1
Q
• What CN deficiencies would you see in C1-C5 lesion and where is the NAL with that lesion? 439
A
• Positional strabismus (rare) and facial hypesthesia in C1-C3 lesions
2
Q
• What gait will you see with C1-C5 lesion? C6-T2?
A
• C1-C5 -> proprioceptive ataxia, UMN gait with long uncoordinated strides in all 4 limbs
• C6-T2 -> two engine gait, short and choppy in TL and long and uncoordinated in PL
3
Q
• What is the NAL for monoparesis/monoplegia?
A
• C6-T2 nerve roots, brachial plexus, spinal nerves
• Will have normal proprioception, motor and reflexes on the contralateral limb
4
Q
• What is seen in the CSF with FCE?
A
• Elevated protein
• Pleocytosis
5
Q
- What affects recovery and prognosis of FCE?
A
Length of lesion
* If lesion is > or = 2 x length of C6 or T2 then 60% chance of recovery
* If not recovered in 2 weeks then worse prognosis
Location
* Cervical/lumbar intum worse than c1-c5, t3-l3
Symmetrical worse than asymmetrical
Lack of sensation
6
Q
• What will happen to the reflexes in C1-C5 lesion vs. C6-T2 lesion?
A
• C1-C5 -> reflexes intact (UMN injury)
• C6-T2 -> reflexes absent or decreased
7
Q
• Where is the localization in a dog with short choppy gait in the TL and long strides in PL, decreased reflexes in TL and normal in PL, loss of cutaneous trunci reflex?
A
• C8-T1
8
Q
• If Horner’s Syndrome is present what is the localization of the lesion?
A
• T1-T3 nerve roots (although could be other location on pathway- just less common)
9
Q
• Why do dogs with cervical lesions have more profound deficits in their pelvic limbs?
A
• UMN to the pelvic limbs are more superficial and laterally located in the spinal cord than those responsible for motor function in the TL so they will be more damaged
10
Q
• What is Central Spinal Cord Syndrome? 439
A
• A dog with more profound neurological deficits in the TL than the PL has a lesion that affects the central spinal cord and therefore the deeper white matter which contains the UMN to the TL
11
Q
• When will a dog have normal PL but neurologic disease in the TL?
A
• Brachial plexus, neuritis, nerve root injury or peripheral lesion in C6-T2 spinal nerve roots
12
Q
- What is the most common test to distinguish a C1-C5 lesion vs. C6-T2 lesion? How many dogs are incorrectly localized with this test?
A
Withdrawal
* Decreased in C6-T2
* Normal to increased in C1-C5
** 34% dogs incorrectly localized with this test - decreased withdrawal does not always indicate C6-T2
13
Q
• What occurs with the muscles of the TL with C1-C5 vs C6-T2 lesion? 440
A
• C1-C5 -> disuse atrophy which takes weeks to occur
• C6-T2 -> neurogenic atrophy which can occur in 7 days and is very severe
14
Q
• What is a finding in chronic cervical myelopathy dogs with regards to CPs? 440
A
• Proprioceptive ataxia WITHOUT CP deficits
15
Q
• Why is it uncommon to see tetraplegic dogs with loss of nociception? 440
A
• Loss of nociception indicates complete loss of ascending and descending pathways in the spinal cord or spinal cord transection. If this occurs in the cervical region there would be damage to the descending respiratory tracts from C5-C7 resulting in inability to breathe.
• Also- larger vertebral canal space
16
Q
• What is a “root signature sign”?
A
• Holding the affected limb in partial flexion. Commonly C6-T2 but can be C1-T2 nerve roots or spinal nerves
17
Q
• Name 9 diagnostic tests to run on a cervical spine case.
A
• CBC
• Chemistry
• Urinalysis
• CSF
• Serology
• Xray
• CT
• MRI
• Electrophysiology
18
Q
• Describe the steps for a MODIFIED ventral approach to the cervical spine (traditional ventral approach not described in TJ). SSLL
A
• Skin: Manubrium to larynx
• Separate sternohyoideus and sternocephalicus (paramedian separate bw right muscle bellies)
• LEFT retraction of muscles, trachea, esophagus and carotid sheath (protects these structures and decreased likelihood of bleeding from right caudal thyroid artery)
• Incise Longus Colli muscle
19
Q
• What is the advantage to the modified ventral approach to the cervical vertebral column?
A
• Protects trachea,
• recurrent laryngeal n., contents of right carotid sheath,
• Decreases likelihood of bleeding from R cd. thyroid a..
20
Q
• What diseases are treated via ventral approach to cervical vertebral column?
A
• Ventral slot
• IVD disk fenestration
• Fracture repair
• AA stabilization
• CSM
21
Q
• Describe the MODIFIED ventral approach to the AA joint.
A
• Similar to ventral approach but Right parasagittal (also sternothyroideus instead of hyoideus)
• Skin: caudal ⅓ mandible to 5cm past thyroid cartilage
• Separation of sternothyroideus, sternocephalicus and carotid sheath from larynx
• Retract the larynx and carotid to the LEFT
• Longus colli incision/ elevation over C1-C2
• (improved ability to drive k wire w/o larynx, trachea in sx field
22
Q
• How is C1-C2 identified? 442
A
• Pointed ventral prominence on the ventral midline of caudal C1
23
Q
• Describe the lateral approach to the cervical spine (C3-C6). 442
A
• Cervical Palpation Before Starting
• Skin: C2 - scapula
• Platysma incised to reveal trapezius and brachiocephalicus m
• Brachiocephalicus muscle dissected in a grid technique parallel to fibers
• Serratus ventralis and splenius dissected from longissimus
24
Q
• Describe the additional lateral approach for C5-C7.
A
• The Best Spine Retains Long and Complex joints
• Trapezius caudal and Brachiocephalicus cranial
• Ligate Superficial Cervical A/V
• Retract and abduct scapula
• Separate the longissimus capitus and complexus m.
• Remove complexus and multifidus attachments to the articular processes and sacrifice the dorsal branch of the spinal nerve
25
• What diseases are treated with lateral approach to cervical vertebral column?
• Lateralized or foraminal IVD herniation
• Nerve sheath neoplasms involving spinal nerves or nerve roots
• Lesions within epidural space
26
• Describe the dorsal approach the cervical spine C1-C3. 443
• Some Boys Really Swing and Yell
• Skin: Occipital to C4
• Median raphe
• Splenius
• Biventer cervicis
• Rectus capitis dorsalis
• Spinalis cervicis
• Yellow ligament
• Remove the occipital-atlanto membrane
27
• Describe the dorsal approach to the cervical spine C4-C6.
• Really Swing, Man! (Ready, set, March!)
• Skin: Occipital to T1
• Median raphe
• Rectus capitis dorsalis
• Spinalis and semispinalis
• Multifidus
• Nuchal ligament
28
• What diseases are treated from a dorsal approach to the cervical spine?
• Dorsal laminectomy
• Fracture
• AA stabilization
• CSM
29
• Describe the lateral approach to the brachial plexus. 443
• Scapular Palpation, Slide Over To C Far Stuff
• Skin: 3-4cm cranial to scapula down to greater tubercle
• Platysma
• Superficial cervical a/v ligation
• Omotransversarious release at scapular spine
• Trapezius and Cleidocervicalis retraction
• Farabeuf retraction of scapula
• Incise Scalenus to reveal C5-T1
30
• What is identified in this image?
• Sternocephalicus
• Sternohyoideus
• Trachea, carotid sheath
• Longus colli m.
• Longus capitis m.
31
• What diseases are treated with lateral approach to the BP?
• Avulsions, neoplasms
32
• Why do large breed dogs often exhibit worse signs to pelvic limbs compared to thoracic limbs w.cervical lesions?
• Tracts to pelvic limbs more peripheral
• *if TL have more dysfunction than PL, than consider more centrally located lesion
33
• How does intracranial disease lead to referred neck pain?
• Elevated ICP = stretching of cerebrovasculature which is densely innervated = painful
34
• What are injuries (two types of pathology) caused by AAI on spinal cord? 445
• Contusion and compression
35
• What causes AAI?
• Ligamentous or osseous abnormalities of the atlas (C1) and axis (C2) causing subluxation of the vertebrae into the vertebral canal
36
• Name the structures. What does the atlas lack?
• Dorsal spinous process
37
• Describe the vasculature associated with the atlas and where they are located in relation to the bone. 445
• Vertebral artery -> runs under the atlas in the atlantal fossa ventral to the wings, enters the Transverse Foramen and into the vertebral canal through the Lateral Vertebral Foramen
• Vertebral vein -> atlantal fossa through the Transverse Foramen and anastamoses with the internal jugular vein at the condyloid fossa rostrally
• Branch of the vertebral vein -> runs dorsally through the cranial notch to become external vertebral venous plexus
38
• Name the parts of the axis identified.
• (No answer provided in source text)
39
• The atlantooccipital joint is formed of what, and what is the main mvmt that is achieved?
• Occipital condyles articulate with atlas via 2 cotyloid cavities
• “Yes joint” - main flexion and extension, mostly extension
40
• The atlantoaxial joint is formed of what, and what is main mmt that is achieved?
• Caudal articular surface of atlas = 2 glenoid cavities; articulates with axis
• “No” joint, mainly rotational
41
• C1 spinal nerve/vessel pass through which foramen?
• Lateral vertebral foramen
42
• How many bony elements compose the atlas? Axis?
• 3 (atlas), 7 (axis), fuse over time
43
• What passes through the transverse foramen of the atlas?
• Vertebral artery, vein
44
• What is the course of the vertebral vein in relation to the atlas?
• Vertebral vein -> transverse foramen (caudal) -> fuses w/internal jugular at ventral condyloid fossa (rostral)
45
• How many ligaments hold the dens in place, and what is their origin/insertion/function?
• 4 ligaments
• Transverse ligament - holds dens in ventral position, allows rotational movement
• Apical ligament - holds dens to basioccipital bone
• Alar ligaments (x2) - hold dens to occipital condyles
• Dorsal atlantoaxial lig = dorsal arch of atlas to spine of axis
46
• What is the most important ligament in withstanding ventrodorsal shear forces at the level of the A-A joint?
• Alar ligaments
47
• Name the anatomy
• Apical ligament - dens to basioccipital bone
• Alar ligament - dens to occipital condyle
• Transverse ligament - runs over the dens across the vertebral foramen
• Fat over dorsal spinous process
• Connective tissue
• Basioccipital bone
• Supraoccipital bone
• Dorsal lamina of the atlas (C1)
• Spinous process of axis (C2)
• Dens
• Longus capitis
• Longus colli
• X
• Atlanto-occipital joint
• X
• Ventro-atlanto-occipital membrane
48
• Name 4 congenital and developmental abnormalities that cause instability in the AA joint. 446
• Dens abnormalities
• Absence of transverse ligament
• Atlas incomplete ossification
• Block vertebrae
49
• Name 4 abnormalities of the dens.
• Hypoplasia/aplasia (46%)
• Dysplasia (34%)
• Dorsal angulation
• Separation
50
• How many dogs with AA-sublux have a normal dens?
• 24%
51
• Which large breed dog may have inherited absence/hypoplasia of the dens?
• Standard poodle
52
• What 3 structures are injured with forceful overflexion of the neck?
• Fractured dens, torn ligaments, fractured laminae of axis
53
• What types of injuries are caused with AAI?
• Compression and contusion from dorsally displaced axis in relation to the atlas
54
• What is the most common clinical sign in dogs with AAI?
• Neck pain 25-60%
55
• Name 6 clinical signs in dogs with AAI?
• CP deficits 56%
• Tetraplegia (< 10%)
• Gait dysfunction 94%
• Head tilt or intracranial signs
• Respiratory compromise
• Torticollis
56
• What are 4 sources (anatomy/pathology) of intracranial signs in dogs with AA-luxation?
• Brainstem injury
• Basilar artery compromise
• Concurrent hydrocephalus
• Concurrent systemic dz (ie, HE)
57
• What is the best MRI weighted imaging to evaluate the ligaments of the occipitalatlanto joint?
• T1 weighted, or proton dense -> appear hypointense
58
• Describe the radiographic findings
• There is a widening of the distance between the dorsal spinous process of the axis (C2) and the dorsal lamina of the atlas (C1)
• The dens appears hypoplastic (odointoid process) on the VD image
• There is subluxation of the axis relative to the atlas with widening of the AA angle
59
• What are radiographic findings associated with AA-I?
• VD - appearance of dens, position of dens
• Lateral - malalignment of axis/atlas (Severe); increased space between spinous of axis and dorsal laminae of atlas
• *in one study, angle <162 between atlas and axis more predictive of AAI compared to decreased overlap
60
• Describe conservative management plan for AAI.
• Splint of fiberglass from mandible to xyphoid
• Splint in place for 6 weeks with weekly bandage changes
• Repeat radiographs
61
• What are indications for conservative management of AA?
• Mild neuro signs, neck pain only, no radiographs abnormalities of dens
• Super young patients that need more time before definitive intent surgery
• Or dogs that owners want to give time to for prognosis reasons
62
• What are the risks associated with conservative management (name 4)
• Recurrence
• Pressure sores
• Dyspnea
• Corneal ulcers
• Migration of splint
• Anorexia
• Otitis externa
63
• What are pro/cons for dorsal stabilization of AA?
Strengths:
• Reduce and stabilize and decompress
• May be more biomechanically sound
• Good for dogs < 2kg that cannot support larger implants
Weakness
• No bony ankylosis -> only rests flexion ,still allows mvmt; possible allowing for more likely failure of implants
• Contraindication -
• if spinal cord compression is from dorsal deviation of dens
64
• What are indications/contraindications for ventral stabilization of AA?
• strengths:
• Approach of choice for fx repair
• Can remove dens in same approach for decompression
• Allows bony ankylosis
65
• Name 5 dorsal fixation techniques for AA-luxation?
• Aa-wiring
• Suture AA technique
• Nuchal ligament suture
• Dorsal cross pinning
• Kishigami AA tension band
66
• Describe AA wiring
• AA wiring
• Drill 2 holes in the dorsal spinous process of C2
• Pass wider under the dorsal lamina of C1 and retrieve from atlanto-occipital space
• Secure to spinous process
• Use 20-24 g wire
67
• Describe the technique shown.
• AA suture technique. Pass suture from obiquus capitis caudalis to obliquus capitis cranialis forming a cross with non-absorbable 2-0 nylon < 2 kg dogs 50% functional improvement in 12 dogs
68
• Describe the technique shown in this image. What is the outcome?
• Kishigami AA tension band Drill 2 holes in spinous process of C2 and thread wire Place band over the arch of C1 into subarachnoid space Tighten wire 75% dogs excellent outcome in 12 mo
69
• Describe the nuchal ligament technique.
• Split the nuchal ligament longitudinally
• Transect at the caudal attachment of T1
• Bring ends from cranial to caudal under the lamina of C1
• Tie in drilled hole of spinous process of C2
70
• Describe this technique shown here
• Dorsal cross pinning
• Reduce joint
• Pass 0.045 across each side of C2 to engage the caudal ½ of the atlas C1 wing
• Cut wires and secure with PMMA
71
• 4 techniques for re-aligning the AA joint from a ventral approach?
• 1.5 mm screw into cd. body of C2, wire threaded around head and used to elevate axis (ie, move it ventrally)
• Stabilize with microhalstead forceps applied to lateral aspects of body
• Gelpi between atlanto-occipital joint and C2-3
• Gelpies in C1-2 not recommended
72
• Name 4 techniques for stabilizing AA from ventral approach
• Transarticular screws or pins
• Ventral plating
• Pins + PMMA
• Screws + PMMA
73
• What are the corridors for transarticular screw/pin placement? Size screw?
• 40 deg medial/lateral from midline
• 20 deg ventral/dorsal from ventral aspect of vertebral foramen of the axis
• Direct to medial border of alar notch of the atlas
• Average length 7mm and width 3-4 mm
• Screws should be 1.5mm
• Can use pins 0.045 - 0.062
74
• Describe the screw placement patterns for screws and PMMA stabilization technique.
• Atlas
• 2 screws - Medial aspect of each wing caudal to transverse foramen
• 1 screw - Middle of the ventral body of C1 - do not go through trans cortex
• Axis
• 4 cortical screws in the body C2
• 2 screws cranially at the caudal aspect of the cranial articular surface directed laterally 30-40 deg
• 2 screws at the base of the transverse process or in C3 directed laterally 30-40 deg
• 2 screws in the body of C2
75
• What technique is being shown in this image? What is the name of the implant? What other implant can be used for this technique?
• Ventral plating for AAI stabilization with butterfly locking plate
• Mini-H plate with 2.0mm screws
76
• What is the success rate for conservative management of AAI and what affects outcome?
• Good outcome in 38%
• Dogs affected < 30 days more likely to have good outcome
77
• What are the common complications for AAI? (Name 5)
• Neurologic, implant failure, fracture of C1 or C2, pain, tracheal necrosis, recurrent laryngeal nerve injury
• Complication rate for dorsal vs ventral stabilization
• Dorsal - 71%
• Ventral - 53%
78
• What is the mortality rate with surgery?
• 4-30%
79
• What AA implant is most commonly associated with implant migration?
• Transarticular pin
80
• What part of atlas/axis is most likely to fracture in AA stabilization for dorsal fixation? How about for ventral?
• Dorsal - dorsal arch of atlas
• Ventral- cranioventral body of axis, improper implant placement or bone immaturity Brachial Plexus
81
• Why are the nerve roots of the brachial plexus susceptible to injury? 455
• They lack epineurium making them more prone to avulsion
82
• Partial injuries of the brachial plexus most commonly affect what area?
• Caudal portion of the brachial plexus
83
• What are the three types of connective tissue that surround the nerve?
• Endoneurium - around a single axon
• Perineurium - around groups of axons
• Epineurium - connective tissue around the entire nerve
84
• Describe what occurs from the axon leaving the spinal cord to becoming the nerve root.
• Axon leaves spinal cord as nerve rootlet and joins other nerve rootlets -> spinal nerve root (ventral-motor and dorsal-sensory) in the spinal canal -> join together to form a spinal nerve -> exit intervertebral foramen
• Axon/nerve rootlets -> covered in CSF in subarachnoid space
• Spinal nerve roots -> covered in pia matter and arachnoid membrane
85
• What is the intradural and extradural segment of a spinal nerve?
• Intradural -> where the nerve root meets the spinal cord and is covered with pia matter and arachnoid
• Extradural -> where the nerve is surrounded more distally by the meningeal tube formed by the outer arachnoid membrane and dura matter
86
• When does epineurium occur on the spinal nerve?
• At spinal ganglion, the meninges that are covering nerve become the epineurium
87
• When is a spinal nerve intradural vs extradural?
• Extradural = nerve root enters a “meningeal tube”, which is outer layer of arachnoid membrane, dura, and the subarachnoid space w/CSF
• Intradural - spinal nerve is covered by extension of pia mater, then arachnoid and subarachnoid space w/CSF as nerve rootlets penetrate the spinal cord
88
• What is the most common site of nerve injury and why?
• Intradural segment - lacks epineurium, making it weakest
• Motor more likely to be damaged compared to sensory
89
• Name the nerves of the brachial plexus.
• Brachiocephalicus
• Suprascapular
• Subscapular
• Musculocutaneous
• Axillary
• Radial
• Median
• Ulnar
90
• What are the 5 classes of types of injuries present in the brachial plexus.
• Class 1 -> neurapraxia
• Interruption in the function but not the structure = reversible
• Class 2 -> Axonotmesis
• Crush or percussion injuries = wallerian degeneration of the distal axon but the internal structures remain intact
• Class 3 -> Neurotmesis
• Disruption of axon and endoneurium but perineurium intact
• Class 4 -> Neurotmesis
• Disruption of the perineurium
• Class 5 -> Neurotmesis
• Severed
• Class 6 -> combination
91
• What are clinical signs of C5-7 avulsion?
• infra/supra muscle atrophy
• Decreased shoulder mvmt, decreased elbow flexion
• Can still bear weight because of elbow extension
92
• What are signs of C8-T2 avulsion?
• MOST common
• Limb held in partial flexion
• Loss of weight bearing/extension of limb (radial)
• Horners (ipsi)
• Loss of lateral cut. Trunci (ipsi often)
93
• What are signs of full avulsion?
• Sensory deficits common, most can’t feel below elbow
• Dropped shoulder
• Dragging limb
• No weight bearing
• Substantial atrophy 1 week post injury
94
• Name the diagnostics used to confirm brachial plexus injury.
• Neuro exam -> monoparesis, cutaneous loss
• Electromyography
• Nerve conduction velocities -> radial and ulnar n.
• MRI
• Swollen nerve - hypointense T1 and hyperintense T2
• Can see nerve retraction
• Ultrasound
95
• What muscle is affected by pre-ganglionic nerve injury, as id’d on MRI?
• Cervical muscles ie mulitfidus m.
96
• What are the indications for surgery.
• Recent injury
• Grade 1,2 injuries
• Severed nerve will heal, not a nerve that has suffered severe avulsion or traction
• Young patients heal better than older patients
97
• Four approaches to treating plexus/nerve injuries?
• Neurotization= Nerve transfer, donor pure motor nerves are best
• Nerve graft
• Re-implantation
• Anastomosis
98
• Describe neurotization
• Transfer of a motor nerve to another motor nerve
99
• Describe reimplantation: Give it 4-6 weeks before prognosis?
• Lateral cervical approach and hemilaminectomy
• Durotomy
• Slits made into the SC and pia matter
• The rootlets and reimplanted into the slits
• Fat graft placed
100
• What are the injury types with IVDD.
• Contusion and compression
101
• Name the widest and narrowest cervical spinal cord segments
• C4-5, 5-6 are widest
• C2-3 narrowest
102
• Where is there no intervertebral disc in the cervical spine.
• C1-C2
• Ligaments of the cervical spine (name
• and their locations.
• Dorsal and ventral longitudinal ligaments -> run over the top and bottom of the discs
• Interspinous ligament -> connects the vertebral spines
• Supraspinous ligament
• Yellow ligament -> sheets between the arches of the adjacent vertebrae and form the zygapophyseal joint
103
• What is the venous plexus?
• Two thin walled vessels that lay on the floor of the vertebral canal and are more lateral in the cervical spine
104
• Which ligament prevents dorsal herniation of disk and why?
• Dorsal longitudinal ligament - thickest in cervical spine
105
• What is the most common type of IVDD?
• Type 1 - disc EXTRUSION
• Caudal cervical IVDD like in large breed dogs is most commonly protrusions
106
• What are the most common cervical sights of IVDD based on conformation/breed size? 462
• Chondrodystrophic C2-C4 80% and 44-59% C2-3
• Yorkies and chihuahuas are affected later in life and at C5-6 and C6-7
• Large breeds affected at C6-7
107
• What should be considered when large breeds are affected by IVDD? 462
• Concurrent malformation like cervical spondylomyelopathy syndrome
108
• What is the most common clinical sign cervical IVD ? Name 3 others? 462
• Neck pain 90%
• Nerve root signature 22-50%
• Tetraparesis 42%
• Non-ampbulatory tetraparesis 11-22%
• Respiratory compromise with bradycardia and second degree AV block
109
• What is the cause of hypoventilation in a dog with cervical IVDD and what is the proposed treatment? 462
• Paresis or paralysis secondary to the damage to the spinal WITH airway hyperresponsiveness causing bronchoconstriction
• Theophylline and aminophylline, mechanical ventilation
110
• Where is the NAL in a dog with tetraparesis and decreased TL reflexes?
• C6-T2
• Exception! Dogs < 10 kg will have decreased reflexes in TL but have C1-C5 lesion
111
• Why will dogs with more cranial lesions have an absence of neurologic signs?
• Cranial intervertebral canal is larger so the SC can move aside when there is disc material
112
• What are 5 differential diagnoses for a dog with neck pain?
• Meningitis
• Meningomyelitis
• GME
• SRMA
• AAI
• Discospondylitis
• Neoplasia
113
• What diagnostics should be performed?
• Cervical radiographs - r/o discospondylitis, neoplasia, congenital malformations, AAI
• Myelography
• CT
• MRI
• CSF
• CBC/Chemistry
• Urinalysis
• Serology
114
• Describe this image. What % accuracy of diagnosis of disc extrusion on radiographs?
• Narrowed disc space at C5-6
• Radio-opaque material within the vertebral canal
• 35% accuracy
115
• Describe this image. What is the diagnosis?
• T2W sagittal and transverse images of the cervical spine
• There is decreased signal in the intervertebral disc at C4-5
• There is hypointense material present in the ventral aspect of vertebral canal over the disc space C4-5 with loss of signal of spinal fluid in that location and compression and T2W hyperintensity consistent with edema of the spinal cord overlying the material
• There is hypointense material that is lateralized within the vertebral canal overlying C5-6 on transverse image
• Diagnosis: Disc extrusion
116
• What is a foraminal intervertebral disc extrusion?
• Disc extrusions close to or within the intervertebral foramen
• Only seen on MRI - transverse images only
117
• Describe this image. What are the characteristics of this specific lesion? 465
• T2W sagittal and transverse images
• Hyperintense material in the ventral vertebral canal overlying C4-5 causing compression of the spinal cord in that location
• Diagnosis: hydrated NP extrusion
• High intensity on T2, isointense to 92% to CSF, dorsal to affected IVD, seagull shaped on transverse image
• Signal low in T1W - isointense to CSF in 78% and hyperintense in 22%
118
• Describe conservative management of cervical IVDD.
• 4-6 weeks cage rest
• Harness
• NSAIDs, steroids, gabapentin, methocarbamol, diazepam, tramadol
119
• What substance has been used for chemonucleolysis in dogs?
• Chondroitinase ABC, injected into affected disk space, 92% dogs improved in 1 week
120
• What is the indication for surgical management?
• Repeated neck pain
• Neck and neuro deficits
121
• Name 4 different surgical techniques for decompression and their approach.
• Ventral slot - slanted slot - ventral
• Fenestration - ventral (should be used in prophylactic not sole treatment)
• Hemilaminectomy - dorsal
• Dorsal laminectomy - dorsal
122
• What size should a ventral slot be? What is the location in which one should drill for ventral slot procedure?
• Drill at the junction between annulus fibrosis and the adjacent vertebrae
• Not > 33% the length of the vertebra
• Not > 50% width of the vertebra
123
• How is a ventral slot different from a slanted slot? Why is slanted slot performed?
• Slanted slot is centered over the vertebra that is cranial to the IVD. It involves removing the caudal aspect of the cranial vertebral body
• Suggested that it preserves stability because it removes less of the annulus
• Do not make bigger than 20% width and 20-25% length
124
• What is the contraindication to fenestration?
• Dogs > 30kg for risk of collapse or subluxation
125
• What is the % complication in ventral slot?
• 9.9% - 14.9%
• Minor in 3.5%
• Major in 6.4%
126
• Name 7 complications with ventral slot.
• Persistent pain
• Deterioration of neuro status
• Hemorrhage - requiring transfusion
• Seroma
• Respiratory compromise
• Cardiac dysrhythmia
• Ventral subluxation
127
• Describe anatomical neuro tract of origin of phrenic n/respiratory?
• Respiratory center in medulla -> enter spinal cord via reticulospinal tract -> project to C5-7, gives rise to phrenic n.
• *also gives rise to spinal nerves innervating intercostal muscles
• *most dogs with ventilation failure have lesions cranial to C5-7
• Rate of respiratory compromise in dogs undergoing cervical surgery.
• 1.8 - 3.5%
128
• What lesions and what surgical technique are most likely to have associated hypoventilation?
• Lesions at C2-C4
• Decompressive laminectomy
129
• What is the likely cause of cardiac dysrhythmia in cervical surgery?
• Retraction of the carotid and vagosympathetic trunk in ventral approach
• Vagus nerve and carotids -> bradycardia
• Sympathetic trunk -> VPCs
130
• What are 2 neurologic deficits that can be seen after ventral slot procedure?
• Horner’s syndrome, Laryngeal paralysis due to soft tissue retraction
131
• What is the likely cause of worsening neurologic status and failure to improve after cervical decompression with ventral slot and why?
• Instability and subluxation of the vertebra due to slot > 0.5 width of the vertebral body and fenestration
132
* What are outcomes in dogs for surgically vs conservatively treated cervical disks?
Conservative
* 33-36% recurrence
* 48% success
* 18% failure
Surgical
* V-slot
* 90% recovered at 1 mo, 98% at 12 mo
* Slanted vs standard - slanted may have longer recovery, fewer comps?
* Large breed for caudal disk - 66% success ( may need combined stabilization?)
Dorsal laminectomy
* 100% successful
Hemi
* 78-88% success
* Recurrence rates - 5-10%
* T1 extrusion - CS improved in 96%
* T2 protrusion - 47% excellent, 32% good
* *overall - T1 disk/small breed better prognosis than large breed/T2 disk
* Small dogs with Hansen type I have a better recovery than large breed dogs with Hansen Type II
133
• What is CSM.
• Cervical spondylomyelopathy is a disease in large and giant breed dogs that results in compression of the SC or nerve roots leasing to variable deficits and neck pain (predisposed to compression based on anatomy- compression comes from either disc or osseous source).
• Wobblers
134
• What are vertebral foramen differences in small vs large breeds?
• Large breeds- relatively smaller and funnel shaped vertebral foramen (especially dobies)
135
• What are 3 factors involved/contributing to DA-CSM
• Large IV disk (dobies affected have large disks can dobies unaffected
• Vertebral canal stenosis
• Pronounced torsion of caudal cervical vertebral column
• Caudal has 3x more axial rotation or torsion vs cranial
• Torsion more than axial compression result in disk degeneration
136
• What is the most common location for DA-CSM
• C5-6 and C6-7
137
• What is the breed associated with DA-CSM and why?
• Dobermans -> autosomal dominant mode of inheritance with incomplete penetrance
• Can be in large middle-aged dogs
138
• What are the factors involved/contributing to OA-CSM
• Proliferation of lamina (dorsal)
• Proliferation of articular process (dorsolateral)
• Articular process/pedicle proliferation (lateral)
• Hypertrophy of ligamentum flavum- not primary (rarely sole source)
• **Primarily OA of zygapophyseal joint + vertebral malformation**
139
• What is the typical signalment of OA-CSM
• Young giant breed dogs
140
• What is the histopathological change/process present in CSM that causes worsening of disease?
• Oligodendrocyte apoptosis interfering with remyelination and causes progression of clinical signs
141
• What is the common age for Dobermans presenting with CSM and the common age for giant breed dogs?
• Dobermans - 6.8 yrs
• Giant breeds - 3.8 yrs
142
• What % dogs have 1 site vs. 2 sites affected?
• Large breed = 50/50
• Giant breed = 80% 2 sites affected
143
• What are the common site(s) affected in large vs. giant breed dogs?
• Large breed = C6-7 then C5-6
• Giant = C6-7 then C5-6 and C4-5
144
• What is the most common clinical signs of CSM?
• Gait abnormalities - tetraparesis and ataxia
• Usually more affected in PL and can be more subtle in TL like floating
• http://www.liveoakvetneuro.com/blog/2015/10/30/what-is-wobblers-disease
145
• What portion of dogs present tetraparetic, nonambulatory?
• 10%
146
• Describe this image. What is your diagnosis?
• Severe OA proliferative change of the zygapophyseal joints
• OA-CSM
147
• What is hallmark radiographic finding in dogs with OA-CSM
• Sclerosing, OA of zygapophyseal joints
148
• What are radiographic findings in DA-CSM?
• Triangular vertebral bodies
• Narrowing of IVD
• Stenosis of vertebral canal
149
• What diagnostics should be performed in CSM? (name 8)
• Cervical radiographs
• Myelography
• MRI
• CT Myelography
• Thyroid - Dobermans
• vWF - Dobermans
• Echocardiogram - DCM in dobermans
• Holter monitor - DCM in dobermans
150
• What are the risks associated with myelography? %?
• Deterioration of neurologic status or seizures
• Seizures in 25-27% dobermans
151
• What is the typical medical management of CSM and what is the response rate?
• Activity restriction
• Harness
• NSAIDs
• Corticosteroids - decrease vasogenic edema, protect from glutamate toxicity
• Possible protein and calorie reduction for OA-CSM
• Response is variable 38-45%
152
• What are the types of decompressive techniques used? Describe each technique and what they are indicated for. (4) 478
Ventral slot
• Ventral approach to the cervical spine. Drill over the affected disc space no longer than 33% the length of the vertebral body and < 50% the width of the vertebral body
• Indications: DA-CSM (static lesions)
Inverted cone ventral slot
• Ventral approach to the cervical spine. Smaller opening at the ventral part of the disc space and widening as it moves dorsally. 20% of the vertebral body and reduces hemorrhage and collapse.
• Indications: DA-CSM (static)
Dorsal laminectomy
• Dorsal approach to the cervical spine. Remove the dorsal lamina for all associated sites. Neurologic decompensation can be caused by postoperative laminectomy membranes. Fat grafts may not be effective but if used should be < 5mm.
• Indications: OA-CSM to remove the dorsal compressions associated with proliferation of the pedicles, zygapophyseal joint, dorsal laminae malformations and yellow ligament hypertrophy
• Can be used for 1 or multiple sites
Cervical hemilaminectomy
• Lateral approach to the cervical spine.
• Indications: DA-CSM or OA-CSM with lateral compression
153
• What is this device and what is it used for?
• Caspar distractor. Used in the cervical spine to distract the disc space for distraction and stabilization techniques. Anchor the distractor in defects made in the cranial and caudal vertebral bodies with high speed burr.
154
* What are the techniques used for distraction and stabilization? What is each technique indicated for treating? Describe the techniques. 478
1) Pins and PMMA
* Ventral approach. Use positive profile pins, smooth steinmann pins or bone screws. Perform a partial or complete ventral slot then place the pins/screws in the cranial and caudal vertebrae in the pedicles and body at 30-35 deg EXCEPT for C7 which requires 45 deg. Place autogenous or allograft into the slot then place PMMA around the implants.
* Indications: Dynamic DA-CSM, if used for multiple sites risk of failure increases
2) Screw-bar PMMA
* Ventral approach. Place bilateral screws in the transverse processes of the cranial and caudal vertebrae. Steinmann pin contoured into a U shape and fixed to the screws. PMMA placed around the construct.
* Indications: Dynamic DA-CSM
3) PMMA plug
* Ventral approach. Discectomy performed with 11 blade leaving 3-5mm annulus on the dorsal aspect. Holes drilled into the cranial and caudal end plates. PMMA inserted into the disc spaces and then autogenous cancellous bone graft is placed into the ventral verbra after PMMA hardens. Lacks bony fusion and initial outcome improvement in 82% that dropped to 62% in long term.
* Indications: multiple or single, dynamic or static, ventral or dorsal compressions in DA-CSM, OA-CSM
4) Locking plate
* Ventral approach. Discectomy or ventral slot. Place bone graft - cancellous autograft, cortical allograft with cancellous autograft and cancellous block grafts (orient parallel to the spine)
* Indications: Dynamic DA-CSM
5) Cervical disc arthroplasty
* Benefit is to preserve the normal motion of the disc space while maintaining distraction. Used to avoid the domino effect whereby decreasing motion of the operated disc space causes injury to the adjacent disc spaces. Benefit in 91% but decreased or absent motion of the operated site in 77%.
* Cages, spacers and screws
* Types
* Titanium cage with monocortical screws
* Intervertebral cage of carbon fiber reinforced polymer (polyetheretherketone) used with locking plate (PEEK)
* Interverbral traction screw with locking plate
* Benefit - most of these implants achieve some bony bridging
* Indications - DACSM
155
• What technique is being used? What is the implant and what is it indicated to treat?
• PEEK with locking plate
• Distraction and stabilization technique used to treat DA-CSM
156
* What are surgical options for static and dynamic compressions for DA-CSM
Static
* V-slot
* Inverted cone slot
* Continuous dorsal laminectomy
Dynamic
* Distraction stabilization
* PMMA plug
* pins/screws embedded in PMMA
* Disc arthroplasty
157
* What are surgical options for static and dynamic compressions for OA-CSM
** Thought to be mostly static, so direct decompression is mostly recommended **
Direct:
* Dorsal laminectomy
* Hemilam
Indirect
* distraction/stabilization ie: PMMA plug vs pins/screws + PMMA
158
• Purely ligamentous surgical options?
• Direct- dorsal laminectomy
• Indirect - pmma plug
• *usually combined with oa or da CSM
159
• Surgical options for multiple sites of compression?
• V-slot - 2 next to each other, but higher risk of complications
• Dorsal laminectomy - can be continuous if multiple sites next to each other; Highly morbidity- majority do worse initially, improve over 3 months or so
• Pins + pmma - can be done at more than one site but higher risk of failure
• Distraction + PMMA plug - up to 3 sites
160
• Describe two instruments and general technique of intervertebral distraction
• Gelpis
• Caspar distractor
• NOT manually
• *do not place in disks as this leads to degeneration of disks and can lead to domino effect - anchor in defect made by burr in cr/cd vertebral bodies
161
• List 4 alternative distraction techniques
• Titanium cage w/monocortical screw fixation
• Intervertebral spacer with monocortical screw fixation
• Intervertebral cage of carbon fiber reinforced polymer
• Intervertebral tract screw + locking plate
162
* List possible complications associated with surgery. (7)
1) Postop neurologic deterioration - most common in continuous dorsal laminectomy
2) Vertebral foramen and transverse foramina penetration with implant - usually with pin placement and can occur in 25-57%
3) Domino-effect - injury to the disc space cranial or caudal to the space that was operated on. Always present in distraction and stabilization procedures.
4) Laminectomy membrane - Occurs after dorsal laminectomy. Do not recommend fat graft in dogs for treatment
5) Implant failure - 7.5 - 30% failure rate. Bone resorption around implant, implant extrusion, disc space collapse, fracture of PMMA, failure at bone/implant interface, pseudoarthrosis
6) Collapse of intervertebral foramina - ventral slot can cause stenosis of intervertebral formina, lameness, pain, short-stride of affected limb
7) Insufficient decompression
163
• What is the % improvement in dogs treated with surgery?
• 80% improvement
164
• What is the % improvement with disc fenestration alone?
• 33%
165
• What is the % improvement with medical management?
• 50%
166
• What is the recurrence rate of DA-CSM with all procedures?
• 24%
167
• What is risk of post op neuro decompensation in dorsal laminectomy vs v-slot?
• 70% vs 42%
168
• What is the MST of dogs treated medically or surgically with CSM?
• 36 mo Extradural Synovial Cysts
169
• What is an extradural synovial cyst and where does it originate from? 483
• Cysts that originate from the zygapophyseal joint and are extradural
170
• How is the cyst thought to form and what is the cyst formation most associated with? 483
• OA of the zygapophyseal joint causes protrusion of the synovium through the joint capsule and it fills with synovial fluid
• Any disease that causes degenerative spinal changes and OA of the joint
171
* What is the signalment and clinical signs associated with cervical cysts? TL cysts? LS cysts?
Cervical
* Young
* Giant breed
* OA-CSM
* Unilateral, bilateral and multiple sites
* C1-C5 or C6-T2 myelopathy
TL
* Middle-aged to older
* Large breed
* Single site
* Unilateral
* T3-L3 without focal pain
LS
* Middle aged to older
* Large breed
* LS signs
* Pain on palpation
* Transitional vertebra are a risk
172
• Describe the findings. What is your diagnosis.
• T2W sagittal and transverse image of the spinal cord. T2 hyperintensity in the dorsolateral aspect of the spinal cord at C5-6
• Synovial cyst
173
• Describe the findings of this image.
• Axial CT image with myelography. Thickened articular process and cyst causing compression at C5-C6
174
• List 6 diagnostic tests and the typical findings for each.
• MRI = gold standard
• T2W = hyperintense
• T1W = hypo/iso or hyperintense
• CT with myelography
• Deviation of the contrast of the spinal cord
• Radiographs
• Degenerative changes in the zygapophyseal joint
• CSF
• Elevated protein
• Aspirate
• Consistent with synovial fluid
• Histopathology
175
• What is main risk factor for development of synovial cysts in dogs?
• Zygapophyseal joint degeneration -> protrusion of synovial membrane through defects of joint capsule -> para-articular cavity filled with synovial fluid
176
• Surgical technique for synovial cyst?
• TL - hemilaminectomy
• LS/cervical - dorsal laminectomy
• *remove cyst and all periarticular soft tissue to minimize risk of recurrence!
177
• Complications of surgical correction of brachial plexus
• Self-mutilation
• Reimplantation causes PL dysfunction
• Outcome for brachial plexus avulsion
• Grave
178
• If bleeding occurs during ventral slot what is the likely cause and how can this be addressed?
• Caused by hemorrhage of the overlying internal vertebral venous plexus
• Pack the slot with gelatin sponge, oxidized cellulose, macerated muscle, use cool lavage
