AC, the most common neurological complication of varicella, occurs about once in 4000 varicella cases among children. (5) Nevertheless, it has been scarcely studied and it is still debated whether it has a postinfectious, immunologic pathogenesis or a primarily infectious origin [
22‐
25]. In our case series, the proportion of AC out of the total varicella cases was 10.5%. Reviewing the occurence of varicella AC complications in scientific published reports, the proportion of complications is slightly higher than those described by other authors, as shown by the metanalysis. In fact, in the literature revised, AC complication occurence lies within the CI of 4-8% (confidence ranges from 0% to 19%). (Figure
1) Varicella immunization has been recommended in only a few Italian Regions since 2003 and coverage has remained very low in the other Italian Regions, including the one where the majority of patients included in this study came from. Therefore, the results that we obtained reflect a scenario not affected by immunization. Indeed, none of the patients included had been vaccinated against varicella. In our case series, the median age of children affected by AC was about 5.5 years. In the literature, the median age of children affected by AC was 4.29 years [
1,
5,
9,
14,
16]. Moreover, in our case series, children with AC were significantly older than the other children hospitalized for varicella (median age 3.2 years; P-values <0.001). They were also older than children affected by other neurological complications (median age 5.06 years). Instead in a previous report in which children affected by AC (median age 4.4) were younger than all other children with neurologic complications (median age 5.4 years). (1) The mean time of onset for cerebellar symptoms was 7.48 days before hospitalization (range 1–21 days). This is in line with the literature, in which the median time between the onset of exanthema and hospital admission was 7 days. (1) Children remained a median of 11.11 days (range 2–23 days) in hospital. The hospitalization of our patients was longer than those reported in the literature (6.72 days) [
1,
9,
16]. This may be due to the fact that four children had a complicated disease course, which required steroids for more than 14 days. At admission, ataxia was the most frequent symptom, with wide-based gait (95.80%). Neurological presentation was also often characterized by dysmetry and difficult speech. Vomiting and cephalea were frequent, while nystagmus or other involuntary eye movements were rare. Moreover, non cerebellar symptoms, such as headache, were frequently referred by patients. In the literature reviewed, we did not find any description of the clinical presentation for cerebellitis, which would have been useful to compare with our data [
5]. In our case-series, diagnosis was made based on patient history of varicella infection and physical examination. In fact, the onset of ataxia following the appearance of a typical chickenpox rash requires no further diagnostic testing. (7) In five cases, a MRI showed hyperintense signal of the cerebellar gray matter in T2-weighted sequences, which is suggestive for acute cerebellitis. Anyway, the result of these tests did not change the treatment. Brain imaging is not necessary for most cases of AC. When it is performed, MRI is vastly superior to CT. In fact, CT is of limited value given the difficulty of imaging the posterior fossa with this modality. Moreover, when obtained, CT is most often normal [
26]. At MRI, bilateral diffuse abnormalities of the cerebellar hemispheres are the most common imaging presentations but are not patognomonic and with a no evident prognostic value [
27]. The role of antiviral therapy is controversial. Some authors reported that acyclovir is indicated because of disease severity, while others did not recommend it, based on the strength of evidence regarding autoimmune pathogenesis [
22‐
25,
28,
29]. The real utility of steroids is controversial as well [
28]. As international guidelines do not clearly establish whether immunocompetent children with cerebellitis should receive intravenous acyclovir and/or steroids, we decided case by case, based on clinical severity. In our case-series, forty-five patients (93.75%) were treated with intravenous acyclovir, and 16 (33.33%) received intravenous steroids. We prescribed antiviral therapy in order to reduce disease severity; in fact, in a recent article on varicella, treatment with antivirals was considered mandatory not only for patients at risk for severe disease, but also for any subject with varicella-zoster virus infection with virally mediated complications, such as AC [
29]. In the revised literature, we found just two papers reporting the frequency of antiviral therapy and only one on the steroids [
1,
4]. Out of 67 children, Rack et al. treated 46% with acyclovir [
1]. Marchetto et al. used antiviral and steroidal therapy in respectively 68.9% and 79% of the 29 enrolled patients [
4]. Finally, as well as in our case-series, other authors generally did not refer invalidating problems at the follow-up [
1,
14].