We’ll walk through a few
To begin with, remember, in us,
as you carry out as humans,
we have two different
types of DNA, right?
We have our somatic or our nuclear DNA,
and then we have our mitochondrial DNA.
The mitochondrial DNA is something
that we inherit from mama, right?
From our mothers.
So here, there’s a couple of
ones that we have to know about,
definitely know about mitochondrial
encephalomyopathy with lactic acidosis
and stroke-like symptoms.
In other words, that’s MELAS.
The other one is --
Pay attention to RRF,
that’s ragged red fiber.
These are the ones that you’ve
also talked about in biochemistry.
Hence, I am not elaborating
on the abbreviation.
inherited or sporadic,
mother may be unaffected carrier though.
Frequently accompanied by other
For example, MELAS, Mitochondrial
lactic acidosis, and,
what does S stand for?
Our muscle biopsy, what
would you expect to see?
What’s that RRF stand for?
Ragged red fiber, which contains what?
You must know what ragged
red fiber contains.
Accumulation of glycogen and
what’s known as your lipids.
Our topic here is
Begin by looking at dermatomyositis.
Allow the name to speak to you.
What does derma mean?
What does myo- mean?
Hence, we’re doing our
skeletal muscle diseases.
Then we have polymyositis.
And finally, we have what’s known
as our inclusion body myositis.
In other words, inflammation.
Shoulder and hip girdle
weakness is present.
Oh, be careful, huh.
There was actually a condition
that we called what?
Limb and hip girdle
myopathies or dystrophies.
So, be careful with those, right?
we’re dealing with shoulder and hip,
but I have to give you further detail,
as will your clinical picture.
Relative sparing of, once
again, the ocular and bulbar,
and cardiomyopathy, once
again, less frequent.
So, those are nonspecific.
We see this earlier with limb and
girdle muscular type of dystrophy.
So what is it about these
conditions that is more specific?
Let’s take a look.
First, we’ll take a look
Most frequently seen in children.
What are you going to find?
Well, when seen in adult, often
associated with underlying malignancy.
Derm, will begin with the skin.
Around the eyes, you have something
called a heliotrope rash.
So, it’s purplish
discoloration of the eyelids.
The first manifestation
is going to be skin,
more common in children.
If it’s adult, then
Then you have what’s
known as Gottron lesion,
and this Gottron lesion are going
to be that around the knuckle.
So, erythematous, which means what?
Red scaly lesion over the knuckles.
In other words, your
Associated cardiac conduction abnormality,
congestive heart failure, or perhaps
even, interstitial lung disease.
Just keep those in mind because not only
could you have then your skin issues.
Ah, you could have issues
with the muscle as well.
It is steroid responsive.
Here, we have polymyositis.
These are more common in older individuals.
Condition: Steroid responsive.
All that I wish to say about
Inclusion body myositis:
Late middle aged to
I just want to make sure that
you’ve heard of such conditions.
Early weakness of finger flexors
and ankle dorsiflexors.
inclusion body myositis.
Here, we’ll take a look
at endocrine myopathies.
Your patient may have
Often subclinical, brisk reflexes.
In other words, there could be
an increase in thyroid hormone.
And you have creatinine kinase,
typically, would be normal.
Versus hypothyroidic type of myopathy.
So, think about decreased T3, T4.
Delayed relaxation, think of your
patient with hypothyroidism,
everything is slowed down.
Creatinine kinase is moderately
to severely elevated.
Steroid myopathy could be caused by
either endogenous or exogenous causes.
CK is typically normal.
With drug and toxin induced myopathy,
there are too many causes to list,
but here are some important ones.
HMG-CoA reductase inhibitors, your statins.
Do not forget, may then cause necrotizing,
what’s known as rhabdomyolysis.
You’d find your creatinine
kinase to be ridiculously high.
Obviously, not very common but
something very much to keep in mind.
Alternate day dosing lessens the risk.
Remember that by
there’s every possibility
that a myopathy could set in.
your patient is on highly active
antiretroviral therapy, heart regimen.
There is a possibility of mitochondrial
myopathy with zidovudine, AZT.
Cimetidine, H2 blocker, maybe your patient
is suffering from a gastric ulcer.
And so therefore, you want to
block the acid production,
and in the process, may result
in inflammatory myopathy.
Keep that in mind along with,
obviously, gynecomastia and such.