Tremors & Cerebellar Disease

Question 1

myoclonus

Answer 1

a sudden, “lightening jerk”, involuntary movement of short duration caused by muscle contractions and pauses in muscle activity

occurs in a muscle, part of a muscle, or in groups of muscles

only in ONE area of the body

Question 2

tremor

Answer 2

rhythmical oscillatory movement of a body part around an axis resulting from alternate or synchronous contraction of antagonistic muscle groups

focal or generalized

Question 3

action tremors

Answer 3

occurs during voluntary contraction of skeletal muscle

can be postural or kinetic

Question 4

postural action tremor

Answer 4

type of action tremor that occurs in a body part that is voluntarily maintained against gravity (ex. standing)

Question 5

kinetic action tremor

Answer 5

a type of action tremor that occurs during directed voluntary movement

Question 6

intention tremor

Answer 6

type of kinetic action tremor that increases in amplitude during the pursuit of a target

Question 7

physiological tremors

Answer 7

normal oscillation that occurs in all body parts (imperceptible, fine action tremors)

Question 8

enhanced physiological tremor

Answer 8

physiological tremor with greater than normal amplitude

typically stressed induced from stimulation of B receptors by adrenalin

Question 9

what are differentials for tremors and myoclonus

Answer 9

1. cerebellar disease
2. diffuse CNS disease
3. motor unit disease

Question 10

dysmyelination of CNS axons

Answer 10

congenital defect causing dys- and hypomyelination of CNS axons

likely genetic/inherited (breed predilections - chow chows, weimeraners, springer spaniels)

present at birth but may not notice until starting to walk

Question 11

clinical signs of dys/hypomyelination

Answer 11

generalized coarse action tremor with NO neurological deficits present

Question 12

dys/hypomyelination treatment and diagnosis

Answer 12

no effective therapy

confirm with genetic testing

Question 13

clinical signs of generalized tremor syndrome of dogs

Answer 13

acute onset
low amplitude
“fine” generalized action tremor

neurologically NORMAL on exam but may have seizures, vestibular, or cerebellar signs

Question 13

generalized tremor syndrome of dogs

Answer 13

“little white shaker disease”

inflammatory cause of tremors that occurs in young (<2 yrs) small breed dogs

Question 14

diagnosis of generalized tremor syndrome of dogs

Answer 14

minimum database
normal MRI
mild pleocytosis on CSF analysis
negative serology for infectious agents

Question 15

treatment for generalized tremor syndrome of dogs

Answer 15

long term corticosteroids (immunosuppressive doses)

good prognosis

Question 16

lysosomal storage diseases

Answer 16

accumulation of metabolic byproducts in neurons and other CNS tissues secondary to an enzyme deficiency

rare heritable condition

Question 17

signalment for lysosomal storage diseases

Answer 17

young animals (<1 year)

Question 18

clinical signs of lysosomal storage diseases

Answer 18

action tremor + systemic abnormalities

Question 19

diagnostics for lysosomal storage diseases

Answer 19

WBC inclusions on CBC
genetic testing
MRI

Question 20

treatment for lysosomal storage diseases

Answer 20

none - elect euthanasia due to poor QOL

Question 21

how do metabolic diseases cause tremors

Answer 21

electrolyte abnormalities - alters resting membrane potential of muscles or nerves causing weakness and tremors due to spontaneous depolarization

diagnose with minimum database

Question 22

function of the cerebellum

Answer 22

coordination of movement (rate, range, and force) that is initiated elsewhere

assists with maintenance of equilibrium

Question 23

cerebellar anatomy

Answer 23

3 layers:
- molecular (axons)
- Purkinje cells
- granular

Purkinje layer and cerebellar nuclei form the external germinal layer –> germinal cells divide then migrate deep into the cerebellum to form the granule cell layer

Question 24

deep cerebellar nuclei

Answer 24

3 pairs of nuclei buried deep within the white matter

should NOT be visible on MRI

Question 25

signs of cerebellar dysfunction

Answer 25

IPSILATERAL signs

1. ataxia
2. dysmetria
3. vestibular signs
4. absent menace
5. CP deficits
6. increased muscle tone +/- hyperreflexia

Question 26

ataxia

Answer 26

failure of motor coordination without muscle weakness

• broad based stance
• truncal ataxia (swaying torso)

Question 27

dysmetria

Answer 27

abnormal rate, range, and force of movement

hypermetria - high stepping
head dysmetria - intention tremor

Question 28

vestibular signs

Answer 28

occurs when there is a lesion in the flocconodular lobe or caudal cerebellar peduncle

signs may be PARADOXICAL to the actual lesion
- Ex. L lesion –> vestibular rights on the R, cerebellar signs on the L

Question 29

what part of menace is causing it to be absent with cerebellar dysfunction

Answer 29

efferent pathway

vision is normal

Question 30

acute decerebellation

Answer 30

dysfunction of the entire cerebellum, often seen with trauma

causes opisthotonus w/ pelvic limb extension or flexion

Question 31

cerebellar abiotrophy

Answer 31

degenerative disease caused by spontaneous, premature neuronal death of purkinje cells

Question 32

signalment for cerebellar abiotrophy

Answer 32

breeds: kerry blue terries, gordon setters, brittany spaniels

age: middle aged to older

Question 33

clinical signs of cerebellar abiotrophy

Answer 33

progressive, diffuse, symmetrical cerebellar signs

Question 34

diagnosis of cerebellar abiotrophy

Answer 34

MRI
biopsy (definitive)

Question 35

cerebellar hypoplasia

Answer 35

idiopathic malformation of the cerebellum caused by in utero infections, toxins, or genetic disorders

perinatal infection/toxin –> destroys the external germinal layer –> germinal cells unable to divide and migrate –> hypoplasia of the granule cell layer –> loss of connections in the cerebellum

Question 36

clinical signs of cerebellar hypoplasia

Answer 36

spectrum of cerebellar signs

present AT BIRTH
NOT progressive - will not improve or worsen throughout life

Question 37

diagnosis and treatment of cerebellar hypoplasia

Answer 37

signalment, history, neuro exam

no effective treatment

Question 38

ischemic infarction

Answer 38

vascular event in the rostral cerebellar artery causing acute onset of cerebellar disease

Question 39

diagnosis and treatment of ischemic infarction

Answer 39

MRI - wedge shaped lesion

supportive care - symptoms improve with time