00:01
Now let's talk a little bit more about ALS,
and the diagnosis of ALS will be by exclusion,
excluding many of those other causes,
but we can also be supported
in the appropriate clinical setting.
00:14
First, let's start with a definition.
00:15
This is a neurodegenerative disease
involving both upper and lower motor neurons.
00:19
There's degeneration of the
primary and secondary motor neurons.
00:24
It's also known as Lou Gehrig's
disease from a famous individual
early in the description of this syndrome.
00:32
It is a progressive disease.
00:34
Patients begin with chronic onset of symptoms
that is relentlessly progressive over time.
00:39
Patients become weaker and
weaker as the condition progresses,
eventually leading to
paralysis and ultimately death,
typically from dysphasia, or pulmonary
dysfunction, weakness of respiratory muscles,
and pneumonia.
00:52
And there is no cure for this condition.
00:56
How about the epidemiology?
This is one of the most common
progressive motor neuron diseases that we see,
90 to 95% of cases are sporadic.
01:05
There is this small group
of cases that are inherited
and a number of genes have been
described, though the vast majority of patients
do not have an underlying
genetic, single genetic etiology.
01:17
And the case is sporadic in onset.
01:20
And the underlying etiology
in those cases is unknown.
01:24
And here we're looking at a patient who has
significant atrophy of multiple muscle groups
throughout the upper and lower
extremities and may have for fasciculations
again supporting the lower motor
neuron findings in this patient.
01:37
In terms of pathologies, one of the
things that we see typically at autopsy,
because biopsies aren't typical for this condition,
are degenerative changes in the motor neurons
in both the cortex and the
anterior horn cells, the cell bodies
of the primary and secondary motor
neurons and we see these inclusions,
these Bunina bodies, which are eosinophilic
inclusions that are contained within the neurons
and are pathognomonic for this condition.
02:03
Now let's talk a little bit about the clinical
manifestations and the diagnostic investigation.
02:08
What do we look for on exam
to support a diagnosis of ALS?
Well, again, we're looking for upper
and lower motor neuron findings
and those upper motor neuron findings are spasticity
slowed, rapid alternating movements from spasticity,
a spastic gait, spontaneous
clonus or hyperreflexia.
02:26
Those are suggestive of
upper motor neuron pathology.
02:30
We can also look for lower
motor neuron symptoms and signs
and that includes prominent
muscle atrophy, fasciculations
which has very good specificity
for lower motor neuron disorder.
02:41
Proximal arm and leg weakness, poor
heel and toe walking from weakness
of the proximal muscles of the legs.
02:48
Poor rise from a chair, also a
proximal muscle weakness symptom,
foot drop, waddling gait and hyperreflexia.
02:56
Asymmetrical weakness
can be one of the earliest signs
and is not uncommon in
patients presenting with ALS.
03:05
Fasciculaitons is very important
and I cannot underscore this enough.
03:08
You don't see it if you don't look
and you have to look in this condition.
03:12
Fasciculations are visible, involuntary
contractions of an entire motor unit,
a motor nerve and all of
the muscles that it innervates.
03:20
This occurs secondary to reinnervation of
denervated fibers that spontaneously depolarize
and we can see this anywhere in the body.
03:28
Some of the places we frequently look
or the first dorsal interosseous muscle,
the upper extremity muscles, lower
extremity muscles and the tongue
and the presence of tongue
fasciculations should strongly suggest
a consideration for a diagnosis of ALS.
03:46
Some of the other clinical
manifestations, we can see limb weakness,
cramping in the early morning, instability
of gait, falling due to spasticity or weakness,
fatigue when walking now that may
suggest neuromuscular junction disease,
but we can also see it with
other causes of weakness.
04:01
Stiffness in the affected limbs, particularly
stiffness in limbs that have significant atrophy
is indicative of a combination of
upper and lower motor neuron signs
and in coordination of the affected limbs.
04:13
Pain is not common in this condition, and we
really shouldn't see pain early in the disease.
04:18
Late in the disease, we can see pain, and that's
commonly due to spasticity or decreased mobility
and so the more spastic and less mobile
that joint is, the more pain we can see in that condition and some of our treatments and management is to reduce pain in those patients.
04:29
and some of our treatments and
management is to reduce pain in those patients.
04:33
Traumatic injury from falls is also not
uncommon and can be a source of pain,
but pain should not be present, typically is
not present at the time of initial presentation.
04:44
ALS is one type of motor neuron disease.
04:47
It's the most common motor neuron disease but
not the only one and there are a number of variants.
04:51
One is progressive muscle atrophy
and this is a lower motor neuron variant.
04:55
This typically occurs sporadically in adults.
04:58
There are no known occurrences of the disease within
family, and this has a lower motor neuron variant.
05:03
Spinal muscle atrophy is another lower
motor neuron variant that is inherited.
05:08
So the sporadic form is progressive muscle atrophy
and the inherited form is spinal muscle atrophy
and this typically occurs in children,
though there are a number of variants
that can present early in life, early
in childhood and then sometimes
rarely in adolescence or rarely in adulthood.
05:24
Progressive bulbar palsy is bulbar face
cranial bulbar predominant motor neuron disease
and there are a couple of
conditions to consider here.
05:33
One, Fazio-Londe Syndrome
or spinal bulbar variant in children
and then Kennedy's disease,
spinal bulbar variant in adults.
05:42
This can also be associated
with areflexia and gynecomastia,
which we don't actually see in the clinic
very often, but can be tested in various settings.
05:51
And then there are a number of
other variants of motor neuron disease
that we can see and need to
consider, which are quite rare.
05:58
When I'm thinking about these
ALS variants, I really like this graph,
and the schematic for how to think through
what's the type of motor neuron disease
I need to be worried about.
06:07
ALS is the most common.
06:08
So if you see something that has combined
upper and lower motor neuron pathology,
throwing out ALS as the most common
motor neuron disease is always the right answer.
06:17
But we can divide the other motor
neuron diseases into those that are sporadic,
or just acquired over the
course of life, or inherited.
06:25
And we can look at those that are upper motor neuron
predominant versus lower motor neuron predominant.
06:31
So let's start with the sporadically
occurring motor neuron diseases.
06:34
The upper motor neuron
variant is primary lateral sclerosis,
and the lower motor neuron variant has progressive
muscle atrophy with ALS right in the middle
presenting with a combination of
upper and lower motor neuron findings.
06:47
There's also a bulbar variant and we
talked about two of those, Fazio-Londe in kids
and Kennedy's disease in adults and those
present with prominent bulbar findings initially.
06:58
There are also some inherited
conditions that can masquerade as ALS.
07:02
The upper motor neuron
variant is hereditary spastic.
07:05
Paraplegia, common in adults and spinal
muscle atrophy is the lower motor neuron variant,
more common in very young children.
07:14
Now let's talk about the treatment
and prognosis for patients with ALS.
07:19
First of all, in terms of treatment,
there is no cure for this condition.
07:22
We're looking for supportive care and
disease modifying therapies that prolong life
but nothing cures this disease.
07:29
Rilutek or Riluzole increases life
expectancy in the order of several months
and there continued to be studies and ongoing
developments in the management and treatment of ALS.
07:38
So it's then in the future, hopefully, we
have more treatments for this condition.
07:42
Additional disease-modifying treatments for ALS include edaravone and sodium phenylbutyrate-taurursodiol.
07:51
Edaravone is a free radical scavenger which reduces oxidative stress and may slow functional decline.
07:57
Sodium phenylbutyrate-taurursodiol is a histone deacetylase inhibitor
which can reduce neuronal cell death and slow the rate of functional deterioration.
In terms of prognosis, the life
expectancy ranges from 3 to 5 years,
but this is highly variable.
08:15
Some patients have a more
rapidly progressive course,
when there's significant
dysphasia or respiratory weakness,
patients have typically a more rapid course, and
others have a more protracted or prolonged course.
08:26
It's important that we evaluate
pulmonary function and swallowing
and we do that by looking at pulmonary function.
08:33
And we see this drops to a concerning level.
08:36
Patients may be considered for
non-invasive positive pressure ventilation,
and for patients with significant
dysphasia, weight loss or nutritional concerns.
08:45
A percutaneous endoscopic gastrostomy
tube or PEG tube can be placed
for alternative means of nutrition
and they may impact both the morbidity,
quality of life and mortality,
the length of life in patients.
09:01
ALS is associated with a number of complications
that also need to be considered and managed.
09:05
We can see laryngospasm, which can result
from fasciculations of the laryngeal muscles
Siallorhea from oropharyngeal weakness,
pseudobulbar affect from damage of the brain
and we can see this commonly in
patients with certain variants of ALS.
09:20
Tongue weakness, offen with fasiculations,
respiratory muscle weakness,
and cognitive impairment is present in
somewhere between 20 to 30 or 40% of patients.
09:30
Importantly, I want to mention this association
between ALS and FTD, Frontotemporal dementia.
09:35
Increasingly, there has been
recognition of an association between ALS,
motor neuron disease and frontotemporal dementia.
09:42
We see a number of patients who have significant
cognitive dysfunction as a result of this link.
09:47
These two conditions have been linked
in FTD, specifically linked to ALS variants,
particularly the bulbar predominant ALS in
which patients often develop pseudobulbar affect
that emotional lability, as
well as dementing conditions.
10:00
There's some evidence from FTD genetic
abnormalities and genetic studies that suggest that
the spectrum of ALS and FTD is
related to an underlying genetic link.
10:14
Lastly, I want to review some of the ALS variants.
10:17
Things that are on the differential
diagnosis and we'll go through these quickly.
10:20
You need to know the names of these conditions and
some of the key features but not all the details.
10:27
First, let's start with Stiff Person syndrome.
10:30
Stiff person syndrome is an autoimmune condition
that typically is a result of antibody production
against glutamic acid decarboxylase or GAD.
10:41
We see increased GAD levels in
these patients who become very stiff
and muscle groups throughout the arms and legs.
10:47
When we think about clinical
manifestations of stiff person syndrome,
there's waxing and waning stiffness with
spasms that can be quite debilitating and painful.
10:55
This begins in the axial muscles of the trunk and
then can spread to the proximal lower extremities.
11:01
Initial complaints include back pain,
upright posture, worse with tension and stress.
11:05
Patients are very stiff, but it can fluctuate, which
is different from typical motor neuron disease.
11:10
Later in the disease, their patients
can develop stimulus-induced spasms
and stiffness at the proximal
upper and lower extremities.
11:16
This is an inflammatory immune mediated disorder
that we treat with immunomodulating therapy.
11:23
Long term complications include bony
abnormalities, joint deformities, and we can see
an association with diabetes,
seizures, thyroiditis, and breast cancer.
11:34
Next, let's talk about
tropical spastic paraparesis.
11:37
This is another important
differential diagnosis of ALS.
11:41
Tropical spastic paraparesis is also
known as HTLV-associated myelopathy
because it's a myelopathy, a spinal cord
disorder associated with HTLV infection,
and that's what you're looking
at here in this pathology slide.
11:54
This is a slowly progressive
condition that presents as a myelopathy.
11:57
So paraperesis, stiffness in the legs hyperreflexia
and the etiology is this association with
human T-lymphotropic virus, or
HTLV-1 which is primarily transmitted
through sexual or intimate
contact.
12:12
This is an important consideration
in patients presenting with
an upper motor neuron-predominant syndrome
The next condition that presents on the
differential diagnosis with motor neuron disease is
Tropical Ataxic Neuropathy or TAN.
12:27
The next condition I want to talk
about is Tropical Ataxic Neuropathy.
12:30
This is an ataxic neuropathy, lower
motor neuron predominant presentation,
we see sensory neuropathy
common in malnourished patients
thought to be related to cyanide
toxicity from cassava intake.
12:42
patients present with subacute to chronic burning
pain in the hands and feet and difficulty walking
and can have a range of neuropathy, ataxia,
hyperreflexia as well as sensory neural hearing loss
and the key feature here is there is
prominent sensory findings in these patients
which is really different from
our typical motor neuron disease.
13:01
Primary Lateral Sclerosis is that sporadic
upper motor neuron form of motor neuron disease.
13:08
These patients typically present
with leg weakness with spasticity.
13:12
There can be spastic bulbar dysfunction as well.
13:14
But the key is there's upper motor neuron pathology
with cortical bulbar and corticospinal tracts.
13:20
It's often asymmetric.
13:22
This often begins with
spasticity followed by weakness,
whereas with ALS, you often see
weakness followed by spasticity.
13:28
And some associated features include
abnormalities with eye movements, saccades
caused by a volunteer goal directed eye movements,
urinary dysfunction and cognitive dysfunction.
13:39
Then there's also primary muscle atrophy.
13:41
This is the lower motor neuron variant,
it's a sporadically acquired condition
and accounts for 10% of motor neuron diseases.
13:49
It's more common in men, presents with
progressive weakness with no other known etiology.
13:54
So you need to rule out other
neuromuscular junction and myopathies
and peripheral nervous system disorders.
14:01
And the prognosis is better than ALS, it's
more slowly progressive than the typical ALS