AM with an unusual presentation is a rare finding, representing fewer than 1 in 10 of all cases of AM. Although uncommon, atypical manifestations of AM should be included in the differential diagnosis given the presence of neurologic symptoms found in our pediatric population, independently of fever. As these children do not seek care more frequently than those with a usual presentation, the signs and symptoms appear insidiously. Their general condition resembled that of patients with a typical presentation, yet the outcome was worse (21.2% vs 100%; P < 0.001). However, length of hospital stay was similar in the 2 groups (P > 0.05).
Since the advent of universal PCV access, and especially PCV13, the incidence of AM has decreased, although it remains the most common complication of AOM.1 The 2008 systematic review by van den Aardweg et al.5 reported an average of 42% of children with a history of otologic disease, compared to 30% (n = 34) in our series. This lower percentage may be due to the retrospective study design used here, as some of the charts may have been incomplete. Also, the authors found a mean duration of symptoms suggestive of AM of 9.8 days. Although this information was often not included in the medical records analyzed, we suspect that it is lower in our series, as the median number of previous visits to the pediatric emergency department or primary care until diagnosis was 1.5 times for both groups. Given that patients are instructed to seek medical care every 2 or 3 days if symptoms persist, we estimate a mean duration of symptoms before AM diagnosis of 4 or 5 days.
Most existing reports describe individual cases of AM with an unusual presentation,3,6 which precludes any comparison between our results and previous research.
In our sample, children in the 2 groups were of similar age and otorhinolaryngological history, which suggests that neither of these 2 variables effectively predict the clinical presentation of mastoiditis (P > 0.05).
Blood testing showed no significant differences between the 2 groups. CRP was the biomarker with the highest sensitivity (approximately 75% of patients had a high CRP level), as described in the literature.2
PICU admission rates did not show statistically significant differences between groups (P = 0.054). However, patients with an unusual presentation had a 7-fold higher risk for PICU admission (33.3% vs 4.8%), mainly due to the higher percentage of poor outcome.
Although the estimated incidence of complications in AM varies, recent reports have found adverse events in 13–38% of cases.7 Intracranial complications are particularly common in the literature, ranging from 4–16%2; meanwhile, ≈20% (n = 22) of the patients in our population had complications and ≈7% (n = 8) had intracranial involvement. Thus, a combined analysis of both groups produces results like those described in the literature. A study by Vergardi et al.8 of AM complicated by cerebral venous sinus thrombosis, which is considered an intracranial complication, revealed that the most important finding in these children was an atypical clinical presentation (5/5, 100%), which included 2 or more neurologic signs and symptoms. Also, the authors use the term “silent mastoiditis” to refer to cases identified by imaging studies in the absence of auricle protrusion, postauricular swelling, and postauricular erythema. In our sample, the group with an atypical presentation had the highest number of intracranial complications (66.7%, or 4/6 children with an atypical presentation vs 3.9%, 4/104 children in the usual presentation group; P < 0.001).
Our study has certain limitations. Firstly, retrospective chart studies such as this one entail a loss of data. Secondly, the low incidence of AM with unusual presentation makes it difficult to fully characterize children with these symptoms.
While AM with an unusual presentation is an uncommon finding, it should be considered in the differential diagnosis of young children with neurologic symptoms. Our results do not suggest a delay in diagnosis, but do show a greater risk of poor outcome.