Cervical vertebral column Flashcards
Why is it common for more pronounced motor dysfunction to be evident in the pelvic limbs rather than thoracic with a cervical spinal cord lesion?
The descending UMN tracts to the pelvic limbs are more peripherally located.
What is central spinal cord syndrome?
When motor function is more severely affected in the thoracic rather than the pelvic limbs due to a lesion affecting the central aspect of the spinal cord
Are reduced thoracic limb withdrawal reflexes with normal mentation definitive for localization to C6-T2?
No, decreased withdrawal reflexes can sometimes occur with C1-C5 lesions
Can a lesion affecting the C6-T2 spinal cord segments cause an absent cutaneous trunci?
Yes, if the lesion affects the C8-T2 spinal cord segments.
How fast does neurogenic atrophy occur compared to disuse?
7 days for neurogenic, disuse likely to take weeks and is less pronounced
Where do the motor neurons of the phrenic nerve originate?
C5-C7 (C7-C5 keeps the diaphragm alive).
Absent nociception is uncommon in dogs with cervical lesions as it would likely also occur with complete respiratory failure.
Describe the cutaneous dermatomes of the thoracic limb
What is nerve root signature?
Holding of the thoracic limb in a partially flexed position, consistent with lesions affecting the C6-T2 spinal nerve roots
Lesions in what part of the cervical spinal cord are most likely to cause Horner’s syndrome?
T1-T3.
Is incontinence common with cervical spinal cord lesions?
No, more common with lesions caudal to T2.
List some diseases that might affect the C1-C5 spinal cord segments.
List some diseases that might affect the C6-T2 spinal cord segments.
Outline a diagnostic approach to cervical spinal cord disease.
What are two potential ventral approaches to the cervical spinal cord?
1) Midline approach.
2) Paramedian approach (separation of the right sternohyoideus and right sternocephalicus muscles. Helps to protect the trachea, right recurrent laryngeal nerve, and right carotid sheath).
What are two potential surgical approaches to the atlantoaxial articulation?
1) Ventral.
2) Parasagittal: dissection between the right sternothyroideus and sternocephalicus muscles. Improves exposure of the joint, and avoids dissection around the thyroid gland, trachea and recurrent laryngeal nerves.
What is the name of the ventral prominence on the caudal aspect of C1?
Ventral tubercle, can be used to locate the C1-C2 joint space
What are the two causes of AA instability?
Ligamentous or osseous abnormalities.
What are primary motions of the atlanto-occipital and atlantoaxial joints)
Atlanto-occipital: flexion and extension (yes joint).
Atlantoaxial: rotational (no joint).
The first spinal nerve pass out of which foramen?
The lateral vertebral foramen of the atlas.
The vertebral artery also passes through the lateral vertebral foramen after passing through the transverse foramen (in the wings of the atlas).
Name the ligamentous attachments to the dens
Transverse ligament of the atlas: holds the dens in the ventral aspect of the vertebral foramen
Apical ligament: attaches dens to basiocciptal bone
Alar ligaments: attaches dens to occipital processes. Most important for ventrodorsal shearing forces
What abnormalities may result in AA instability?
Atlantoaxial joint hypoplasia or aplasia (46% of dogs), dysplasia (34%), dorsal angulation, absence of transverse ligament and separation of dens.
Trauma can also cause tearing of the ligaments or fracture of the dens.
What proportion of dogs with AA instability have a normal dens?
24%
What is the most common clinical sign associated with AA luxation?
Neck pain.
How common are gait dysfunctions in dogs with AA subluxation?
In up to 94% of dogs
Is tetraplegia common in dogs with AA luxation?
No, <10%
What radiographic signs are consistent with AA instability?
Increased distance between the dorsal laminae of the atlas and spinous process of the axis.
If no abnormalities are seen the neck can be carefully flexed under fluoroscopic imaging to assess for instability.
Why are CT and MRI useful in the work-up of AA instability?
CT: can be used to assess dens conformation, as well as for the presence of fracture.
MRI: can provide information on concurrent spinal cord pathology (syringohydromyelia, etc) as well as ligamental deformities (absence of the apical, alar or transverse ligament).
Label the following image.
What does conservative management of AA instability entail?
Strict rest (6 weeks), analgesia, and external coaptation.
What are the landmarks for splint application in AA lux cases?
From cranial to the ears and rostral mandible to the cranial thorax and xiphoid. Must immobilize the occipitoatlantoaxial articulation
What are some complications associated with use of external coaptation for AA instability?
Recurrence of disease, corneal ulcers, migration of the splint, moist dermatitis, decubital ulcers, hyperthermia, respiratory compromise, anorexia, otitis externa, accumulation of food between the splint and mandible.
What is the goal of surgical AA stabilization?
Bony ankylosis of the AA joint
Is the ventral or dorsal approach preferred for AA luxation repair?
Ventral repair as allows for bony ankylosis. Dorsal approach only resists motion in flexion resulting in persistent joint movement and failure of ankylosis.
Dorsal approach might be useful for small dogs in which placement of ventral implants is not possible, as well as in cases of previous ventral failure. It may also be more biomechanically sound than ventral fixation.
What is a contraindication for dorsal stabilization of the AA joint?
Dorsal deviation of the dens
What are dorsal surgical methods of AA stabilization?
- Atlantoaxial wiring (or suturing in small dogs <2kg).
- Dorsal cross-pinning.
- Nuchal ligament technique.
- Kishigami AA tension band
What surgical technique for AA instability repair is shown?
Dorsal atlantoaxial wiring
What surgical technique for AA instability repair is shown?
Suturing of the obliquus capitis caudalis to the obliquus capitis cranialis.
What surgical technique for AA instability repair is shown?
Cross-pinning. Cross pins are typically incorporated into PMMA. Pins penetrate half the wing of the atlas.
What surgical technique for AA instability repair is shown?
Kishigami atlantoaxial tension band.
What are the surgical options for ventral AA lux stabilization?
- Transarticular screws or pins.
- Pins and PMMA
- Screws and PMMA
- Ventral plating
What muscles must be separated to gain access to the AA joint via a ventral approach?
The longus capitis and longis colli muscles.
What are the optimal angles for screw placement in ventral AA transarticular screw fixation?
40 degrees medial to lateral, and 20 degrees ventral to dorsal. Angled toward the medial aspect of the alar notch.
Ideal angles for small dogs are ideally obtained from CT scan.
What are the two screw configurations that can be used in ventral screw and PMMA fixation of AA instability?
In both techniques 2-3 screws are placed in the atlas (1 on each wing, and one midline).
Screws in the axis are then placed in one of two ways:
1) Four screw technique: screws are placed bilaterally in the cranial and caudal axis (or caudally in C3). K-wires or Steinmann pins are used to bridge the screws (connected by orthopedic wire), and the whole construct is encased in PMMA.
2) Two screw technique: a cranial and caudal screw are placed on the midline of C2. Two cross-pins are passed through the atlantoaxial articulations to maintain reduction and the entire construct is encased in PMMA.
What types of plates have been used for plating of the AA joint?
Mini-H-plates, butterfly plates (see image).
What are the reported complication rates for ventral and dorsal AA stabilization?
Dorsal: 71%
Ventral: 53%
What are the main surgical complications associated with AA luxation repair?
- Neurologic deterioration.
- Respiratory compromise: damage to the recurrent laryngeal nerve, compression on the trachea (PMMA), or tracheal necrosis.
- Implant migration/breakage: migration most common with transarticular pins secondary to improper pin placement and inadequate bone purchase.
- Vertebral fracture: dorsal arch of the atlas (dorsal techniques), ventral C2 body (central techniques).
- Recurrent pain
What is the reported rate of implant failure in AA luxation repairs?
May be as high as 48% for dorsal and 44% for ventral repairs
Dogs affected less than how many days was associated with greater likelihood of successful AA conservative management?
30 days.
38% of dogs managed conservatively reported to have a good outcome.
What is the perioperative mortality rate reported for AA stabilization techniques?
4-30%
What was the least successful ventral surgical stabilization method for AA luxation?
Use of transarticular pins alone
What risk factors have been identified for dogs undergoing surgical repair of AA luxation?
Older patients at the time of onset of clinical signs (>24-months), longer duration of clinical signs (>10 months)
The brachial plexus arises from which spinal cord segments?
C6-T2.
How frequently is the fifth cervical spinal cord segment involved in the brachial plexus?
In 24% of dogs
Outside of the CNS what is responsible for providing the myelin sheath?
Schwann cell plasma membranes. Schwann cells are separated by nodes of ranvier that aid in nervous conduction
What are the function of the dorsal and ventral spinal nerve roots?
Dorsal nerve root is for afferent sensory information, the ventral nerve root is for motor function and autonomic innervation.
Describe the supporting connective tissue structures of the nerve.
Endoneurium surrounds each axon. Groups of axons are surrounded by perineurium. The epineurium surrounds the entire nerve (not present in nerve roots).
What is the most common location of traction injury to the brachial plexus?
The intradural portion of the spinal nerve roots due to lack of epineurium (motor nerves most frequently affected)
Describe the anatomy of the brachial plexus
What are the 5 classes of injury after trauma to nerves?
- Neuropraxia: no damage to structure of nerve.
- Axonotmesis: Wallerian degeneration but architecture remains intact.
- Neurotmesis: complete nerve disruption but intact perineurium
- Neurotmesis: rupture of perineurium
- Neurotmesis: nerve completely severed
What diagnostics can aid in evaluation of brachial plexus trauma?
Electromyography, nerve conduction velocity studies, somatosensory evoked potentials, ultrasound, MRI.
Are the cranial or caudal nerves of the brachial plexus more commonly affected by trauma?
Caudal nerves
What are the different types of brachial plexus avulsion injury?
- Cranial: C(5)6-C7: Musculocutaneous, subscapular, suprascapular, axillary. Rare. Can still bear weight. Reduced shoulder movement and elbow joint flexion. Atrophy of supraspinatous and infraspinatous
- Caudal: C8-T2: Radial, median and ulnar nerves. Cannot extend carpus or elbow due to absence of innervation of triceps brachii. Limb carried in a flexed position as C6-C7 nerves intact. Horner’s syndrome (T1-T3) and ipsilateral cutaneous trunci reflex loss (C8-T1) are possible.
- Injury to entire plexus: Limb is dragged knuckled on the ground.
When is surgical repair of brachial plexus trauma indicated?
1) In cases of acute transection/neurotmesis.
2) If there is no improvement in 3-6 months following traction injury.
What are surgical methods of brachial plexus injury repair?
- Anastomosis (in cases of neurotmesis).
In instances of brachial plexus avulsion injury (where neurotmesis is rare), the following techniques are reported:
2. Neurotization: transfer of a nerve to a injured nerve, not as reliable as grafting. The lateral thoracic and thoracodorsal nerves have been used.
3. Nerve grafting
4. Nerve rootlet reimplantation
5. Amputation (after 4-6 weeks)
How is nerve root reimplantation performed?
Associated with significant ipsilateral or bilateral pelvic limb dysfunction post-operative.
What is the main complication associated with treatment of brachial plexus avulsion?
Self mutilation, especially when regeneration occurs (secondary to paresthesia). Gabapentin may be useful.
What are the widest intervertebral spaces in the cervical vertebral column?
C4-C5, C5-C6
Is the annulus fibrosus thicker dorsally or ventrally?
1.5 to 3 times thicker ventrally
What are the ligaments of the vertebral column?
- Dorsal and ventral longitudinal ligaments.
- Interspinous ligaments (blend dorsally with the supraspinous ligament).
- Yellow ligament (between the arches of adjacent vertebrae, above the epidural space, blend with the articular capsules of the zygapophyseal joints).
Where is the dorsal longitudinal ligament thickest?
The cervical vertebral column offering increased protection to herniation
Where is the internal vertebral venous plexus largest?
Cervical vertebral canal (larger and more lateralized)
Is cervical disc herniation more common cranially or caudally?
In chondrodystrophic breeds most common cranially (80% affect C2-C4).
Yorkshire terrier, chihuahua and large breed dogs more commonly affected caudally.
What is the most common clinical signs associated with cervical IVDH?
Neck pain (in up to 90% of dogs, and 60% of dogs with no neurologic deficits).
Why is it possible for a dog with neck pain to have evidence of spinal cord deviation but no neurologic signs in the cervical region?
The ratio of the vertebral canal to spinal cord diameter is greater in the cervical spine which allows greater cord displacement without compression
How frequently is nerve root signature observed in dogs with cervical IVDH?
22-50% of dogs
Is tetraplegia common in dogs with cervical IVDH?
No, only 2-7% of cases. Neurologic deficits are typically more pronounced with caudal lesions.
Is neck pain a common clinical feature of cervical ANNPE?
No, but neurologic signs are often more severe (non-ambulatory).
Why can cervical spinal cord lesions lead to respiratory dysfunction?
Paralysis of respiratory muscles and loss of sympathetic innervation leading to bronchoconstriction. Can be treated with mechanical ventilation and bronchodilators (theophylline)
What diagnostics might be useful in the work-up of cervical disc disease?
- CSF analysis (protein Tau may be a prognostic indicator).
- Radiographs (35% accuracy for site of IVDH) +/- myelogram.
- CT +/- myelogram.
- MRI (allows for much better identification of foraminal IVDH than myelographic techniques).
What is the most common myelographic finding with cervical IVDH?
Deviation of the ventral contrast column. Splitting of the ventral contrast column on lateral view indicates extradural lesion (image pg 463 Tobias)
What is a foraminal disc extrusion?
Disc extrusion close to or within the intervertebral foramen. Can be missed on myelography and on single midline sagittal MRI view. Need transverse MRI sections for accurate diagnosis
What is the appearance of hydrated nucleus pulposus extrusion on MRI?
High signal intensity (isointense to CSF) on T2W, low signal intensity on T1W
What are conservative treatment options for IVDH?
- Rest, analgesics (tramadol, gabapentin for nerve root signature) +/- NSAIDs or corticosteroids.
- Muscle relaxants (methocarbamol, diazepam).
- Chemonucleolysis (less effective in more severely affected dogs).
When is surgery indicated for dogs with cervical IVDH?
Dogs can be classified according to one of three groups:
1) first episode, neck pain only.
2) repeated episodes of neck pain.
3) neck pain and concurrent neurologic deficits.
Surgery recommended for groups 2 and 3.
What surgical approaches can be used for treatment of cervical IVDH?
1) Ventral slot: minimal muscle dissection and allows concurrent disc fenestration. Disadvantages include a limited field of view, hemorrhage from the vertebral venus plexus, and inability to decompress lateral or foraminal discs.
2) Slanted ventral slot: allows maintenance of the of the annulus and greater stability. The slot is 20% of the width and 20% of the length of the cranial vertebral body, angled toward the dorsal aspect of the annulus.
3) Dorsal laminectomy, or hemilaminectomy: increased muscle dissection, but provide greater spinal cord compression, and greater access to lateralized disc material.
What are the length and width limitations of the ventral slot procedure?
Should not be greater than 33% of the length of the vertebral bodies, or 50% of the width (although 33% also preferred)
How far can dorsal laminectomy extend along adjacent vertebral bodies for removal of cervical IVDH?
75% of the cranial and caudal laminae (the zygapophyseal joints are preserved).
In what size dog should cervical fenestration not be performed?
> 30 kg
How much of the annulus fibrosis should be removed in cervical fenestration?
1/3 to 1/2
What factors may be associated with an increased risk of post-operative hypoventilation?
Lesions between C2-C4, and dorsal laminectomy surgery
What are potential surgical complications associated with ventral slot surgery
- Respiratory compromise (more likely with lesions between C2-C4 and treatment by dorsal laminectomy associated with increased risk of respiratory complications).
- Cardiac dysrhythmias (stimulation of vagosympathetic trunk during the approach, disruption of descending UMN tracts to the sympathetic nervous system).
- Blood loss (internal vertebral venous plexus).
- Neurologic deterioration
- Seroma (particularly dorsal approaches).
- Vertebral subluxation (8% of cases)
What are some potential prognostic factors affecting outcome with cervical spine decompressive surgery?
- Site of IVDH: worse prognosis with more caudal lesions. May represent cervical spondylomyelopathy which could require concurrent stabilization.
- Type of treatment: prognosis better for surgical intervention (90% recovery and 10% recurrence following ventral slot, compared to 50% success and 36% recurrence for conservative approaches).
Factors with mixed reports as to whether prognostic:
1. Duration of clinical signs (not found to be prognostic, although dogs that were not walking at 2 wks post-operative at greater risk of non-recovery).
2. Severity of clinical signs (mixed, but not generally considered a significant predictor).
Do large or small breed dogs have a better prognosis following treatment for cervical IVDH?
Small breed dogs. Treatment of large breed dogs may be complicated by concurrent cervical spondylomyelopathy (only 66% success rate in these cases).
What is cervical spondylomyelopathy?
Disease of the cervical vertebral column commonly seen in large and giant breed dogs characterized by compression of the cervical spinal cord or nerve roots.
Why is cervical spondylomyelopathy less common in small breed dogs?
They have a proportionally larger vertebral foramen. Dobermans have a funnel shaped foramen.
What are the two recognized types of cervical spondylomyelopathy?
Disc associated: large breed dogs (Doberman), middle aged (7-years).
Osseous associated: Giant breed dogs, young (4-years).
What are the three factors that lead to disc associated cervical spondylomyelopathy?
- Vertebral canal stenosis
- High levels of torsion in the caudal cervical spine
- Large volume intervertebral discs
What is the pathophysiology of osseous associated cervical spondylomyelopathy?
Proliferation of the lamina, articular processes, or articular processes and pedicles cause varying degrees of vertebral foramen stenosis. This is through a combination of malformation and osteoarthritic changes.
Occasionally might be complicated by IVDH. Hypertrophy of the ligamentum flavum also often a feature.
Are single site or multiple site lesions more common in large or giant breed dogs with cervical spondylomyelopathy?
Giant: 20% had single lesion, compared to 50% of large breed
What is the most common location for compression in cervical spondylomyelopathy?
C6-C7 for both osseous and disc, followed by C5-C6 (disc), C5-C6/C4-C5 (osseous).
How is cervical spondylomyelopathy a dynamic disease?
Extension of the neck leads to narrowing of the vertebral foramen by 16.5% compared to normal. This worsens compression in any direction
What is the most common clinical finding in patients with cervical spondylomyelopathy?
Proprioceptive ataxia.
Neck pain is present in only 5% of cases. Tetraparesis in 10% and is more commonly disc associated.
What is the normal neuro-localization for a patient with cervical spondylomyelopathy?
C1-C5 or C6-C8 (with a reduction in withdrawal reflexes due to involvement of the musculocutaneous nerve).
What diagnostics are recommended for the work-up of cervical spondylomyelopathy?
- Radiography (of limited value).
- Myelography: risk of seizures and worsening of neurologic signs (seizures in 25% of Dobermans).
- CT: difficult to identify the main site of compression.
- MRI: gold standard. Should be performed in traction, flexion and extension to assess dynamic component.
Describe the findings in the following MRI/CT images.
What additional diagnostic tests are recommended prior to surgery in dogs with cervical spondylomyelopathy?
- Thyroid panel (hypoT common in Dobermans).
- von Willebrands antigen assay.
- Electrocardiogram, to assess for occult DCM.
What does medical management of cervical spondylomyelopathy entail?
- Exercise restriction +/- prednisone (to reduce vasogenic edema). If neck pain is a significant concern NSAIDs can be considered instead.
Clinical signs are improved or stable in 81% of dogs treated medically (surgical treatment led to improvement in 81% of dogs, compared to 54% managed medically).
What are factors to consider during surgical planning for disc associated cervical spondylomyelopathy?
- Decompress the spinal cord.
- Selection of the surgical technique based off the direction of spinal cord compression, and whether the lesion is static or dynamic.
What are surgical treatment options for CSM?
Direct decompressive techniques:
1) Ventral slot
2) Inverted cone v-slot
3) Dorsal laminectomy
4) Cervical hemilaminectomy
Indirect decompression:
1) Pins and PMMA
2) Screw bar-PMMA
3) PMMA plug
4) Locking plate
Motion preserving techniques
1) Cervical disc arthroplasty
What surgical treatment options are recommended for disc associated cervical spondylomyelopathy?
Static lesions: Ventral slot or cone ventral slot.
Dynamic lesions: distraction stabilization techniques such as PMMA plug or pins/screws embedded in PMMA. Continuous dorsal laminectomy also an alternative.
What surgical treatment options are recommended for osseous associated cervical spondylomyelopathy?
Generally considered a static disease (although all cervical spondylomyelopathy cases have some degree of dynamic component).
Due to primarily static nature, decompressive surgeries are prioritized: dorsal laminectomy, cervical hemilaminectomy.
Ventral distraction/stabilization with PMMA plug was thought to potentially reduce osseous degeneration/proliferation but there is no evidence of this.
What is the reported success rate of ventral slot when used in the treatment of CSM?
72%.
In the inverted cone ventral slot what is the width at the ventral vertebral body limited to?
20% of the vertebral body. By reducing bone removal the risk for vertebral subluxation is minimized.
What is the major problem with dorsal laminectomy procedures in the treatment of cervical spondylomyelopathy?
High morbidity rate (65-75% of dogs are worse post-operatively) which can be challenging to manage in large breed patients.
Success rate is 79-95%, although 30% of dogs can have recurrence.
How can postoperative laminectomy membrane formation be prevented following dorsal laminectomy for CSM?
- Fat grafts (may or may not be effective, should be limited to <5mm).
- Dorsal laminoplasty.
Are pins and PMMA more commonly used for single or multiple site ventral dynamic compressions?
Single site.
Success rate is 73%.
What angle should be used for pin placement in the cranial and caudal vertebral bodies when using pins and PMMA for stabilization of cervical spondylomyelopathy?
35 degrees dorsolateral, with increase to 45 degrees at C7
What are the advantages/disadvantages of PMMA plugs for the treatment of CSM?
Advantages: can be used to treat multiple sites concurrently.
Disadvantages: bony fusion unlikely to occur, long-term outcomes are varied, if combined with a ventral slot need to insert Gelfoam into the slot to prevent migration of PMMA into the vertebral canal.
What is the success rate of locking plate fixation for the treatment of CSM?
73% (3 cases reported). Can be combined with use of a PEEK cage.
What is the success rate of cervical disc arthroplasty?
Positive outcome in 91% of dogs, although subsidence was seen in all dogs and loss of motion was detected in 77%.
List direct decompressive surgical techniques described for the treatment of cervical spondylomyelopathy?
Ventral slot, inverted cone ventral slot, dorsal laminectomy, cervical hemilaminectomy
List indirect decompression (distraction stabilization) surgical techniques described for the treatment of cervical spondylomyelopathy?
Pins and PMMA, PMMA plug, locking plates
What are some complications associated with treatment of cervical spondylomyelopathy?
- Postoperative neurologic deterioration (70% with dorsal laminectomy, 40% with ventral slot).
- Vertebral foramen or transverse foramen implant penetration.
- Domino effect (20%). Typically effects one intervertebral disc space cranial or caudal. More common with distraction/stabilization techniques.
- Laminectomy membrane. Free fat grafts are not recommended due to high risk of failure.
- Implant failure: distraction-fusion techniques associated with a failure rate of 8-30%.
- Collapse of intervertebral foramina (particularly following ventral slot).
- Insufficient decompression.
What is the rate of domino effect following surgery for cervical spondylomyelopathy?
20% - appears more frequent following distraction stabilization techniques
What is the recurrence rate following surgical treatment of cervical spondylomyelopathy?
24%.
Some evidence to suggest that CSM may progress independent of the method of treatment.
What are extradural synovial cysts?
Cysts that originate from the zygapophyseal joint.
Can be divided into synovial and ganglion cysts.
Can occur anywhere throughout the vertebral column. In the cervical region may be associated with osseous cervical spondylomyelopathy
What are the most common locations affected by extradural synovial cysts?
- Cervical: most often young giant breed dogs with concurrent CSM.
- Thoracolumbar: middle aged and older large breed dogs.
- Caudal lumbar/lumbosacral: large breed, middle aged or older.
How are synovial extradural cysts diagnosed?
MRI (imaging modality of choice). Myelography may show a nonspecific extradural pattern of deviation.
What are treatment options for extradural synovial cysts?
- Rest and corticosteroids.
- Percutaneous cyst rupture with corticosteroid injection.
- Dorsal laminectomy (cervical or lumbosacral), or hemilaminectomy (thoracolumbar) if causing neurologic signs.
In a study by Bonelli 2024 in Vet Surg, what were the main MRI findings in German shepherds with cervical spondylomyelopathy?
Osseous proliferation of the articular processes +/- hypertrophy of the ligamentum flava.
In a study by Kikuchi 2023 in JAVMA, did vertebral stabilization following ventral slot decompression for IVDH in small breed dogs affect outcome?
No difference in outcome depending on whether or not vertebral stabilization performed. Increasing age was associated with recurrence.
In a study by Strobel 2019 in JAVMA, what were the two most common causes of cervical hyperasthesia in dogs? What two clinical signs were useful in differentiating cervical spine from multifocal disease? What CBC changes were common with multifocal disease?
Cervical spine (63%, specifically IVDH), and multifocal (22%, specifically steroid responsive meningitis arteritis) were the most common diseases.
Dogs with cervical spine disease were typically older than 36 months and were non-hyperthermic.
CBC changes common with multifocal disease were leucocytosis, neutrophilia, and monocytosis.
In a study by Argent 2022 JSAP, what was the complete recovery rate following medical and surgical management of cervical IVDH? What was the recurrence rate?
Medical: 30%, surgical: 70%.
The recurrence rate was 34%. Normally within 2 years of diagnosis. In medically managed dogs recurrence mainly occurred at the same site whereas after surgery normally occurred at an adjacent disc.
In a study by Jones 2022 in JSAP, what procedures for subarachnoid diverticulum correction were used?
Marsupialization, durotomy, shunt placement, durectomy, stabilization.
What diagnosis can be made based off the following CT scan of the cervical region in a 4 year old French bulldog with neck pain and left forelimb lameness (from a case report by Thibault 2023 in JSAP).
OCD of the cranial endplate of C5. Resolved by removal via ventral slot.
In a study by Bonelli 2021 in VRU, what percentage of dogs presenting with osseous associated cervical spondylomyelopathy were male? How many had multiple sites of spinal cord compression? Was there a correlation between neurologic grade and severity of spinal cord compression?
75% of dogs were male, and 78% had multiple sites of spinal cord compression. Dogs with multiple sites of compression were more likely to have severe spinal cord compression, foraminal stenosis, and ligamentum flavum/soft tissue proliferation.
Dogs with more severe spinal cord compression tended to have a higher neurologic grade.
Intervertebral disc degeneration was observed in 80% of dogs. Age was not associated with the manifestation of OA-CSM.
In a study by Reints Bok 2019 in Vet Surg, what implant (pictured) was used for cervical fusion in dogs with caudal cervical spondylomyelopathy?
SynCage (in conjunction with two Unilock plates). Outcomes were generally good, with subsidence, implant failure, and infraclinical pathology at adjacent vertebral segments the major post-operative complications).
In dogs <2 years of age, what were the 5 most common causes of myelopathy according to a study by Pilkington 2024 in JVIM?
Vertebral malformation, subarachnoid diverticulum, traumatic fracture, AA instability, osseous associated cervical spondylomyelopathy.
In a study by Bonelli 2023 in JVIM, what was the mean age of dogs presenting for combined disc and osseous cervical spondylomyelopathy? Was compression by both components at the same site associated with a higher neurologic grade?
7 years old (58% large breed, 37% giant breed).
Compression at the same site was associated with worse neurologic grade (67% occurred at the same location).
In a study by Murthy 2023 in JVIM, what type of cervical myelopathy was Horner’s syndrome most frequently associated with?
Noncompressive intraparenchymal lesion (FCE most common, compared to IVDH with non-Horner’s patients).
