Basal Ganglia Clinical Correlates Flashcards
BG impairments appear ______ to the lesion because:
contralateral
crossing of C-S tract through which deficits are manifested
PD is due to loss of dopaminergic cells in the ____. What % loss before symptomatic?
SNc
70-80% loss
Severely impaired PD patients have lost > __% of striatal dopamine.
90%
What is the most likely etiology for PD?
combo of accelerated aging, genetic predisposition, exposure to toxins and abnormality in oxidate mechanism
Oxygen free radical damage results in accumulation of:
lewy bodies in dopamine neurons in SNc
PD epidemiology:
onset 40-70 yoa infrequent before 30yoa men>women black 1/4 that of whites 1 million in north ameraica 60,000 new cases/year
What are the key clinical features of PD?
How many required to receive clinical diagnosis of PD?
Must have 2 of the first 3 below AND consistent response to L-dopa replacement therapy:
- pill rolling tremor
- bradykinesia and poverty of mvmnt
- cog-wheel rigidity
- loss of equilibrium and postural reflexes
What is micrographia?
small handwriting
What is akinesia?
complete loss of mvmnt
Bradykinesia presents as:
dec. amp and speed of mvmnt difficulty initiating increased latency to onset of voluntary mvmnt loss of reciprocal mvmnt loss of facial expression akinesia micrographia
PD motor control impairments include:
- difficulty generating internally triggered mvmnt
- freezing
- festinating gait
- difficulty with sensory organization
- rigidity
- impaired postural control
- impaired eye mvmnts
What might a PD patient freeze?
difficulty in switching motor programs
inflexible program selection
challenge with divided attention
difficulty processing sensory info
What is the major contributor to falls with PD patients?
freezing
*PD has the highest fall rate of any common neurological disorder
PD patients have trouble with sensory organization, therefor rely more heavily on:
vision
can’t filter relevant from irrelevant sensory cues in the environment but vision tends to be more accurate
What does rigidity look like in PD?
flexed posture
dec. trunk rotation
How do impaired eye mvmnts present in PD?
hypometric saccades
breakdown of smooth pursuit (insufficient activation of agonist muscles)
What influences postural control in PD?
dec. LOS (esp. backwards)
dec. / ineffective strategies in response to perturbations
trunk rigidity
impaired anticipatory responses
What cognitive/limbic impairments are expected in PD?
difficulty in divided attention situations (freeze or unsteady)
concurrent depression and/or dementia as disease progresses
Later PD impairments include:
autonomic issues: orthostasis, dec. bowel motility, urinary frequency
sleep disturbances: periodic leg mvmnts, no muscle relaxation, sleep apnea
What secondary PD impairments might contribute to mobility difficulties?
contractures, dec. respiratory excursion, etc
What are two common PD rating scales?
Hoehn and Yahr
UPDRS = united PD rating scale
What meds are used in PD?
dopamine agonist (mirapex) L-dopa replacement therapy (sinemet)
Why do you want to delay drug treatment as long as possible in PD?
side effects develop over time with tx, dyskinesias, on/off phenomenon
What non-pharmacological medical management is avail for PD?
DBS
can have dramatic effects
most common side is STN
Parkinson’s plus syndrome are ddx of PD vs. other degenerative disorders. What are some similarities and differences?
early on may present with one or more PD-related signs like tremor or bradykinesia
these diseases are NOT dopamine responsive and progress more RAPIDLY than PD
Name some parkinson’s plus syndromes:
MSA = multiple system atrophy PSP = progressive supranuclear palsy corticobasal degeneration lewy body dementia olivopontocerebellar atrophy
Chorea is a type of _____ due to damage of the _____.
dyskinesia
damage to striatum
Describe sxs of chorea:
Series of continuous rapid mbmtns of face, tongue, and limbs (esp fingers/toes).
Usually resemble fragments of fxnal mvmnts but are involuntary.
(greek word for “dance”)
Athetosis is a type of _____ due to damage of the _____.
dyskinesia
damage to striatum
Describe sxs of athetosis:
(greek word for “without position”)
slow writhing mvmnts, snakelike, mostly limb involvement
What distinguishes chorea vs. athetosis?
athetotis involves more of limbs than chorea
What is an intermediate form b/w chorea and athetosis?
choreoathetosis
Hemiballismus is a type of _____ due to damage of the _____.
dyskineisa
damage to STN (rarely result from stroke involving sm. branch of post. cerebral artery)
Describe sxs of hemiballsismusL
(greek word for “jumping about”)
violent flailing / ballistic mvmnts of usually one arm or one leg
What tis the etiology of huntington’s chorea?
autosomal dominant genetic disorder (50% chance of inheritance)
huntingtons allele on chromosome 4
genetic testing available
consists of extended CAG trinucleotide repeat > 40 repays causes huntington’s disease
Describe the pathological changes in huntington’s chorea:
profound loss of interneurons in caudate and putamen
reactive gliosis (inflammatory response) in striatum
other neuron loss in Cx and Cb
enlarged ventricles
cell death though to be due to accumulation of oxygen free radicals or failure of mitochondrial energy metabolism
Describe the epidemiology of huntington’s chorea:
rare: 6.5/100,000 (all races)
mean are onset 35-42 (small percentage in young and old age)
What diagnostic testing avail for huntington’s chorea?
genetic testing
MRI/CT: reduced volume in striatum
PET scan: reduced D1 and D2 binding
SPECT: reduced blood flow caudate > putamen
Hungtington’s chorea usually presents initially with:
cognitive changes
depression, irriability
slowing cognition, decreased ability to problem solve
subtle changes in coordination, choreoathetotic mvmnts in fingers
Later huntington’s chorea sxs include:
chorea advancing distal to proximal
ataxic gait with chorea
choreoathetotic mvmnts of face and tongue
depression and dementia
Dystonia is defined as:
involuntary muscle contractions causing abnormal twisting mvmnts or postures with contractions that can be sustained, intermittent, rhythmic, or tremulous
What is the physiology behind dystonia?
cortical disinhibition
indirect BG circuit does not inhibit the surround
sensory gating affected so abnormal links between sensory input and motor output
abnormal body schema representations in the cortex
What is the age of onset for dystonia?
infantile < 2 yrs
childhood 2-26 yrs
adult > 26 years
What is the etiology of dystonia?
primary: genetic
secondary: iatrogenic, tumor, stroke, trauma, CRPS
plrimary +: dystonia plus other neuro signs
part of another degenerative disorder like huntington’s disease
What are some distributions of dystonia?
focal: bletherospasm (eyelid), torticollis (cervical), writers cramp, musicians
segmental (whole limb)
generalized (whole body)
How is dystonia treated?
some can be sensitive to dopamine replacement
botox injections (useful for focal)
maintain mobility/fitness
carefully evaluate the benefit of bracing as a way to alter sensory input
DO NOT stretch
DBS not as reliably effective as in PD
What are 4 subclassifications of CP?
- spastic
- extrapyramidal
- hypotonic
- mixed and atypical types
Common factors in CP?
- abnormality in motor control
- early onset (pre/peri-natal)
- absence of recognized underlying progressive disease
What are common associated features in CP?
seizures, cognitive impairment, visual and visuo-motor abnormalitites, deafness, speech and learning impairments
Spastic CP signs and sxs:
UMN with hyperreflexia
abnormal postural reflexes
sustained clonus, adductor tone
dominiant tonic neck reflexes
What are topographic subclassifications of spastic CP?
hemiplegia spastic diplegia spastic quadriplegia monoplegia triplegia
What is the most common spastic CP sub classification?
spastic diplegia
due to damage of medial portion of internal capsule
What are sxs of extrapyramidal CP?
athetosis, chorea, choreo-athetotic
CP in low birth weight infants
spastic diplegia most common
predisposing factors to both CP and prematurity/low birth weight (i.e.: congenital malformation)
CP can influence full term infants as well:
infection
majority (80%) do not have serious perinatal asphyxia
can develop CP without obvious postnatal insult as well
What are predisposing factors for CP?
1/3 have cortical dysgenesis with abnormal neuronal migration hyperbilirubinemia with athetotic CP exposure to toxins in utero infection perinatal maternal infection/fever
