Difference between revisions of "Cervical Vertebral Stenotic Myelopathy"

Revision as of 11:53, 7 August 2011

Also Known As: Wobblers — Cervical Vertibral Malformation — Cervical Vertebral Stenosis

Introduction

Cervical vertebral stenotic myelopathy (CVM) is an equine disease common in Thoroughbred horses between the ages of 6 months to 3 years. It is most typically seen in rapidly growing colts. It is the most common differential diagnosis in equine ataxia cases.

Pathogenesis

A narrowing of the vertebral canal due to malalignment or maldevelopment of the cervical vertebrae, causing progressive compression of the spinal cord.

There are two types of the disease:

(1) Type 1 CVM — Dynamic

This form is more common in younger horses. Spinal cord compression is caused by excessive movement of the vertebrae during flexion and extension of the neck and is therefore dynamic in nature. Vertebrae C3-C5 are most commonly affected.

(2) Type 2 CVM — Static

This form is more common in older horses, as a result of osseous change in the vertebrae. The spinal cord is constantly compressed. Vertebrae C5-C7 are most commonly affected.

Aetiology

The disease produces OCD-like lesions on the vertebrae, producing an irregular joint surface. Nutrition is thought to play a part in the development of disease, with excessive protein and zinc, copper, calcium and phosphorous imbalances indicated as contributing factors. As horses with cervical vertebral malformation appear to be more likely to develop OCD lesions in other joints there is thought to be a heritable component.

Clinical signs

Hind limb ataxia, spasticity and weakness are the main clinical signs. The development of these signs are normally insidious but may come about suddenly following trauma. Ataxia is normally bilateral and symmetrical. Forelimbs may also be affected.

Diagnosis

Standing lateral radiographs of the spine are required for diagnosis.

Subjective radiographic signs:

Spinal cord mal-alignment
Osteoarthritis of articular processes
Caudal epiphyseal flare aka ski-ramping (a triangle of new bone into the spinal canal)

Objective radiographic signs:

Intravertebral ratios
Intervertebral ratios

If the radiographs are of a high quality, a combination of these signs should be sufficient to make the diagnosis of CVM.

Abscesses, tumours, synovial cysts, ligamentar hypertrophy and trauma may not show signs radiographically despite producing the clinical signs of CVM.

Myelography is generally only indicated in potential surgical cases.

Differential Diagnosis

Equine Herpes Virus 1 (EHV-1) myeloencephalitis
Equine Degenerative Myeloencephalopathy
Trauma
Migrating strongyles - rare now due to ivermectin treatment
Polyneuritis equi
Ryegrass staggers
Equine Protozoal Myeloencephalitis - in foreign imports
Neoplasia

Treatment

The mainstays of treatment are box rest (for several months), anti-inflammatories (NSAIDS), and dietary adjustment (to a low protein diet to slow the growth of the horse, allowing the canal growth to 'catch up').

Surgery can be performed. This involves ventral stabilisation of the vertebrae using a steel or titanium implant.

Prognosis

Horses with a grade 1 ataxia on the Mayhew scale may retain athletic function. Conservative treatment in mildly affected horses normally improves clinical signs and surgery may improve the ataxia score by one or two grades on the Mayhew scale.

Cervical Vertebral Stenotic Myelopathy Learning Resources
Flashcards Test your knowledge using flashcard type questions	Equine Orthopaedics and Rheumatology Q&A 05

References

Hahn, C (2006) The wobbly horse: differential diagnose In Practice 2006 28: 8-1

RVC staff (2009) Nervous System and Special Senses RVC Intergrated BVetMed Course, Royal Veterinary College

May, SA & McIlwraith, CW (1998) Equine Orthopaedics and Rheumatology Self-Assessment Colour Review Manson Publishing Ltd

@@ Line 1: / Line 1: @@
-aka Wobblers
+Also Known As: '''''Wobblers — Cervical Vertibral Malformation — Cervical Vertebral Stenosis'''''
 ==Introduction==
-Cervical vertebral stenotic myelopathy is an equine disease common in Thoroughbred horses between the ages of 6 months to 3 years. It is most typically seen in rapid growing colts.
+'''Cervical vertebral stenotic myelopathy (CVM)''' is an equine disease common in '''Thoroughbred''' horses between the ages of '''6 months to 3 years'''. It is most typically seen in '''rapidly growing colts'''. It is the most common differential diagnosis in equine ataxia cases.
 ==Pathogenesis==
-Narrowing of the vertebral canal due to malalignment or maldevelopment of the vertebrae, causing progressive compression of the spinal cord.
+A '''narrowing''' of the '''vertebral canal''' due to '''malalignment''' or '''maldevelopment of the [[Spinal Column - Anatomy & Physiology|cervical vertebrae]]''', causing '''progressive compression of the spinal cord'''.
 There are two types of the disease:
-(1) CVM Type 1 - Dynamic
+'''(1) Type 1 CVM — Dynamic'''
-This form is more common in younger horses. Spinal cord compression is caused by excessive movement of the vertebrae during flexion and extension of the neck. Vertebrae C3-C5 are most commonly affected.
+This form is more common in '''younger''' horses. Spinal cord compression is caused by excessive movement of the vertebrae during '''flexion''' and '''extension''' of the '''neck''' and is therefore '''dynamic''' in nature. Vertebrae '''C3-C5''' are most commonly affected.
-(2) CVM Type 2 - Static
+'''(2) Type 2 CVM — Static'''
-This form is more common in older horses, as a result of osseous change in the vertebrae. Vertebrae C5-C7 are most commonly affected.
+This form is more common in '''older''' horses, as a result of '''osseous change''' in the vertebrae. The spinal cord is constantly compressed. Vertebrae '''C5-C7''' are most commonly affected.
 ==Aetiology==
-The disease produces OCD (osteochondrosis dessicans)- like lesions on the vertebrae, producing an irregular joint surface. Nutrition is thought to play a part in the development of disease, with excessive protein and zinc, copper, calcium and phosphorous imbalances indicated as contributing factors. As horses with Cervical Vertebral Malformation appear to be more likely to develop OCD lesions in other joints there is thought to be a heritable component.
+The disease produces '''[[Osteochondrosis|OCD]]-like lesions''' on the vertebrae, producing an irregular joint surface. '''Nutrition''' is thought to play a part in the development of disease, with excessive '''protein''' and zinc, copper, calcium and phosphorous imbalances indicated as contributing factors. As horses with cervical vertebral malformation appear to be more likely to develop [[Osteochondrosis|OCD]] lesions in other joints there is thought to be a '''heritable''' component.
 ==Clinical signs==
-Hind limb ataxia, spasticity and weakness are the main clinical signs. The development of these signs are normally insiduous
+'''Hind limb ataxia''', '''spasticity''' and '''weakness''' are the main [[Site of Spinal Lesions Determination - Horse|clinical signs]]. The development of these signs are normally '''insidious''' but may come about suddenly following trauma. Ataxia is normally '''bilateral''' and '''symmetrical'''. Forelimbs may also be affected.
-===Cervicospinal Arthropathy===
+==Diagnosis==
-* = "'''Wobbler'''" in horses
+'''Standing lateral radiographs of the spine are required for diagnosis'''.
-*Usually presents in first two years of life
-*Mainly in fast growing thouroughbreds
+'''Subjective''' radiographic signs:
-*Most common site is C3-C4, can occur anywhere
-*Abnormal laxity between the vertebrae + cervical vertebral malformation may be evident
+* Spinal cord mal-alignment
-*[[Musculoskeletal Terminology - Pathology|Osteophyte formation]] at edges of synovial components of joint
+* [[Degenerative Joint Disease|Osteoarthritis]] of articular processes
-*Some due to stenosis of neural canal later in life (1-4 years of age)
+* Caudal epiphyseal flare aka ski-ramping (a triangle of new bone into the spinal canal)
-*Clinical signs:
-**Ataxia - hindlimbs more affected
+'''Objective''' radiographic signs:
-*Presumed cause is rapid growth
+* Intravertebral ratios
+* Intervertebral ratios
+If the radiographs are of a high quality, a combination of these signs should be sufficient to make the diagnosis of CVM.
+Abscesses, tumours, synovial cysts, ligamentar hypertrophy and trauma may not show signs radiographically despite producing       the clinical signs of CVM.
+'''Myelography''' is generally only indicated in potential '''surgical''' cases.
+==Differential Diagnosis==
+* [[Equine Herpesvirus 1|Equine Herpes Virus 1]] (EHV-1) myeloencephalitis
+* Equine Degenerative Myeloencephalopathy
+* Trauma
+* Migrating strongyles - rare now due to ivermectin treatment
+* [[Polyneuritis Equi|Polyneuritis equi]]
+* Ryegrass staggers
+* [[Equine Protozoal Myeloencephalitis|Equine Protozoal Myeloencephalitis]] - in foreign imports
+* Neoplasia
+==Treatment==
+The mainstays of treatment are '''box rest''' (for several months), '''anti-inflammatories''' ([[NSAIDs|NSAIDS]]), and '''dietary adjustment''' (to a low protein diet to slow the growth of the horse, allowing the canal growth to 'catch up').
+'''Surgery''' can be performed. This involves ventral stabilisation of the vertebrae using a steel or titanium implant.
+==Prognosis==
+Horses with a '''grade 1''' ataxia on the Mayhew scale may retain '''athletic''' function. Conservative treatment in mildly affected horses normally improves clinical signs and surgery may improve the ataxia score by one or two grades on the Mayhew scale.
+{{Learning
+|flashcards = [[Equine Orthopaedics and Rheumatology Q&A 05]]
+}}
+==References==
+Hahn, C (2006) '''The wobbly horse: differential diagnose''' ''In Practice 2006 28: 8-1''
+RVC staff (2009) '''Nervous System and Special Senses''' RVC Intergrated BVetMed Course, ''Royal Veterinary College''
+May, SA & McIlwraith, CW (1998) '''Equine Orthopaedics and Rheumatology Self-Assessment Colour Review''' ''Manson Publishing Ltd''
@@ Line 39: / Line 76: @@
 [[Category:Joints - Degenerative Pathology]]
 [[Category:Bones - Developmental Pathology]]
+[[Category: To Do - Siobhan Brade]]
+[[Category:To Do - Manson review]]