Spinal Trauma Flashcards
Pre-dental space
Transverse ligament rupture without an associated fracture can occur in older patients from a direct blow to the occiput. Radiographic diagnosis relies on measuring the predental space, which is the space between the posterior aspect of the anterior arch of C1 and the anterior border of the odontoid. A predental space of >3 mm on a lateral radiograph (2 mm for CT images) implies damage to the transverse ligament; >5 mm implies rupture of the transverse ligament.
Flexion teardrop fracture
(highly unstable) Extreme hyperflexion causes complete disruption of the spinal ligaments at the level of injury. The “teardrop” is the anteroinferior portion of the vertebral body that is separated and displaced from the vertebral body by the anterior spinal ligament. “Fanning” of the spinous processes may be present, with or without fracture. A sagittal fracture through the vertebral body may be seen on CT. Anterior spinal cord syndrome is associated with this injury
Unilateral facet dislocation
(stable unless associated with an articular mass fracture)
mechasim: Flexion-rotation
A unilateral facet dislocation occurs when the articular mass and inferior facet on one side of the vertebra are anteriorly dislocated. On a lateral radiograph, the involved vertebral body will be displaced <50% of its width. On the anterior view, the spinous process at the level of the rotation will be pointing toward the side that is dislocated.
Jefferson burst fracture of atlas
(potentially unstable)
Mechanism: vertical compression
[Reproduced with permission from Block J, Jordanov MI, Stack LB, Thurman RJ (eds): The Atlas of Emergency Radiology. McGraw-Hill, Inc., 2013. Fig 11-13.]
Vertical compression forces the occipital condyles downward and produces a burst fracture by driving the lateral masses of C1 apart. This is best seen as outward displacement of the lateral masses on the open-mouth odontoid radiograph or on CT. If displacement of both lateral masses (measured as offset from the superior corner of the C2 vertebral body on each side) is >7 mm when added together, rupture of the transverse ligament is likely, and the spine is unstable.
Traumatic spondylolisthesis (hangman’s fracture)
(unstable)
The hangman’s fracture is a fracture of both pedicles of C2, with the anterior displacement of C2 on C3. This was associated with the neck hyperextension from judicial hangings, where the noose knot is placed under the subject’s chin and snaps the head backward. Suicidal hangings do not usually cause extreme hyperextension and are not associated with the hangman’s fracture. Because the spinal canal at the level of C2 is large, a hangman’s fracture does not cause neurologic injury.
Odontoid (dens) fractures
(type II and III are unstable)
Frequently involves other injuries to the cervical spine and multisystem trauma. Conscious patients will usually describe immediate and severe high cervical pain with muscle spasm. The pain may radiate to the occiput. Neurologic injury is present in 18% to 25% of cases with odontoid fractures, ranging from minimal sensory or motor loss to quadriplegia. Odontoid fractures are classified according to the level of injury. CT can miss odontoid fractures if the fracture line is aligned with the cut of the CT (en face).
Primary vs Secondary Spinal Cord Injury
Damage to the spinal cord is the result of two types of injury. First is the primary injury from mechanical forces from traumatic impact. This insult sets into motion a series of vascular and chemical processes that lead to secondary injury
Complete vs Incomplete Injury and Spinal Shock
The severity of spinal cord injury determines the prognosis for recovery of function, so it is important to distinguish between complete and incomplete spinal cord injuries.
The American Spinal Injury Association defines a complete neurologic lesion as the absence of sensory and motor function below the level of injury. This includes loss of function to the level of the lowest sacral segment. In contrast, a lesion is incomplete if sensory, motor, or both functions are partially present below the neurologic level of injury. This may consist only of sacral sensation at the anal mucocutaneous junction or voluntary contraction of the external anal sphincter upon digital examination.
Complete lesions have a minimal chance of functional motor recovery. Patients with incomplete lesions are expected to have at least some degree of recovery. The differentiation between complete and incomplete spinal cord damage may be complicated by the presence of spinal shock.
Patients in spinal shock lose all reflex activities below the area of injury, and lesions cannot be deemed truly complete until spinal shock has resolved.
Spinal Cord Anatomy - tracts
corticospinal tracts
spinothalamic tracts
dorsal (posterior) columns
Corticospinal Tract
The corticospinal tract is a descending motor pathway
In the lower medulla, approximately 90% of the fibers cross to the side opposite that of their origin and descend through the spinal cord as the lateral corticospinal tract.
Damage to the corticospinal tract neurons (upper motor neurons) in the spinal cord results in ipsilateral clinical findings such as muscle weakness, spasticity, increased deep tendon reflexes, and a Babinski’s sign.
Spinothalamic Tract
The two major ascending pathways that transmit sensory information are the spinothalamic tracts and the dorsal columns.
The spinothalamic tract transmits pain and temperature sensation.
When the spinothalamic tract is damaged, the patient experiences loss of pain and temperature sensation in the contralateral half of the body.
The (pain and temperature) sensory loss begins one or two segments below the level of the damage.
Dorsal Columns
The dorsal columns transmit vibration and proprioceptive information.
Injury to one side of the dorsal columns will result in ipsilateral loss of vibration and position sense.
The sensory loss begins at the level of the lesion. Light touch is transmitted through both the spinothalamic tracts and the dorsal columns.
Therefore, light touch is not completely lost unless there is damage to both the spinothalamic tracts and the dorsal columns.
Naming of spinal nerve roots
Each spinal nerve is named for its adjacent vertebral body.
In the cervical region, there is an additional pair of spinal nerve roots.
The first seven spinal nerves are named for the first seven cervical vertebrae, each exiting through the intervertebral foramen above its corresponding vertebral body.
The spinal nerve exiting below C7, however, is referred to as the C8 spinal nerve, although no eighth cervical vertebra exists.
All subsequent nerve roots, beginning with T1, exit below the vertebral body for which they are named.
Cauda Equina anatomy
During fetal development, the downward growth of the vertebral column is greater than that of the spinal cord.
Because the adult spinal cord ends as the conus medullaris at the level of the lower border of the first lumbar vertebra, the lumbar and sacral nerve roots must continue inferiorly below the termination of the spinal cord to exit from their respective intervertebral foramina.
These nerve roots form the cauda equina.
A potential consequence of this arrangement is that injury to a single lower vertebra can involve multiple nerve roots in the cauda equina. For example, an injury at the L3 vertebra can involve the L3 nerve root as well as the lower nerve roots that are progressing to a level caudal to the L3 vertebra.
Spinal Injury and airway / breathing concerns
The higher the level of spinal injury, the more likely is the need for early airway intervention.Unstable spine lesions above C3 can cause immediate respiratory arrest.
Lesions affecting C3-C5 can affect the phrenic nerve and diaphragm function.
Delayed respiratory compromise can occur if spinal cord edema from more caudal lesions progresses rostrally to cause phrenic nerve paralysis.
Many patients can initially support ventilatory function using intercostal muscles or abdominal breathing, but they eventually tire and subsequently develop respiratory failure.
Spinal Injury Level assessment
Determine the level of sensory loss), and investigate proprioception or vibratory function to examine posterior column function.
Test for “saddle anesthesia,” which is sensory deficit in the region of the buttocks, perineum, and inner aspect of the thighs
Test for “saddle anesthesia,” which is sensory deficit in the region of the buttocks, perineum, and inner aspect of the thighs.
Test deep tendon reflexes along with anogenital reflexes because “sacral sparing” with preservation of anogenital reflexes denotes an incomplete spinal cord level, even if the patient has complete sensory and motor loss.
To test the bulbocavernosus reflex, squeeze the penis to determine whether the anal sphincter simultaneously contracts. Assess rectal tone at the same time.
Test the cremasteric reflex by stroking the medial thigh with a blunt instrument. If the scrotum rises, some spinal cord integrity exists.
Document rectal tone and sensation around the anus. An “anal wink reflex” (contraction of the anal musculature when the perianal region is stimulated with a pin) indicates some sacral sparing.
Conversely, priapism implies a complete spinal cord injur
Central cord syndrome
•common in the elderly following hyper-extension injury
-causes buckling and central haematoma of the cord
•incomplete paralysis
- weakness greater distally than proximally
- weakness greater in arms than legs
- proximal decrease in sensation
- variable reflexes
- sensation
- reduced pain and temperature sensation in arms, often with hyperaesthesia
- normal vibration sense and proprioception in limbs
•usually good outcome
-50% with severe initial involvement will ambulate, have bowel / bladder control and some hand movement
Anterior cord syndrome
Damage to the corticospinal and spinothalamic pathways, with preservation of posterior column function.
Loss of motor function and pain and temperature sensation distal to the lesion.
Vibration, position, and tacticle sensation are preserved.
May occur following direct injury to the anterior spinal cord. Flexion of the cervical spine may result in cord contusion or bone injury with secondary cord injury.
Alternatively, thrombosis of the anterior spinal artery can cause ischemic injury to the anterior cord.
Anterior cord injury can also be produced by an extrinsic mass that is amenable to surgical decompression.
The overall prognosis for recovery of function is poor.
Brown - Sequard lesion
The Brown-Séquard syndrome results from hemisection of the cord.
It is manifested by ipsilateral loss of motor function, proprioception, and vibratory sensation, and contralateral loss of pain and temperature sensation.
The most common cause of this syndrome is penetrating injury. It can also be caused by lateral cord compression secondary to disk protrusion, hematomas, spine fractures, infections, infarctions, or tumors.
