Movement disorders Flashcards
learn (18 cards)
What is paroxysmal dyskinesia (PD) in dogs?
An episodic movement disorder characterized by involuntary, hyperkinetic muscle contractions and transient abnormal postures without loss of consciousness or autonomic signs during episodes.
PD is recognized by its characteristic episodes and has been studied for its potential genetic and environmental causes.
What is a dominant theory regarding the cause of PD in dogs?
A strong genetic basis with multiple breed-specific genetic mutations identified or suspected to underlie these disorders.
Genetic investigations have revealed specific mutations in various breeds linked to PD.
Which gene mutation is linked to episodic falling syndrome in Cavalier King Charles Spaniels?
Mutation in the BCAN gene, which encodes brevican.
Brevican is a key extracellular matrix proteoglycan involved in synaptic stability.
What mutation is associated with Soft Coated Wheaten Terriers in relation to PD?
Mutation in the PIGN gene affecting glycosylphosphatidylinositol anchor biosynthesis.
This mutation supports the theory of disrupted cell surface protein anchoring provoking dyskinetic episodes.
Name another genetic anomaly implicated in exercise-induced dyskinesia.
PCK2 variant in Shetland Sheepdogs.
This variant highlights the heterogeneity in genetic causes of PD among different dog breeds.
What environmental factors can trigger episodes of PD in predisposed dogs?
Stress, exercise, and excitement.
These factors suggest that genetic defects may sensitize neuronal circuitry to external stimuli.
What neurophysiological dysfunction is theorized to underlie PD?
Dysfunction within the basal nuclei and possibly the cerebellum.
These regions are critical for motor control and may involve abnormal neurotransmitter release or receptor function.
Which neurotransmitter signaling disturbances have been proposed in the context of PD?
Disturbances in dopamine signaling or compensatory receptor upregulation.
Such disturbances may be precipitated by genetic abnormalities or external factors.
What are some drug-induced triggers of paroxysmal dyskinesias?
Phenobarbital, propofol, or metoclopramide.
These agents are known to affect dopaminergic and GABAergic pathways, leading to dyskinetic episodes.
What syndrome is particularly associated with gluten sensitivity in Border Terriers?
Canine Epileptoid Cramping Syndrome (CECS).
This association suggests an immune-mediated or metabolic disturbance as a triggering mechanism.
What potential role do ion channel dysfunctions play in PD?
They may interfere with neuronal excitability.
While not well characterized in canines, this hypothesis links to basal nuclei dysfunction and altered neurotransmission.
Summarize the etiology of canine paroxysmal dyskinesia.
Multifactorial involving genetic mutations, environmental triggers, and functional disturbances in basal nuclei and neurotransmitter systems.
This complexity explains the varied clinical expression of PD in different dogs.
What is the current understanding of the link between dopamine levels and paroxysmal dyskinesia (PD) in dogs?
There is no direct, robust evidence linking alterations in dopamine levels to PD in dogs.
The available data suggest an indirect involvement of the dopaminergic system in the pathogenesis of PD.
Which brain structures are implicated in the pathogenesis of paroxysmal dyskinesia in dogs?
The basal nuclei.
These structures are critical for motor control and heavily modulated by dopamine.
What evidence links dopamine dysfunction to paroxysmal dyskinesia in humans?
Reduced dopamine synthesis and storage can lead to compensatory upregulation of postsynaptic dopamine receptors.
This mechanism might precipitate PD episodes.
What has been observed regarding the basal nuclei in dogs during PD episodes?
Dysfunction of basal nuclei has been noted during PD episodes.
These structures are sensitive to dopaminergic neurotransmission.
What type of drug is metoclopramide and how is it related to paroxysmal dyskinesia in dogs?
Metoclopramide is an anti-emetic that antagonizes dopamine D2 receptors.
It can trigger dyskinetic episodes in dogs.
What does the evidence from Richter et al. suggest about dopamine metabolism in affected calves?
Reduced levels of homovanillic acid, a dopamine metabolite, were noted.
This hints at decreased dopamine metabolism.
