31. Cervical Spine Flashcards
why are more severe neurologic signs seen in the pelvic limbs vs the cervical limbs in patients with cervical spinal cord dz?
motor pathways to pelvic limbs are more peripherally locations than those responsible for thoracic limb motor function
thoracic limb gait with C1-C5 lesion vs C6-T2 lesions
THORACIC limbC1-C5 long strides, increased limb stride lengthC6-T2 short stilted choppy (often accompanied by long strides pelvic limbs–two engine gait)
percentage of single level cervical disc lesions incorrectly localized based on reflex examination
34% of dogs with single level cervical disc lesion were incorrectly localized based on spinal reflex examex. dogs with C1-C5 lesion may have decreased withdrawal and incorrectly localize dz
how long does it take for neurogenic or den nervation atrophy to be seen in front limbs
7 dayswhereas disuse atrophy may take up to several weeks
Horners may be seen with C1-C5 lesions or C6-T2 lesions?
C6-T2 lesions esp if affecting T1-T3 nerve roots and loss of SNS in this area
phrenic nerve spinal cord segments
C5-6-7
structures involved in cervical pain
meningesannulus fibrosisperiosteumjoint capsule of zygapophyseal jointepaxial musculatureligamentous structures
nerve “root signature” signs may accompany what cervical lesion localization
C6-T2
surgical approaches to the cervical spine
- ventral–routine ventral, modified ventral with paramedian dissection btwn R sternocephalicus and sternohyoideus m2. lateral–bunt dissection through brachiocephalicus m (superficial cervical artery/vein); , splenius is medial (deep)3. dorsal
approach to the brachial plexus
- lateral platysma, cleidocervicalis, omotransversarius (inserts on spine of scapula–is transected), trapeziussuperficial cervical artery/vein
benefit of modified ventral approach to cervical spine
paramedian dissection btwn R sternocephalicus and sternohyoideus musclesprotects trachea, right recurrent laryngeal n, vagosympathetic n, right carotid sheathprovides increase exposure to caudal cervical vertebradecreases likelihood of hemorrhage from right caudal thyroid artery
paired muscle group on floor of cervical vertebra
paired longus colli muscle
anatomy of AA joint
atlas (C1) lacks a spinous process; wing like transverse processes—develops from 3 boney elementsaxis (C2) large spinous process–develops from 7 boney elements; dens (odontoid process) held down by transverse ligament”no joint”
ligamentous attachments of C1-2 (7)
dens is held down by TRANSVERSE ligamentdens attaches to foramen magnum via APICAL ligamentdens attaches to occipital condyles via ALAR ligamentsC1-C2 dorsal AA ligamentC1-C2 AA joint capsuleC1-C2 AA lateral ligamentsC1 to occipital bone AO joint capsule
developmental malformations of the dens
young small breed dogshypoplasia/aplasia 46%dysplasia 34%dorsal angulationseparation of densabsent transverse ligament
T/F24% of dogs with AA instability will have a normal dens
TRUE24% of dogs with AA instability will have a normal dens
1 clinical sign of AA instability
1 NECK PAIN (30-60%)(aymmetric, mild postural rxn abN, rarely tetraplegic, worse pelvic than thoracic limbs, torticollis due to concurrent syringohydromyelia)
radiographic signs of AA instability
increased space btwn dorsal lamina of atlas and spinous process C2malalignment of C1 and C2 vertebral bodies (sublux/lux)angle btwn C and C2 of < 162 degrees is more predictive of instability presence/size of dens (VD film or oblique)
complications with splinting/conservative tx of AA instability
- recurrence2. corneal ulcers3. splint movement4. moist dermatitis/ulceration5. hyperthermia6. respiratory compromise7. anorexia8. otitis
SURGICAL techniques for AA repair
- DORSAL (decompress, reduce and stabilize)–AA wiring +/- PMMA, Braided suture, nuchal ligament technique, dorsal cross pinning +/- PMMA, Kishigami AA tension bandDOES NOT RESIST MOVEMENT IN DIRECTIONS OTHER THAN FLEXION (minimal osseous fusion occurs)2. VENTRAL (–bone plating, transarticular screws/pins, pins +/-PMMA, screw +/-PMMA, combo pins/screws +/- PMMAMay require odontoidectomy, cancellous bone graft and removal of cartilageADVANTAGE OF JOINT FUSION TO OCCUR With VENTRAL TECHNIQUES
what is a contraindication for dorsal stabilization for AA instability
compression of spinal cord due to dorsal deviation of dens
drill position for transarticular screw placement to tx AA instability
Ventral approach1.5 mm screw 1.1 drill bitdrill is directed craniolaterally 30 degrees from midlineaim for medial border of alar notch
complication rates btwn ventral and dorsal stabilization of AA instability
dorsal 71% complications; failure 48%ventral 53% complications; failure 44%
types of complications following surgery for AA instability
- neurologic deterioration (concussive injury)2. Respiratory system compromise (recurrent laryngeal n damage, compression of trachea from implants/PMMA, CNS trauma, aspiration pneumonia3. implant failure (improper bone purchase 25% dorsal, 18% ventral)4. fracture of C1, C25. recurrent pain