Now let's talk about
or also called Corticobasal
Corticobasal degeneration is
also a progressive, asymmetric,
dementia-movement disorder with sporadic
neurodegenerative 4-repeat tauopathy.
So it's a mouthful.
What it means is
this is a tauopathy
which makes it different in terms
of what is depositing on the brain
disease and MSA.
It is asymmetric and that's
a really important feature
of CBD that we don't see with some of
the other Parkinson's-plus syndromes.
But we do see with
It is a movement
It begins in the cortex,
there's prominent parietal dysfunction
as well as
So let's talk about some of the
brain areas that are involved
and degenerate in
We see prominent
parietal lobe atrophy,
as well as involvement
of the basal ganglia
and to some degree,
the brain stem.
What's going on in the brain?
Well, this is a tauopathy.
So we see hyperphosphorylation
of tau protein
that leads to increase in microtubule
formation and abnormalities.
protein resists proteolysis
and forms aggregates and these
aggregates come together in the neurons
and have been termed
which you can see in
the schematic here.
As tau protein accumulates into
these neurofibrillary tangles,
this contributes to the degenerative
pathology and abnormal neural function.
CBD is classified as
a 4-repeat tauopathy
which is a different interval
of the number of taus
compared to other
develop into astrocytic plaques, and other
dystrophic glial tau findings are seen.
And this is similar to what's seen
in other tauopathies such as PCP,
Alzheimer's disease and Frontotemporal
dementia or formerly Pick's disease.
And there is extensive neuronal
loss in this condition,
and that contributes
to patient's symptoms.
What about the clinical
What do we hear from patients
and what are we evaluating?
Well, number one,
we want to look for that asymmetric onset
that's common in patients who
have seen present with CBD.
Falls are not uncommon
and behavioral changes
consistent with a dementing illness
are very common in this condition,
and often are reported
family members and loved
ones of these patients.
On physical exam,
we may see findings of asymmetric apraxia,
rigidity and postural instability
can be seen it as a Parkinsonism
and we can see speech
disturbances as well.
Some of the unique
features of CBD
include myoclonus or
hyperreflexia in some rare cases.
Alien-limb phenomenon is
a very unique phenomenon.
It's highly specific for CBD.
This is unintended motor actions
such as grasping, groping, drifting
or undoing of things that the patient
is not aware of or in control of.
The arm literally does
what it wants to do.
It buttons a shirt, it unbuttons a
shirt, it moves something,
it keeps something,
it grabs a hold of things,
and it's doing without the patient's
willingness or volitional control.
Patients can also have slowed
gait, Frank dementia,
and slow saccadic movements or
goal directed eye movements.
So this is really a multisystem disease
with prominent parietal dysfunction.
Again, the diagnosis
is made clinically.
We do not use imaging to
diagnose this condition.
But late in the disease,
we can see imaging findings
that are indicative
of a CBD diagnosis.
We're looking for atrophy,
we don't see lesions on the brain.
Early brain imaging is important
for excluding other causes.
And late in the condition,
we see prominent atrophy.
We can see it throughout
the entire brain,
but we often see prominent
atrophy in the parietal lobes.
And here on the
axial T2 on the left,
we're looking at diffuse atrophy with
prominent atrophy in the parietal lobes.
That's evidence on the coronal,
we're looking at a parietal section
and you see deep sulci with
a lot of CSF in those areas.
And then on the
sagittal T1 here,
we also see predominance
of parietal lobe atrophy
which is suggestive of a diagnosis of
CBD in the appropriate clinical setting.
What about treatment?
Well like all of the Parkinson-plus
syndromes, we begin with a Levadopa trial.
And unfortunately, typically,
this is met without much success.
Levadopa does not reduce symptoms
in CBD unlike Parkinson's disease.
And that's really one of the
between idiopathic PD and all of
the Parkinson's-plus syndromes.
There is no other disease
propranolol, and clonazepam can be
used to treat tremors and myoclonus
Cholinesterase inhibitors can
help with cognitive dysfunction
and we really focus on symptomatic
management and supportive care.