Alar Ligament – Craniocervical Junction

alar liagment

A PARTIAL REVIEW OF THE LITERATURE OF THE CRANIOCERVICAL JUNCTION
 

  1. The upper cervical ligaments are the most brittle ligaments in the human body, and were never meant to withstand the forces generated in a motor vehicle collision (MVC).

 

Saldinger P, Dvorak J, et al.  (1990) The Histology of the Alar and Transverse Ligaments.  Spine 15, 257-261

  • The authors noted that collagen structures fail at 6-8% of stretch beyond their resting length, and that elastin could tolerate elongation up to 200%, and then abruptly fail.
  • The elastin fibers were found to tolerate only 20% of the load that collagen could tolerate.
  • They noted that the elastic properties of ligaments decrease with age.
  • They reported that both the alar and transverse ligaments consisted almost entirely of collagen fibers, and they could only find a few isolated elastin fibers in the loose connective tissue that surrounded the transverse ligament. The transverse ligament transitioned into fibrocartilage on the ventral side (which contacts the dens), and the ligament thickened somewhat in the central area.
  • Since the contribution from the few elastic fibers to the mechanical behavior of both the transverse ligament and the alar ligaments is “neglibly small,” the authors stated that “a major elongation of the ligament is almost impossible.”  They went on to state, “the fact that the alar ligaments  consist mainly of collagen fibers supports the hypothesis that those ligaments could be irreversibly overstretched or even ruptured when the head is rotated and in addition flexed, a movement seldom induced physiologically.   However, in motorcar accidents, especially in unexpected rear-end collisions, the head, initially slightly rotated, will go into maximal rotation followed by a ‘whiplash’ movement caused by the impact.”

 

  1. The medical literature throughout the past three decades has been loaded with articles about the damage done to the alar ligaments as a result of MVC’s.

Dvorak J, Panjabi MM.  Functional Anatomy of the Alar Ligaments.  Spine 1987;12:183–9

  • Upper cervical spine ligament may remain undetected radiographically and may lead to clinical instability causing neurologic deterioration in as many as 33% of patients.

Dvorak J, Froehlich D, Penning L, et al. Functional Radiographic Diagnosis of the Cervical Spine: Flexion/Extension. Spine 1988;13:748–55.

  • The alar and transverse ligaments play key roles in stabilizing the upper cervical spine because of the absence of intervertebral discs and the presence of horizontally aligned facet at the atlantooccipital region.

Panjabi M, Dvorak, J, Crisco J, et al.  Flexion, Extension, and Lateral Bending of the Upper Cervical Spine in Response to Alar Ligament Transections.  Journal of Spinal Disorders (1991), Vol 4., No. 2, pp. 157-167

  • The alar ligaments limit lateral flexions ipsilaterally at C1-C2, and also limit flexion at C0-C1; increases in all of the above indicates alar ligament damage.

Radcliffe KE, Hussain BS, Moldavsky MS, Klocke MS, et al.  In Vitro Biomechanics of the Craniocervical Junction- A Sequential Sectioning of Its Stabilizing Structures.  Spine 15 (2015), pp. 1618-1628

  • The transverse and alar ligaments appear to be the main stabilizers of the craniocervical junction.

White AA, Panjabi MM. Clinical Biomechanics of the Spine, 2nd ed. (Philadelphia: Lippincott, 1990).

  • “Rupture of the alar and transverse ligaments often occurs without associated vertebral fracture and may result in upper cervical spine instability leading to neurologic injury or death.”

Maak, TG, Tominaga, Y, Panjabi, MM, and Ivancic, PC.  Alar, Transverse, and Apical Ligament Strain Due to Head-Turned Rear Impact.  Spine 2006 (Volume 31, Number 6), pp 632-638

  • Whiplash-Induced soft tissue injuries produce chronic head and neck pain and upper cervical spine instability.

Saternus K. Die Wirbelsaulenuntersuchung im Rahmen der Forensischen Obduktion. Beitr Gerichtl Med 1988;46:489–95. (No, I didn’t actually read this one.)

  • The author found that among 397 whiplash patients, 85.6% had upper cervical ligamentous lesions whereas only 14.4% had bone fractures.

 

Volle E, Montazem A. MRI Video Diagnosis and Surgical Therapy of Soft Tissue Trauma to the Craniocervical Junction. Ear Nose Throat Journal 2001;80:41-4,46-8

  • This MRI study of 95 whiplash patients demonstrated alar ligament lesions in nearly 75% of subjects.

Krakenes J, Kaale BR, Moen G, et al. MRI Assessment of the Alar Ligaments in the Late Stage of Whiplash Injury: A Study of Structural Abnormalities and Observer Agreement. Neuroradiology 2002;44:617–24

  • In a follow-up MRI study of between two and nine years, Krakenes et al documented persistent injury of the alar ligaments in 51% of whiplash patients. (Krakenes also published five other papers from the same study which documented the use of thin slice proton density MRI data sets for the diagnosis of injury to the tectorial membrane, the posterior atlanto-occipital membrane, the posterior atlanto-axial membrane, the transverse ligament, and the apical ligament.  More on this one later).

Adams, VI.  Neck Injuries:  III.  Ligamentous Injuries of the Craniocervical  Articulation  Without Occipito-Atlantal or Atlanto-Axial Facet Dislocation:  A Pathologic Study of 21 Traffic Fatalities.  J Forensic Sci 1993;38:1097-104

  • Post-mortem evaluation of 21 fatalities with atlanto-occipital dislocation revealed alar ligament injuries ranging from partial to complete rupture in 95% of the cases, elucidating the vital role of the alar ligaments in stabilizing the atlantooccipital region.

 

  1. Some of the best information about upper cervical ligament damage and the resulting subluxations is found in rheumatoid arthritis literature.

Weissman, BNW, et al.  Prognostic Features of Atlantoaxial Subluxation in Rheumatoid Arthritis Patients.  Radiology 144:  September 1982, pp. 745-751

  • While anterior atlanto-dental subluxation (aADI) is very well known as a manifestation of rheumatoid arthritis in the cervical spine, the researchers noted that lateral subluxation of C1 on C2 was documented concurrently in 20.6% of the study’s subjects. “Because this deformity further reduces the diameter of the spinal canal, it is more frequent in neurologically abnormal patients.”

Taniguchi, D, et al.  Evaluation of Lateral Instability of the Atlanto-Axial Joint in Rheumatoid Arthritis Using Dynamic Open-Mouth View Radiographs.  Clin Rheumatol (2008) 27:851-857

  • The authors studied a group of 30 patients with rheumatoid arthritis in comparison with a control group of 22 patients.
  • Standard flexion-extension stress radiographs and special anterior-posterior (AP) open mouth with maximum right and left lateral bending views were made.
  • The ADLS (lateral shift) in the rheumatoid arthritis group was significantly greater than that in the control group;
  • The authors believed the lateral shift was due to weakening of the alar ligaments and “loosening” of the lateral atlanto-axial joint (which would implicate the accessory ligaments).
  • “In the present study, we found dynamic lateral instability of the atlanto-axial joint in rheumatoid arthritis, and its frequency of occurrence was as high as that of anterior atlanto-axial subluxation (aAAS).”

Pisitkun P, et al.  Reappraisal of Cervical Spine Subluxation in Thai Patients with Rheumatoid Arthritis, Clin Rheumatol (2004) 23: 14-18

  • The overall prevalence of cervical spine subluxation was 68.7%, which could be characterized into anterior (26.9%), posterior (14.9%), lateral (17.2%), vertical (16.4%), and atlantoaxial and subaxial subluxation (28.4%).
  • Corticosteroid use was associated with cervical subluxation, regardless of dose and duration of treatment because the steroids lead to ligament laxity, osteoporosis, and decreasing muscle mass, which accelerated the subluxation.

The point is that it doesn’t really matter what causes the lateral instability at C1-C2- a disease process or an abrupt trauma- the outcome is the same and is manifested by lateral translation of C1 on C2 during side bending (lateral flexion).

 

  1. Anecdotal Case Studies of Alar Ligament Injury

Demetrious J.  Post-Traumatic Upper Cervical Subluxation Visualized By MRI:  A Case Report, Chiropractic & Osteopathy, December 19, 2007, 15:20

  • Smart chiropractor Dr. Demetrious spots abnormal C1-C2 lateral translation not spotted by the reading radiologist, corrects him on it, and proceeds to a good outcome with his patient, who lives happily ever after. Probably should be made into a made-for-TV movie.

Tasharski, CC, Heinze, WJ, and Pugh JLDynamic Atlanto-axial Aberration:  A Case Study and Cinefluorographic Approach to Diagnosis.  JMPT 1981; 4:65-8

  • Tasharski is a long-time DACBR at National University of Health Sciences (formerly National Chiropractic College) who uses videofluoroscopy to diagnose ligamentous damage in the cervical spine of a 35-year old male.

Derrick LJ, and Chesworth BM.  Post-Motor Vehicle Accident Alar Ligament Laxity, JOSPT, Vol. 16, No. 1, July, 1992

  • The authors are physical therapists who describe a case presentation in a patient whose radiological findings supported the clinical findings of right alar ligament laxity.
  • The radiological findings? APOM with lateral flexion, bilaterally.

It has been well established in the literature for several decades that there is no lateral flexion movement available at C1-C2 with side bending.

 

Because the rheumatoid literature will allow 1-2 mm. of movement between C1-C2 with lateral flexion, we do not consider very mild lateral translation there to be of clinical significance.  Krakenes (2002) stated that he considered 1.7 mm of lateral translation at C1-C2 to be indicative of subluxation and poor prognosis.  And his statement was based on patients who only had images created in the neutral position, without the benefit of dynamic positioning.  So who’s right?  I’d say, when in doubt, always remember that radiographic findings of all types must be correlated to the patient’s clinical presentation; otherwise, they are of no relevance.

 

  1. Should MRI be the gold standard in the diagnosis of spinal ligament injuries? 

Stabler, A., Eck J., Penning R., Milz, SP, Bartl R., Resnick D, Reiser M.  Cervical Spine:  Postmortem Assessment of Accident Injuries- Comparison of Radiographic, MR Imaging, Anatomic, and Pathologic findings.  Radiology, 2001; 221 (2):340-6

  • 28 lesions were identified.
  • 3 lesions were fractures (11%) with two of them not visible with x-ray.
  • Only 11 (total!) of the 28 lesions were initially found with MRI.
  • The other 17 were found only after using specially prepared 3-micrometer slices of the spinal segments.
  • “Direct depiction of the ruptured apophyseal (facet) joint capsule was almost impossible.”- Donald Resnick, MD
  • Bottom line? The resolving power of X-ray and MRI is insufficient to visualize the full spectrum of trauma.

Long DM, et al.  Fusion for Occult Posttraumatic Cervical Facet InjuryNeurosurg Q, Vol. 16, No. 3, September 2006

  • 67 patients with intractable neck pain and headaches following MVC
  • All had failed at 2 months of physical therapy and exercise rehabilitation.
  • All patients had no positive diagnostic findings, including plain film, CT, and MRI.
  • Facet capsule damage was diagnosed with anesthetic blocks (sixteen patients had negative results and were eliminated from surgical options).
  • 44 patients opted for the offer of posterior surgical fusion (Brooks’ triple wire fusion) of the symptomatic levels, with good results, because the instability was corrected.
  • Parting shot from the authors? MRI could not identify the ligament lesions:  “Imaging studies currently available do not define these ligamentous injuries.”  This statement did not include the use of digital motion x-ray.

 

 

 

  1. Imaging of upper cervical ligaments-  Jostein Krakenes, MD

These articles describe the use of thin slice proton density MRI data sets in imaging the ligaments and membranes of the upper cervical spine.  Jostein Krakenes is a Danish radiologist who did a landmark study in 2001, out of which he generated a half dozen game changing papers about the upper cervical ligaments.

Vetti N, Krakenes J, et al.  MRI of the Alar and Transverse Ligaments in Whiplash-Associated Disorders (WAD) Grades 1-2:  High-Signal Changes by Age, Gender, Event and Time Since Trauma.  Neuroradiology (2009) 51: 227-235

  • “High-signal changes of the alar and transverse ligaments are common in WAD 1-2 and are unlikely to represent age-dependent degeneration.”

Krakenes, et al.  MRI Assessment of the Alar Ligaments in the Late Stage of Whiplash Injury- A Study of Structural Abnormalities and Observer Agreement.  Neuroradiology (2002) 44:  617-624

  • “For detailed resolution of the alar ligaments good spatial resolution and optimized contrast are critical. A slice thickness of 2 mm gives excellent spatial resolution.  T2-weighted images gave inadequate discrimination between ligament, bone and soft tissue due to low signal-to-noise ratio.  T1-weighted images afforded poorer contrast resolution and thus less ability to differentiate small variations in signal.  We therefore found a proton-density weighted sequence the technique of choice for assessment of ligamentous abnormalities.”

Kaale RB, Krakenes J, et al.  Whiplash-Associated Disorders Impairment Rating:  Neck Disability Index Score According to Severity of MRI Findings of Ligaments and Membranes in the Upper Cervical SpineJournal of Neurotrauma, Vol. 22, No. 4, 2005, pp. 466-475

  • “In the WAD patients, MRI lesions to the alar ligaments showed the most consistent association to the reported pain and disability. Lesions to other structures often occurred in combination with lesions to the alar ligaments.  Lesions to the transverse ligament and to the posterior atlanto-occipital membrane also appeared to be related to the NDI score.”

Krakenes J and Kaale BR.  Magnetic Resonance Imaging Assessment of Craniovertebral Ligaments and Membranes After Whiplash Trauma.  Spine Vol. 31, No. 24, pp 2820-2826

  • “The number of high-grade changes in whiplash patients compared with noninjured individuals indicates that these lesions are indeed caused by a whiplash trauma…Our findings add support to the hypothesis that injured soft tissue structures in the upper cervical spine, particularly the alar ligaments, play an important role in the understanding of the chronic whiplash syndrome.”

 

Krakenes J, Kaale BR, et al.  MRI of the Tectorial and Posterior Atlanto-Occipital Membranes in the Late Stage of Whiplash Injury.  Neuroradiology (2003) 45:  585-591

  • “This study strongly indicates that whiplash trauma can damage the tectorial and posterior atlanto-occipital membranes; this can be shown on high resolution MRI.”

Kaale BR, Krakenes J. et al.  Head Position and Impact Direction in Whiplash Injuries:  Associations with MRI-Verified Lesions of Ligaments and Membranes in the Upper Cervical SpineJournal of Neurotrauma, Vol. 22, Number 11, 2005

  • “The difference in MRI-verified lesions between WAD patients and control persons, and in particular the association with head position and impact direction at time of accident, indicate that these lesions (to the alar, transverse, tectorial, and posterior atlanto-occipital membrane) are caused by the whiplash trauma.”

 

  1. Recently published literature:

Lindgren KA, Kettunen JA, Paatelma M, and Mikkonen, RHM.  Dynamic Kine Magnetic Resonance Imaging in Whiplash Patients and in Age- and Sex-matched Controls.  Pain Res Manage 2009;14(6):427-432

  • 25 whiplash trauma patients with longstanding pain, limb symptoms and loss of balance indicating a problem at the level of C0-C2, as well as matched healthy controls were imaged using dMRI.
  • Coronal T2, PD weighted, and FSE axial sequences were used.
  • A physiotherapist performed the bending and rotation of the upper cervical spine for the subjects to ensure that the movements were limited to the C0-C2 level.
  • The signal from the alar ligaments was abnormal in 92% of the patients and in 24% of the control subjects.
  • Abnormal movements at the level of C1-C2 were more common in whiplash patients than in controls (56% vs. 20%).

Smith FW and Dworkin JS (ed). The Craniocervical Syndrome and MRI, Chapter 2, by Franck JI and Perrin P. “The Cranial Cervical Syndrome Defined:  New Hope for Postwhiplash Migraine Headache Patients- Cervical Digital Motion X-Ray, FONAR Upright Weight-Bearing Multi-Position MRI and Minimally Invasive C1-C2 Transarticular Lag Screw Fixation Fusion.”  Basel, Karger, 2015, pp. 9-21

  • “The essential radiological feature of the CCS is lateral C1-C2 ligamentous instability. Easily detected utilizing DMX, all patients underwent this low-radiation, portable, 15 minute, video-fluoroscopic exam of cervical motion in all axes, including open-mouth, odontoid, coronal lateral flexion-extension views.”
  • Postwhiplash headache of migraine intensity
  • Neck pain
  • Difficulty with concentration and focus
  • Diminished memory
  • Tinnitus
  • Ataxia
  • Nausea/vomiting
  • Autonomic disturbances
  • Paresthesia
  • Weakness
  • Chronic pain

 

Steilen D, Hauser R, et al.  Chronic Neck Pain:  Making the Connection Between Capsular Ligament Laxity and Cervical Instability.  The Open Orthopedics Journal, 2014, 8, 326-345

The following chart is taken from the text of the article, and it describes how the cervicocranial syndrome has been present in the literature for decades, but under different, unrelated names, which have existed as separate entities- until now.  All of them feature subfailure of the upper cervical ligaments, and the different authors describe numerous similarities in symptoms.