Movement Disorders 1 Flashcards
2 medications associated with chorea?
OCP
Dopamine agonists
2 toxic causes of chorea?
Alcohol
Carbon monoxide poisoning
2 metabolic disturbances associated with causing chorea?
Hypocalcaemia
Hyperthyroidism
What is the genetic basis of Huntington’s disease?
Prolonged CAG triplet repeat in the huntingtin gene, found on chromosome 4
Where is the major pathology in Huntington’s Disease?
The striatum (caudate nucleus and putamen), in turn affecting corticostriatal projections
What reflexes are present in Huntington’s Disease?
Primitive reflexes - pout, grasp, palmomental
Extensor plantars
What MRI sign may be present in Huntington’s disease?
Increased T2 signal in caudate nucleus
What is an unequivocally normal CAG triplet repeat length?
Less than 26 repeats
What is an unequivocally abnormal CAG triplet repeat length?
Over 40
What do intermediate CAG triplet repeat lengths signify (26-40)?
Reduced penetrance
What might a huge CAG triplet repeat length result in?
Juvenile onset/Westphal variant HD - onset less than 20 with a more pronounced akinetic-rigid presentation
What is interesting about the inheritance of Westphal HD?
Typically paternally inherited
4 medications of use to treat chorea?
Tetrabenzene
Phenothiazones e.g. Risperidone
Benzodiazepines
Haloperidol
What is Sydenham’s chorea?
Post GAS (strep pneumoniae) infection, like a subacute rheumatic fever (weeks to months after primary infection)
What is the pathophysiology behind Sydenham’s chorea?
Necrotising arteritis in thalamus, caudate nucleus and putamen
Can Sydenham’s chorea recur? When?
Yes - during pregnancy or occasionally intercurrent infection
At what stage of pregnancy is chorea gravidarum most likely to occur?
First trimester
What comprises the pyramidal system?
Motor cortex
Corticospinal columns
What comprises the Extrapyramidal system?
Paired subcortical masses/basal ganglia - caudate nucleus, putamen, globus pallidus, subthalamic nuclei and substantia nigra
What part of the brain projects information between the basal ganglia and the motor cortex?
Thalamus
What cells are reduced in number in the substantia nigra pars compacta in PD?
Neuromelanin cells
What dopaminergic receptor changes occur in striatal cell membranes in PD?
Reduced D1 and D2 receptor expression
What 2 Sx may precede the movement disorder in PD?
Constipation
Anosmia
Describe the typical Parkinsonian tremor?
Coarse, slow (4-7Hz) resting tremor
Initially unilateral, often in hands, before spreading to all 4 limbs later
Improves with movement, worse with stress
Disappears when asleep