What about symptoms how to
patients with idiopathic PD present?
Well, first we think about the motor symptoms
and this presents as a typical Parkinsonism.
with bradykinesia, rigidity, postural instability,
and typically for idiopathic PD with tremor.
But there are also a number of
non-motor symptoms that we can also see
that are very characteristic of idiopathic
PD, including anosmia (loss of smell),
REM behavior disorder, where
patients will act out their dreams
or caregivers will describe
acting out the dreams.
Typically, patients are flaccid, there is
a loss of tone, atonia during REM sleep.
But in Parkinson's disease, we can see a loss of
atonia, patients develop tone during REM sleep.
REM sleep is when we dream.
So these patients have the ability to
act out dreams as they're happening.
And this may predate the motor
symptoms and being very early feature
of subsequent development
of Parkinson's disease.
Now let's talk about the diagnosis.
How do we diagnose idiopathic Parkinson's disease.
And I'd like for you to think
about this in four categories.
I want you to think about the motor
symptoms and motor Parkinsonism,
which is really how we have established the diagnosis,
in the vast majority of patients over the years,
I want you to think about two
supportive criteria having to be fulfilled.
I want you to know the
exclusion criteria to think about
and then also some red flags to
consider when evaluating these patients.
So let's start with the motor symptoms.
What motor symptoms do we evaluate?
Well, here we're looking for a Parkinsonism.
So we're looking for evidence of bradykinesia,
rigidity, postural instability and tremor.
For bradykinesia we're looking at
the speed and rhythm of finger taps
or opening and closing of
the hand or tapping of the foot.
We're looking for the speed of movement, and
bradykinesia is evidence of reduced speed of movements.
Often patients with idiopathic
PD present asymmetrically,
and so we can see the differences
from one side to the other.
When we evaluate rigidity, we're looking for
increased resistance to passive movement,
And again often in idiopathic
PD, this is asymmetric.
Postural instability is evaluated
by the pull test and rest tremor.
We're evaluating by observing the patient.
When we think about motor symptoms, it is important
to differentiate pyramidal tract of dysfunction
from extrapyramidal dysfunction.
We can go back to the
origin of these tracts.
The pyramidal tracts begin in the cerebral cortex,
the key tracts of the corticospinal and corticobulbar.
And here, patients have difficulty
with voluntary muscle control,
upper motor neuron symptoms,
That's different from the extra pyramidal tracts.
So those four cardinal features, motor features of
Parkinsonism result from dysfunction of these tracts,
and this system.
The extrapyramidal system begins in the
brainstem, descending tracts that carry information,
for modulation of movement, or the vestibulospinal,
reticulospinal, rubrospinal and tectospinal.
They're keeping the axial skeleton upright.
movement while it's occurring,
and dysfunction and problem in those tracts
result in the development of Parkinsonian symptoms.
These tracts are involved in involuntary
and automatic control of musculature,
and that's why we see problems
with those functions in patients.
Importantly, motor Parkinsonism comes from
dysfunction of this extrapyramidal symptom.
It is an extrapyramidal disorder.
So let's look a little bit at the tracts and
understand what what they are and how they work.
First, let's begin with the pyramidal
system and this is one we know well.
The pyramidal system is
composed of two tracts -
the corticospinal tract, which controls
voluntary muscle movement and control.
There's the lateral corticospinal tract which
contains about 85% of the motor neurons
from the primary motor cortex and the anterior
corticospinal tract which carries the other 15%.
There's also the corticobulbar tract which carries
information about voluntary control of muscles
of the face and bulbar fibers.
This is different from the
Here we're dealing with
four tracts and four pathways.
The first is the rubrospinal tract
which controls fine motor control.
The reticulospinal tract, there is a medial,
the reticulospinal tract which is involved in
in contraction and increasing axial
tone and a lateral reticular spinal tract,
which is involved in relaxation and
decreasing axial tone to keep us upright,
and our bodies moving in an upright posture.
The vestibulospinal system is involved
in modulation of balance and posture
and so we see importance in
balance and posture in this tract
And dysfunction of this tract can lead to the
postural instability that we see in Parkinsonism.
And then finally, the tectospinal or
colliculospinal tract is involved in head coordination,
keeping the head above the body and moving along
with the rest of the body and maintaining posture.
So the next criteria that we think about in
establishing a diagnosis of idiopathic PD
is looking for exclusion criteria and making sure
there are no absolute exclusions for this diagnosis.
There are a number of red flags that
could come up that would point towards an
that's not idiopathic PD.
And in general, these are things that suggest
an alternative neurodegenerative Parkinsonism
so these patients may have Parkinsonian
signs - bradykinesia, rigidity, postural instability,
but also something else that points us away from
idiopathic PD towards some some other etiology.
A prominent cerebellar abnormalities would
be uncommon in a patient with idiopathic PD,
and may suggest a diagnosis
of multiple system atrophy.
Problems with downward supranuclear
gaze palsy, reduced a vertical down gaze,
or reduced vertical downward saccades,
goal-directed downward eye movements
is uncommon in idiopathic PD and may suggest
a diagnosis of progressive supranuclear palsy.
An early diagnosis of frontotemporal dementia
within the first 5 years of onset of Parkinsonian signs
would be atypical of Parkinsons disease and
may suggest a diagnosis of Lewy Body disease.
PD patients, idiopathic PD patients can
develop dementia, but it's often late in the course.
Parkinsonian features that are restricted
to the lower limbs for more than 3 years
is uncommon in idiopathic PD and should
prompt an evaluation for spinal cord pathology.
And then finally, treatment in the past
year with a dopamine receptor blocker
should warrant a workup for
Drug-induced Parkinsonism can be seen with
a number of agents including Metoclopramide
and other dopamine antagonists.
Stopping of those agents can often
result in improvement of the symptoms,
and drug induced Parkinsonism is
often more symmetric than idiopathic PD.
In addition, absence of observable
responses to high dose levodopa
should question the
diagnosis of idiopathic PD.
PD, Parkinson's disease is
often responsive to levodopa
whereas many of the
Parkinson's plus disorders are not,
And the lack of response to leave a dopa
should warrant a workup of alternative diagnoses.
Unequivocal cortical sensory loss, things like
agraphesthesia, astereognosis, Alien Hand Syndrome,
ideomotor apraxias, or progressive aphasias,
should suggest an early cortical problem
such as corticobasal degeneration, and these
are uncommon early in the course of idiopathic PD.
The next area I'd like us to
focus on is supportive criteria,
things that help to establish
a diagnosis of idiopathic PD,
but are not definitive
when present outright.
So what are some of
those supportive criteria?
Well, one is a dramatic improvement
of symptoms with dopaminergic drugs.
This should strongly suggest an
underlying diagnosis of idiopathic PD.
Asymmetry at onset is commonly
seen in Parkinson's disease.
Rest tremor of limbs, particularly unilateral
and then ultimately progressing to bilateral
is common and supportive of that diagnosis.
And a history of anosmia or REM behavior disorder
is also suggestive and supportive
of a diagnosis of PD.
Finally, we want to think about red flags
things that would suggest an alternative diagnosis.
A number of red flags can be considered
rapid progression of gait impairment
should warrant evaluation for structural
problems, or alternative diagnoses.
Absence of progressive motor symptoms
or signs for five years is also inconsistent
and should warrant alternative workup.
Early bulbar dysfunction, severe dysphonia,
dysarthria, dysphasia is uncommon in PD
It can be seen late but is uncommon early
and would be more likely to occur and progress
to supranuclear palsy.
Inspiratory stridor, dyspnea,
spasmodic dysphonia also should suggest
evaluation for brainstem pathology or PSP.
Severe autonomic failure in the first five
years of the disease is uncommon in PD.
We can see autonomic failure late, but
early autonomic dysfunction, early orthostasis,
early erectile dysfunction, early urinary
retention should warrant structural evaluation
for a brainstem pathology or can
be seen with multiple system atrophy.
And then recurrent falls due to impaired
balance within the first three years
should warrant workup for cerebellar
pathology or progressive supranuclear palsy.
Falls can be seen in idiopathic PD but
are more common late in the disease.
So here we're talking about symptoms
not only about whether they're occurring,
but the timing in which they're occurring that
can help us with establishing this diagnosis.
Involuntary flexion of the neck or contraction of
the hands and feet should warrant alternative workup,
Absence of common non-motor
symptoms, anosmia, REM behavior disorder
should prompt a consideration
for alternative diagnoses.
Unexplained pyramidal tract signs,
hyperreflexia, or spasticity is a red flag
and really should prompt neuroimaging.
And bilateral symmetric Parkinsonism should
warrant a careful evaluation of medication history
as this would be more common
in drug induced Parkinsonism.
And then, lastly, we can use imaging.
Structural brain imaging with
CTs and MRIs are really not helpful
in evaluating patients
with Parkinson's disease.
They don't establish the diagnosis,
but they can help exclude other causes.
The scan we can do to help establish the diagnosis
is the DAT scan or the dopamine transporter scan.
This is a nuclear medicine scan.
Patients are given a radiolabeled dopamine agent
this traffic's through the body and up into the brain,
where it has a predilection for for appearing in the
substantia nigra and the deep basal ganglia structures.
Here we're looking at a series of DAT scans,
on the far left you see the normal DATscan.
They're symmetric uptake and adequate
uptake in both basal ganglia bilaterally.
On the right, we see two abnormal DATt scans.
The left image or in the middle shows
mildly reduced right putamen uptake
of the tracer and that asymmetry is common.
This patient may have asymmetric
symptoms which is consistent with idiopathic PD,
and we see that also on the DAT scan.
On the far right, we see markedly reduced right
putamen uptake of the dopamine transporter tracer
and this is consistent with more
severe moderate to severe disease
and would be consistent with a diagnosis of a
Parkinsonism, and specifically for idiopathic PD.
Parkinson's patients also
fall, often fall backwards early,
whereas PSP patients often fall forward
early as a result of that vertical down gaze.