Thread by @AdamJBrownMD

Sensory Ganglionopathy & Sjogren Syndrome

⚡️what is it?

⚡️how to recognize/diagnose it

⚡️what's the underling cause?

latest @HRheuminations is up with link at the end of this ripping 🧶

a thread

#neurology #sjogren #rheumatology

Let's review anatomy 1st

Sensory nerves: travel from skin to the nerve cell body in the Dorsal Root Ganglion (DRG) then⬆️dorsal column of spine to the brain

DRG- ‼️cell body of sensory nerves‼️

Motor nerves: travel from brain and exit ventral (anterior) spinal cord ➡️muscle

Okay, so dorsal root ganglion only contains sensory nerves. This is an important part of the story.

Next important part, Sensory nerves are not all created equal.

Large fiber (myelinated) ➡️ small fiber (unmyelinated)

⭐️and lots in between

⭐️and they do different things

Okay let's make it simple:

⚡️large fiber: proprioception, vibration

⚡️small fiber: pain, temperature

Now back to Sensory Ganglionopathy

What is it?

⚡️Destruction of the DRG (cell body of sensory nerves outside of spine)⚡️

⚡️causing a primary SENSORY loss in a patchy distribution⚡️

Pic from NEJM article-A) inflammation in DRG B) pallor of doral column

Importantly Sensory Ganglionopathies can occur anywhere along the spinal cord

⚡️making it NON-Length dependent

⚡️In contrast, the vast majority of neuropathies are length DEPENDENT, meaning the furthest nerves are typically involved 1st (diabetes for example)

So a Sensory Gangliopathy may start with:

⚡️unilateral hand numbness

⚡️then develop right sided facial numbness

⚡️then numbness across half the chest

the point being, the pattern is typically "patchy"

Next important part:

For reasons not too clear, Sensory Gangliopathies primarily involve Large Fiber sensory nerves.

meaning the patient will experience:

⚡️loss of touch sensation
⚡️loss of vibration sense
⚡️pronounced PROPRIOCEPTIVE loss-leading to...

When your hands and legs don't know where they are in space:

⭐️pseudoathetosis-the hands will wonder with eyes closed
⭐️Ataxia: the feet won't know where they are in space, making it extremely difficult to walk

IMPORTANTLY-motor nerves are SPARED, patients have normal strength

So the diagnosis can be considered with just the physical exam findings demonstrating a:

⭐️NON-length dependent (patchy)
⭐️primary LARGE fiber (pseudoathetosis and ataxia) ⭐️sensory neuropathy (numbness)

with INTACT strength

But wait, what's causing it? the differential, is fairly small...

This is how Rheumatology gets involved,

⭐️When Sensory Gangliopathy is suspected, SSA is part of the workup

⭐️in fact over half of patients with Sjogren related sensory ganglionopathy are not known to have Sjogren until after presenting with the neuropathy.

Learn more about presentation, workup, imaging, EMG findings and treatment? by taking a listen to the next Rheuminations episode! up now

Making Sense of Sensory Gangliopathies and Sjogren Syndrome

References in podcast link

protect-us.mimecast.com/s/MtTfCo2KwWUD…