Discussion:
SBO refractory to medications result in multiple antibiotics, prolonged symptoms and loss of quality of life for the patient. The aim of the study was to evaluate the role of surgery in such cases. In our study, the surgical group showed better clinical outcome in terms of relief of pain, canal wall edema, granulations, ear discharge, duration of treatment and hospital stay compared to the medical group. Patients usually received empirical treatment with dual anti- pseudomonals like quinolones and Ceftazidime, monotherapy with Ceftazidime, or Piperacillin with Fluoroquinolones.12 Antimicrobials were changed when indicated by culture (Table- 1). Pseudomonas aeruginosa was the usual organism cultured (34%), followed by fungus (21%). The number of fungal pathogens and negative cultures were more in the surgical group, which might explain the refractoriness to medical treatment (Table- 1).
Besides, some patients developed transaminitis, changes in renal parameters, and exfoliative dermatitis during the course, which resulted in a change of antibiotics (Table- 2).
Oral antibiotics given included those with good bone penetration, like Quinolones, Cloxacillin, Linezolid, and Minocycline. Injection to oral switch therapy was possible with culture-specific oral antibiotics, given after six weeks of systemic antibiotics.13
Patients generally became asymptomatic after a few weeks of antibiotic therapy, but it might be ideal to continue medications till inflammatory markers and or PET CT became normal.7, 8 We observed a sequence, of symptom resolution followed by stabilization of inflammatory markers and later radiological stability. After the initial diagnosis, we did not repeat imaging unless there were new symptoms. The decreasing values and normalization of inflammatory markers would guide in determining the timing of the PET CT scan.7 Using radiological resolution by PET CT as the criteria for cure in our study, 28 patients in the medical group and 33 patients from the surgical group were cured. Another clinical criteria for cure described is an asymptomatic patient for 18 months after cessation of treatment.9
It was difficult to predict who might need surgical intervention at the initial presentation. Clinical variables like nerve palsy, relapse, fungal disease, and extensive radiological involvement were associated with severe disease.14 However, we observed various combinations of these variables in both groups, some successfully treated with medicines alone (Table- 2). The surgical group had rapid symptomatic improvement with clinical and radiological resolution compared to the medical group, which was statistically significant across all variables(Table- 3). In both groups, the mean duration of treatment was more with antifungal therapy and negative culture. Antifungal therapy was for a minimum of three months.
With complete debridement, all 22 patients in our series responded immediately though medications were continued as per protocol (Table- 4). Wide debridement till viable tissue was the key to successful treatment.15 The debridement may expose the healthy bone to the pathogen worsening disease.16 Among our surgical patients, only one patient with partial debridement continued to have pain after surgery, and none showed worsening. There was one recurrence in our series. Early debridement may prevent the emergence of biofilms and resistant bacteria. According to Spellberg and Benjamin, there was no solid evidence for support therapy beyond 4- 6 weeks after surgical debridement.17 Apart from removing poorly vascularized (infected) bone, surgery brought well-vascularized tissue to the area, thus facilitating the healing process and allowing antibiotics to reach the target area.18 The abundant vascularity of the flat bones compared to the long bones and mandible may account for the excellent response to antibiotics alone in most cases of SBO. But, flat skull bones of more than 4 mm essentially behaved like long bones in microvasculature and hence may resemble chronic osteomyelitis elsewhere in the body.19Treatment of chronic osteomyelitis of the long bones includes surgery and antibiotics for 3 to 6 months.15
According to Chen et al., the role of surgery may be limited to abscess drainage, sequestrum debridement, and specimen acquisition for microbiological and pathologic examination and play a complementary role to antibiotics.20 In their study of 20 patients, Peled et al. suggested the role of surgery in prolonged treatment, readmissions, and facial nerve palsy. The minimum surgery should be a canal wall-up mastoidectomy, and further treatment should be based on radiological findings.21, 22 He suggested deep tissue sampling for culture in SBO since the concordance with the local swab and bone culture was less than 50%. 23 In our observation surgery itself was sufficient when debridement was complete. However, in incomplete debridement our observations were similar to Chen et al..
Hyperbaric oxygen (HBO) has been advocated for refractory cases though not supported by definite evidence.24 We had three patients for HBO, but poor compliance due to bilateral earache was a drawback. Gruber et al. observed that surgery promoted the cure of fungal osteomyelitis.25 In our series, there were 15 proven cases of fungal SBO, of which ten underwent surgery. Empirical administration of Voriconazole should be restricted as far as possible.
Since surgery was neither done at the first visit nor antibiotics stopped, the role of surgery alone in SBO could not be studied. Partial response by antibiotics could not be ruled out. Surgery would alter inflammatory markers and imaging, parameters on which termination of treatment was decided. All asymptomatic patients after complete debridement were also given antimicrobials as per protocol till the markers and imaging normalized. A longer duration of antimicrobial therapy than necessary might have been given for them. Though early termination by as early as two to four weeks was possible after complete debridement, study protocol was adhered to . In all such cases, patients could resume normal life faster. At the same time, partial surgery also bettered clinical response through improved culture yield and targeted therapy. So, it was observed that surgery had both curative and faciliatory roles depending on surgical access. A large number of patients added to the strength of the study. However, heterogeneous factors like comorbidities, polypharmacy, and the various antimicrobials administered may have acted as confounding variables.