Backward Slip of C1 over C2

A backward slip of the first cervical vertebra (atlas, C1) over the second cervical vertebra (axis, C2) is commonly known as atlantoaxial instability or subluxation. In this condition, excessive movement or misalignment at the C1–C2 joint can compress neural structures, leading to pain and neurologic symptoms. Below is an evidence-based, SEO-optimized overview in plain English.

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Anatomy

Structure & Location

The atlantoaxial joint comprises three articulations between C1 and C2: one median joint (between the anterior arch of C1 and the dens of C2) and two lateral facet joints. This joint sits just below the skull base, at the top of the neck, forming the most mobile segment of the spine. NCBIKenhub

Origin & Insertion (Ligaments)

• Transverse Ligament of the Atlas: Originates from the medial aspects of the C1 lateral masses and inserts on the opposite side, wrapping behind the dens to hold it in place.

• Alar Ligaments: Arise from the posterolateral dens and insert on the medial occipital condyles, limiting excessive rotation.

• Apical Ligament: Extends from the tip of the dens to the anterior foramen magnum, providing minor stabilization. Kenhub

Blood Supply

Arterial branches from the vertebral, deep cervical, and occipital arteries form a rich network around C1–C2, ensuring good perfusion of bones, ligaments, and surrounding soft tissues. Kenhub

Nerve Supply

Sensory fibers from the ventral primary ramus of C2 (the greater occipital nerve) innervate the atlantoaxial joint, transmitting pain and proprioceptive signals. Kenhub

Functions

1. Rotation: Allows ~40° of head turning (“no” motion).

2. Flexion: Small forward bending of the head.

3. Extension: Slight backward tilting.

4. Lateral Flexion: Minimal side-bending.

5. Proprioception: Senses head position.

6. Stability: Maintains alignment under load. Kenhub

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Types of Atlantoaxial Instability

1. Traumatic (e.g., fracture-dislocation)

2. Congenital (e.g., Down syndrome, os odontoideum)

3. Inflammatory (e.g., rheumatoid arthritis pannus)

4. Infectious (e.g., Grisel’s syndrome)

5. Neoplastic (e.g., tumor erosion)

6. Degenerative (e.g., spondylosis)

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Causes

1. Acute trauma (e.g., motor vehicle accident)

2. Jefferson fracture

3. Os odontoideum (congenital dens anomaly)

4. Down syndrome–associated laxity

5. Rheumatoid arthritis–related erosion

6. Infectious arthritis (e.g., Grisel’s)

7. Tumor infiltration (e.g., metastasis)

8. Congenital ligament laxity

9. Chronic steroid use (ligament weakening)

10. Ankylosing spondylitis

11. Hydrocephalus shunt overdrainage

12. Paget’s disease of bone

13. Ehlers-Danlos syndrome

14. Morquio syndrome

15. Trauma-induced ligament rupture

16. Chronic cervical degeneration

17. Gout depositing crystals

18. Hyperparathyroidism bone changes

19. Fibrous dysplasia

20. Radiation-induced bone fragility

These causes reflect bony or ligamentous factors that permit excessive C1–C2 motion. Medscape

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Symptoms

1. Neck pain and stiffness

2. Occipital headache

3. Limited neck motion

4. Cervical muscle spasm

5. Paresthesia in arms/hands

6. Upper limb weakness

7. Gait ataxia

8. Drop attacks (sudden falls)

9. Torticollis (twisted neck)

10. Dysphagia (difficulty swallowing)

11. Dysarthria (speech trouble)

12. Vertigo

13. Bladder/bowel dysfunction

14. Hyperreflexia

15. Lhermitte’s sign (“electric” shocks)

16. Clonus in ankles

17. Respiratory compromise

18. Nystagmus (eye jerking)

19. Temperature tolerance issues

20. Fatigue

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Diagnostic Tests

1. Plain X-rays (flexion-extension views)

2. CT scan (bone detail)

3. MRI (cord/ligament assessment)

4. Dynamic fluoroscopy

5. Myelography

6. Electromyography (EMG)

7. Nerve conduction studies

8. Somatosensory evoked potentials

9. Vertebral artery Doppler

10. Bone scan

11. Dual-energy X-ray absorptiometry

12. Serologic tests (e.g., rheumatoid factor)

13. Inflammatory markers (ESR, CRP)

14. Genetic testing (e.g., Down syndrome)

15. CT angiography

16. Dynamic ultrasound of ligaments

17. Vestibular testing

18. Urodynamic studies

19. Swallow study

20. Pulmonary function tests

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Non-Pharmacological Treatments

1. Rigid cervical collar

2. Halo vest immobilization

3. Cervical traction

4. Physical therapy (strengthening)

5. Neck stabilization exercises

6. Posture correction training

7. Ergonomic workstation setup

8. Heat and cold therapy

9. Ultrasound therapy

10. Electrical stimulation

11. Transcutaneous electrical nerve stimulation (TENS)

12. Cervical mobilization/manipulation (trained therapist)

13. Acupuncture

14. Massage therapy

15. Yoga for neck stability

16. Pilates focusing on core/neck

17. Biofeedback for muscle control

18. Cervical orthotic inserts

19. Sleep posture optimization

20. Aquatic therapy

21. Soft tissue release techniques

22. Traction table therapy

23. Education on activity modification

24. Cervical proprioception drills

25. Vestibular rehabilitation

26. Tai Chi for balance

27. Cervical stabilization bracing during sports

28. Nutritional counseling for bone health

29. Vibration platform therapy

30. Cognitive-behavioral therapy for pain coping

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Drugs

NSAID = nonsteroidal anti-inflammatory drug; DMARD = disease-modifying antirheumatic drug; TCA = tricyclic antidepressant; SSRI = selective serotonin reuptake inhibitor. Medscape

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Dietary Supplements

Always consult a healthcare provider before starting supplements. Medscape

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Surgeries

1. Posterior C1–C2 fusion with rod-screw fixation

2. Transarticular screw fixation (Magerl technique)

3. C1 lateral mass and C2 pedicle screw fixation (Goel–Harms technique)

4. Transoral odontoidectomy (for irreducible dislocation)

5. Posterior wiring and bone graft fusion

6. Occipitocervical fusion (if occiput involved)

7. Endoscopic transnasal odontoid resection

8. Anterior cervical approach with C1–C2 plating

9. Minimally invasive percutaneous screw fixation

10. Halo vest–assisted closed reduction and in situ fusion

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Prevention Strategies

1. Early rheumatoid arthritis treatment to prevent ligament erosion

2. Safe sports practices with neck protection

3. Fall prevention in the elderly

4. Posture awareness and ergonomics

5. Avoidance of excessive cervical extension/flexion

6. Regular bone density screening in high-risk patients

7. Genetic counseling for congenital ligament laxity

8. Infection control to prevent septic arthritis

9. Strengthening neck stabilizer muscles

10. Regular follow-up imaging in known anomalies

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When to See a Doctor

• Sudden onset of neck pain with neurologic signs

• New weakness or numbness in arms/legs

• Difficulty walking or loss of coordination

• Drop attacks or unexplained falls

• Bowel or bladder dysfunction

• Severe headache with neck movement

• Worsening symptoms despite conservative care

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Frequently Asked Questions

1. What exactly is a backward slip of C1 over C2?
   It’s when C1 moves excessively backward relative to C2, risking spinal cord compression.

2. How is it different from a herniated disk?
   This involves vertebral misalignment, not disk material protruding.

3. Can it happen without trauma?
   Yes—congenital conditions or inflammatory diseases can cause it.

4. Is surgery always required?
   Not always; mild cases may be managed with bracing and therapy.

5. What’s the role of a cervical collar?
   It stabilizes C1–C2 to prevent further slip and allows healing.

6. Are vaccines relevant?
   Indirectly—preventing infections (e.g., meningitis) reduces septic arthritis risk.

7. Can children get this condition?
   Yes, especially with Down syndrome or congenital anomalies.

8. How long is recovery after fusion surgery?
   Typically 3–6 months for bony fusion, with physical therapy.

9. Will I lose head rotation after fusion?
   Yes, fusion reduces rotation, but stabilization outweighs motion loss.

10. Can supplements replace medications?
    No—supplements support but don’t replace anti-inflammatory or disease-modifying drugs.

11. How is it diagnosed on X-ray?
    Flexion-extension views show abnormal spacing or movement between C1–C2.

12. What complications can occur?
    Cord injury, chronic pain, or hardware failure post-fusion.

13. Is physical therapy safe?
    Yes, under guidance it strengthens stabilizers and improves posture.

14. Can obesity worsen it?
    Extra weight strains cervical structures, potentially worsening instability.

15. What is the long-term outlook?
    With proper management, many return to normal activities; untreated, it risks permanent neurologic damage.

Disclaimer: Each person’s journey is unique, treatment plan, life style, food habit, hormonal condition, immune system, chronic disease condition, geological location, weather and previous medical  history is also unique. So always seek the best advice from a qualified medical professional or health care provider before trying any treatments to ensure to find out the best plan for you. This guide is for general information and educational purposes only. Regular check-ups and awareness can help to manage and prevent complications associated with these diseases conditions. If you or someone are suffering from this disease condition bookmark this website or share with someone who might find it useful! Boost your knowledge and stay ahead in your health journey. We always try to ensure that the content is regularly updated to reflect the latest medical research and treatment options. Thank you for giving your valuable time to read the article.

The article is written by Team Rxharun and reviewed by the Rx Editorial Board Members

Last Updated: May 06, 2025.