Atlanto-occipital dislocation

Last updated

Atlanto-occipital dislocation, orthopedic decapitation, or internal decapitation describes ligamentous separation of the spinal column from the skull base. It is possible for a human to survive such an injury; however, 70% of cases result in immediate death. It should not be confused with atlanto-axial dislocation, which describes ligamentous separation between the first and second cervical vertebra.

Contents

Mechanism

The injury is a result of disruption of the stabilizing ligaments between the occiput, or posterior skull base, and the C1 vertebral body, otherwise known as the atlas. The diagnosis is usually suspected by history and physical exam, but confirmed by imaging, typically by CT due to its faster speed in the acute trauma setting, although MRI can also help with assessment in equivocal cases. The treatment is initial stabilization with a cervical spine collar, and then surgical intervention in cases in which reversal of paralysis is possible. The most common mechanism of injury is high-speed motor vehicle accidents. The injury is more likely in children due to the large size of their heads relative to their bodies, and more horizontal orientation of the occipital condyles. It represents <1% of all cervical spine injuries. [1]

Several subtypes of atlanto-occipital dislocation are known. One suggested categorization scheme includes anterior, vertical and posterior of the head relative to the spine. Other variants with lateral or rotatory displacement have been described, as well as mixed types. Common etiology for such injuries is sudden and severe deceleration leading to a whiplash-like mechanism. [2]

Diagnosis

The distances between the dens and surrounding structures are also key features that can suggest the diagnosis, with the normal distance between the dens and basion (i.e., dens–basion interval; BDI) measuring less than 9 mm on CT, and the distance between the atlas and dens (i.e., atlas–dens interval; ADI) measuring less than 3 mm on CT, although this can be increased in cases of rheumatoid arthritis due to pannus formation. [3]

Several indirect measurements on CT can be used to assess ligamentous integrity at the craniocervical junction. The Wackenheim line, a straight line extending along the posterior margin of the clivus through the dens, should not intersect the dens on plain film, with violation of this relationship raising concern for basilar invagination. The basion to axion interval, or BAI, is also used, which is determined by measuring the distance between an imaginary vertical line at the anterior skull base, or basion, at the foramen magnum, and the axis of the cervical spine along its posterior margin, which should measure 12 mm, an assessment more reliable on radiograph than CT. The distance between the atlas and the occipital condyles, the atlanto-occipital interval (AOI), should measure less than 4 mm, and is better assessed on coronal images. [4]

The Powers ratio was formerly used, which was the tip of the basion to the spinolaminar line, divided by the distance from the tip of the opisthion to the midpoint of the posterior aspect of the anterior arch of C1. It is no longer recommended due to low sensitivity and difficulty identifying landmarks. It also will miss vertical or posterior displacement of the cervical spine. [5]

Other measurements include occiput-atlas distance, angle between anterior arch of atlas and axis, vertical distance between posterior arch of atlas and spinous process of axis, vertical atlanto-dens interval, and joint space between C1 and C2. [6]

Treatment

Treatment involves fixation of the cervical spine to the skull base, or occipitocervical fusion, using paramedian rods and transpedicular screws with cross-links for stabilization. The patient is subsequently unable to rotate their head in the horizontal plane. [7] If there is obstructive hydrocephalus, a pseudomeningocele can form, which is decompressed at the time of surgery. [8]

Prognosis

The injury is immediately fatal in 70% of cases, with an additional 15% surviving to the emergency room but dying during the subsequent hospital stay. A basion-dental interval (BSI) of 16 mm or greater is associated with mortality. In those with neurologic deficits, survival is unlikely. [9]

Most deaths result from mechanical damage to the spinal cord and lower brainstem, ranging from localized contusion to diffuse axonal injury to complete transection. Vascular complications are also frequent and may contribute significantly to delayed mortality. Combined dissections of the vertebral and carotid arteries can lead to severe cerebral ischemia, whereas rupture of the vertebral artery–PICA junction results in subarachnoid hemorrhage, compressing the brainstem. Hydrocephalus may also develop and cause a dangerous increase of intracranial pressure. Further possible complications include damage to prevertebral structures (pharynx, lower cranial nerves) and the cerebellum. Therefore, initial survivors of atlantooccipital dislocation may show severe and variable neurologic deficits, including reversible or irreversible tetraplegia, multiple cranial nerve deficits, loss of consciousness, and recurrent respiratory and/or cardiac arrests.

Children are more likely to survive with neurologic compromise than adults. Isolated cases of near-complete recovery after life-threatening symptoms are known. [10] [11]

In case of posterior displacement of the head, a concomitant fracture of the atlas with backward migration of the posterior arch is associated with improved chance of survival, as this allows the spinal cord and medulla to migrate backward without getting crushed. [12]

Proximal cervical fractures associated with injury

The Jefferson fracture can be associated with this injury, with the C1 ring, or atlas, being fractured in several places, allowing the spine to shift forward relative to the skull base. The Hangman's fracture which is a fracture of the C2 vertebral body or dens of the cervical spine upon which the skull base sits to allow the head to rotate, can also be associated with atlanto-occipital dislocation. Despite its eponym, the fracture is not usually associated with a hanging mechanism of injury. [13]

In Michael Connelly's 2020 thriller novel Fair Warning, protagonist Jack McEvoy investigates occurrences of atlanto-occipital dislocation. It is later learned that these deaths were at the hands of a serial killer, who manually twists the heads of his victims until their necks break and stages their deaths as accidents or suicides. In the TV show The Good Doctor one patient had to undergo surgery for this problem after a car accident. In the TV show 9-1-1 a teenage boy is treated for this injury after a train derailment.

Related Research Articles

<span class="mw-page-title-main">Atlas (anatomy)</span> First cervical vertebra of the spine which supports the skull

In anatomy, the atlas (C1) is the most superior (first) cervical vertebra of the spine and is located in the neck.

<span class="mw-page-title-main">Axis (anatomy)</span> Second cervical vertebra of the spine

In anatomy, the axis or epistropheus is the second cervical vertebra (C2) of the spine, immediately inferior to the atlas, upon which the head rests.

<span class="mw-page-title-main">Cervical spine disorder</span> Medical condition

Cervical spine disorders are illnesses that affect the cervical spine, which is made up of the upper first seven vertebrae, encasing and shielding the spinal cord. This fragment of the spine starts from the region above the shoulder blades and ends by supporting and connecting the skull.

<span class="mw-page-title-main">Clearing the cervical spine</span> Process of determining the existence of a cervical spine injury

Clearing the cervical spine is the process by which medical professionals determine whether cervical spine injuries exist, mainly regarding cervical fracture. It is generally performed in cases of major trauma. This process can take place in the emergency department or in the field by appropriately trained EMS personnel.

<span class="mw-page-title-main">Cervical vertebrae</span> Vertebrae of the neck

In tetrapods, cervical vertebrae are the vertebrae of the neck, immediately below the skull. Truncal vertebrae lie caudal of cervical vertebrae. In sauropsid species, the cervical vertebrae bear cervical ribs. In lizards and saurischian dinosaurs, the cervical ribs are large; in birds, they are small and completely fused to the vertebrae. The vertebral transverse processes of mammals are homologous to the cervical ribs of other amniotes. Most mammals have seven cervical vertebrae, with the only three known exceptions being the manatee with six, the two-toed sloth with five or six, and the three-toed sloth with nine.

<span class="mw-page-title-main">Cervical fracture</span> Medical condition

A cervical fracture, commonly called a broken neck, is a fracture of any of the seven cervical vertebrae in the neck. Examples of common causes in humans are traffic collisions and diving into shallow water. Abnormal movement of neck bones or pieces of bone can cause a spinal cord injury, resulting in loss of sensation, paralysis, or usually death soon thereafter, primarily via compromising neurological supply to the respiratory muscles as well as innervation to the heart.

<span class="mw-page-title-main">Vertebral artery</span> Major arteries of the neck

The vertebral arteries are major arteries of the neck. Typically, the vertebral arteries originate from the subclavian arteries. Each vessel courses superiorly along each side of the neck, merging within the skull to form the single, midline basilar artery. As the supplying component of the vertebrobasilar vascular system, the vertebral arteries supply blood to the upper spinal cord, brainstem, cerebellum, and posterior part of brain.

<span class="mw-page-title-main">Rectus capitis posterior minor muscle</span> Tendon

The rectus capitis posterior minor is a muscle in the upper back part of the neck. It is one of the suboccipital muscles. Its inferior attachment is at the posterior arch of atlas; its superior attachment is onto the occipital bone at and below the inferior nuchal line. The muscle is innervated by the suboccipital nerve. The muscle acts as a weak extensor of the head.

<span class="mw-page-title-main">Atlanto-axial joint</span>

The atlanto-axial joint is a joint in the upper part of the neck between the atlas bone and the axis bone, which are the first and second cervical vertebrae. It is a pivot joint.

<span class="mw-page-title-main">Atlanto-occipital joint</span> Articulation between the occipital bone and the cervical atlas

The atlanto-occipital joint is an articulation between the atlas bone and the occipital bone. It consists of a pair of condyloid joints. It is a synovial joint.

<span class="mw-page-title-main">Transverse ligament of atlas</span>

In anatomy, the transverse ligament of the atlas is a broad, though ligament which arches across the ring of the atlas posterior to the dens to keep the dens in contact with the atlas. It forms the transverse component of the cruciform ligament of atlas

<span class="mw-page-title-main">Vertebral artery dissection</span> Tear of the inner lining of the vertebral artery

Vertebral artery dissection (VAD) is a flap-like tear of the inner lining of the vertebral artery, which is located in the neck and supplies blood to the brain. After the tear, blood enters the arterial wall and forms a blood clot, thickening the artery wall and often impeding blood flow. The symptoms of vertebral artery dissection include head and neck pain and intermittent or permanent stroke symptoms such as difficulty speaking, impaired coordination, and visual loss. It is usually diagnosed with a contrast-enhanced CT or MRI scan.

<span class="mw-page-title-main">Hangman's fracture</span> Medical condition

Hangman's fracture is the colloquial name given to a fracture of both pedicles, or partes interarticulares, of the axis vertebra (C2).

<span class="mw-page-title-main">Occipital condyles</span> Undersurface protuberances of the occipital bone in vertebrates

The occipital condyles are undersurface protuberances of the occipital bone in vertebrates, which function in articulation with the superior facets of the atlas vertebra.

<span class="mw-page-title-main">Posterior atlantooccipital membrane</span> Membrane at the base of the skull

The posterior atlantooccipital membrane is a broad but thin membrane extending between the to the posterior margin of the foramen magnum above, and posterior arch of atlas below. It forms the floor of the suboccipital triangle.

<span class="mw-page-title-main">Cruciate ligament of atlas</span> Ligament forming part of theatlanto-axial joint

The cruciate ligament of the atlas is a cross-shaped ligament in the neck forming part of the atlanto-axial joint. It consists of the transverse ligament of atlas, a superior longitudinal band, and an inferior longitudinal band.

<span class="mw-page-title-main">Spinal fracture</span> Medical condition

A spinal fracture, also called a vertebral fracture or a broken back, is a fracture affecting the vertebrae of the spinal column. Most types of spinal fracture confer a significant risk of spinal cord injury. After the immediate trauma, there is a risk of spinal cord injury if the fracture is unstable, that is, likely to change alignment without internal or external fixation.

<span class="mw-page-title-main">Cervicocranial syndrome</span> Medical condition

Cervicocranial syndrome or is a neurological illness. It is a combination of symptoms that are caused by an abnormality in the neck. The bones of the neck that are affected are cervical vertebrae. This syndrome can be identified by confirming cervical bone shifts, collapsed cervical bones or misalignment of the cervical bone leading to improper functioning of cervical spinal nerves.Greenberg Regenerative Medicine | Bryn Mawr, Pennsylvania Cervicocranial syndrome is either congenital or acquired. Some examples of diseases that could result in cervicocranial syndrome are Chiari disease, Klippel-Feil malformation osteoarthritis, and trauma. Treatment options include neck braces, pain medication and surgery. The quality of life for individuals suffering from CCJ syndrome can improve through surgery.

Craniocervical instability (CCI) is a medical condition where there is excessive movement of the vertebrae at the atlanto-occipital joint and the atlanto-axial joint, that is, between the skull and the top two vertebrae. This can cause neuronal injury and compression of nearby structures including the spinal cord, brain stem, vertebral artery or vagus nerve, causing a constellation of symptoms. It is frequently co-morbid with atlanto-axial instability, Chiari malformation and tethered cord syndrome.

Empty vertebral body sign is a radiological sign used for diagnosing any injury with flexion-distraction mechanism of the vertebrae, particularly Chance fracture of the vertebrae. In Chance fracture, there is disruption and angulation superiorly or inferiorly of posterior elements of the vertebrae. As a result, the affected vertebral body is seen as radiolucent in the anterio-posterior view.

References

  1. ↑ Theodore, N; Aarabi, B; Dhall, SS; Gelb, DE; Hurlbert, RJ; Rozzelle, CJ; Ryken, TC; Walters, BC; Hadley, MN (March 2013). "The diagnosis and management of traumatic atlanto-occipital dislocation injuries". Neurosurgery. 72 Suppl 2: 114–26. doi:10.1227/NEU.0b013e31827765e0. PMID   23417184.
  2. ↑ Lee, I. L; Vasquez, L. F; Tyroch, A. H; Trier, T. T (2017). "Association of Atlanto-Occipital Dislocation, Retroclival Hematoma, and Hydrocephalus: Management and Survival in a Pediatric Patient". Journal of Neurological Surgery Reports. 78 (1): e53–e58. doi:10.1055/s-0037-1600914. PMC   5357215 . PMID   28321388.
  3. ↑ Bisson, E; Schiffern, A; Daubs, MD; Brodke, DS; Patel, AA (15 April 2010). "Combined occipital-cervical and atlantoaxial disassociation without neurologic injury: case report and review of the literature". Spine. 35 (8): E316–21. doi:10.1097/brs.0b013e3181c41d2c. PMID   20308946. S2CID   19468690.
  4. ↑ Chaput, CD; Walgama, J; Torres, E; Dominguez, D; Hanson, J; Song, J; Rahm, M (20 April 2011). "Defining and detecting missed ligamentous injuries of the occipitocervical complex". Spine. 36 (9): 709–14. doi:10.1097/brs.0b013e3181de4ec1. PMID   21192303. S2CID   20243076.
  5. ↑ Hanson, JA; Deliganis, AV; Baxter, AB; Cohen, WA; Linnau, KF; Wilson, AJ; Mann, FA (May 2002). "Radiologic and clinical spectrum of occipital condyle fractures: retrospective review of 107 consecutive fractures in 95 patients". AJR. American Journal of Roentgenology. 178 (5): 1261–68. doi:10.2214/ajr.178.5.1781261. PMID   11959743.
  6. ↑ Chang W, Alexander MT, Mirvis SE (January 2009). "Diagnostic determinants of craniocervical distraction injury in adults". AJR. American Journal of Roentgenology. 192 (1): 52–8. doi:10.2214/ajr.07.3993. PMID   19098179.
  7. ↑ Theodore, N; Aarabi, B; Dhall, SS; Gelb, DE; Hurlbert, RJ; Rozzelle, CJ; Ryken, TC; Walters, BC; Hadley, MN (March 2013). "The diagnosis and management of traumatic atlanto-occipital dislocation injuries". Neurosurgery. 72 Suppl 2: 114–26. doi:10.1227/NEU.0b013e31827765e0. PMID   23417184.
  8. ↑ Gutiérrez-González, R; Boto, GR; Pérez-Zamarrón, A; Rivero-Garvía, M (September 2008). "Retropharyngeal pseudomeningocele formation as a traumatic atlanto-occipital dislocation complication: case report and review". European Spine Journal. 17 Suppl 2 (Suppl 2): S253–56. doi:10.1007/s00586-007-0531-7. PMC   2525892 . PMID   17973127.
  9. ↑ Cooper, Z; Gross, JA; Lacey, JM; Traven, N; Mirza, SK; Arbabi, S (1 May 2010). "Identifying survivors with traumatic craniocervical dissociation: a retrospective study". The Journal of Surgical Research. 160 (1): 3–8. doi:10.1016/j.jss.2009.04.004. PMID   19765722.
  10. ↑ Brinkman, William; Cohen, Wendy; Manning, Thomas (2003). "Posterior Fossa Subarachnoid Hemorrhage Due to an Atlantooccipital Dislocation". American Journal of Roentgenology. 180 (5): 1476. doi:10.2214/ajr.180.5.1801476. PMID   12704071 . Retrieved 2018-05-14.
  11. ↑ "Traumatic Atlantooccipital Dislocation with Survival" (PDF). www.ajnr.org. Retrieved 2018-05-14.
  12. ↑ Park JB, Ha KY, Chang H. Traumatic posterior atlantooccipital dislocation with Jefferson fracture and fracture-dislocation of C6-C7: a case report with survival. Eur Spine J. 2001 Dec;10(6):524-8. doi: 10.1007/s005860100334. PMID 11806394; PMCID: PMC3611534.
  13. ↑ Chaput, CD; Torres, E; Davis, M; Song, J; Rahm, M (August 2011). "Survival of atlanto-occipital dissociation correlates with atlanto-occipital distraction, injury severity score, and neurologic status". The Journal of Trauma. 71 (2): 393–95. doi:10.1097/ta.0b013e3181eb6a31. PMID   21206289.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.