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Chiari like malformation & Syringomyelia

Lecture synopsis

• What is syringomyelia

• Clinical signs of syringomyelia

• Diagnosis of syringomyelia

• Treatment of syringomyelia

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Syringomyelia

Syringomyelia - fluid-filled cavities in the spinal cord

Due to obstruction of cerebrospinal fluid movement

Pan and Syrinx Peter Paul Rubens 1618

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Post traumatic syringomyelia

7y M Labrador – 6 years after a traumatic C2/C3 disc extrusion

Dermoid sinus & 2° syringomyelia

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Chiari-like malformation

most common cause SM in dog

Mismatch between brain and skull size

Syringomyelia in CKCS (history)

1st scientific reports ~ 1997

- UK, South African & Australia almost simultaneous

- Coincided with availability spinal MRI for animals

1st case UK (retrospective) - 1987

Widening Vertebral canal C2

Presented to RVC with neck

pain and shoulder scratching

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CM – characteristics

Overcrowding of the skull

Normal CM

Pathogenesis syringomyelia

High velocity jet

Spinal cord “pulled

out” and cavity forms

Piston like action

cerebellar vermis

Decreases hydrostatic pressure (Venturi effect)

Extracellular fluid

accumulates

Increased pressure within cord

Decreased pressure outside cord

Systolic pulse

pressure

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Breeds CM/SM • Any toy breed dog and SBT

• Especially

– Cavalier King Charles spaniel

– King Charles spaniels

– Griffon Bruxellois

– Affenpinscher

– Maltese (miniature)

– Yorkshire terrier (miniature)

– Pomeranian (miniature)

– Chihuahua (miniature)

CM – characteristics

changes in proportions of the skull

Griffon with no CM or SM Griffon with CM and SM

basicranium (skull base) shortens parietal bone lengthens

supraoccipital bone is shorter and straighter smaller frontal sinuses

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CKCS with CM

• Similar skull volume to other toys

• More brain tissue within skull

– Statistically similar volume to Labradors

Cross H. R., Capppello R, Rusbridge C Comparison of cerebral cranium volumes between CKCS with

chiari-like malformation, small breed dogs and Labradors JSAP 2009 50 399-405

CKCS with SM

• Skull (caudal fossa) volume

– Significantly smaller for CKCS with early onset SM

(<2y) compared to clear CKCS (> 5y)

• Parenchyma (brain) within skull

– significantly greater for CKCS with SM

– Especially in CKCS with early onset SM

• SM associated with brain / skull mismatch

– Early onset SM greater disparity

– Increased parenchyma (brain) within skull = larger syrinx

– Big syrinx = Big ventricles

Vet Rec. 2010 Dec 18;167(25):978-9. Morphometric assessment of cranial volumes in age-matched Cavalier

King Charles spaniels with and without syringomyelia. Driver CJ, Rusbridge C, McGonnell IM, Volk HA.

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Clinical signs – CM/SM

PAIN

Before medication After medication

Pain face

Canine syringomyelia

Pain - Most common clinical sign

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Unusual sleeping posture /

interrupted sleep Poor exercise tolerance

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Unwilling / pain on jumping Shoulder scratching

Especially

• Walking

• Excited

• Touched

• “clothing”

– neck collar

– snoods

• “air guitar”

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Other possible clinical signs

Scoliosis

Imbalance control of neck

and spinal muscles

Association between scoliosis and syrinx width - i.e. more

likely with wide syrinxes

Dorsal grey

column damage

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Clinical signs of SM

• Not all dogs with SM have signs

• Depends on width and location of syrinx

– Wide syrinx = pain +/- scratching

• Many dogs with SM have no / subtle signs

– a “problem in waiting”

– May produce offspring with SM

– May produce offspring with pain from SM

MRI from 16 month CKCS in severe pain

Wide asymmetrical syrinx

White = fluid; light grey = spinal cord

CM associated pain

Cartoons - Thanks to Tania Ledger www.cavaliermatters.org

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Canine CM/SM

Pain - Most common clinical sign

Chiari-like malformation associated pain

CM associated pain

Signs of pain Asymptomatic CM

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Canine SM - Clinical signs Neurological deficits in more severe cases

2 year old female CKCS

Severe neurogical deficits - uncommon

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“Fear and aggression positive correlation

to neuropathic pain (CM/SM)”

BEHAVIOUR ANALYSIS OF CKCS DIAGNOSED WITH

SYRINGOMYELIA L Rutherford at al ECVN Annual Symposium 2010

Diagnosis SM

• Rule out

– other causes of scratching e.g. skin and ear dx.

– Other neurological diseases

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Other causes of scratching

• CM associated pain

• Ear disease

• Skin disease

– Cheyetilia

– Atopy

– Flea allergic dermatitis

Diagnosis

MRI (under GA) only method confirming CM/SM

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Other causes spinal pain / paresis

GME

Multifocal neuro signs

Atlantoaxial subluxation

Dogs < 2 years, hypermetric gait, tetraparesis

Disc disease

Dogs > 2 years

Disc disease unlikley in CKCS < 2 y Treatment of Syringomyelia

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Cranial cervical decompression Cranial cervical decompression

C1 laminectomy ~ 3mm caudal

to vermis / attachment dorsal

spinous process of C2

kite shaped incision

dura and arachnoid

atlantooccipital membrane

removed (scalpel blade and

bipolar electrocautery)

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Dog 9 - Pre and post op MRI

Pre-op 4 months post-op

Treatment – surgical Prognosis

Surgery usually successful at reducing the pain

but…

• Syringomyelia is still present!

• May still have discomfort /scratching

• ~ 50% deteriorate by 2.5y post-op

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Neuropathic Pain

Dorsal horn damage Dogs in pain are more likely to have a wide

syrinx with dorsal grey column damage

Sequential transverse TW2 images between C1 and C2 from a 16 month CKCS

unable to be walked because of severe pain

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Treatment – medical

Drugs which reduce CSF production

• Antacids

– Proton pump inhibitors

• Omeprazole

– H2 receptor antagonist

• Cimetidine

• Diuretics

– Furosemide

Treatment – medical Painkillers • NSAIDS

– May be effective for mild cases

– Coxibs more effective for central pain?

• Neurogenic analgesics – Gabapentin (Neurontin; Pfizer)

– Pregabalin (Lyrica; Pfizer)

– Amantadine

• antiviral drug, also used for Parkinson's Disease

• prevents pain “wind up” in spinal cord dorsal horn

– Tramadol

• μ-opioid receptor, inhibits reuptake serotonin & noradrenalin

• Useful for “bad periods”

• Oral opioids, e.g. pethidine or methadone • Only useful in short term

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Treatment – medical

• Corticosteroids

– in short term effective at reducing pain and

improving neurological status

– Side effects of immunosuppression, weight

gait and skin changes

Medical Treatment – what I do Start Cimetidine 5-6mg/kg 2-3 x daily

Or

or Omeprazole at 0.5-1.5mg/kg 1x daily

• If response reconsider surgery

• If inadequate add NSAIDS

• If inadequate add gabapentin +/- NSAIDS

• If inadequate reconsider surgery – if not an option then add corticosteroids +/- gabapentin

• Also – Pregabalin

– Amantadine

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Exercise • To within own limits

• Inability to exercise

– Indication more serious disease

• During aerobic exercise

– Heart beats faster and with more force

– Increases pulse pressure

– Signs are exacerbated

– Progression CM/SM accelerated?

• Humans – advised against aerobic

exercise prior to decompression

– Most symptomatic patients cannot anyway

Little things

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Complementary therapy & CM/SM

Remember that touch can hurt! Must be tailored to the individual

Lack of data regarding CM/SM

What is appropriate?

• Gentle massage?

• Low level laser therapy

• Ultrasound therapy

• Acupuncture?

What is not appropriate?

• Spinal manipulation

• Guarded if…

– wide syrinx

– first clinical signs before 4 years of age.

• NeP progresses in ¾ CKCS with CM+/-SM

despite medical treatment (study of 48 dogs)

– Many still enjoy reasonable quality of life

– 15% euthanatised CMSM

– Live with CMSM and die from MVD

Prognosis Medical management

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Conclusion

• Syringomyelia is a painful spinal cord disease

• A multimodal approach to pain relief is more

likely to be successful.

– Surgery

– Drugs

– Complementary therapy

www.veterinary-neurologist.co.uk

Thank you for listening!

Any questions?