FTLD, or not?

RE: report for Daniel Kensmith tested on 06/21/21
The clinician detected a major issue of expressive aphasia marked by articulation difficulty starting two years before in this 72 yo; he offered this Diagnostic Impression:

G31.84 Mild Neurocognitive Disorder due to Alzheimer’s Disease

My feedback consisted of: Described in the Summary was an impression of Primary Aphasia due to Alz. Disease, largely because there was no clear evidence of a vascular etiology. MRI was normal, but that was by only the patient’s report. And, that doesn’t rule out microvascular disease which the radiologist may have noted even if Mr. K. only recalled his results as normal. At our age we will have it too. It can be so “micro” it doesn’t really show up well on an MRI. There was hyperlipidemia, vasodepressor syncope, varicose veins (implicating heart valve problems causing high blood pressure) and the biggie: diabetes type 2 which plays a HUGE role in heart attack and stroke risk. The biggest problem with the diagnostic impression used is that Primary Progressive Aphasia is caused by Fronto-Termporal Lobar Dementia, not AD. Yes Alzheimer’s can occur early with odd, idiosyncratic presentations like garbled speech; however, by two years after symptoms are noticed you would see STM problems other problems like reasoning difficulty, if it was AD.

The case against FTLD:
In brief this was a guy with only expressive aphasia (garbled speech starting around two years ago), while all other NP results were WNL. The clinician writing the report argued for a Mild NCD due to Alzheimer’s Disease (AD) because of the patient’s wife’s observations supporting the aphasia, which made good sense. However, there is a fault in the logic as AD is always a global disorder; i.e., you need at least two areas of cognitive deficit (one of which includes STM) to consider this diagnosis. So that dog won’t hunt in this case. Yes, there are other issues that are now emerging, which we have to address, but they are still too mild relative to his expressive aphasia, two years into course of illness.

Moreover, for Mild NCD you “should” have some difficulty with instrumental ADLs, which is not there for this patient. So we have a focal deficit, garbled speech, that developed (I’ll say was acquired) about two years ago. There are two possibilities: 1.) hysteria or 2.) a Broca’s type aphasia due to vascular disease (probably multiple TIA’s/tiny strokes) damaging this area of the brain. #1 is unlikely. Despite my reservations about the technicality of “should” have ADL problems, I buy the interpretation that the wife’s comments about emerging issues are legitimate enough to support the Mild NCD dx you offer – but as I edited the report (with the clinician’s permission) I removed the “…due to Alz. Disease” suffix from the dx for reasons I’ll argue below. These are the new Impressions:

G31.84 Mild Vascular Neurocognitive Disorder
F98.5 Adult-Onset Fluency Disorder (Broca's Dysphasia)

It was beyond the scope of this evaluation, but ideally we would have tested him for signs of receptive aphasia (Wernike’s disorder, which most often is due to ETOH use) as to his ability to comprehend connected discourse in both reading comprehension and hearing spoken language to see if one or both were impaired. Reading comprehension involves a lot of input from the angular gyrus which is adjacent to Wernike’s area in the posterior of the brain. You did this pretty well for receptive spoken language, BTW.

Also, testing would look for Conduction Aphasia (damage to the arcuate fasciculus, the large bundle of white fibers that connects Wernike’s area to Broca’s area in the brain). In a nutshell if the receptive language comprehension part of the brain (Wernike’s area at the back) is “disconnected” from Broca’s area, then a person can’t repeat what s/he hears. Now you know why “Repeat after me, ‘No ifs, ands or buts” on the MMSE is an important subtest. Mr. K. could do that, so probably there is no conduction aphasia in him. Much of behavioral neurology (cf. Geschwind’s textbook Language and the Brain) is all about disconnection syndromes, and it is pretty interesting stuff. Although, not light reading!

Interview might have focused more on ETOH use and brain injury two years ago and now, as well as for signs of TIA’s, moment’s of garbled speech. I wonder if his difficulties fluctuated in a manner consistent with TIA’s. Where there are TIA’s there will be stroke disease not long after. Problems with my theory are your report that he has moments of confusion and STM difficulty like repeating himself – this argues against a pure focal deficit in just expressive speech. To explore this I would have interviewed to see if these problems are episodic; i.e., if the come and go which could support the TIA/mini stroke hypothesis. Confusion while driving is also a problem. My guess is these additional issues support a microvascular stroke disease process that is happening at the cellular level throughout his brain (thus too small to show up yet on MRI) with a focal point of worst disease in the Broca’s region of the left hemisphere. (Frankly, I suspect a ministroke there.) BTW Broca’s region is in the L hemisphere in about 98% of all people, but is more often (around 5+% of the time) in the R hemisphere in left-handed people and folks with mixed dominance. Left-handed and mixed hand dominance people are more likely to retain language skills after a L side stroke. This is why neuropsychologists often start reports like “Mr. Smith is a left hand dominant, married…” as handedness is important to prognostic outcome of insult/stroke to the brain.

I’m not worried about worsened dysnomia indicating a more global problems, as that deficits can result from dysfunction almost anywhere in the brain. Recommendations are focused on maintaining vascular health is essential for this guy.