Spine Flashcards
Is the inferior articular process of the facet joint anterior or posterior in the cervical spine?
Posterior
What is the orientation of the zygopophyseal joints of the cervical, thoracic and lumbar spine?
see image
What does a high riding vertebral artery refer to?
An abnormal course in C2
From what levels do the vertebral artery normally run?
C1-C6
In what percent of the population does the vertebral artery run in C7?
7.5% Normally runs from C1-C6
What is spinal shock?
All phenomena surrounding transaction of the spinal cord that results in temporary loss of all or most spinal reflex activity below the level of injury. Characterized by loss of bulbocavernosus reflex
What is neurogenic shock?
Hypotension and bradycardia following SCI
Which vertebrae have bifid spinous processes?
C2-C6
In what percent of people does the vertebral artery run in C7?
7.5% Remember - mostly it’s C1-C6
Describe the safe zone for 8mm occipital screws. What are the dangers?
+/-2cm at Nuchal line +/-1cm, 1cm below the nuchal line +/-0.5cm, 2cm below the nuchal line The dangers are: Dural venous sinuses that are immediately behind these regions
Describe the insertion point for thoracic pedicle screws:
Intersection point of 2 lines: A: Vertically along: Midpoint of facet joint and/or insertion of TP into the lamina (the Valley) B: Horizontally along: Superior ridge of TP and/or inferior base of facet joint
Describe the insertion point for lumbar pedicle screws
Intersection of 2 lines: A: Vertically along the superior facet B: Horizontally along the mid-point of the TP
What level has the smallest pedicle? The largest?
Smallest overall: T4 Smallest in L-spine: L1 Largest in T-spine: T1
Define the motor level
Most caudal level with 3/5 power with 5/5 power above
What is the grading system in the ASIA scale?
E: “Excellent.” No neurological compromise D: Incomplete: >50% muscles below level >/= 3/5 C: Incomplete: /= 3/5 B: Incomplete: only sensory preserved. Motor dysfunction includes sacral segments S4-5 A: “Awful”. Complete. No motor or sensory function is preserved, including sacral segments S4,5
Define the sensory level
Most caudal level with normal pinprick and light touch
What is the most common incomplete cord injury?
Central cord
With respect to central cord syndrome, what is the presentation, pathophysiology and prognosis?
Presentation: Motor deficit UE>LE, hands>arms Pathophysiology: Corticospinal tract, with part controlling hands centrally, are more affected Prognosis: Good. Full function rare but omst ambulatory
With respect to anterior cord syndrome, what is the presentation, pathophysiology and prognosis?
Presentation: Motor dysfunction LE>UE & dissociated sensory deficit below SCI with STT lost and dorsal columsn preserved
With respect to Brown-Sequard syndrome, what is the presentation, pathophysiology, prognosis?
Presentation: ipsilateral loss of motor function, proprioception and vibration with contralateral loss of pain and temperature Pathophysiology: Ipsilateral: Motor: LCST, Sensory: DC Contralateral: Sensory: LSTT Prognosis: Excellent 99% ambulatory
What is posterior cord syndrome?
Loss of proprioception only. Very rare
What tract is the main descending motor pathway in the cervical spinal cord?
Lateral corticospinal tract
The occiput is the thickest in what location?
5cm lateral to the external occipital protuberance
In the setting of bilateral C5-6 facet dislocation, which of the following structures is usually preserved? A: Facet joint capsules 2: Ligamentum flavum 3: Poseterior annulus 4: Anterior longitudinal ligament 5: Interspinous ligament
4: Anterior longitudinal ligament
Which of the following pedicles has the smallest transverse diameter in most people? A: T1 B: T12 C: L1 D: L3 E: S1
3: L1 Remember, T4 is the smallest overall, with L1 being the second smallest, but T4 is not listed in this question
Which area of the spinal cord has the worst collateral blood supply? The best?
Worst: T4-T9 Best: Cervical and lumbar - they have redundant supply
Describe the main blood supply to the spine? What is the name of the collateral blood supply?
Main: 1x median longitudinal anterior spinal artery 2x (right & left) longitudinal posterior spinal arteries These are supplied by various radicular arteries Collateral: Vaso Corona: anastomosis between the longitudinal vessels forming a fine pial plexus Gives limited blood supply
What artery provides the largest blood supply to the lumbar area? Where does it arise?
Artery of Adamkeiwicz. Arises most commonly from left T8-10
What is the Artery of Adamkeiwicz?
Major radicular artery supplying the longitudinal arteries in the T/L spine Usually arises from left T8-10 Can arise on right or left, anywhere from T7-L4 Usually Left T10
What are the signs of sacral dysmorphism? Why is it important and what should you do instead?
Signs: Sacralization of L5 Lumbarization of S1 Presence of mammillary processes Oval or oblong foramen Tongue in Groove sign of SI joint Important to recognize to avoid iatrogenic injury to L5 during SI screw insertion. If dysmorphic, plan for S2 screw instead (of S1)
What is the highest motor level that the patient can have and initially still be ventilator independent? Why?
C5 C3,4,5 make up the phrenic nerve, which supplies the motor function of the diaphragm (C3,4,5 keep the diaphragm alive) People with C3-C4 levels can progress to be ventilator independent
What are Harris’ measurements of the spine? What do they measure?
They measure atlanto-occipital dissociation There are 2 measurements: Basion to the tip of the dens (BDI) & Basion to the posterior axial line Neither one should be >12mm (Rule of 12’s)
What is the rule of 12’s in the spine?
Harris’s Rule of 12’s: Measures occipito-atlantal dissociation. On the Harris measurements, neither the BDI or BAI should be >12mm. If it is, it’s a sign of occipito-atlantal dissociation
What is a Jefferson’s fracture? mechanism?
Fracture of the lateral mass of C1 - essentially a “burst fracture” of c1 from axial loading - usually diving into a pool or similar mechanism
In a Jefferson’s fracture, how much lateral overhang on open mouth x-ray indicates disruption of the transverse ligament?
A total overhand (both sides added up) of >8mm indicates disruption of the transverse ligament (>6.9mm on CT, though there is some controversy)
What are the risk factors for non-union of odontoid fractures?
Displacement >6mm Angulation >10
What is a Hangman’s fracture? mechanism?
bilateral c2 pars fracture. hyperextension and distraction. traumatic spondylolisthesis of c2 on c3
What are the contents of the carotid sheath?
Common carotid artery +/- internal carotid artery Internal jugular vein Vagus nerve Deep cervical lymph nodes Artery is medial to vein, with nerve in between
Name the surface landmarks for the following spinal levels: C2-3 C3 C4-5 C6 C7 T4 T7 T8 L2 L4 L4-5 S1
C2-3: Mandible C3: Hyoid C4-5: Thyroid cartilage C6: Cricoid cartilage C7: Cervical vertebral prominence T4: Nipples T7: Distal scapular angle T8: Belly button L2: Renal arteries L4: Bifurcation of aorta L4-5: Iliac crest S1: Iliac bifurcation
What are the ligamentous attachments to the dens?
Transverse atlantal ligaments Alar ligaments x2 Apical odontoid ligament
Anterior atlantoaxial ligament
What is the rule of 12’s in the spine?
Measurements of occipito-atlantal dissociation - Neither one of the Harris measurements (BDI, BAI) should be greater than 12mm
What is Swischuk’s Line?
Connects the anterior aspect of the spinous processes of C1 and C3.
If the anterior aspect of the spinous process of C2 misses this line by ⩾2 mm true subluxation of hangman’s fracture must be considered.
This line is only applicable to those demonstrating subluxation.
The distance is frequently 2 mm or more if no subluxation is apparent.
Figure: (A) No subluxation. Therefore, PCL cannot be applied. Anterior aspect of spinous process of C2 commonly misses PCL by 2 mm. (B) Subluxation is present. The anterior aspect of spinous process of C2 misses the PCL >2 mm. Finding is suggestive of a hangman’s fracture of the neural arches of C2. (C) Pseudosubluxation is present. The anterior aspect of spinous process of C2 touches or lies within 2 mm of PCL. (Adapted from figure from Fesmire FM and Luten RC.16)
Describe the cervicomedullary angle and its significance:
The cervicomedullary angle can be measured on MRI by drawing a line along the anterior aspect of the cervical spinal cord and the medulla.
This angle is normally between 135° and 175°
With progressive craniocervical disease, the brainstem angulates ventrally over the displaced odontoid process, leading to increased obliquity of the cervicomedullary angle.
Figures 8a and 8b show the radiograph and MRI scan of a 31-year-old man with severe back pain and intermittent leg pain. Which of the following anatomic measurements has been best correlated with this patient’s condition?
- Pelvic tilt
- Pelvic Incidence
- Lumbar Lordosis
- Thoracic Kyphosis
- C7 Sagittal plumb line
2.Pelvic Incidence
Figure 255 shows the axial CT scan of a 33-year-old man with severe neck pain after a motor vehicle collision. Which structure is most important in guiding treatment?
- VA
- Alar Lig
- Apical Lig
- Transverse Lig
- Post Lig Complex
- Transverse ligament
What osseous structure is seen by the * in Figure 237?
1- Inferior articular facet of C4
2- Inferior articular facet of C5
3- Superior articular facet of C5
4- Pedicle of C5
5- Pars interarticularis of C5
- Inferior articular process of C4
Figures 89a and 89b are the parasagittal and axial CT scans of a 42-year-old patient seen after a motor vehicle collison. What anatomic structure is identified by the asterisk in Figure 89b?
- C6 facet
- C7 facet
- C6 pars
- C6 pedicle
- C7 pedicle
- C6 Facet
What is the nerve injury shown?
CN VI
No lateral gaze
What is autonomic dysreflexia?
In a high-level spinal cord injury, intact lower motor neurons sense the painful stimuli below the level of injury and transmit the message up the spinal cord (see diagram). At the level of the spinal cord injury, the pain signal is interrupted and prevented from being transmitted to the cerebral cortex. The site of the spinal cord injury also interrupts the two branches of the autonomic nervous system and disconnects the feedback loop, causing the two branches to function independently. The ascending information reaches the major splanchnic sympathetic outflow (T5-T6) and stimulates a sympathetic response. The sympathetic response causes vasoconstriction, resulting in: hypertension pounding headache visual changes anxiety pallor goose bumps below the level of injury This hypertension stimulates the baroreceptors in the carotid sinuses and aortic arch. The PSNS is unable to counteract these effects through the injured spinal cord, however. Instead, the PSNS attempts to maintain homeostasis by slowing down the heart rate. The brainstem stimulates the heart, through the vagus nerve, causing bradycardia and vasodilation above the level of injury. The PSNS impulses are unable to descend past the lesion, and therefore no changes occur below the level of injury.
