Friday, October 21, 2011

CONSULT ROUNDS: Expressive Aphasia in ESRD

Expressive aphasia in a hemodialysis patient? What does one think of as a differential diagnosis?

1. Rule out Stroke/TIA.
2. Seizures
3. Dialysis associated dementia
4. Aluminium toxicity
5. Micro bubbles associated injury

CNS injury in dialysis can be from multiple causes: uremia, anemia, electrolytes, acid base, drugs, trace elements, aluminium, dialysis disequilibrium, impaired cerebral circulation and hypertension.

Lets discuss the last 3 a little bit more in detail. What is Dialysis associated dementia? This was a syndrome that was first described in 1972 which was also called dialysis encephalopathy and can occur as early as 15 months on dialysis to as long as seven years.  Interestingly, the first sign of presentation is a speech disorder:- stuttering or slurring of speech- can even be mutism.  Agitation and hallucinations are not uncommon. Usually, the stroke workup, lumbar puncture and metabolic workup is negative.  Usually, the symptoms are intermittent with worse at the end of dialysis. EEG maybe abnormal showing some high voltage theta and delta waves after dialysis.
This is different from dialysis disequilibrium syndrome. Dialysis dialysis or transplantatation doesn't change the course of the dementia.  Later literature on this suggests that this might be a variant of vascular dementia or a combination of alzheimer and vascular dementia.
Some studies might link dementia as above to aluminium toxicity and perhaps that might be the case as the symptoms of aluminium toxicity are also similar.
Microbubbles have been detected in dialysis patients.  These originate in extracorpeal lines and tubing of hemodialysis machine and circulate in the blood stream until they lodge perhaps in a organ. Air emboli can lead to some CNS changes and eventually dementia in HD population.  2-5% of physiologic right to left shunt can allow the mircobubbles to get to the brain and if someone has a PFO, even more.

Besides acute events, there are other factors in ESRD patients that can lead to expressive aphasia.


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