Purpose: 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.
Methods: We present four cases of SPM. All patients sustained a severe UCI. Three patients were symptomatic with delayed and progressive clinical signs.
Results: 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.
Conclusions: 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.