![]() Type 4 includes posterior displacement of atlas. Type 3 includes bilateral facet dislocation with anterior displacement. Type 2 includes unilateral facet dislocation with anterior displacement of 3-5 mm which may signify transverse ligament rupture. Type 1 is a unilateral facet dislocation. Typical cock -robin position is described with head rotated to one side with some lateral flexion. The patient presents with pain, restricted range of motion and torticollis. Infectious etiology also known as Grisel syndrome which occurs commonly after upper respiratory infection, but can also occur after tonsillectomy or retropharyngeal abscess. Ĭommon causes of atlantoaxial rotatory subluxation are trauma and infection other rare causes include congenital and iatrogenic. Normal measurements of upper cervical spine on CT as shown in various reports are powers ratio less than 0.9, atlanto-dental interval less than 2.6 mm, atlanto-occipital interval less than 2.5 mm, atlantoaxial interval less than 3.9 mm, basion dens interval with ossification less than 9.5 mm and without ossification less than 11.6 mm. It is advisable to use limited CT in the area of injury as seen in plain roentgenograms. CT scan provides excellent view of bony architecture, however pediatric spine is mainly cartilaginous and ligamentous injury are common and thus its routine use is debated. Generally a kilovoltage of less than 120 kVp and tube current ranging from 60 to 120 mAs is used depending on the age and size of the child. Specialized CT protocols are set in many centres to limit radiation exposure. In these situations, CT scans are highly helpful as they are done quickly without any sedation or anesthesia. Ĭommon lines used to assess basilar invagination.Ĭonventional radiography is not useful in uncooperative and unconscious patients. 2) normally less than 5 mm in children, pseudosubluxation of C2 on C3 less than 4 mm, widened retropharyngeal space more than 6 mm at C2 and greater than 22 mm at C6, neurocentral synchondrosis closes by 7 years of age, loss of cervical lordosis and anterior wedging of vertebral bodies. This includes increased atlanto-dens interval (Fig. Normal radiographic parameters in the pediatric cervical spine should be borne in mind to avoid misdiagnosis. ( 1) helps to determine basilar impression. ![]() McRae line, McGregor line and Chamberlain line as shown in Fig. Powers ratio is measured by dividing the distance between basion and posterior arch C1 to distance between opisthion and posterior arc C1. Wackenheims line passes along the posterior arch of clivus and intersects the posterior third of dens. The anterior cervical line, posterior cervical line and spinolaminar line should be carefully seen for disruption to pick up subtle ligamentous injuries. Flexion-extension views should not be done in acute trauma setting they are used to diagnose late spinal instability. Plain anteroposterior, lateral and open-mouth x rays views can be used to assess and clear the cervical spine in cooperative children with a normal physical examination and a low-energy trauma. ![]()
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