The pharyngovertebral veins. An anatomical rationale for Grisel's syndrome

Non-traumatic subluxation of the atlanto-axial joint following peripharyngeal inflammation (Grisel's syndrome) has been attributed to laxity of the transverse ligament caused by hyperemia, but a satisfactory anatomical rationale for the association of these conditions has been lacking. Injection of the cervical epidural sinuses of a series of human perinatal cadavera showed retrograde filling of a previously undescribed system of veins with frequent lymphovenous anastomoses. This system appears to drain the posterosuperior pharyngeal region. Because of their direct connection with the periodontoidal venous plexus and the suboccipital epidural sinuses, the pharyngovertebral veins may provide a hematogenous route for the transport of peripharyngeal septic exudates and neoplastic cells to the upper cervical spinal structures and provide an anatomical explanation for the atlanto-axial hyperemia of Grisel's syndrome.