00:00
So, let's go back to our case. Recall this was a 54-year-old woman who presented with
progressive weakness. She's got thyroid disease and is on a statin for cholesterol lowering.
00:11
She has prominent proximal weakness both on history with difficulty walking upstairs and
getting up out of chairs and is starting to have some symptoms in her arms. She has no
sensory findings, normal reflexes and no bulbar symptoms. So, where do we localize this
condition, peripheral nerve, neuromuscular junction or muscle? But we don't see those
typical findings of neuromuscular junction pathology. There are no bulbar findings. And that
should really point us away from a neuromuscular junction condition and towards the muscle.
00:42
The pattern is inconsistent with a peripheral neuropathy. We don't see sensory findings. The
reflex exam is normal. We don't see reduced or areflexia. And the pattern of proximal
weakness is really suggestive of a muscle condition. And this is the typical presentation of a
myopathy. We've localized this problem, now we need to figure out what's causing it. And
in a subsequent lecture, we'll focus on that. How do we evaluate most muscle diseases? Well,
it starts with the history and the examination. And then we think of a slew of tests, biopsies
and nerve conduction studies or electromyography and serologic testing to figure out what
type of condition it is. And remember we think of those 5; inflammatory, infectious, neoplastic
or paraneoplastic, toxic, metabolic and inherited. And we're using our testing to drive into
those. This is a nice table that walks through how we think of the evaluation of this specific
muscle diagnosis. When we localize a problem to the muscle, we're going to evaluate first
for signs of inflammation and think of the inflammatory myopathies if we see inflammatory
signature. If we don't see inflammation within the muscle, we may consider infections or
paraneoplastic causes. We're going to screen for toxin or metabolic disorders and think about
these diagnoses that could be causing that problem. And it's important to consider inherited
and congenital causes of myopathies. So, this table may be a good reference as you're
evaluating cases or patients who present with a myopathic complaint. Once we have honed
in on the diagnosis, we use information about that condition to prognosticate and understand
inheritance for certain inherited or congenital conditions. The treatment is supportive for
many patients with muscle disorders but there are new treatments that are emerging for
many of these conditions that can provide important improvement in that patient’s symptoms
and function over time.