6.07 Parkinson's Disease Flashcards
Dystonia
Relates to abnormalities of tone. There are many causes. Involves co-contraction of inappropriate muscles.
Syndrome of sustained muscle contractions, frequently causing twisting and repetitive movements, and abnormal postures
NB Dystonia is a subcategory of dyskinesia
How is dystonia currently classified?
In terms of age of onset (adult, infantile, juvenile), and distriution (focal, segmental, generalised)
Primary dystonia
Develops spontaneously in the absence of any apparent cause and show no other neurologic symptoms
Pathology of dystonias
Most of the mutations affect dopaminergic neurons and L-Dopa improves dystonias dramatically
What types of movement disorders are there?
Akinesias, tremor, ataxia, hyperkinesia/dyskinesia (dystonia, athetosis, chorea, ballism, medicative dyskinesias, myoclonus)
Athetosis
Slow irregular writhing of digits and face, related to cerebral palsy
Chorea
Dance-like pattern of involuntary movement, constant movement and unpredictable, includes the face
Types of chorea
Huntington’s chorea (autosomal dominant), Sydenham Chorea (children with rheumatic fever), various blood disorders
Tardive dyskinesia
caused by neuroleptics, anti-emetics.
Bucco-lingual, grimacing, tongue protrusion, lip smacking, puckering
Hemiballismus
Most violent form of dyskinesia, flinging, throwing, bizarre, dance-like.
Can be caused by subthalamic strokes and hyperglycaemic coma.
Myoclonus
Brief, shock-like involuntary twitching of a muscle or group of muscles
May arise form abnormal oscillatory activity in SC, BS, or cortex
Types of tremor
Physiological Exaggerated physiological Essential tremor Hyperthyroid Parkinsonian Intention
Physiological tremor
Seen normally - fine, low amplitude
Becomes exaggerated under anxiety caffeine, exercise, endocrine disorders
Can be alleviated by beta-blockers (under what circumstances?)
essential tremor
Very common movement disorder
Often synchronised contraction of agonist and antagonist muscles 5-8Hz
Exacerbated by anxiety
Alleviated by alcohol, beta-blockers
Hyperthyroid tremor
Looks like exaggerated physiological tremor or essential tremor if severe
Worsened by anxiety
Responds to beta-blockers and anti-thyroid medications e.g. carbimazole
Parkinsonian tremor
Exhibited in PD and related disorders e.g. Dementia with Lewy Bodies, Multiple Systems Atrophy
4-5Hz, resting tremor, “pill-rolling”
Some improvement after beta-blockers
Responds to L-dopa
Cerebellar intention tremor
Most evident when making precise or skilled movement
Can be quite low frequency 2-3Hz
Tics
Twitchy, repetitive movements, not tremor-related
Hypokinesia
Decreased activity level measured over time
Includes both bradykinesia and akinesia
Main features of PD
Rigidity, bradykinesia, disordered postural reflexes, with/without resting tremor
What are the three alpha-synucleinopathies?
PD, Dementia with Lewy Bodies, Multiple-Systems Atrophy
What are the other types of Parkinsonism?
Tauopathies (PSP, Corticobasal degeneration, Frontotemporal dementia with Parkinsonism), TDP-43 proteinopathies
What are the deep cerebellar nuclei?
Dentate, emboliform, globose and fastigial
How do you diagnose PD?
Resting tremor, asymmetry of signs and symptoms, good response to L-dopa
no biological marker, though increased CSF alpha-synuclein can help diagnose it
Brain imaging to exclude other conditions
(Autopsy diagnosis is the gold standard.)
Epidemiology of PD
Age of onset is usually 60-70
Only 4% have early onset ( usually genetic
Where are neurons lost from PD?
Substantia nigra in midbrain: loss of dopaminergic neurons
Locus ceruleus (noradrenergic neurons)
Raphe neurons (serotonergic neurons)
Basal nucleus and mesencephalic locomotor area (cholinergic neurons)
Autonomic neurons
How much dopaminergic cells need to be lost from SNc before symptoms?
60%
What are Lewy bodies?
They are round pink, with a hyaline core and pale staining halo.
They are found in surviving neurons in the Snc, locus ceruleus, DMX of vagus. They are signs of a dying cell.
