Difficult localization

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Phantom Spike

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I'm having trouble making sense of the exam of a patient, and was wondering if anyone else on this forum could provide any insights.

This is an 80+ year old man who underwent an elective surgery for severe aortic stenosis, and they noticed he wasn't completely "with it" after the procedure performed under general anesthesia. While off all sedation, 24 hours after his urgery, he would not follow commands, but moved his head from side to side spontaneously, would open his eyes on his own and had spontaneous roving eye movements. Also, various examiners noted he seemed to have trouble moving the left arm and the right leg, but at other times he moved both legs strongly and equally, although he wouldn't withdraw to pain in the right leg (despite moving it on his own just seconds earlier). There was no hypoxic-ischemic event during the surgery. He also had an unusual coarse tremoring of the right arm at this point. Eventually, he was extubated and "woke up"; per his family, he's back to his baseline now, about a week later, although he seems to have trouble following complex commands and has a degree of perseveration, I think. The right arm tremoring has disappeared.

He's diffusely arreflexic, although I believe that's related to his diabetes. What's odd about his exam now is that he has almost full strength in his left deltoid, biceps and triceps, but 0/5 in the finger flexors, finger extensors, wrist flexors and extensors and interossei; the only intrinsic hand movement he has on the left is trace opponens of the thumb. It's very hard to tell how weak he is in his right leg, as he complains of pain and says he can't move it because it's "weak"; again, it has been noted to move pretty well on other occasions spontaneously. Sensory exam is unreliable since it's inconsistent.

Everyone's concern is for a stroke; he does have a history of atrial fibrillation but he's not considered a candidate for anticoagulation for many reasons. We can't get an MRI because of a pacemaker. Two head CTs have been negative.

It almost looks like a peripheral process, given the degree and distribution of the weakness in the left hand, but I can't localize it to any particular nerve, root, or plexus lesion. His history would be inconsistent with a peripheral process as well. It just seems very localized for a stroke. Also, I'm not sure how the right leg weakness (if it truly is real) fits into it.

Any thoughts?

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Consider anterior spinal infarct.
 
Consider anterior spinal infarct.

I did think of a spinal cord localization as well, but I would have expected at least his left leg to be weak, with interruption of the corticospinal tract on that side. Hyperreflexia might be precluded by the underlying diabetic neuropathy, of course. I apologize, I just noticed I didn't mention that the strength in the right arm and left leg is full. Is there a way it could still be in the spinal cord that I'm missing?
 
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Im thinking of a metabolic prob here given the waxing-waning phenom and that as you pointed out yourself, you can't really localize it anywhere. Post-op for a really strenuous and stressful surgery is also the perfect background for that. Check his calcium levels. Good luck!
 
I'm going to go with embolic stroke of the hand knob area of the precentral gyrus. Perhaps there was some showering of emboli during the valve replacement (although I am sure the surgeons will deny this possibility).

Was he on cardiopulmonary bypass during the procedure? His mental status could be related to bypass encephalopathy, this is quite common in elderly people.

In terms of the fluctuating leg, I am reserving judgement. You will see what he does when the pain and confusion are better.
 
Sigh...I love neuro.
 
We can't get an MRI because of a pacemaker. Two head CTs have been negative.

Talk to your cardiologists.

Most of todays pacers won't get fried during an MRI, they just switch into their default mode (the same mode the pacer falls into if the cardiologist or ED doc plunks that testing magnet on it). The worst thing that can happen is that the pacer looses its program and has to be re-programmed.
If your cards are willing to have someone at hand with:
- the programming dohicky and laptop for that particular patients pacer
- an external pacer/defib if the pacer actually croaks (+ample MSandversed)
- EKG monitoring available in the MRI scanner
- some balls
it is actually feasible to perform an MRI on a pacer patient.

Pacer deaths in MRI happen if nobody watches the shop.
 
The fluctuating leg is a little goofy. But assuming it's real and he has genuine contralateral arm and leg weakness, there is a phenomenon called "cruciate hemiparesis" which gives that clinical picture. Localization is in the caudal medulla I think, right at the decussation of the pyamidal tracts. Probably embolic in nature.

Other etiology of contralateral arm/leg would be multiple emboli (defies Occams razor, I know, but sometimes one location just doesn't cut it . . .)

Plus, I agree with Gopher that if he was on bypass he probably also has what we lovingly refer to as "pump head."

And as for an MRI, many pacers are OK in MRIs nowadays. You just need to figure out what kind he's got and consult your neighborhood cardiologist and radiologist. And remember that if need be, pacemakers can always be explanted if you want to go through the hassle . . .
 
Could he have an iatrogenic brachial plexus injury? How were his arms positioned during the procedure, and for how long? Plexopathy is a known complication of some operations (esp. median sternotomy). Left upper extremity EMG/NCS may be useful.

Of course, this wouldn't explain the fluctuating leg weakness, if you believe that it is real. You could needle the leg while you're at it :)
 
Summary:

Elderly male noted to have some cognitive impairment after surgery for SEVERE AORTIC STENOSIS. Improves a week later but remains with persistent higher cortical functioning deficits. Nothing abnormal is reported during surgery. Patient was noted to have decreased spontaneous movement of the LEFT ARM and RIGHT LEG. Patient was also noted to have TREMOR of the RIGHT ARM for about a week, post op.
Patient is ARREFLEXIC. NO STRENGTH of FINGER FLEXORS, FINGER EXTENSORS, WRIST FLEXORS AND EXTENSORS, INTEROSSEI and TRACE OPPONENS POLLICIS. Sensory exam is unreliable.

Patient has been noted to move RIGHT LEG SPONTANEOUSLY at times. At other times, patient states he is WEAK.

PMH: Diabetes, atrial fibrillation and s/p aortic stenosis repair.

I would say that the patient had a hypoperfusion event during surgery, perhaps global, which went unnoticed. This is not that unusual for the type of surgery he had. The global cognitive deficits that he had upon coming off anesthesia and the persistent higher cortical function problems are indicative of that.

Furthermore, the RIGHT ARM TREMOR and the RIGHT LEG WEAKNESS, further help localize a lesion that may be secondary to the vascular insult. The tremor seems to have been "RUBRAL", and the leg may actually not be WEAK but ATAXIC which is a fairly common mistake that patient's make when describing the "inability to move the extremity because it is not going in the direction they want". The improvement seen "post insult" is fairly typical as well after a vascular event.

The problem seems to be with the LEFT ARM WEAKNESS. Assuming the examination is correct, this points to another lesion. As Neurologists, we tried to find one lesion to explain the pathology but in some cases you may have a few things going on.

Preserved strength of deltoid, biceps and triceps, indicates that he DOES NOT have an axillary, musculocutaneous nor radial nerve lesion (above elbow). The combination of muscle groups suggests a plexus lesion. Most likely, MIDDLE and LOWER TRUNK lesion (given that wrist flexion is affected and that's FCR, plus finger flexors FPL and Flexor Digitorum Profundus are also affected.). Positioning during surgery, or even one of the surgeons leaning on the patient's axilla, may cause this type of lesion. Only thing to do is an EMG, which maybe inconclusive as well since the patient may have denervation changes anyway as a result of an underlying diabetic neuropathy.
 
so if the lesion is located, does that offer any different treatment options? or is it just prognostic? or this is just curiousity?
 
so if the lesion is located, does that offer any different treatment options? or is it just prognostic? or this is just curiousity?

It's neurology !
 
No comment at the above medical student statement.
 
so if the lesion is located, does that offer any different treatment options? or is it just prognostic? or this is just curiousity?

Generally speaking: yes
Specifically to this case: yes

Treatment: treating peripheral neuropathy & stroke & hypoperfusion are different. Also from a disability rehab point of view, if the patient has a rubral tremor (that might get a lot worse) some treatment at the movement aspect may be considered e.g. levetiracetam [very weak evidence, case reports]

Prognostic: the diagnosis give different prognosis. Also even within a diagnosis (stroke) the localisation gives prognostic info. e.g. posterior circulation strokes have better prognosis in the longterm if you survive them. right insular strokes have more arrhythmias etc etc.

Curiousity: the main reason we go to work in the morning!!
 
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