Spinal Surgery in the Dog

Review localization of compressive lesions of the spinal cord.

Upper motor neuron lesions:Paresis or paralysisIntact = hyperreflexiaPreserved = increased muscle toneAtrophy = from disuse

Lower motor neuron lesions:Paresis or paralysisDecreased = hyporeflexiaHypotonia = decreased muscle toneNeurogenic atrophy

Spinal cord lesions: If lesion is between C1-C5=UMN lesion If lesion is between C6-T2=(area of innervation of

forelimbs)= LMN lesion If lesion is between T3-L3=UMN lesion If lesion is between L4-S1=(area of innervation of pelvic

limbs)=LMN lesion If lesion is between S2-S3=LMN to bladder and rectal

sphinters disrupted If lesion is between Cd1-Cd5=LMN to tail muscle are

disrupted

What are the important components of

conservative treatment for spinal cord disease?

• Used for management of mild cases and for postoperative management

• Conservative treatment includes:

• Absolute cage rest

• Anti-inflammatory drugs +/- muscle relaxants

• Serial neurological examinations

What is the most common cause of failure?

• b/c owner does not provide accurate cage rest

Why is fenestration alone seldom used in

management of spinal cord disease? • Because it does not remove the nuclear

material from the spinal canal and foramina, only from intervertebral spaces, therefore need another procedure for the other areas

Why is it used in conjunction with decompressive surgery?

• reduces risk of recurrence of disk disease

What are the 2 decompressive approaches for

the cervical spinal cord?

• Ventral slot decompression

• Cervical dorsal laminectomy and hemilaminectomy

What approaches are used for the thoracolumbar spinal cord?

• Fenestration

• Dorsal laminectomy

• hemilaminectomy

When is a durotomy indicated?

• Used for decompression of spinal cord and for direct examination of traumitized cord to assess damage

Describe postoperative management of the

spinal surgery patient. • Cage rest – water bed, air mattress

• Hydrotherapy, tail walking, passive range of motion exercise

• Care of urinary tract:

• Empty bladder at least 3 times/day

• Culture urine, treat as needed

In general, which neurological functions return first?

• Normal urination = 10-21 days

• Normal pain sensation = 10-21 days

• Voluntary paddling motions= 14-35 days

• Voluntary support of weight=14-42 days

• Ambulation= 14-90 days

• Proprioception= 21-180 days

What is the average time interval for

recovery of urinary tract function? • 10-21 days

of complete function?

• I am assuming this means complete fxn of everything….

• 21-180 days = proprioception last to return

Compare Hansen’s Type I and Hansen’s Type II Disk Disease in terms of: etiopathogenesis, signalment,

history, neurological signs and presenting complaint,

prognosis. • Hansen’s type I:• Etiology: • chondroid degeneration of disk• Nucleus pulposis becomes granular or calcified and thus less compressible• Annulus ruptures and nucleus is extruded into spinal canal or foramen• Signalment:• Chondrodystrophoid breeds = dachshund and beagle are most commonly affected• Adult, usually middle aged• No sex predillection• Disk rupture may occur with normal activity• HX:????• Hansen’s Type II:• Etiololgy:• Fibrinoid metaplasia of disk – common aging change in disk• Annulus fibrosis hypertrophies and protrudes into ventral spinal canal but does not rupture• No extrusion of nuclear material• Signalment:• Non-chondrodystrophoid breeds,often large breeds• Middle age to old dogs• No sex predilection

Why is the Hansen’s Type I patient with thoracolumbar disk extrusion more likely to show severe signs of cord compression than the patient

with cervical disk protrusion?• because cervical herniation has the dorsal

longitudinal ligament which decreases the cord compression

What are the indications for decompression in Hansen’s Type I

patients with cervical disk extrusion?

• Neurological abnormalities, severe pain, frequent repeated episodes of mild pain

• Rad evidence of disk material compressing the spinal cord or nerve root

• Deterioration while undergoing conservative treatment

What are the indications for these patients when the disk extrusion is

in the thoracolumbar region? • Recurrent pain +/- mild paresis

• Severe paraparesis

• Paraplegia +/- deep pain sensation

• Patient that becomes worse during conservative tx

List 3 factors associated with poor prognosis for these patients.

• Acute onset

• Severe neuro signs

• Duration of paraplegia >48 hours

What are the types of lesions seen in wobbler’s syndrome?

• Type 2 disk

• Vertebral tipping

• Congenital osseous malformation

• Hourglass compression

• Ligamentum flavum/ vertebral arch malformation

Which 2 are most common?

• Type 2

• Vertebral tipping

Which may be dynamic?

• Chronic degenerative disk disease

• Vertebral tipping

• Malformation of the vertebral arch w hypertrophy of the ligamentum flavum

In what position of the neck are these animals worse?

• If they hold their head up (dorsal extension)

Describe medical management for the patient with wobbler’s

syndrome. When is it indicated? • Indicated for dogs with pain only or with mild

weakness and motor deficits

• Strict confinement for 3-4 weeks followed by gradual return to normal activity over next 3-4 weeks

• Neck brace

• Use of harness instead of collar

• Anti-inflammatory drugs

What are the 3 objectives of surgical treatment?

• Relief of SC compression

• Cervical spinal stabilization

• Reversal of neuro deficits

If you were to do surgery on a dog with a Type II disk lesion and ventral vertebral tipping, what approach would you choose? • Ventral

If this dog had a dynamic compressive lesion, what additional

procedure (in addition to decompression) would be required?

• Ventral stabilization-traction

Define cauda equina syndrome.

• Complex of neuro signs caused by compression of the terminal nerve roots in the lumbosacral spinal canal

What are the common history and clinical signs?

– Chronic lameness, back pain and hind limb weakness

– Urinary or fecal incontinence– Abnormal tail carriage or movement– Muscle atrophy– Self mutilation of the tail or hind feet

What is the surgical approach and treatment?

• Dorsal laminectomy +/- facetectomy and removal of interarcuate ligaments

• Retract nerve roots to remove disk

• Remove fibrous tissue surrounding nerve roots

• Stabilize, if instability is diagnosed

What 1 neurological abnormality is most often associated with a poor

prognosis?• Chronic cases with incontinence

Define atlanto-axial instability

• An alteration of the dens or the ligaments of the atlantoaxial articulation that causes instability, vertebral subluxation and spinal cord or nerve root compression

What is one very important problem to avoid during physical

examination and radiography of these patents’?

• Avoid flexion of the neck and avoid open mouth views when doing rads

Describe, in general terms, 2 surgical methods of treating this

condition.• Ventral approach: removal of dens and

reduction of subluxation; Cross pin stabilization

• Dorsal approach: hemilaminectomy place suture through dorsal process of axis and arch of axis

Where are spinal fractures most likely to occur?

• C2

• L1

• L7

When will you treat these fractures conservatively?

• If patient has good motor and sensory function treat conservatively

When is surgical treatment required?

• If motor or sensory function is impaired decompression and stabilization are indicated

Review the types of stabilization that can be used on these fractures.

• Cervical fx

– Dorsal stabilization: wire or screw fixation of laminae or articular facets

– Ventral stabilization: cross pins +/- bone cement, ventral plate or interbody screw fixation

• Thoracolumbar fx– Hemilaminectomy – Dorsal spinous process stabilization plus body cast– Vertebral body plates– Dorsal cross pins and bone cement – Combination techniques (pins and bone cement + Lubra

plate)