In this talk, we're going to review peripheral neuropathies.
Let's start with the case.
This is a 21-year-old triathlete who presents with progressive weakness.
The patient says that she was in her normal state of health until about three days prior
when she began to experience heaviness of her bilateral feet.
This is rapidly worsened such that now she describes heaviness and weakness
spreading proximally up to her thighs.
Tingling like pins and needles in her feet, and slight problems
with gripping of her hands when trying to open a soda.
As you further question her, in retrospect, she notes some mild back pain.
Her exam confirms 4 out of 5 weakness throughout the legs and mild sensory loss,
most notable in the feet. You are unable to elicit any deep tendon reflexes.
So, when we approach this case, there are a few important things that I want you to think about.
First is the distribution of the symptoms.
The symptoms are present bilaterally and they appear rather symmetric.
They began in the feet, and they are spreading proximally up to the hands.
This has a length-dependent ascending distribution.
The second is there's an important - this important wild card of the rapid progression.
And this has begun really quickly over the course of three days
and now reached already the patient's hand.
This is a rapidly ascending progressive symmetric motor and sensory problem.
The third of the sensory findings, there is mild sensory loss, so the motor nerves are involved,
causing weakness and there's some sensory loss and sensory nerve involvement.
And importantly, the reflex exam shows absent deep tendon reflex, and that's really important.
Hyporeflexia can be seen in muscle disorders and neuromuscular junction disorders,
but areflexia should point us towards a problem in the peripheral nerve.
So, what's the most likely diagnosis in this patient?
Is this heavy metal toxicity with lead, transverse myelitis, acute flaccid paralysis
such as West Nile virus associated flaccid paralysis,
or acute inflammatory demyelinating polyneuropathy?
Well, this is not really the story we hear with heavy metal toxicity.
Heavy metals can cause polyneuropathy,
but it doesn't typically present acutely with this rapid progression.
Patients develop neuropathy that's associated with long term
or chronic exposure to heavy metals such as lead.
With lead exposure in particular, there's minimal sensory involvement.
It's primarily a motor neuropathy. This doesn't sound like transverse myelitis.
Transverse myelitis is a central nervous system problem.
We expect to see hyperreflexia or spasticity or other upper motor neuron signs,
and the presence of areflexia in this patient strongly supports
a peripheral nervous system and peripheral nerve disorder.
This is not the story we tend to hear with acute flaccid paralysis from West Nile.
West Nile virus is associated with an acute polyradiculopathy,
and it can present very similar to Guillain-Barre,
but we don't have any historical details to suggest of West Nile exposure in this patient.
This is a typical story for a patient with AIDP or acute inflammatory demyelinating polyneuropathy,
and the other name we give to that is Guillain-Barre syndrome.