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.