Comparison with other studies and clinical implications
Within the limitations of the retrospective data which are discussed below, the outcomes of the initial treatment approach were evaluated and compared. The rates of revision surgery were similar across the four groups with approximately a half of patients requiring second operation after 5 days due to progression of intracranial abscess. Notably, 9 out of 15 patients were successfully treated with sinus drainage thus avoiding a craniotomy. While we recognise that there was a trend of larger intracranial abscesses found in patients treated with neurosurgical drainage, the findings suggest that ENT only interventions may have a role in reducing the number of patients undergoing a craniotomy and its associated morbidity. The key question remains as to which patient group is most suited for this approach. Garin et al. have previously reported that the presence of SDE was a contraindication to endoscopic sinus surgery (ESS) only approach as 87% ultimately required a craniotomy[9]. On the contrary, 3 out of 4 patients with EDA were successfully managed with ESS alone. In the present study, we found that that 60% of patients managed with sinus interventions only did not require a craniotomy despite the high proportion of patients with SDE (60%). This begs the question whether factors other than the type of intracranial abscess has more deterministic effect on the need for revision surgery. Indeed, in the univariate logistic regression analysis we found that the size of an intracranial abscess (≥10mm) had the strongest prediction for the need to return to theatre, while the presence of SDE was not found to be significant. Our results are in contrast with those reported in the study by Gitomer et al.[14], which found that the presence SDE was the key predictor for the need to return to theatre, however the authors did not include the size of an abscess in the analyses. Therefore, it remains to be determined whether patients with small intracranial abscesses including SDE may be suited for ESS only. Non-operative initial treatment with close observation may also be an option. Three out of 4 patients in our cohort were successfully managed with intravenous antibiotics alone. None of the patients had neurological disability and had markedly shorter hospital stay (median 12.5 days). However, no firm recommendations can be made regarding the indications for conservative treatment.
Irrespective of the initial approach, two thirds of our cohort underwent neurosurgical intervention at some point during the inpatient stay. While ESS may prevent the need for a craniotomy in some patients, its role when used in conjunction with neurosurgical intervention is controversial. We found that two thirds of patients required revision surgery despite a joint neurosurgical and ENT approach, the highest proportion when compared to the other treatment arms. Combined treatment was also not found to affect the rates of revision surgery, neurological disability and hospital length of stay. As mentioned before, inherent selection bias may be responsible for the lack of apparent benefit of combined procedures, however the clinical and disease characteristics were largely comparable across the treatment groups as summarised in table 5. The current study findings are also consistent with the results from previous studies in adults[13,17]. In a retrospective cohort study on 255 adult patients with sinogenic intracranial suppuration, Koizumi et al. investigated the effects of ESS in addition to neurosurgical drainage[17]. The authors did not find that ESS resulted in an improvement in any of the study outcomes including mortality, requirement for blood transfusion, revision surgery, readmission and the LOS. These findings raise an important question as to whether sinus interventions, which can be more technically challenging in children are warranted in the acute setting considering the likelihood of increased operative time, bleeding and orbital injury. This is particularly relevant in centres where rhinological expertise may not be available. Some authors argue that ESS may serve as an important diagnostic tool by enabling the surgeon to obtain microbiological samples[9]. However, in the present study we found that in only 3/20 cases intracranial samples did not yield a culture growth and the wash out from the sinuses provided microbiological data instead.
The present study found significantly increased risk of ND in patients treated with neurosurgery alone (75%) when compared to ENT only interventions (6.7%). The findings should be interpreted with caution due to the limited cases in the neurosurgery group (n=4). This observation is most likely as a result of a considerable difference in the median size of an intracranial abscesses across the groups (median 10mm in the neurosurgery vs. 5.5mm in the ENT only), although not statistically significant.
Finally, three deaths were observed in our cohort, two of which were in the ENT only group. All three patients presented with severe sepsis. One patient was deemed too unwell to undergo a craniotomy and only antral wash out was performed. In a second patient, the abscess was located in the pons and was not surgically accessible. A third patient passed away from the complications related to sepsis despite a craniotomy and antral wash out.