06, 07 Spinal Cord Disease of Dogs and Cats

Clinical features of: – Degenerative diseases of the spinal cord of dogs • Intervertebral disc disease (IVDD) • Cervical spondylomyelopathy (CSM) • Degenerative lumbosacral stenosis (DLSS) (also known as cauda equina syndrome) • Canine degenerative myelopathy (DM) – Other types of disc disease • Acute non-compressive nucleus pulposus extrusion (ANNPE) • Hydrated nucleus pulposus extrusion (HNPE) • Fibrocartilaginous embolism (FCE

Degenerative diseases of the spinal cord of dogs includes 4

1. Intervertebral disc disease (IVDD)

2. Cervical spondylomyelopathy (CSM)

3. Degenerative lumbosacral stenosis (DLSS) (also known as cauda equina syndrome)

4. Canine degenerative myelopathy (DM)

Other types of disc disease

Acute non-compressive nucleus pulposus extrusion (ANNPE) • Hydrated nucleus pulposus extrusion (HNPE) • Fibrocartilaginous embolism (FCE)

Intervertebral disc – normal anatomy

Intervertebral disc : present between all vertebrae except C1-2. (C1-2 synovial joint instead)

2 components:

• Nucleus pulposus: inner component, gelatinous in young normal animals

• Annulus fibrosus: outer layer, fibrous, ventral portion thicker than dorsal

Intercapital ligament – between rib head on either side of vertebrae, T2 to T10

• cover annulus fibrosus dorsally to reinforce, IVDD unusual in these locations

IVDD— normal anat

is the lack of IVD in C1/C2 normal?

No disc at C1-2 is normal as it is a synovial joint

IVDD - Pathogenesis

• describe

• 3 main factors

• what will genetic predispose animal to IVDD

Degeneration of the intervertebral disc (multifactorial)—> mineralisation/ whitening of nucleus propulus

• Process of aging

• Biomechanical strain & trauma

• Genetic (FGF4 gene)

  • Chondrodystrophic breeds eg Dachshund, French Bulldog.

  • short limb phenotype FGF4

Stages of IVDD degeneration

1. Chondroid metaplasia

   • nucleus pulposus and then the annulus fibrosis

   • notocordal cells (NP) and spindle shaped fibroblasts (AF) replaced by chondrocytes

2. Dehydration of nucleus pulposus

   • loss of glycosaminoglycan from NP

3. Fissures in annulus fibrosus

   • tears and clefts form in AF, most commonly dorsal or dorsolateral regions

4. Necrosis and secondary calcification

   • mainly NP periphery and occasionally in AF

Types of degenerative intervertebral disc disease (IVDD)

Hansen type I : Intervertebral disc extrusion (IVDE)

• Complete rupture of the annulus fibrosus

  • spilling-out of the nucleus pulposus into the vertebral canal

• Chondrodystrophic breeds : frenchies, daschund

• early as < 1 year old

• acute onset histological degenerative

Hansen type II: Intervertebral disc protrusion (IVDP)

• Fissures form in the annulus fibrosus

  • bulging of the annulus fibrosus and nucleus pulposus

• Non-chondrodystrophic breeds

• Older > 5 years

• Chronic, more slowly progressive onset

Neurological examination includes 6

• name an extra one if patient is paralysed

• Mentation/Behaviour

• Gait – ambulatory, non-ambulatory; paretic or plegic

• Posture – kyphosis, lordosis or scoliosis

• Proprioception – e.g. paw replacement and hopping

• Muscle tone and muscle mass – limbs and bladder tone

• Spinal reflexes e.g. Withdrawal reflexes, patellar reflex, perineal reflex and cutaneous trunci reflex

  • not indicative of degree of leision

• (Sensation or pain perception Important only test in paralysed patients.)

  • if motor ability ok sensation will be ok

name this posture

Kyphosis

name the posture

Lordosis

name the posture

Scoliosis (DV view)

Neurolocalisation clasificaiton

dogs

• C1-C5 = cervical

• C6-T2 = cervical intumescence

• T3-L3= thoracolumbar

• L4-S3 = lumbosacral intumescence

  • Split into L4-S1 and S1-S3

Grading of dysfunction: name from least significant to most 5

1. Pain or hyperaesthesia

2. Proprioceptive ataxia and ambulatory paresis

3. Non-ambulatory paresis (not able to walk but still see movemetn when moving ox)

4. Plegia

5. Plegia with loss of pain perception

Paresis (para, tetra)

weakness, voluntary movement present

Plegia or paralysis

loss of voluntary movement

Effect when motor neuron s affected: Upper and lower motor neuron

Upper motor neuron (UMN):

• Increased muscle tone

• normal or increased spinal reflexes

Lower motor neuron (LMN)

• Decreased muscle tone

• decreased or absent spinal reflexes

• when intumescences are affected

muscle mass and bladder effect: in each location of the spincal cord

• where is the UMN of baldder and where is LMN)

For bladder

Upper motor neuron (UMN) (C1-S1)

• When referring to the bladder, increased bladder wall (detrusor muscle) tone

• difficult to express due to increased tone in urinary sphincters

Lower motor neuron (LMN) (S1-S3)

• When referring to the bladder, decreased bladder wall (detrusor muscle) tone

• easy to express due to loss of tone in urinary sphincters

Cervical IVDD (C1-5, C6-T2)

• Clinical Signs 5

• describe 4 types of gait presentation

1. Pain/Hyperaesthesia

   • Reluctance to move, reduced range of movement in the neck

2. Posture – Low head carriage

3. Gait

   • Single thoracic limb lameness = ‘nerve root signature’ (see pic)

   • Ambulatory hemi- or tetra-paresis and proprioceptive ataxia

   • Non-ambulatory tetraparesis

   • Tetraplegia

4. Respiratory arrest (C5-7, phrenic nerve)

5. Horner's syndrome (T1-3, sympathetic innervation to the eye)

describe Ambulatory tetraparesis, generalized proprioceptive ataxia— gait

• 3

Gait in all 4 limbs uncoordinated and unsteady

Long strides in all 4 limbs

Wide based in pelvic limbs

cervical IVDD causes resp arrest via

(C5-7, phrenic nerve)

cervical IVDD causes horner syndrome via

(T1-3, sympathetic innervation to the eye)

cervical IVDD if frequent in these location:

• small breed

• large breed

small breed, C5-6

large breed, C6-7

Thoracolumbar IVDD

• Clinical Signs 4

• 2 posaible gait

• most frequent in

1. Pain/Hyperaesthesia – reluctance to move

2. Posture – Kyphosis

3. Gait – Pelvic limb lameness = ‘nerve root signature’

   • Ambulatory mono- or para-paresis and proprioceptive ataxia

   • Non-ambulatory paraparesis – Paraplegia Loss of pain perception

4. Urinary and faecal incontinence

Most frequent between T11-12 to L3-4.

Thoracolumbar IVDD most common location is between ______ and ___

• it is especially common in____ and ____

between T11-12 to L3-4.

Especially T12-13 and T13-L1

Ambulatory paraparesis and proprioceptive ataxia gait discription 2

Pelvic limb gait uncoordinated and unsteady

Varies between narrow based and wide based

gait describe— Non-ambulatory paraparesis and proprioceptive ataxia 2

lift/ sling neeeded

not relaly moving HL

Lumbosacral IVDD

• Clinical Signs 4

• gait possibility 3 /4

• what is nerve root signiture for lumbosacral

Pain/Hyperaesthesia (reluctance to move)

Posture

• Crouched stance in pelvic limbs • Low tail carriage

Gait

• Pelvic limb lameness = ‘nerve root signature’

• Ambulatory mono or paraparesis and proprioceptive ataxia

• Non-ambulatory paraparesis

• Paraplegia with or without deep pain perception

Urinary and faecal incontinence

Radiography IVDD: px positioning and sensitivtiy

– lateral and ventrodorsal, patient under sedation

sensitivity of 50-60% in the thoracolumbar region, 35% in the cervical region o

Radiographic changes supportive of IVD extrusion (hanson type1) 4

• Narrowing of the disc space

• Narrowing of the articular facets

• Narrowing and/or increased opacity of the intervertebral foramen

• Presence of mineralized disc material within the vertebral canal

radiographic evidence supportive of intervertebral disc degeneration but not disc extrusion 1

• what would you remind O if dog is under 2 y/o 2

Mineralisation (or calcification) of the disc space in situ

• disc calcification at 2 years old is a significant predictor of disc herniation later in life

• risk factor for recurrent herniation following surgery.

Computed Tomopgraphy for IVDD diagnosis

3D image free from superimposition o Wider availability, less costly and much faster – vs. MRI o Characteristics compatible with acute intervertebral disc extrusion in CT: hyperattenuating (white) material within the vertebral canal, loss of epidural fat and distortion of the spinal cord o Soft tissue structures have similar appearance – spinal cord, cerebrospinal fluid and meninges o 82-100% sensitivity in the thoracolumbar region

CT myelography

Contrast injected into the subarachnoid space o Delineates compressive lesions not visible on non-contrast CTs

MRI IVDD

Gold standard o Can differentiate anatomical structures of vertebral column better to CT, including supporting ligamentous structures, synovial joints, bone marrow, nerve roots, spinal cord parenchyma, cerebrospinal fluid, epidural fat and the layers of the intervertebral disc o Characteristics of IVDE include extradural compression of the spinal cord centred over or near the intervertebral disc space ▪ Compression and/or displacement of the spinal cord = displacement or loss of the hyperintense (white/bright) signal associated with subarachnoid and epidural spaces on T2W images ▪ Extruded nucleus pulposus typically = hypointense (black/dark) mass within the epidural space on T2W images o Requires GA whereas CT can be done under sedation o Sensitivity 98.5%

Conservative treatmentI VDD tx

onservative treatment o Indications:

• First episode of spinal hyperaesthesia with mild or no neurological deficits ▪ Chronic but mild neurological deficits ▪ Financial limitations

EXERCISE RESTRICTION

Analgesia – discuss risks of analgesia if strict rest is not implemented (patients feel better and more mobile which can lead to further disc material extruding)

Monitor urination and defecation

Rehabilitation / physiotherapy if required

IVDD Surgical treatment disc removal indication

Indications: ▪ Significant neurological deficits – inability to walk to loss of pain perception ▪ Pain or mild neurological deficits unresponsive to rest and analgesia ▪ Frequent recurrence of pain or neurological deficits following medical management

• wil nver fully heal dc

IVDD sx In the cervical vertebral column

t commonly a ventral slot procedure is performed ▪ Section of the intervertebral disc and 2 adjacent ventral bodies is removed to access the vertebral canal from the ventral aspect

IVDD sx In the thoracolumbar vertebral column

hemilaminectomy procedure is performed o The articular facet joint and lamina of 2 (or more) adjacent vertebrae is removed to access the vertebral canal from the dorsolateral aspect (blue arrow) o Additionally a fenestration may be performed. A section of the lateral aspect of the annulus fibrosus is removed and the nucleus pulposus is curetted (scooped) out (yellow arrow)

Prognosis • Intervertebral disc extrusion

Prognosis: cervical

prognosis • Intervertebral disc protrusion

Surgery: 75% improve o Medical: 40% improve o Chronic presentation, likely to have permanent neurological deficits due to irreversible spinal cord damage

Cervical spondylomyelopathy (CSM)

Causes vertebral canal stenosis (narrowing) ▪ Combination of static and dynamic compression ▪ Static – compression always present ▪ Dynamic – compression improves or worsens with different positions of the cervical vertebral column o 2 forms with different pathophysiology ▪ Disc-associated CSM ▪ Osseous-associated CSM o Signalment: ▪ All canine breeds ▪ 60-70% Doberman and Great Dane

Disc-associated CSM

Signalment: Middle-aged large breed dogs (primarily Dobermans) o History: Typically chronic o Clinical signs: As for cervical IVDD o Pathogenesis: ▪ Degenerative (with likely genetic component, although unproven) ▪ Intervertebral disc protrusion and ligament hypertrophy (dorsal and ventral to the spinal cord) leads to narrowing of the vertebral canal and spinal cord compression ▪ C5-6 and C6-7 most commonly affected o Diagnosis: MRI

thickening of ligament (dorsal) and extrucion in ventral

• Osseous-associated CSM

Young, giant breed dogs

History: Typically chronic o Clinical signs: As for Cervical IVDD o Pathogenesis: ▪ Unknown aetiology, suspected combination of genetic, conformational and nutritional ▪ Vertebral malformation + degenerative osseous change ▪ Leading to osseous proliferation of vertebral arch, articular processes (osteoarthritis) and pedicles. ▪ Most giant breed dogs have osseous compression, can have disc protrusion, especially in older dogs ▪ C4-5, C5-6 and C6-7 o Diagnosis: MRI or CT

CSM Conservative treatment

▪ Exercise restriction, body harness rather than collar ▪ Anti-inflammatories (NSAIDs or corticosteroids) and analgesia

CSM Surgical treatment:: lots of types

Ventral slot for disc decompression +/- stabilisation ▪ >> Dorsal laminectomy to address osseous compression +/- stabilisation

CSM Prognosis

Surgery 70-90% improvement ▪ Conservative 14-54% ▪ However, progression of disease with both treatment strategies

spinal cord end l5

3. Degenerative lumbosacral stenosis (DLSS)

Lumbosacral junction = L7-S1 Cauda equina = L7, S1-3, Cd1-5 nerve roots

DLSS Signalment/Histor

Medium to large dogs of middle to older age o Especially German Shepherd dogs o Variable - acute or chronic and may be persistent or episodic

DLSS clins gin

Pelvic limb hypometria (short strided, reduced stride height) o Lumbosacral pain, pain on elevation of the tail o Lameness (‘nerve root signature’) – unilateral or bilateral o Urinary or faecal incontinence o Tail weakness o Reduced perineal and pelvic limb withdrawal reflexes

normal anatomy

sc end sat L5

DLSS Pathogenesis

= multifactorial: o Congenital vertebral malformation o L7-S1 intervertebral disc degeneration ▪ Protrusion ▪ Collapsed disc space o Hypertrophy of ligaments of lumbosacral joint (caused by instability) o Degenerative joint disease of articular processes o Spondylosis deformans • Collectively lead to narrowing of the vertebral canal and intervertebral foramen and nerve impingement

DLSS dx

which on egold stamdard

o Radiography – able to identify the osseous changes o CT – able to identify the osseous changes o MRI – better for assessing nerves of cauda equina and intervertebral disc changes

DLSS tx: Conservative treatment:

Exercise restriction and analgesia ▪ Epidural steroid injections – Variable response, may provide long lasting resolution of clinical signs

DLSS tx: Surgical treatment:

Dorsal laminectomy +/- foraminotomy ▪ +/- spinal distraction-stabilisation if instability

DLSS Prognosis: Usually good (but what if urine inconinuence)

Chronic cases likely to require long-term analgesia ▪ Poor prognosis in dogs presenting with chronic urinary incontinence

Canine Degenerative Myelopathy (CDM) Signalment

Middle age to older dogs, usually large breed o German Shepherd Dogs (GSD), Boxer, Pembroke Welsh Corgis (PWC) , Bernese Mountain Dog, Chesapeake Bay Retrievers, Rhodesian Ridgebacks, and other breeds o GSD median age onset 9 years, PWC 11 years

CDM • History and clin sign

Slowly progressive clinical sign o Non-painful

• Initially: asymmetrical T3-L3 myelopathy o Progresses to involve L4-S3 and C6-T2 spinal cord segments and eventually involves the brainstem

CDM staging

not in slides

CDM pathogenesis

Concurrent axonal and myelin degeneration of the spinal cord o Multifactorial: Immunological, metabolic or nutritional, oxidative stress, excitotoxicity and genetic mechanisms o CDM has genetic and clinical similarities with amyotrophic lateral sclerosis (ALS) in humans

CDM dx

• defin dx

reported breed, supportive neuro sign

Exclusion of other conditions

• E.g., Intervertebral disc protrusion, neoplasia

Genetic test

• SOD1 gene o Positive result to support pre-existing clinical suspicion, not diagnostic o See: http://www.offa.org/dnatesting/dmexplanation.html

Definitive diagnosis can only be achieved with post-mortem evaluation of the spinal cord

Other types of intervertebral disc disease

• Acute non-compressive nucleus pulposus extrusion (ANNPE)

Hydrated nucleus pulposus extrusion (HNPE)

Fibrocartilaginous embolism (FCE) —> ** Vascular myelopathy

Acute non-compressive nucleus pulposus extrusion (ANNPE)

non compressive—> contrindication for sx

• brighter, bruising but nothing else

History: associated with a trauma or high-impact activity

Clinical signs:

• acute onset, lateralised neurological deficits

• Non progressive after first 24 hours

• Often vocalize at onset and may be painful in first 24h

• Neurological signs depend on location and degree of spinal cord damage

Pathogenesis: Sudden extrusion of small volume of disc material, impacts spinal cord with force

Diagnosis: MRI

Treatment: Conservative

Prognosis: Recovery of ambulation excellent, variable recovery of continences

Hydrated nucleus pulposus extrusion (HNPE)

Signalment: o Any breed, chondrodystrophic and non-chondrodystrophic o Typically middle aged or older

History: o Spontaneous, without inciting cause

Clinical signs: o Acute onset, non-progressive, symmetrical neurological deficits o Cervical location more common – tetraparesis, tetraplegia, respiratory compromise also possible o Typically non-painful

Pathogenesis: o Partially or non-degenerate disc extrudes, varying degree of compression

Diagnosis: MRI

Treatment: o Conservative (see earlier slide) – surgery if not improving( and dryspnoea) • Prognosis: o usually excellent, same conservative vs. surgical

Fibrocartilaginous embolism (FCE)

Signalment: o Most common in medium to large breed o Typically nonchondrodystrophic o Miniature Schnauzer o Rare in cats

History: o Typically spontaneous o Inciting cause of exercise or trauma in 30%

Clinical signs: o Peracute onset of nonpainful, lateralising clinical signs Dewey, 2015 o Majority of cases clinical signs don’t progress beyond first 24 hours

Pathogenesis: o Ischaemic infarct secondary to occlusion of artery/vein supplying the spinal cord o Caused by fragment of fibrocartilage thought to come from intervertebral disc • Diagnosis: MRI

Treatment: Conservative (see earlier slide) • Prognosis: usually excellent, but depends on response in the first 2 weeks of treatment and MRI findings

02

Clinical features of: – Steroid responsive meningitis-arteritis (immune mediated) – Discospondylitis (infectious) – Congenital or anomalous diseases • Chiari-like malformation and syringomyelia • Atlanto-axial subluxation • Hemivertebrae • Spinal arachnoid diverticula Clinical features and management of acute spinal cord trauma

Immune mediated diseases of the spinal cord

Steroid responsive meningitis-arteritis (SRMA)

Meningomyelitis of unknown origin also known as Granulomatous meningoencephalomyelitis (GME) - see notes on vestibular disease

Steroid responsive meningitis-arteritis

Signalment:

• Young (< 2 years of age) dogs

• Medium and large-breed dogs most often (but any breed can be affected)

• predisposition in Boxers, Beagles, Bernese Mountain dogs, vizlaw, Golden retrievers, German Short-haired Pointers, and others

History: Acute onset, recurrent episodes, wax/waning

Clinical signs:

• severe neck pain, low carriage head and neck

• pyrexia (systemic; vs memningial myelitis main difference)

• exercise intolerance and stiff gait (some cases develop concurrent polyarthritis)

Steroid responsive meningitis-arteritis (SRMA): pathogenesis and dx

Immune-mediated inflammation of the meninges and associated blood vessels

1. Cerebrospinal fluid (CSF) analysis:

   • neutrophilic pleocytosis (non-degenerate) +/- haemorrhage

   • can be normal if on/recently had anti-inflammatories

2. Elevated serum C-reactive protein (crp) supports clinical suspicion, but not diagnostic

3. Rule out infectious causes:

   • Imaging (radiographs, CT or MRI)

   • CSF bacterial culture

   • PCR/serology for protozoal and tick-borne diseases

red erythrocyte; neutrophil even if lack of bacteria

Steroid responsive meningitis-arteritis (SRMA) • Treatment:

Immunosuppressive doses: corticosteroids (prednisolone)

• Slow tapering over 4-6 months to prevenbt relapse

  • relapse desribed

• Check serum C-reactive protein prior to reducing dose

Regular monitoring for side effects of chronic steroid treatment

• physical examination, haematology and biochemistry

Concurrent antibiotics may be necessary whilst pending infectious disease results

Steroid responsive meningitis-arteritis (SRMA): Prognosis

Good to excellent for cases with prompt diagnosis and treatment – Recurrence common (16-48%) – can re-start prednisolone tapering protocol or add another immunosuppressive drug – If severe side effects from prednisolone can use another immunosuppressive drug and taper prednisolone quicker

Infectious diseases of the spinal cord

Discospondylitis – infection of the intervertebral disc (IVD) and adjacent vertebral body endplates

Distemper myelitis - notes on forebrain disease

Feline infectious peritonitis (FIP) – See Prof. Gunn-Moore’s slides and notes

• Dry form of FIP may involve the central nervous system (CNS)

• Can cause multifocal CNS signs including signs of spinal cord disease

Discospondylitis signalment

Large breed, GSDs and Dobermans over-represented ▪ But can occur in any age/breed o Male (intact or castrated) dogs o Reported in cats

Discospondylitis hx

y: o Subacute or chronic, typically >72 hours duration o **Can present acutely with pathological vertebral fracture/luxation o Recent corticosteroid use or surgery (any region) are risk factors

discospondylitis Clinical signs

Vague spinal pain - focal or multifocal o Lameness, pyrexia (8%), lethargy, anorexia, abdominal pain and weight loss o ±Neurological deficits range from mild ataxia to plegia ▪ Caused by secondary IVDD, pathological vertebral fracture/luxation, or empyema (pus in vertebral canal)

± defi

Discospondylitis pathogenesis

Bacterial or fungal infections:

• Staph. intermedius most common ▪

• . coli, Bacteroides, Strep., and others

• Brucella canis (zoonotic, notifiable disease) ▪

• spergillus, Actinomyces o Route of infection

Haematogenous spread = most common ▪

Migrating foreign body (grass awn) ▪ Iatrogenic – surgery or epidural injection complication o L7-S1 most commonly affected site, but can occur anywhere along the vertebral column o Multifocal in over a third of cases

dc

Discospondylitis• Diagnosis

Bloodwork: ▪ Haematology ▪ C-reactive protein o Radiographs ▪ Radiographic changes can lag 2 weeks behind clinical signs ▪ Radiographic findings suggestive of discospondylitis • Collapsed IVD space • Lysis of vertebral end plates and adjacent vertebral bodies • Sclerosis of vertebral end plates • Bony proliferation adjacent to IVD space o CT or MRI with contrast – MRI most sensitive o Blood culture: only successful in 27-50% of cases o Urine culture

Intervertebral disc culture – surgical approach or image-guided ▪ Screen for Brucella canis in entire dogs / those with travel history

Intervertebral disc culture – surgical approach or image-guided

• indication

Indications: negative urine or blood cultures, or lack of clinical response to broad spectrum antimicrobial therapy ▪ Complications – rare based on currently available literature • For surgical approach: haemorrhage, vertebral destabilization, postoperative neurological worsening and those associated with prolonged general anaesthesia. • For percutaneous approach: inadvertent damage to the spinal cord, spinal nerves, or large vessels, worsening pain, progression of neurological deficits, and seeding of bacteria from the disc into the epidural space, subarachnoid space or both o

Treatment

o Minimum 6-8 weeks antibiotics (median duration 16 weeks)

• Cave if SRMA was suspected... steroids

• Empirical treatment pending culture and sensitivity

• Potentiated amoxicillin, cephalosporin

• Negative culture: treat for Staph. intermedius

• No improvement in 1 week: re-evaluate therapy

• Biopsy and/or surgery in medically refractory cases

Antifungal agents e.g. itraconazole

Analgesia - NSAIDs, paracetamol, gabapentin

Surgery – decompressive or stabilisation

Discospondylitis: Follow up and Prognosi

Response to treatment monitored by serial imaging, usually every 6-8 weeks

Continue antibiotic/antifungal treatment until no evidence of lesion progression

Relapse in 12% o Progressive neurological dysfunction in 12% ▪ More likely if have pre-existing steroid treatment o Good prognosis if the organism is bacterial and it is identified early in the course of the disease when neurological deficits are not present o Guarded to poor with significant neurological deficits and/or fungal infection

Anomalous (Congenital) diseases of the spinal cord

Syringomyelia (+ Chiari-like malformation)

Vertebral malformations a. Hemivertebrae b. Block vertebrae, transitional vertebrae and Spina bifida c. Atlanto-axial subluxation

Dermoid sinus

Spinal arachnoid diverticulum

Chiari-like Malformation and Syringomyelia (CLM/SM): • Signalment:

Cavalier King Charles Spaniels, Griffon Bruxellois, other toy and small breeds o Also described in brachycephalic cats o Broad age range, typically < 4 years old

Chiari-like Malformation and Syringomyelia (CLM/SM) hx and clin sign

History: typically chronic, insidious

Clinical signs: o ‘Phantom-scratching’ neck/shoulder/flank area o Spinal pain (cervical or thoracolumbar) and/or allodynia (pain triggered by stimuli that don't normally cause pain, e.g. touch) o Chronic cases may develop ataxia and paresis o (Cerebellovestibular dysfunction)

Chiari-like Malformation and Syringomyelia (CLM/SM) pathogenesis

CLM = congenital malformation of small-breed dogs similar to Chiari type I malformation in humans o Causes a mismatch between the volume available in the caudal fossa and the brain parenchyma located in this space, resulting in herniation of the cerebellum into the foramen magnum ▪ Caudal fossa contains cerebellum, pons and medulla

CLM is associated with progressive formation of syringomyelia (SM), however, SM pathophysiology is still not clear

• Syringomyelia = fluid filled cavity within the spinal cord

• One hypothesis is that CLM leads to increased pressure difference between cranial and spinal compartments o CLM and SM are often associated but they can occur independently of the other

caudal fossa

intracranial space between tentorium cerebelli and occipital bone (green)

CLM/SM: Diagnosis

vMRI best modality to show effect of cranial malformation on brain tissue and also changes within the spinal cord

• CLM/SM: medical tx

▪ Analgesia - gabapentin, pregabalin, tramadol, NSAIDs

Drugs that may reduce CSF productio

1. all evidence is anecdotal (omeprazole, acetazolamide, furosemide) ▪ Corticosteroids –

2. anti-inflammatory effects, decreased CSF production and decreased substance P expression.

   • Taper to lowest effective doseresponse ok to gaba

CLM/SM: sirg tx

Foramen magnum decompression and cranioplasty

• Prognosis:

Medical: 50-75% patients improve but resolution unlikely and disease will progress

Surgical: 80% short term improvement but relapse in 25-50%, typically due to excess scar tissue formation

Vertebral malformation a. Hemivertebrae

Signalment: Frequently reported in screw-tailed brachycephalic breeds o French bulldog, English bulldog, Boston Terriers, Pugs • History: typically, chronic and slowly progressive • Clinical signs: variable o Subclinical: Commonly found in neurological normal dogs ▪ 78% of French Bulldogs o Depends on site and degree of spinal cord compression ▪ Thoracic vertebral column most common site >>> paraparesis and proprioceptive ataxia o Abnormal angulation – kyphosis, lordosis, scoliosis o More likely to be associated with neurological deficits in Pugs

Hemivertebrae pathoenesis

pathgenesis: o Failure of vertebrae to form properly, usually vertebral body o Typically wedge shaped o Vertebral column instability and spinal cord compression

Vertebral malformation dx, tx, px

Diagnosis: o Radiographs, plain CT o MRI or CT myelogram to assess effect on spinal cord • Treatment: o Conservative: exercise restriction, anti-inflammatories and pain relief ▪ Likely to continue to progress o Surgical stabilisation

Prognosis: variable depending on degree of spinal cord compression, aim of surgery it to limit progression

not exmaminablle —block junction

Atlanto-axial subluxation: signalment and hx

o Anomalous: Toy or small-breed dogs less than 2 years old, occasionally cats ▪ Yorkshire terriers, miniature or Toy Poodles, Chihuahua and Pekingese o Traumatic: Any age/breed

hx Acute or chronic

Acute or chronic vc. Atlanto-axial subluxation

Clinical signs: Variable – Mild cases: neck pain alone (avoid neck flexion) – Moderate: ataxia and tetraparesis – Severe: tetraplegia and respiratory difficulties • Pathogenesis (for anomalous): – Congenital malformation of the dens (agenesis or hypoplasia) or abnormal ligaments – AA joint is unstable, leading to luxation/subluxation and cervical spinal cord compression

AA subluxation: diag tx, px

Diagnosis o Radiographs and MRI o CT scan • Treatment o Conservative: Rest and neck brace o Surgery: Fixation e.g. with pins or screws with bone cement (Polymethylmethacrylate, PMMA) • Prognosis o Depends on severity of neurological deficits o High rate of complications with surgery o 0-30% complication rate, 5-10% in more recent publications

. Spinal arachnoid diverticulum:

effect special part og thoraloccolubar

Signalment: o Congenital: Rottweilers in cervical region o Acquired: Pugs and French Bulldogs ▪ Male pugs predisposed o Also reported in cats o Age of onset variable • History: Typically chronic, slowly progressive • Clinical signs: Depend on site o Tetra- or paraparesis and proprioceptive ataxia o Typically, no associated with pain (present in ~20%) o Urinary and faecal incontinence (typically with thoracolumbar site)

4. Spinal arachnoid diverticulum

Signalment: o Congenital: Rottweilers in cervical region o Acquired: Pugs and French Bulldogs ▪ Male pugs predisposed o Also reported in cats o Age of onset variable • History: Typically chronic, slowly progressive • Clinical signs: Depend on site o Tetra- or paraparesis and proprioceptive ataxia o Typically, no associated with pain (present in ~20%) o Urinary and faecal incontinence (typically with thoracolumbar site)