.78; 95% CI, 0.55-1). The normalized mean ADC was significantly higher in patients with skull base osteomyelitis than in those with nasopharyngeal cancer (median, 1.90 versus 0.87; P < .001). The cutoff value of normalized mean ADC was 1.55 (area under the curve, 0.96; 95% CI, 0.87-1). The area under the curve of the combination of dynamic contrast-enhanced MR imaging parameters (Kep and extravascular extracellular space volume per unit tissue volume) was 0.89 (95% CI, 0.73-1), and the area under the curve of the combination of dynamic contrast-enhanced MR imaging parameters and normalized mean ADC value was 0.98 (95% CI, 0.93-1).

CONCLUSIONS

Quantitative dynamic contrast-enhanced MR imaging parameters and normalized ADC values may be useful in differentiating skull base osteomyelitis and nasopharyngeal cancer. The combination of dynamic contrast-enhanced MR imaging parameters and normalized ADC values outperformed each measure in isolation.

Skull base osteomyelitis mimicking skull base tumor in immunocompetent pediatric patient: case report

Central skull base osteomyelitis (CSBO) is a rare complication of infection in pediatric patients, especially when there are no comorbidities like immunosuppression or metabolic illness. The diagnosis of CSBO is a challenge in children, and imaging findings can mimic skull base tumor. We describe the clinical history and image diagnosis of a case in a 6-year-old girl with no relevant history who presented an extensive skull base lesion. She underwent tumor resection surgery. The intraoperative finding confirmed clivus osteomyelitis, and the histopathological studies discarded malignancy. After diagnosis, the patient completed 6-week antibiotic treatment with adequate evolution. In conclusion, CSBO should be considered within the differential diagnoses due to the fact that it can mimic skull base lesions and it may present without relevant history.

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.

Central skull base osteomyelitis manifesting with a preclival mass and internal carotid artery mycotic aneurysm

Central skull base osteomyelitis is a rare entity that can demonstrate confounding radiologic, clinical, and laboratory data leading to a delay in diagnosis. The morbidity and mortality for skull base osteomyelitis are both high, thus a rapid diagnosis is required for appropriate treatment. In this case report, we discuss a 68-year-old male who presented with acute left facial nerve paralysis in the setting of chronic headache and left mucoid middle ear effusion. Radiologic evaluation revealed abnormal hypointense marrow of the central skull base on T1 weighted magnetic resonance imaging, preclival mass-like tissue, and short segment luminal narrowing of the left cervical ICA with mycotic aneurysm formation.

Extensive workup via a multidisciplinary approach, including neurology, otolaryngology, neurosurgery and radiology led to a diagnosis of central skull base osteomyelitis. A familiarity of this disease process is important for the radiologist in order to facilitate appropriate patient referral and treatment. This case emphasizes the importance of considering this diagnosis in the setting of headache, cranial neuropathy, and abnormal skull base imaging with adjacent preclival soft tissue mass.

Efficacy of HRCT Imaging vs SPECT/CT Scans in the Staging of Malignant External Otitis

OBJECTIVE

The prognosis of patients with malignant external otitis (MEO) depends on the extent of the inflammatory changes in the temporal bone and skull base. The efficacy of high-resolution computed tomography (HRCT) imaging in accurately assessing the extent of disease is compared with that of single-photon emission computed tomography/computed tomography (SPECT/CT) scan.

STUDY DESIGN

A clinical chart review was conducted with medical records and radiologic images.

SETTING

Tertiary care medical college hospital.

SUBJECTS AND METHODS

This study involved patients with clinically diagnosed MEO who underwent both modalities of imaging of the skull base. Staging of the disease extent was compared between the imaging systems among patients. Symptom control and survival rates were analyzed with respect to the SPECT/CT staging of MEO.

RESULTS

Out of 28 patients included in this study, 72% had SPECT/CT scans showing higher staging than the HRCT imaging. Four patients had mild uptake (stage 1), and 15 had disease confined to the mastoid/temporal bone, not reaching midline (stage 2). All patients in stages 1 and 2 were surviving with good symptom control. Five patients with petrous involvement reaching midline (stage 3) had persistent symptoms, and all 4 cases with SPECT/CT showing sphenoid involvement and crossing midline (stage 4) died within a year of diagnosis.

CONCLUSIONS

SPECT/CT scan is more sensitive than HRCT imaging in detecting the extent of disease and is a better prognosticator for patients with MEO.

Advanced Imaging Techniques in Skull Base Osteomyelitis Due to Malignant Otitis Externa

PURPOSE OF REVIEW

To give an up-to-date overview of the strengths and weaknesses of current imaging modalities in diagnosis and follow-up of skull base osteomyelitis (SBO).

RECENT FINDINGS

CT and MRI are both used for anatomical imaging, and nuclear techniques aid in functional process imaging. Hybrid techniques PET-CT and PET-MRI are the newest modalities which combine imaging strengths.

SUMMARY

No single modality is able to address the scope of SBO. A combination of functional and anatomical imaging is needed, in the case of newly suspected SBO we suggest the use of PET-MRI (T1, T2, T1-FS-GADO, DWI) and separate HRCT for diagnosis and follow-up.

Clival Osteomyelitis Presenting as a Skull Base Mass

Central skull base osteomyelitis is a rare, but potentially life-threatening disease entity often lacking otologic symptoms or external auditory canal pathology. We present a case of a man in his 70s who had developed cranial nerve deficits with radiographic evidence that was consistent with a tumor due to this uncommon entity. The radiologic findings and our experience are discussed to increase awareness in the otolaryngology community.