Atlantoaxial Instability (Atlantoaxial Subluxation) Clinical Presentation

Updated: May 21, 2021
  • Author: Chris G Koutures, MD, FAAP; Chief Editor: Craig C Young, MD  more...
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Most patients with atraumatic AAI are asymptomatic. [1, 2, 3, 4, 5] Clinical evidence of the condition is usually not detected until the subluxation is severe enough to cause damage to the spinal cord. Many patients do not present with active disease; rather, these patients are evaluated because of requests for screening radiography or for guidance regarding sports participation. This condition is rarely discovered as an incidental finding during radiologic evaluation for an acute neck injury. During such evaluations, the clinician must obtain a full history to provide adequate management, such as the following:

  • In obtaining the history, a review of any current or past neck trauma, head injury, or fall is essential, especially in children. Previous spine trauma may have resulted in an improperly healed odontoid injury that causes instability and neurologic symptoms years later.

  • A complete review of the patient's medical history is also important because many medical conditions are associated with an increased incidence of AAI.

  • In individuals examined for screening radiography or sport-specific counseling, it is important to obtain a full description of past symptoms as well as their desired sports participation. Certain organizations, such as the Special Olympics, had a mandatory radiographic requirement for participation in a certain event. [6] More recently, this requirement has been changed and is no longer a national requirement, but one which may be required by some state Special Olympic organizations. Screening neurologic examination and review of symptoms are also part of the preparticipation evaluation.

  • Individuals with symptomatic AAI may present with nonspecific symptoms, including neck pain, limited range of motion, and torticollis. A history of worsening symptoms (eg, headache, fatigue, transient upper-extremity paresthesias) with neck flexion is particularly revealing. Other symptoms may include distal muscle weakness and spasticity, gait disturbance, and bowel and/or bladder dysfunction. Quadriplegia due to cord compression is another dramatic presentation.


Physical Examination

In any case of suspected head or cervical spine injury (including cases of unconsciousness or altered mental status) primary on-field management of the patient includes an assessment of the airway, breathing, and circulation (ABCs), with immediate stabilization of the cervical spine in a neutral position.

Great caution must be placed into maintaining the airway without compromising the injured cervical spine. Note: If intubation is needed in the field, use the jaw-thrust maneuver rather than cervical extension.

The injured athlete should not be moved in any fashion until he or she is properly placed on a rigid backboard and the head and neck is immobilized with a rigid cervical collar and head stabilization device.

For an athlete wearing a helmet and/or shoulder pads, special precautions must be taken. For example, the helmet and pads should be removed only if the responders are trained in the proper technique or if the initial screening radiographs are negative.

Arranging for expedient and safe transport is another immediate priority.

A complete neurologic examination can wait until the athlete is in a more controlled environment.

Any athlete who leaves the field with neck pain, limited cervical range of motion, extremity weakness, or paresthesias should be considered at high risk for a cervical spine injury. The athlete should be removed from the activity pending a full evaluation before any considerations of return to play.

High-dose intravenous steroids should be considered in patients with suspected cervical cord injuries to reduce spinal cord swelling.

Formal physical examination of the spine and extremities should be limited until unstable lesions of the cervical spine are ruled out. Once the atlantoaxial joint and cervical spine are deemed stable, further examination can proceed. In the office setting, the clinician must use the history to rule out potentially unstable lesions before performing a full physical examination.

The cervical neck examination includes an assessment of the cervical range of motion, palpation of the cervical spine, and performance of the Spurling maneuver (ie, axial load on head with neck extension and lateral rotation toward each shoulder). Paresthesias radiating past either shoulder signify a positive Spurling maneuver for cervical nerve root impingement.

Full reflex, motor, and sensory examination of the upper extremity is also indicated, with the neck in neutral as well as in a flexed position.

The physical findings are often completely normal in patients with radiographically documented AAI but who have no symptoms.