Spine Flashcards
What are 4 types of vertebrae seen in the pediatric c-spine?
- Oval- immature
- Reounded upper corner
- Anterior wedging
- Rectangular - mature
How many pairs of cervical nerve roots are there?
Thoracic? Lumbar? Sacral? Coccygeal?
Total?
- Cervical - 8
- Thoracic - 12
- Lumbar- 5
- Sacral -5
- Coccygeal - 1
- Total- 31
At what level does the Cauda Equina start?
L1
What is the function of the rubrospinal tract? Crossed or uncrossed?
- Involuntary control, flexors and extensors (posture)
- Works with corticospinal tract
- Crossed
What is the function of the Ventral Spinocerebellar Tract? Crossed or uncrossed?
- Unconscious muscle sense
- Crossed
Describe Central Cord Syndrome
- Most common incomplete spinal cord lesion
- Upper extremity weaker than lower extremity (hands have more pronounced deficits than arms)
- Upper extremity has LMN signs
- Lower extremity has UMN signs
- Sacral sparring
- Prognosis good
Describe Brown Sequard Syndrome
- Complete cord hemitransection
- Ipsilateral Defects
- LCS - motor function, spastic paralysis
- Dorsal Column - proprioception & vibration
- Contralateral Defects
- LST - pain & temp
- Spinothalamic tract crosses 2 levels below
- LST - pain & temp
- Best prognosis, 99% ambulate
What is the function of the lateral corticospinal tract. Crossed or uncrossed?
- Voluntary control of skeletal muscles
- Crossed
What is the function of the ventral corticospinal tract? Crossed or uncrossed?
- Voluntary control skeletal muscles
- Uncrossed (Crosses at level of termination)
What is the function of the Dorsal Column? Crossed or uncrossed?
- Fasiculus gracile and cuneate
- Proprioception & vibration sense
- Crossed
What is the function of the Dorsal Spinocerebellar Tract? Crossed or uncrossed?
- Muscle Sense
- Uncrossed
What is the function of the Lateral Spinothalamic Tract? Crossed or uncrossed?
- Pain & Temperature. Light Touch
- Crossed
Describe Anterior Cord Syndrome.
- Motor and sensory deficit below level of SCI
- Lower extremity > upper extremity
- Loss of LCT - motor, LST - pain & temp
- Preserved dorsal column - proprioception and vibration
- Worst prognosis
Where does the spinothalamic tract cross?
Two levels below site.
ASIA Spinal Cord Injury Scale
- A - Complete motor and sensory
- B- Sensory preserved, no motor
- C- >50% muscles, <3/5 below level
- D - >50% muscles, >3/5 below level
- E- Full motor and sensory
B-D are incomplete. Sacral sparring.
What is the bulbocavernosus reflex, how do you preform it, and what does it represent?
- Yank on a foley in both men and women and look for an anal wink (present)
- If bulbocavernosus reflex is absent, patient is in spinal shock
- Cannot declare ASIA level when patient is in spinal shock
What is the mechnaism of autonomic dysreflexia?
- Spinal Cord Injury - T6 or above
- Hypertension bleow the level of injury dues to nerves detecting painful stimumi
- Reaches T5-T6 where splanchnic sympathetic chain perpetuates sympathetic response
- Baroreceptors in Aortic Arch and Carotid sinus sense these changes, stimultes PNS
-
VAGUS NERVE - stimulates bradycardia and vasodilation above the level of injury
- This does not signal down the cord due to the spinal cord injury
-
Result: bradycardia and hypotension above the lesion, and perpetual hypertension below the lesion
- Only way to stop is to remove the painful stimuli
Where do you find the exiting nerve root at:
The level of the Pedicle?
Level of the Body?
Level of the Disc?
Where do you find the exiting nerve root at:
The level of the Pedicle? - Central
Level of the Body? - Lateral Recess
Level of the Disc? - Foramen
Causes of Spinal Stenosis
- Facet Hypertrophy
- Thickened Ligamentum Flavum
- Herniated Discs
- Osteophytes
- Spondylolisthesis
What are the levels of the “3 Storey House”?
- Top Floor: Pedicles (TP, bottom, part of facet)
- Middle Floor: Foramen (top part facet). Supeiror facet can migrate up and impinge foramen
- Ground Floor: Disc (bulk of facet)
- Majority of the stenosis happens here
Where is the descending nerve root at the Pedicle?
Body?
Disc?
Pedicle - Central
Body - Central
Disc - Central
What is normal thoracic kyphosis?
10-40 degrees
What is normal Lumbar Lordosis?
Thoracic Kyphosis + 30 degrees
What is normal Cervical Lordosis?
20-40 degrees
What is the Spinal Vertical Axis (SVA), and what does it help determine?
- Plum line from centre of C7
- Determines sagitall balance
- Normal crosses superior corner of S1 body +/- 2.5cm
- Behind = increased lordosis
- Infront = hip flexion contracture
What is Pelvic Tilt and it’s normal value?
- Angle between:
- Vertical line through centreof femoral head
- Line from centre of fremoal head to centre of S1 endplate
- Normal = 13 +/- 12 degrees
When doing sagital deformity correction of the lumbar spine, what degree of correction do you aim for?
Aim to correct lumbar lordosis within 10 degrees of pelvic incidence
What is the placement zone for 8mm occipital screws?
+/- 2cm at the nuchal line
+/- 1cm, 1cm below the nuchal line
+/- 0.5cm, 2cm below the nuchal line
What screw length do you use for occipital screws?
8mm
What are the contraindications to transarticular C1 C2 screws?
- Medial, “high-riding” vertebral artery (20% of patients)
- Subluxation C1 on C2
- Cervothoracic kyphosis
What percentage of people have a high-riding vertebral artery?
20%
What is pelvic incidence?
- Angle between:
- Line perpendicular to S1 endplate
- Line from centre of S1 endplate to centre of femoral head
- Fixed in each individulal
- Pelvic Incidence = Pelvic Tilt + Sacral Slope
- Normal 54 +/-20
What is sacral slope? Normal values?
- Angle between:
- Horizontal line
- Line along superior endplate of S1
- Normal 41 +/- 16 degrees
Describe different vertebral osteotomies for correction of sagital alignment. (2)
- Ponte Osteotomy (aka Smith Peterson)
- Remove inferior articular process of superior vertebrae and superior articular facet of inferior vertebrae
- Resect ligamentum flavum
- 10 degree correction per osteotomy level
- Pedicle Subracting Osteotomy
- Posteiror resection of facet, portions of the laminae and pedicles
- Correction:
- 35 degrees per level lumbar spine
- 25 degrees per level thoracic spine
What are fixation options for C1? (3)
- Transarticular
- Lateral Mass Screws
- Clamping/Wiring
What are fixation options for C2? (5)
- Transarticular
- Clamping/Wiring
- Pars Screws
- Pedicle Screws
- Laminar Screws
Which cervical vertebrae have a vertebral foramen? Though which does the vertebral artery run?
All of them have foramen.
Vertebral artery runs through C1-C6
What is the contraindication to C1C2 fixation with wiring?
Cannot wire if you don’t have intact posterior elements (trauma, tumour, decompression)
What is immediately behind fixation zones for occipital screws?
Dural venous sinuses
What is the difference between Neurogenic Shock and Spinal Shock?
- Neurogenic Shock - cardiovascular shock resulting in bradycardia and hypotension
- Spinal Shock is shock to the spinal cord itself secondary to trauma. Results in decrease motor/sensation and lack of bulbocavernosus reflex.
What is the orientation of the cervical facets?
45 degrees in sagittal, 0 degrees in axial
What is the orientation of the thoracic facets?
60 degree sagittal, 20 degrees frontal
What is the orientation of the lumbar facets?
90 degrees sagittal, 45 degrees on axial
What is the start point for lumbar pedicle screws?
- Vertically along superior facet
- Hortizontally inersect the TP
What structure is at risk with C1-C2 lateral mass screws?
Internal Carotid A.
What are 2 techniques for insertion of lateral mass screws?
- Roy-Camille Technique
- Entry point in middle of lateral mass
- Aim 10 degrees lateral, and 0 degree in vertical plane
- Magerl Technique
- Entrypoint slightly medial and superior to middle of lateral mass
- 25 degrees in lateral, 45 degrees in vertical plane
Where is the occiput thickest?
5cm lateral to the occipital protuberence
Which thoracic verterbrae has the smallest pedicle? Lumbar?
- Thoracic - T4
- Lumbar - L1
What is the start point for thoracic pedicle screws?
- Verticle - middle of facet
- Horizontal - superior ridge of TP or inferior base of facet joint