Occipitoatlantoaxial Injuries Flashcards
Occipitoatlantal injuries are twice more common in children than in adults because of flatter condyles, higher ratio of cranium to body weight, and ligament laxity. Which of the following methods are devised radiographically to diagnose atlantooccipital dislocation (AOD)?
● A. Basion axial interval is the distance between the basion and rostral extension of posterior axial line (which is posterior cortical margin of body of C2). It should be from 4 to 12 mm in adults and 0 to 12 mm in children on X-rays
● B. Basion to dental interval (BDI) which is the distance from the basion to the closest point on the tip of dens should be less than 8.5 mm (range 1.4–8.5 mm) on CT, while it should be less than 10.5 mm in children
● C. Atlantooccipital interval also known as condyle–C1 interval which should be less than 1.4 mm in adults and less than 2.5 mm in children
● D. Power’s ratio or Dublin measure which is ratio between BC (basion to posterior arch of C1) and AO (anterior arch of C1 to opisthion) should be less than 1 in adults and less than 0.9 in children
● E. All of the above
E. All of the above
Power’s ratio of more than one encompasses all the cases of AOD. According to the Traynelis classification of atlanto-occipital dislocation normal alignment of clivus and dens is that inferior tip of clivus should point directly to the tip of dens, while
types I, II, and III are anterior dislocation of foramen magnum, longitudinal dislocation, or posterior dislocation of foramen magnum. According to grading and management of AOD, which of the following statements is correct?
● A. Grade 1 AOD is no abnormal CT criteria and only moderately abnormal MRI (high signal in posterior ligament or occipitoatlantal joint)
● B. Grade 1 needs only external orthosis
● C. Grade 2 includes more than or equal to one abnormal criteria on CT and gross abnormal MRI findings on occipitoatlantal joints, tectorial membrane, or alar or cruciate ligament
● D. Grade 2 requires surgical stabilization
● E. All of the above
E. All of the above
A patient presents after blunt trauma with high energy with occipital pain or tenderness, impaired cervical movement, lower cranial nerve palsies, and retropharyngeal soft tissue swelling. Which statement is not correct about the Anderson and
Montesano classification of occipital condyle fractures and their treatment?
● A. Type I is comminuted from impact which may occur with axial loading and treated with or without external immobilization (collar or halo)
● B. Type II is extension of linear basilar skull fracture treated with or without external immobilization
● C. Type III is avulsion of condyle fragment which may occur during rotation, lateral bending, or a combination of mechanisms, and it is treated with external immobilization for 6 to 8 weeks
● D. There is difference in outcome between surgically treated patients or patients with only external immobilization
D. There is difference in outcome between surgically treated patients or patients with only external immobilization
A young child after head trauma presents with cock robins head position with head in 20-degree rotation to one side, 20-degree rotation to the other, and slight 10-degree flexion with reduced range of motion. X-ray of cervical spine shows frontal
projection of C2 with simultaneous oblique projection of C1. Which of the following is true regarding Fielding and Hawkins classification of rotatory atlantoaxial subluxation and its management?
● A. Type I is intact TAL, bilateral facet injury with AD less than or equal to 3 and it is treated with soft collar
● B. Type II is injured TAL and unilateral facet injury with AD 3.1 to 5 and it is treated with SOMI or rigid collar
● C. Type III is injured TAL with bilateral facet joint disruption and AD more than 5 and it is treated with halo
● D. Type IV is incompetence of odontoid because of fracture or erosion with posterior displacement of C1
● E. After 6 to 8 weeks of immobilization, stability with flexion–extension X-rays is done and surgical fusion is never done with residual instability with posterior lateral mass fixation
E. After 6 to 8 weeks of immobilization, stability with flexion–extension X-rays is done and surgical fusion is never done with residual instability with posterior lateral mass fixation
A patient after head injury presents in neurosurgical emergency in which total overhang of both C1 lateral masses on C2 is more than or equal to 7 and MRI shows loss of continuity of TAL and high signal within TAL. Dickman type is anatomic disruption of TAL without osseous component with possible findings in type IA of loss of continuity of TAL with high signal within the TAL and type IB with osteoperiosteal TAL disruption. All type I Dickman injuries are fused while in case of Dickman type II which is physiologic disruption of TAL with detachment of C1 tubercle from C1 lateral mass what is the treatment?
● A. Treat with immobilization only
● B. Immobilization with fusion in all cases
● C. Fusion is done only in cases that are still unstable after 3 to 4 months of immobilization
● D. Fusion is not recommended in irreducible subluxation
● E. None of the above
C. Fusion is done only in cases that are still unstable after 3 to 4 months of immobilization
Jefferson type I is anterior arch of C1 fracture or posterior arch fracture, type II is anterior and posterior arch fracture, while type III is lateral mass fracture. All are treated with rigid immobilization for 10 to 12 weeks except?
● A. Cases with TAL disrupted are treated with surgical stabilization and fusion
● B. Cases with type III fracture
● C. Cases with instability
● D. Cases with neurologic deficit
● E. None of the above
A. Cases with TAL disrupted are treated with surgical stabilization and fusion
According to Levine classification of hangman’s fracture (modified Effendi system), traction is contraindicated in which fractures?
● A. In type I (vertical pars fracture just posterior to VB)
● B. In type IA (fracture lines on each side are not parallel and fracture may pass through foramen transversarium on one side)
● C. Type II (vertical fracture through pars with disruption of C2–C3 disk and posterior longitudinal ligament)
● D. Type IIA oblique fracture usually anterior–inferior to posterior–superior with little subluxation of less than 3 mm but more angulation of more than 15 degrees
● E. Type III which is type II plus C2 and C3 facet capsule disruption
● F. Both type IIA and type III
F. Both type IIA and type III
Indications for surgery of hangman’s fracture are inability to reduce the fracture, failure of external immobilization to prevent movement at the fracture site, traumatic C2–C3 disk herniation with compromise of the spinal cord, and established
nonunion. Which of the following is hangman’s fracture requiring surgery?
● A. Levine types II and III
● B. Francis grades 2, 4, and 5
● C. Anterior displacement of C2 by more than 50% of the AP diameter of C3 VB
● D. If angulation produces widening of either the anterior or posterior border of the C2–C3 disk space more than the height of C3–C4 disk below
● E. All of the above
E. All of the above
According to the Anderson and D’Alonzo classification of odontoid fractures, type I is through the tip, type II is through the base of the neck, type IIA is similar to type II but with large bone chips, and type III is through the body. Following are the indications of surgical management of these fractures except?
● A. Isolated type II odontoid fractures in adults more than 50 years of age should be considered for surgical stabilization and fusion
● B. Types II and III with dens displacement of more than or equal to 5 mm
● C. Type IIA fracture
● D. Inability to maintain or achieve alignment with external immobilization
● E. Nondisplaced type I, II, and III fractures
E. Nondisplaced type I, II, and III fractures
A patient presents with occipitocervical neck pain and myelopathy. On investigation, there is a separate bone ossicle of variable size with smooth cortical borders separated from a foreshortened odontoid peg. Type I is orthotopic in which ossicle
moves with anterior arch of C1 while type II is dystopic in which ossicle is functionally fused to the basion. Which of the following are true regarding management of these fractures?
● A. Patients without neurologic signs and symptoms may be followed with clinical or radiographic surveillance or with posterior C1–C2 fusion
● B. Patients with neurologic signs and symptoms or C1–C2 instability are treated with posterior C1–C2 internal fixation and fusion
● C. If surgery is done and rigid internal immobilization is not done, then postoperative halo immobilization is done
● D. For patients with irreducible cervicomedullary compression and/or evidence of associated occipito-atlantal instability, occipital cervical fusion with or without C1 laminectomy should be done
● E. For patients with irreducible cervicomedullary compression, consider ventral decompression
● F. All of the above
F. All of the above
In Traynelis classification, anterior dislocation of occiput relative to the atlas is what type?
● A. I
● B. II
● C. III
● D. IV
● E. V
A. I
In pediatric patients, the highest sensitivity and specificity for AOD is CT measurement of which of the following?
● A. Condyle–C1 interval (CCI)
● B. Basion–axial interval (BAI)
● C. Basion–dental interval (BDI)
● D. Power’s ratio
● E. X-line method
A. Condyle–C1 interval (CCI)
