What is atlantoaxial rotatory subluxation?

What is atlantoaxial rotatory subluxation?

Atlantoaxial rotatory subluxation is a rare condition in which patients present with the acute onset of torticollis. Atlantoaxial rotatory subluxation represents a spectrum of disease from muscle spasm to a fixed mechanical block to reduction of the atlantoaxial complex.

What is subluxation of C1 and C2?

(C1–C2 Subluxation) Atlantoaxial subluxation is misalignment of the 1st and 2nd cervical vertebrae, which may occur only with neck flexion. (See also Evaluation of Neck and Back Pain.

What is rotational subluxation?

Rotational subluxation or dislocation of C1 on C2. Can develop from osseous or ligamentous abnormalities resulting from acquired or congenital disorders. As a result of instability, excessive motion and spinal cord compression may occur at the atlantoaxial joint.

How is atlantoaxial subluxation measured?

The ADI is determined by measuring the distance between the posterior edge of the anterior arch of C1 and the anterior edge of the dens. A value less than three mm is considered normal in adults and a value less than 4.5 mm is considered normal in children.

What causes atlantoaxial subluxation?

The causes of atlantoaxial subluxation may be multifactorial, including transverse ligament damage by a periodontoidal proliferative pannus or sequelae of ossification of the anterior and posterior longitudinal ligaments, associated inflammatory lesions (cervical spine osteoarthritis, atlantodental synovitis, erosions …

Where is the atlantoaxial joint?

cervical spine
The C1 C2 spinal motion segment, also called the atlantoaxial joint, is located in the upper portion of the cervical spine. It consists of the C1 and C2 vertebrae, and the anatomical structures connecting them. This segment provides rotational motion, supports the head, and protects the spinal cord and nerve pathways.

How common is atlantoaxial subluxation?

Spontaneous atlantoaxial subluxation is a well-recognized complication affecting about 2% of patients with AS, presenting with and without signs of spinal cord compression.

What happens atlantoaxial subluxation?

Atlantoaxial instability (AAI), also known as atlantoaxial subluxation, is radiologically identified increased mobility or laxity between the body of the first cervical vertebra (atlas) and the odontoid process of the second cervical vertebra (axis) (see the image below).

How is atlantoaxial instability diagnosed?

CT and MRI Use of computed tomography (CT) can provide additional information regarding the stability of the atlantoaxial joint. Measuring displacement of defining rotation may be difficult on plain radiographs. Fine-cut CT with reformatting can be used for measuring the amount of displacement.

What is atlantoaxial interval?

The atlantodental interval is the horizontal distance between the posterior cortex of the anterior arch of the atlas (C1) and the anterior cortex of the dens in the median (midsagittal) plane.

What is atlas and axis?

The atlas and axis vertebrae are the two most superior bones in the vertebral column, and they are part of the seven cervical vertebrae. The atlas is the top-most bone, sitting just below the skull; it is followed by the axis. Together, they support the skull, facilitate neck movement, and protect the spinal cord.

What type of joint is atlantoaxial joint?

pivot joint
The median atlantoaxial joint is formed between the dens of axis and an osteoligamentous ring of the atlas anteriorly and transverse ligament posteriorly. It is classified as a pivot joint….Atlantoaxial joint.

Type Atlantoaxial joint complex: Synovial joint; biaxial
Blood supply Deep cervical, occipital, vertebral arteries