Grisel's syndrome: the two-hit hypothesis--a case report and literature review.

Grisel's syndrome is a rare but well-documented clinical entity. It is a nontraumatic, fixed rotary subluxation of C1 on C2 (atlantoaxial). Although first described in 1830, the exact mechanism of Grisel's syndrome remains unclear. We present a postoperative case of Grisel's syndrome and an extensive literature review, and we propose a mechanism for its pathogenesis. In addition, we propose a treatment algorithm for Grisel's syndrome.