Posterior fossa arachnoid cyst herniation through craniocervical junction

Abstract

A 36-year-old female patient presented with a history of intermittent headache. Magnetic resonance imaging (MRI) showed a well-defined, extraaxial cystic mass lesion located in the left retrocerebellar part of the posterior fossa which was compitable with an arachnoid cyst (Fig. 1a, b). Although arachnoid cysts are a not infrequent occurence in daily neuroradiological practice, this arachnoid cyst demonstrated partial herniation through the foramen magnum. To the best of our knowledge, it is an unusual feature of this lesion (Fig. 2a, b). As a matter of fact, we did not encounter any case report in the medical literature describing a herniation of cranial arachnoid cyst through the foramen magnum into the cervical spinal canal, as it was seen in our patient.Furthermore, the images also showed a Chiari Type 1 malformation (Fig. 2c). Most of Chiari type 1 malformations are congenital. In rare cases, Chiari malformations can be acquired during life due to the spaceoccupying conditions, especially within the posterior fossa (mass lesions, hematomas, etc) [1,2]. Because the arachnoid cyst in our patient is located in the left side of the posterior fossa, while the tonsillar herniation is nearly symmetric on both the sides (Fig. 2d), we consider that the arachnoid cyst and the tonsillar herniation are coexistence in our case.Because we believe the patient's headache to be related to both the herniated arachnoid cyst and the Chiari

Posterior Fossa Arachnoid Cysts as Findings in an Ataxia Clinic

“…After excision of the cyst, and 30-50% after endoscopic procedure. Other post-surgical complications include spasticity, hemiparesis, headache, CSF leakage, hydrocephalus, subdural hygroma [Pradilla], hemorrhage, tonsillar and craniocervical herniation [30,31]. In the case of placing a shunt, it may malfunction or become infected [32] while relatively good results have been described using marsupialization or endoscopic cisternostomy in children with PFAC [33].…”