Case Report
Natural History, Neuroradiological Workup, and Management Options of Chronic Atlantoaxial Rotatory Fixation Caused by Drug-Induced Cervical Dystonia
| Fielding and Hawkins AARF classification [4] | Type 1 | Rotatory fixation with no anterior displacement | Type 2 | Rotatory fixation with anterior displacement of 3 to 5 millimeters | Type 3 | Rotatory fixation with anterior displacement of more than 5 millimeters | Type 4 | Rotatory fixation with posterior displacement |
| Pang AARF classification [9, 17] | Type 1 | AARF patients show essentially unaltered (“locked”) C1-C2 coupling regardless of corrective counterrotation | Type 2 | AARF patients show reduction of the C1-C2 separation angle with forced correction, but C1 cannot be made to cross C2 | Type 3 | AARF patients show C1-C2 crossover but only when the head is cranked far to the opposite side |
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