Atlantoaxial Instability (AAI)
Etiology
Other
- Cartilage-Hair Hyperplasia
- Cerebral Palsy (see Cerebral Palsy)
- Chondrodysplasia Punctata
- Congenital Scoliosis
- Corticosteroid Therapy (see Corticosteroids)
- Down Syndrome (see Down Syndrome)
- Physiology: tranverse ligament laxity
- Dwarfism (see xxxx)
- Head and Neck Infection (Especially Pharyngeal Infection) (see Deep Neck Infection)
- Physiology: transverse ligament inflammation, predisposing to atlantoaxial subluxation
- Hypoplasia or Absence of Dens
- Kniest Syndrome
- Larsen Syndrome
- Metatropic Dysplasia
- Morquio Syndrome
- Mucopolysaccharidoses
- Neurofibromatosis (see Neurofibromatosis)
- Odontoid Abnormalities
- Os Odontoideum
- Ossiculum Terminale
- Osteogenesis Imperfecta
- Pseudoachondroplasia
- Scott Syndrome
- Spondyloepiphyseal Dysplasia Congenita
- Third Condyle
- Trauma to Neck
- Tumors
- Physiology: may cause fracture of body of the axis
Physiology
Mechanisms of Atlantoaxial Instability
- Bony Odontoid Abnormalities: may be due to either abnormal odontoid development/ossification or fracture
- Fracture of Body of the Axis: may occur with tumors
- Transverse Ligament Laxity/Inflammation: may occur with RA and infections
Clinical Manifestations
Neurologic Manifestations
References