Horizontal gaze palsy

I spoke with a colleague recently about the topics for our local stroke convention in the fall and we shrugged shoulders: nothing new really. Really? Quite to the contrary. I stumbled upon a patient last week that had the curious combination of a horizontal gaze palsy to the left with only slight proximal paresis of the left arm, maybe some dysarthria, but you couldn’t quite tell, because his local accent was so thick. And his MRI: shows a microangiopathic lesion only in the right internal capsule, in the posterior crus right behind the genu, perhaps touching the latter a tiny little bit. No thalamic involvement, nothing else.

We reviewed the functional anatomy of the horizontal gaze system and localized the various structures (such as the frontal eye fields, the capsule, the PPRF, MLF, IIIrd and VIth cranial nerve nuclei) in an MRI. I am always surprised how hard this can be, but we use Kretschmann’s atlas to do the main work. The rest can be left to Brazis’ localization book, which – incidentally – has been edited in 2012.


A localization conundrum

Every respectable textbook mentions this, but it is still a wonder to see it (as we did last Saturday).

A 52 yo female is brought in by the Notarzt (EMS doc) with dense hemiplegia on the right. It seems that the patient just managed to call the EMS, before she collapsed; the Notarzt found her with paralysis of the right arm and leg, progressing to dense hemiplegia over the 20 minutes it took to reach the ER. Now the patient is restless, throws her head back and forth, right and left, crying that she is in pain, her arm is hurting and her leg is. She does not respond to any question, is in grave distress. After an opiate she becomes somnolent and whispers that the problem started 10 mins before she called the EMS (about 40 mins ago now) and then stops, obviously at peace with the world.

On examination she is somnolent, GCS 10 with intact cranial nerves. Her right arm is MRC 0, as is her right leg. She is also analgesic on the right arm and leg, though not on the trunk. The face is intact. On the left she has some degree of weakness at her leg, but develops enough strength to turn in her bed. The reflexes are pretty much down on the right, normal at the left arm, brisk at the left lower extremity, with some ankle clonus and Babinski’s on the left.

This is it. You can make a diagnosis out of that. There is no differential. Any ideas?

Ocular bobbing and dipping

Ocular bobbing, dipping and floating are not too rare, if you keep examining your comatose and brainstem patients repeatedly. We discuss the few things that are known about these eye movement disorders and relish the wonderful poem of Ross 1992:

You’re called to the bedside, the eye movements are strange.
There must be a reason, can you give it a name?
You’ve seen this before, but can you recall?
You’re the Neurologist, you’re supposed to know all!

In bobbing and dipping, the eyes go down.
“How is that?” you ask with a frown.
The first is brisk, the second is slow.
The meaning differs; you must know.

Bobbing suggest pons; dipping an anoxic brain.
As always, there are some exceptions to name.
Metabolic encephalopathy can make the eyes bob.
Cerebellar hemorrhage and trauma complete the log.

To remember all this, you need something terse.
But wait, don’t forget, it could be reverse!
In each of these cases, it’s up the eyes go.
Bobbing is fast and dipping is slow.

Reverse bobbing may be something you see,
again, with metabolic encephalopathy.
Reverse dipping, a rare clinical nidus,
is reported in AIDS with cryptococcal meningitis.

Despite the confusion, one thing is plain.
The eyes don’t work right, whatever the name.
Wheter bobbing or dipping or reversing is true,
it can’t be good; just be glad it’s not you!

I would add that in Bobbing usually the horizontal VOR fails (with calorics or doll’s head maneuver). Here is a link to an article about the stuff (although I got my facts from Frank Thömke’s great book on Augenbewegungsstörungen):