Lecture 36: IVDD

What are the chondrostrophic breeds?

Dachshund, Beagale, Pekingese, French Bulldog, Cocker Spaniel

Fibrocartilaginous lamellae, thicker ventrally

Annulus fibrosis

Amorphous gels, absorbs compressive loads

Nucleus pulposus

A- Nucleus pulposus

B- Annulus fibrosis

• Cartilaginous end plates

• Hyaline cartilage

• Permeable outer and inner zones

• Primary supplies of disk nutrition

Intervertebral disk

A- Cranial articular process

B- Dorsal longitudinal ligament

C- Vertebral venous plexus

D- Annulus fibrosus

E- Ventral longitudinal ligament

F- Caudal articular process

What makes up the spinal meninges?

1. Dura mater

2. Arachnoid mater

3. Subarachnoid space

4. Piamater

What layer of spinal meninges do we collect CSF from and inject contrast into?

Subarachnoid space

What makes up the spinal vasculature?

Paired vertebral venous sinuses, more lateralized in the thoracolumbar spine compared to cervical spine

What does degeneration of the nucleus pulposus cause?

Loss of water and proteoglycan molecules, increased collagen, calcification

Who does fibroid degeneration occur in?

Non-chondrodystrophic breeds

Disk degeneration of chondrodystophic breeds that occurs at first year of life

Chondroid metaplasia

• Herniation of nucleus pulposus thru the annulus w/ extrusion into the spinal canal

• Acute onset

• Young chondrodystrophic breeds

Hanon type I

What is the most common areas?

T10-L1

• Protrusion of the annulus into the spinal canal

• Slow progressive onset

• Older nonchondrodrodystrophic breeds

Hanson Type II

• Forceful extrusion of small volume of nucleus pulposus thru the annulus w/ contusion of spinal cord

• Acute onset

• Young, chondrodystrophic breeds

Hanson Type III

What does primary trauma cause to the spinal cord?

• Inflammation

• Focal hemorrhage

• Spinal cord swellling

• Initiation of secondary mechanisms of injury

What are the secondary mechanisms of injury?

• Vasoconstrictive substances (ischemic injury)

• Increased in intracellular calcium (impaired metabolism)

• Formation of lipid perioxidases (chemical damage)

Proprioception

Large, mylinated

voluntary muscle control

Intermediate, mylinated

Superficial pain

Smaller, mylinated

Deep pain

Small, unmylinated

When are surgery rads essential?

For differential diagnosis

What can you see with surgery rads?

• narrowing/wedging of disk space

• Alteration of intervertebral foramen shape

• Presence of mineralized disk material

What is the seizure risk of myelography?

0-10%

Where do you perform a lumbar puncture?

L5-L6 or L4-L5 disk space

Where do you take cistern puncture?

Ceremedulary cistern

What should you do during a neuro exam for suspected IVDD dog?

• Observe gait

• Assess CP’s

• Test patella reflexes

• Palpate entire spine

• Assess superficial pain

• Assess deep pain

Differential diagnosis for IVDD

• FCE

• Spinal fracture/ luxation

• Neoplasm

• Diskospondylitis

• Meningitis/myelitis

• Single or occ. Episode of mild to moderate back pain ± CP deficits, no motor weakness

• Conservative treatment

• Favorable prognosis

Stage I thoracolumbar disk disease

• Second episode or persistent and marked back pain, ± CP deficits

• Dogs are able to stand and walk but may be ataxic

• Conservative or surgical decompression

• Favorable to guarded prognosis

Stage II thoracolumbar disk disease

• Uncontrolled sever back pain, ± CP deficits

• Dog are ataxia and ambulation is difficult

• Surgical decompression

• Excellent prognosis

Stage III thoracolumbar disk disease

• No hindlimb motor function but deep pain sensation is present

• Surgical decompression

• Excellent prognosis

Stage IV thoracolumbar disk disease

• No hindlimb motor function, no deep pain sensation

• Surgical decompression <48 hrs

• Unfavorable prognosis

Stage V thoracolumbar disk disease

What occurs during conservative therapy?

• Strict immobilization

• Minimum 3 weeks

• Resolution of inflammation

• Resorption

• Fibrosis

What drugs are used in medical therapy?

Methylprednisolone, prednisone, methocarbamol, carprofen

Hemilaminectomy

Pediculectomy

Modified dorsal laminectomy

When can you perform fenstration/laser ablation?

In combination with spinal cord decompressive surgery

Prognosis if deep pain is present?

80-96% with 4 week recovery time

What is needed for recumbent nursing care?

• Keep clean, dry, well padded

• Check and express bladder three to four times a day

• Physical therapy

What does prognosis if deep pain is absent?

Depends on duration of time between loss of deep pain and surgical treatment (38-50% success if 12-48 hrs after loss of deep pain)

Cervical disk disease

Differential diagnosis for cervical disk disease

• FCE

• Spinal OA

• Wobbler’s

• Spinal fracture/luxation

• Neoplasm

• Atlantoaxial instability

• Meningitis/myelitis

• Diskospondylitis

• Single or occ. episode of mild to moderate neck pain

• Conservative

• Favorable prognosis

Stage I Cervical disk disease

• First episode of severe neck pain, or second episode of mild to moderate neck pain

• Conservative treatment, surgical decompression

• Favorable to execellent

Stage II cervical disk disease

• Uncontrolled neck pain, or repeated episode of neck pain

• Surgical decompression

• Excellent

Stage III cervical disk disease

• Ambulatory tetraparesis

• Conservative and surgical decompression

• Guarded to excellent

Stage IV cervical disk disease

• Nonambulatory tetraparesis w/out forelimb sensory deficits

• Surgical decompression

• Excellent

Stage V cervical disk disease

• Nonambulatory tetraparesis w/ forelimb sensory deficits

• Surgical decompression

• Guarded prognosis

Stage IV cervical disk disease

What is seen with conservative management of cervical disk disease?

• Strict cage confinement

• ± medical therapy

• NO neck leads

• Very minimal risk of tetraparesis

Ventral slot

Dorsal hemilaminectomy

prognosis of cervical disk disease

• Excellent for dogs with neck/forelimb pain only

• Non-ambulatory dogs w/ good forelimb sensation 75% success rate

• Non-ambulatory dogs with loss of forelimb sensation have a guarded prognosis

Which of the following breeds is commonly affected by IVDD? a) Labrador Retriever b) German Shepherd c) Dachshund d) Golden Retriever

c) Dachshund

Which of the following is a typical Physical Exam (PE) finding associated with Thoracolumbar (TL) IVDD? a) Decreased range of motion in the neck b) Ataxia in the hindlimbs c) Pain upon palpation of the cervical spine d) Forelimb lameness

b) Ataxia in the hindlimbs

Hanson Type I IVDD is characterized by: a) Slow, progressive protrusion of the annulus. b) Typically affecting older, nonchondrodystrophic breeds. c) Acute herniation of the nucleus pulposus through the annulus. d) A forceful extrusion of a small volume of the nucleus pulposus causing contusion.

c) Acute herniation of the nucleus pulposus through the annulus.

Which type of breed is most commonly affected by Hanson Type I IVDD? a) Large breed dogs b) Giant breed dogs c) Young, chondrodystrophic breeds d) Older, non-chondrodystrophic breeds

c) Young, chondrodystrophic breeds

The annulus fibrosis of the intervertebral disk is described as: a) An amorphous gel that absorbs compressive loads. b) Fibrocartilaginous lamellae, thicker ventrally. c) Hyaline cartilage responsible for disk nutrition. d) Composed of paired vertebral venous sinuses.

b) Fibrocartilaginous lamellae, thicker ventrally.

The nucleus pulposus of the intervertebral disk primarily functions to: a) Provide the main source of disk nutrition. b) Form the outer layer of the disk. c) Absorb compressive loads. d) Protect the spinal meninges.

c) Absorb compressive loads.

Which of the following is NOT a layer of the spinal meninges? a) Dura mater b) Arachnoid mater c) Pia mater d) Periosteum

d) Periosteum

Degeneration of the nucleus pulposus involves: a) Increased hydration and proteoglycan molecules. b) Decreased collagen content. c) Reduced calcification. d) Loss of water and proteoglycan molecules.

d) Loss of water and proteoglycan molecules.

Which diagnostic technique has limited accuracy in localizing disk extrusions? a) Myelography b) CT scan c) MRI d) Survey Radiographs

d) Survey Radiographs

What contrast agent is commonly used in myelography for diagnosing IVDD? a) Barium sulfate b) Iohexol or iopamidol c) Propofol d) Ketamine

b) Iohexol or iopamidol

What is a potential risk associated with performing myelography? a) Bradycardia b) Hypertension c) Seizures d) Hypothermia

c) Seizures

Assessment of which neurological function is crucial in determining the prognosis for Thoracolumbar IVDD? a) Palpebral reflex b) Pupillary light reflex c) Deep pain sensation d) Patellar reflex

c) Deep pain sensation

According to the staging chart for Thoracolumbar Disk Disease, a dog with no hindlimb motor function but with deep pain sensation (Stage IV) typically has what treatment recommendation? a) Strict confinement b) Medical management only c) Surgical decompression d) Euthanasia

c) Surgical decompression

What is the most common surgical procedure performed for Thoracolumbar IVDD? a) Fenestration b) Hemilaminectomy c) Laminectomy d) Pediculectomy

b) Hemilaminectomy

For Thoracolumbar IVDD, conservative therapy primarily involves: a) Moderate exercise b) Short walks on a leash c) Strict immobilization d) Hydrotherapy

c) Strict immobilization

Methylprednisolone (Solu-Medrol) is sometimes used in the medical management of IVDD to: a) Provide long-lasting pain relief. b) Inhibit oxygen free-radical lipid peroxidation. c) Stimulate appetite. d) Prevent urinary tract infections.

b) Inhibit oxygen free-radical lipid peroxidation.

Which of the following is NOT a differential diagnosis for Thoracolumbar Disk Disease? a) Spinal fracture/luxation b) Neoplasm c) Atlantoaxial instability d) Diskospondylitis

c) Atlantoaxial instability

In Cervical Disk Disease, a surgical treatment option includes: a) Dorsal laminectomy b) Ventral slot c) Hemilaminectomy (primarily TL) d) Fenestration (not sole treatment)

b) Ventral slot

What is a critical aspect of conservative management for Cervical Disk Disease? a) Encouraging gentle neck exercises. b) Using a neck lead for walks. c) NO neck leads. d) Massaging the neck muscles.

c) NO neck leads

According to the prognosis for Cervical Disk Disease, dogs with only neck/forelimb pain undergoing surgical treatment typically have a(n): a) Guarded prognosis b) Fair prognosis c) Excellent prognosis d) Poor prognosis

c) Excellent prognosis