Open Reduction and Decompression of Atlantoaxial Subluxation with Basilar Impression Due to Grisel Syndrome Using the Cervical Management Base Unit

Background: Intraoperative manipulation of the craniocervical junction with the Cervical Management Base Unit (CMBU) has been used as an adjunct for achieving optimal anatomic alignment during instrumented fusion procedures in a variety of disease settings. Here, we present our experience using the CMBU as a supplement to achieving a successful reduction and fixation of a reducible craniocervical subluxation with associated basilar impression/medullary compression in the setting of Grisel syndrome. Case Description: Under fluoroscopy and neuromonitoring guidance, the elevator and axial translation mechanisms of the CMBU safely allowed for presurgical assessment of reducibility and facilitated complete reduction of the deformity with restitution of a normal atlantodental interval, spinolaminar line, and clivoaxial angle. Magnetic resonance imaging acquired 1 month after surgery and antibiotic therapy showed resolution of a large epidural abscess in the region of the dens and no evidence of residual neural impingement. Upright plain films at 9 months showed maintenance of the desired craniocervical alignment. Conclusions: Intraoperative manipulation of the craniocervical junction using the CMBU, when implemented under fluoroscopy and neuromonitoring, can safely facilitate an enduring anatomic correction of craniocervical deformity in the setting of Grisel syndrome. The dynamic utility of the CMBU for translation of the head and neck obviated the need to apply forces directly to hardware-bone interfaces, and its utility may extend to craniocervical disorders of other etiologies, especially those of a reducible nature and in the setting of poor bone quality and joint laxity.