Atlantoaxial rotatory instability secondary to odontoid hypoplasia as a cause of acute torticollis in children: report of one case.

One patient with the chief complaint of acute torticollis was diagnosed as atlantoaxial rotatory instability secondary to hypoplasia of odontoid process. The diagnosis was confirmed by cervical radiography and computerized tomography. The attack of wryneck was first misdiagnosed as cervical muscle strain. Detailed physical examination revealed the tenderness to be located not at the sternocleidomastoid muscle. The fixed and painful rotatory deformity strongly indicated a cervical spinal lesion. Plain radiographic tests of the cervical spine revealed atlantoaxial rotational subluxation. Hypoplasia of the odontoid process, rarely reported as associated with this problem, was noted. Computerized tomographic tests further delineated the pathological alterations. Treatment with gentle reduction and traction for three days, and maintenance with neck collar for the three subsequent weeks, achieved a successful solution. No recurrence was noted after a two-year observation period.