The pharyngovertebral veins: an anatomical rationale for Grisel's syndrome.

UNLABELLED: 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. CLINICAL RELEVANCE: 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.