Cervical Spine Flashcards
What CN deficits can be seen with a C1-C5 lesion?
Positional strabysmus and/or facial hyperaesthesia with C1-C3
v. rare!
Damage to what nerve roots can cause Horners syndrome?
T1-T3
What does paresis or paralysis indicated?
- A disease process affecting the descending UMN tracts
- Or a diffuse neuromuscular disease
Why do dogs with cervical lesions often present with more pronounced motor dysfunction in the pelvic limbs?
The descending UMN tracts to the pelvic limbs are more peripherally located within the spinal cord
What percentage of tetraparetic dogs are incorrectly localaised based on the FL withdrawal?
34%
How quickly does neurogenic atrophy become clinically obvious? Disuse atrophy?
- Neurogenic wtihin 7 days
- Disuse will take several weeks
What is a transverse myelopathy?
No transmission of ascending or descending impulses across the site of the lesion
What is Horners Syndrome?
What spinal cord segment can cause this?
What is the path of the sympathetic nerves?
- Horners syndrome is loos of sympathetic innervation to the eye causing miosis, ptosis, enophthalmos and elevation of the third eyelid
- T1-T3
- Hypothalamus -> descends sp. cord in lateral tectotegmental tracts
What are the advantages of the modified ventral approach to the cervical spine?
- Helps to protect the trachea, right recurrent laryngeal nerve and right carotid sheath
- Provided increased exposure of the caudal cervical vertebrae
- Decreases risk of haemorrhage from right caudal thyroid artery
What are the benefits of the right parasagittal approach for the ventral approach to the AA joint?
- Improved exposure of the joint
- Avoids dissection around the thyroid gland, trachea and recurrent laryngeal nerve
What surgical landmark can be used for ventral C1-C2
Pointed ventral prominence (ventral tubercle) on the caudal aspect of C1. This indicates the ventral midline of C1-C2 joint space
What is a lateral approach to the cervical spine good for?
Lateral or foraminal IVD herniation and nerve sheath neoplasms
What muscles required dissection for the lateral approach to C1-C4?
How does this differ for C5-C7?
- Platysma
- Blunt seperation through brachiocephalicus
- Splenius
- Serratus vantralis
- Plane of dissection between longissimus capitus and complexus muscles to expose articular facet
- Dorsal branch of the spinal nerve needs to be sacrificed, the tendinous attachments of the complexus and multifidus are then detached from the articular process
- Longissimus capitus sharply dissected from transverse process and reflected ventrally to fully expose the joints
C5-C7 requires seperation of brachiocephalicus from trapezium (not dissection through). The superficial cervical artery and vein will be located between these muscles and is ligated
What retractor can be used to retract the scapula on approach to the brachial plexus?
Farabeuf retractor
What muscle do the spinal nerves of the brachial plexus lie deep to?
Scalenus muscle
What joint is considered the yes joint?
And the no joint?
- Yes joint - occipitoatlas joint
- No joint - atlantoaxial joint
How many pairs of foramina does the atlas have?
Two
- Transverse foramen - passes obliquely through transverse process
- Lateral vertebral foramen - perforates the craniodorsal part of the vertebral dorsal arch. First cervical spinal nerve and its associated vasculature run through here
What are the atlantal fossae?
Depressions ventral to the wings on each side where the vertebral vein and artery run
How many bony elements for the atlas and axis develop from?
How long does it take for fusion?
- Atlas - 3 boney elements
- Axis - 7 boney elements (pair of arches, 3 parts of the body, the dens, apical elements of the dens)
- Fusion of dorsal atlas by 106d, ventral suture by 115d
- Fusion of all parts of axis from 30 - 396d
What is another name for the dens?
Odontoid process
List the stabilising ligaments of the AA joint
- Transverse ligament - holds the dens within the ventral aspect of the vertebral foramen. Prevents dorsal movement which allowing rotation
- Apical ligament - attachs dens to basioccipital bone
- Bilateral alar ligaments - Attach dens to the occipital condyles
- Dorsal atlantoaxial ligament - Joins dorsal arch of atlas to craniodorsal spine of axis
Alar ligaments provide the most important stabilisation against VD shearing forces
List possible congenital or developmental abnormalities of the AA joint
- Dysplasia (34%)
- Hypoplasia or aplasia (46%)
- Dorsal angulation of the dens
- Seperation of the dens
- Absense of the transverse ligament
- Incomplete ossification of the atlas
- Block vertebrae
What percentage of dogs with AA sublux will have a normal dens?
24%
What breeds are predisposed to congenital abnormalities predisposing to AA instability?
- Yorkies
- Chihuahuas
- Min Poodles
- Poms
- Pekingese
Standard Poodles! - inherited ansense/hypoplasia of the dens
What is predictive of AA instability on a plain lateral radiograph?
An angle between the atlas and axis of less than 162 degrees
What is a contraindication for dorsal stabilisation of AA sublux?
What are the advantages of ventral stabilisation?
Dorsal deviation of the dens
Ventral advantages:
- odontoidectomy can be performed if required
- Provides a means for bony ankylosis for permanent joint fusion (approach of choice for AA fractures)