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Atlantoaxial Instability Clinical Presentation

  • Author: Daniel P Leas, MD; Chief Editor: Jeffrey A Goldstein, MD  more...
Updated: Feb 03, 2015


Usually, persons with congenital anomalies do not become symptomatic before the third decade of life. The spine is assumed to be able to accommodate differing regions of hypermobility and fusions. With time, the degenerative changes occurring in the lower cervical spine increase rigidity and alter the balance. This gradual loss of motion places increasing loads on the atlantoaxial articulation.

The cervical spine is involved more frequently in patients with rheumatoid arthritis (RA). Cervical involvement tends to be asymptomatic in the scenario of systemic rheumatoid manifestations. In addition, the severity of the systemic manifestations should serve as a marker of the degree of cervical involvement.[20]

In cases associated with trauma, head and facial injuries may be present. The flexion-extension moment exerted on the spine can cause ligamentous disruption with subsequent atlantoaxial instability (AAI).

In some persons with Grisel syndrome, an antecedent illness or infection occurs.[21]

For patients with genetic or metabolic syndromes with higher rates of AAI or AAS as compared with a normal population, there are multiple additional details that are relevant to the clinician. A thorough cervical spine examination is warranted for patients presenting with the following conditions:

  • Down syndrome - Approximately 13% of patients with DS will have asymptomatic AAI, and 1.5% will have neurologic symptoms stemming from this instability [7]
  • Spondyloepiphyseal dysplasia (SED) - SED congenita is associated with a 40% risk of AAI; SED tarda usually does not manifest AAI [22]
  • Morquio syndrome - AAI is usually secondary to odontoid hypoplasia or aplasia; patients tend to present later in childhood and usually later than those with SED congenita; nearly all patients with Morquio syndrome will develop AAI, and some surgeons recommend prophylactic stabilization to combat the morbidity associated with spinal cord compression [23]
  • Chondrodysplasia punctata - AAI is the primary cause of disability and death in these patients; about 20% will present with weakness, and 20% will present with hyperreflexia; spinal cord compression can occur at an early age [24]
  • Metatropic dysplasia - Patients with this rare syndrome patients survive into young adulthood but develop AAI early; nearly all appear to have odontoid hypoplasia, and in a small series, 75% of these patients had associated instability [25]

Physical Examination

A careful neurologic examination should be conducted, especially for children at risk. Assess sensory, motor, and other neurologic functions. Upper motor neuron signs, including hyperreflexia, clonus, and extensor plantar reflexes, may be indicative of symptomatic AAI. Somatosensory evoked response may reveal information regarding neurologic involvement.

In individuals with rotatory displacement, a cock-robin deformity or torticollis can be the presenting symptom.

Many patients with RA present with occipital pain. Others develop myelopathy, vertigo, brainstem signs, or lower cranial nerve palsies. The brainstem findings occur either with basilar invaginations or with the alteration of the path of the vertebral artery with changing of normal anatomy. Rana reported the subtle association of involvement of the fifth cranial nerve, which has a descending tract that extends to C2.[26] Pyramidal signs, including hyperactive reflexes, a positive Babinski sign, and proprioceptive loss, should alert the physician for developing myelopathy.

The most specific physical findings in patients with symptomatic AAI secondary to infections of the head and neck are torticollis, tenderness over the spinous process of the axis with palpation, and the Sudeck sign (displacement of spine of the axis in the direction of head tilt).

A reduction in size of the nasopharynx and increased nasal resonance also may be present due to forward displacement of the arch of the atlas.

Persons with atlantoaxial subluxation (AAS) due to inflammatory processes less frequently exhibit signs of root or cord involvement.



Spinal cord compression can arise or worsen if susceptible patients are subjected to extreme ranges of motion. Symptoms of progressive neurologic dysfunction can include upper motor neuron signs, including the following:

  • Spasticity
  • Myelopathy
  • Neck pain
  • Radicular symptoms
Contributor Information and Disclosures

Daniel P Leas, MD Post-Doctoral Research Fellow, Resident Physician, Department of Orthopaedic Surgery, Carolinas Medical Center

Disclosure: Nothing to disclose.


Daxes M Banit, MD Partner, Middle Georgia Orthopaedic Surgery and Sports Medicine

Daxes M Banit, MD is a member of the following medical societies: American Medical Association

Disclosure: Nothing to disclose.

Daniel Murrey, MD Co-President, OrthoCarolina

Daniel Murrey, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Association for Physician Leadership, North Carolina Medical Society, American Medical Association, North American Spine Society

Disclosure: Nothing to disclose.

Bruce V Darden, II, MD Director, Spine Surgery Fellowship, OrthoCarolina Spine Center; Spine Teaching Staff, Orthopaedic Residency Program, Carolinas Medical Center

Bruce V Darden, II, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Orthopaedic Association, Scoliosis Research Society, Cervical Spine Research Society, AO North America, International Society for the Advancement of Spine Surgery, Lumbar Spine Research Society, North Carolina Medical Society, American Medical Association, North American Spine Society, Southern Medical Association, Southern Orthopaedic Association, American Society of Neurophysiological Monitoring, North Carolina Orthopaedic Association, North Carolina Spine Society, Scoliosis Association, Inc, Spine Society of Europe

Disclosure: Received consulting fee from Synthes for speaking and teaching; Received grant/research funds from Synthes for other; Received royalty from Stryker for other; Received consulting fee from Stryker for consulting; Received consulting fee from 4Web for consulting; Received consulting fee from Spineguard for consulting; Received ownership interest from BioMedFlex for other.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

William O Shaffer, MD Orthopedic Spine Surgeon, Northwest Iowa Bone, Joint, and Sports Surgeons

William O Shaffer, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Orthopaedic Association, Kentucky Medical Association, North American Spine Society, Kentucky Orthopaedic Society, International Society for the Study of the Lumbar Spine, Southern Medical Association, Southern Orthopaedic Association

Disclosure: Received royalty from DePuySpine 1997-2007 (not presently) for consulting; Received grant/research funds from DePuySpine 2002-2007 (closed) for sacropelvic instrumentation biomechanical study; Received grant/research funds from DePuyBiologics 2005-2008 (closed) for healos study just closed; Received consulting fee from DePuySpine 2009 for design of offset modification of expedium.

Chief Editor

Jeffrey A Goldstein, MD Clinical Professor of Orthopedic Surgery, New York University School of Medicine; Director of Spine Service, Director of Spine Fellowship, Department of Orthopedic Surgery, NYU Hospital for Joint Diseases, NYU Langone Medical Center

Jeffrey A Goldstein, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American College of Surgeons, American Orthopaedic Association, North American Spine Society, Scoliosis Research Society, Cervical Spine Research Society, International Society for the Study of the Lumbar Spine, AOSpine, Society of Lateral Access Surgery, International Society for the Advancement of Spine Surgery, Lumbar Spine Research Society

Disclosure: Received consulting fee from Medtronic for consulting; Received consulting fee from NuVasive for consulting; Received royalty from Nuvasive for consulting; Received consulting fee from K2M for consulting; Received ownership interest from NuVasive for none.

Additional Contributors

James F Kellam, MD, FRCSC, FACS, FRCS(Ire) Professor, Department of Orthopedic Surgery, University of Texas Medical School at Houston

James F Kellam, MD, FRCSC, FACS, FRCS(Ire) is a member of the following medical societies: American Academy of Orthopaedic Surgeons, Orthopaedic Trauma Association, Royal College of Physicians and Surgeons of Canada

Disclosure: Nothing to disclose.

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Transverse ligament holds dens against anterior arch of atlas.
Midsagittal section of upper cervical spine. Note landmarks for measuring anterior atlantodental interval (AADI) and posterior atlantodental interval (PADI).
Shown are 4 types of atlantoaxial rotatory subluxation.
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