Diagnosis and Treatment of Atlantoaxial Instability
Atlantoaxial instability (AAI) is characterized by excessive movement at the junction between the atlas (C1) and the axis (C2), as a result of either a bony or ligamentous abnormality. Early diagnosis and treatment are vital for patients. Clinical symptoms and signs may be different according to the cause, type, site, and specific situation of the atlantoaxial instability. Neurological dysfunction can occur when the spinal cord or adjacent nerve roots are involved. Imaging examinations, especially computed tomography and magnetic resonance imaging (MRI), can provide visual evidence to make a proper diagnosis. Treatments for AAI can be nonsurgical or surgical. The nonsurgical treatments include relative pharmacotherapy and routine immobilization methods. Surgical treatments comprise treatment of primary upper cervical diseases and/or trauma and techniques of C1–C2 fusion (C1–C2 fusion is discussed briefly because it is covered in depth in the following chapter).