[Epidemiology and classification of arachnoid cysts in children]

The yield of structural magnetic resonance imaging in autism spectrum disorders

AIMS

The aim of our study was to assess the yield of routine brain magnetic resonance imaging (MRI) performed at our hospital as part of the diagnostic procedures focused on autism.

METHODS

Our retrospective study involved children who had attended a diagnostic examination focused on autism and underwent brain MRIs between 1998-2015. The International Classification of Diseases, 10^th edition was used to make clinical diagnoses. In 489 children (404 boys, 85 girls; mean age 8.0±4.2 years), a diagnosis of a pervasive developmental disorder was confirmed. Forty-five children, where the autism diagnosis was ruled out (but other psychiatric diagnoses found), served as a control group (36 boys, 9 girls; mean age 7.0±2.4 years). We can assume that in such a control group, brain abnormalities might occur at a higher frequency than in truly healthy children which would have the effect of reducing the difference between the groups.

RESULTS

MRI pathologies were more common in the autistic (45.4 %) compared to the control group (31.8%) but the difference was significant only at the trend level (P=0.085). Hypoplasia of the corpus callosum (CC) was significantly more common in the autistic vs. the control group (13.7 vs. 0%; P=0.009). In contrast, nonmyelinated areas of white matter were significantly more common in controls (31.8 vs.17.3%; P=0.018). Differences in other parameters were not significant.

CONCLUSION

The occurrence of CC hypoplasia on routine MRI scans could represent a "red flag" for suspicion of autism.

Rare Case of Tricompartmental Arachnoid Cyst Spanning Infratentorial, Supratentorial, and Extracranial Compartment and Presenting as Posterior Parietal Meningocele

BACKGROUND

Arachnoid cysts constitute a mere 1% of all nontraumatic intracranialspace-occupying lesions, and only 10% of these are present in theinfratentorial compartment. We hereby report a case of a 10-month-old femalechild with a tricompartmental arachnoid cyst.

CASE DESCRIPTION

The arachnoid cyst spanned both the infratentorial and supratentorialcompartment of the intracranial space. In addition, the cyst was alsoherniating into the extracranial compartment through a congenital defect in theparietal bone. The child was brought to us with a disfiguring swelling over herscalp, which was progressively increasing in size. We managed the patient byexcision of the extracranial part and placed a cystoperitoneal shunt to take care of the intracranial part. Follow-up magneticresonance imaging after 6 months of intervention showed a significant reductionin the size of the intracranial portion of the cyst with no recurrence of theextracranial part.

CONCLUSIONS

This case of arachnoid cyst involves multiplestructures. But interestingly, all these structures (arachnoid, dura, veins,and bone) are of mesodermal origin. So we would like to suggest that thispathology may be a result of developmental deviation during mesodermal differentiationrather than a simple expanding arachnoid cyst.