Ultrasonography
Neuroradiology
Case TypeClinical Cases
AuthorsJ.R.Torino, R.Puy, J.Blanch, E.Sainz*, V.Cusí**
Patient12 months, female
Ultrasonography, CT and MRI of the cranium were performed, and revealed a cerebellar mass suggestive of an abscess with an adjacent daughter abscess and with associated obstructive hydrocephalus.
Physical examination demonstrated an occipital dermal sinus. At surgery the dermal sinus communicated with the abscess through a tract. Histological examination demonstrated the abscess and the dermal sinus.
The most frequent cause of cerebellar abscess is local extension from an otic infection. Less frequent causes include paranasal infections; disseminated infections originating in the heart, lung or bone; trauma or surgery; immune deficiencies, etc. Up to 25% of cerebellar abscesses are of unknown cause (1).
As this case in childhood illustrates, with a posterior fossa abscess and no associated cause, the presence of an occipital dermal sinus should be investigated, always looking for the characteristic skin stigma and underlying bone defect (2).
The dermal sinus is a thin epithelial tube extending from the occipital dermis into intracranial structures, being the consequence of a failure in closing of the neuropore during embryogenesis, around the fourth week of gestation. During neuroectodermic migration, the mesoderm remains interposed during closure of the middle line (3).
CT scan and MRI are very sensitive techniques to detect and characterise this lesion. Both techniques show a single or multiple cystic mass, with annular contrast enhancement, and local oedema (2,3). MRI has the advantage of better spatial resolution and higher sensitivity in studying the posterior fossa. However, the presence of a small dermal sinus is easily detected with CT because of its better bone definition. Besides allowing for the localisation of the lesion, both techniques may occasionally point towards the primary septic origin and are mandatory for the follow-up of surgical and medical treatment (1,2,3).
[1] D䀀hnert W. Radiology Review Manual, 4th edn. Williams & Wilkins, Philadelphia, p 213 (1999).
[2] Groen RJ, van Ouwerkerk WJ. Cerebellar abscess caused by an occipital dermal sinus in an infant. Ned Tijdschr Geneeskd. 1994 Jul 30;138(31):1575-8. (PMID: 8072570)
[3] Barkovich AJ. Infections of the nervous system. In Barkovich AJ, Pediatric Neuroimaging, 2nd edn. Lippincott-Raven, Philadelphia. pp 569-617 (1996).
URL: | https://www.eurorad.org/case/1367 |
DOI: | 10.1594/EURORAD/CASE.1367 |
ISSN: | 1563-4086 |