EQ SC Disease Flashcards
Neurological signs
Paresis - disorder of descending motor tracts
Ataxia - disorder of ascending sensory tracts
Dysmetria - disorder of descending motor tracts or ascending sensory tracts
Signs of paresis
Low arc of swing in stride
Dragging toe
Excessive toe wear
Knuckling over at fetlock
Stumbling
Signs of ataxia
Abnormal placement of limbs
Crossing limbs or stepping off
Prolonged pivoting of limb when circling
Signs of dysmetria
Hypometria - stiff movement of limbs, reduced flexion of larger carpal & tarsal joints
Hypermetria - spasticity - stiff movement of limbs, prominent extensions of limbs, overly forceful limb placement
Presentation of hypometria in pelvic limbs
Pelvic limbs only suggest lesions in the thoracolumbar spinal cord
Pelvic and thoracic limbs suggest a lesion in the cervical spinal cord
Cervical spinal cord
Divided into two functional regions
Upper cervical region (C1-C5)
Lower cervical region (C5-C7)
Focal lesion in upper cervical spinal cord (C1-C5)
Sings of weakness, ataxia and hypometria that are one grade worse in pelvic limbs than compared to thoracic limbs
Focal lesion in lower cervical spinal cord region (C5-C7)
Signs of weakness, ataxia and hypometria that are the same or worse in the thoracic limbs compared to the pelvic limbs
Differential diagnoses
Trauma *
Cervical stenotic myelopathy *
EQ protozoan myeloencephalitis*
EQ motor neuron disease
EQ degenerative myeloencephalopathy
Occipitoatlantoaxial malformation
Cervical stenotic myelopathy
Developmental disorder of cervical spinal vertebrae (malform) or intervertebral joint (malartic) for continuous or intermittent compression of CSC
Pathogenesis of CSM
Compression of cervical spinal cord causes pressure-induced degeneration usually of white matter
Signalment of CSM
Usually young colts
Light breeds are effected
Warmbloods ^^ but present older
History for CSM
Sudden or gradual onset of in coordination
Sudden onset of in coordination is commonly linked with a traumatic event
Severity of signs often fluctuates but deterioration is slow
Physical exam for CSM
Large for age, excellent body condition
Secondary developmental orthopedic disease
May have excessive toe wear
May have evidence of injury’s to distal limb
Neurological exa
Symmetric weakness, ataxia or hypometria in pelvic limb and thoracic limbs
- compression of upper CSC = pelvic 1 grade worse
- compression of lower CSC = thoracic same or 1 grade worse
Diagnosing CSM
Radiographs - contrast radiography (myelography)
CSF - could see increased protein, RBC or xanthochromia
CT or MRI
Expected findings for radiographs of CSM
Lateral views
Enlargement of caudal epiphysis
DJD of adjacent vertebrae
Sublux of adjacent vertebrae
Sagittal ratio
Objective assessment of width of spinal canal
Minimum Sagittal diameter of vertebral canal
Calculate intravertebral Sagittal ratios for C 4, 5, 6, 7,
Reference values for Sagittal ratio
Reference value for C4, 5, 6, >52%
Reference valve for C7>56%
Myelography
Required for definitive diagnosis of CSM
RISKY! General anesthesia & lateral recumbency
Contrast is injected into atlantoccipital space (after withdrawal of CSF)
Diagnosis of CSM is based on the reduction (>50%) of dorsal and ventral dye columns at opposing sites
Treatment for CSM
Stall rest, neck brace, elevated food & water
Altered diet & exercise restrictions - retard bone growth
Surgical - ventral intervertebral fusion
VIF surgery
General anesthesia and dorsal recumbancy
Fuses vertebrae in extension and reduces compression during flexion
Prognosis for CSM
Poor for athletic performance without surgery
Prognosis with surgery varies
Equine degenerative myeloencephalopathy
Degenerative disorder of SC and brainstem associated with dietary deficiency of Vitamin E
