Anterior spinal pseudomeningocele after C0-C2 traumatic injuries: role of the "dural transitional zone" in the etiopathogenesis.

Abstract

Spinal pseudomeningoceles (SPM) are extradural collections of CSF (cerebrospinal fluid); a frequent association with upper cervical injuries (UCI) has been observed. We propose a possible etiopathogenetic mechanism supporting the formation of cervical SPM based on some considerations. We present four cases of SPM. All patients sustained a severe UCI. Three patients were symptomatic with delayed and progressive clinical signs. One patient was misinterpreted as epidural hematoma and operated on due to progressive signs with postoperative clinical improvement. The rest of patients were treated conservatively; spontaneous reduction of CSF collection occurred. From a radiological standpoint: (1) a line of demarcation separated the intradural cervical compartment from the anterior epidural space, (2) CSF epidural collection was never evident at C0-C2 level and extended from C2 downwards, and (3) shape of collection was similar to epidural hematomas suggesting a ball-valve mechanism. The dural layer at C0-C2 level is adherent to the thick ligamentous apparatus, as opposed to the segments below where it is solely covered by the posterior longitudinal ligament. A "transitional zone" of dura exists between the C0-C2 region and subaxial segment of the cervical spine. This watershed area constitutes a point of minor resistance. Lacerations of the meningeal layers, caused by severe UCI at the "transitional zone", drain CSF into the anterior epidural space and form SPM.