Frontotemporal lobar degeneration
Updates to Article Attributes
Frontotemporal lobar degeneration (FTLD) is the pathological description of a group of neurodegenerative disorders characterised by focal atrophy of the frontal and temporal cortices. The conditions grouped under this term vary from publication to publication, depending on whether clinical, pathological or genetic factors are used in the classification.
The term Pick disease should probably be avoided when discussing clinical presentation. Rather it should be reserved for the pathological entity characterised by Pick bodies.
It should also be noted that the termfrontotemporal dementia (FTD) is used inconsistently in the literature, sometimes synonymously with behavioural behavioural variant frontotemporal dementia and other times to denote frontotemporal lobar degeneration (FTLD) more generally2-3. As such it is also best avoided.
A convenient division convenient division based on clinical presentation is into behavioural and language variants. The former demonstrates predominantly frontal lobe changes whereas the latter has a predilection for the temporal lobe (particularly the left), and is further subdivided into a number of clinical distinct entities distinct entities. As such frontotemporal lobar degeneration can be divided as as follows 3-4:
- behavioural variant fronto-temporal lobar degeneration dementia(bvFTLD), (behavioural variant frontotemporal dementia)1
-
language variant fronto-temporal lobar degeneration (lvFTLD), (primary progressive aphasia (PPA)6
- agrammatic variant primary progressive aphasia, (progressive non-fluent aphasia(PNFA)
- semantic variant primary progressive aphasia, (semantic dementia)
- logopaenic variant primary progressive aphasia
As if this wasn't complicated enough, in addition to a broad division into behavioural (frontal) and language (temporal) variants, an anatomical variant of right temporal frontotemporal dementia has been described with relatively distinct clinicopathological presentation 7.
Epidemiology
The majority of cases are sporadic, however 20-40% may relate to an autosomal gene. Typically FTLDs occur in younger patients than Alzheimer's, usually with onset between 40-60 years of age.
Given the difficulty in clearly defining this group, the incidence is similarly fuzzy, however it is thought to be the fourth most common cause of progressive dementia (afterAlzheimer disease, vascular dementia andLewy body dementia) accounting for up to 20% of cases.
Clinical presentation
Due to the prominent frontal lobe involvement, there tends to be more pronounced and earlier involvement of behaviour and language, whereas the decline in short term memory seen prominently in Alzheimer is is seen much later in FTLD.
Radiographic features
Although, as the name suggests, the frontal and temporal lobes are predominantly affected, there is often striking asymmetry both of involvement of frontal vs temporal lobes, and involvement of left and right hemispheres.
In addition the degree of frontostriatal dysfunction varies between the different FTLD subgroups, with behavioural variant frontotemporal dementia (bvFTD) having the greatest involvement. As a result the caudate heads tend to be reduced in size in these patients, to a much greater degree than in the language variants of frontotemporal dementia5.
-<p><strong>Frontotemporal lobar degeneration (FTLD)</strong> is the pathological description of a group of <a href="/articles/neurodegenerative-disease">neurodegenerative disorders </a>characterised by focal atrophy of the frontal and temporal cortices. The conditions grouped under this term vary from publication to publication, depending on whether clinical, pathological or genetic factors are used in the classification.</p><p>The term <a href="/articles/pick-disease">Pick disease</a> should probably be avoided when discussing clinical presentation. Rather it should be reserved for the pathological entity characterised by Pick bodies.</p><p>It should also be noted that the term <a href="/articles/frontotemporal-dementia-ftd">frontotemporal dementia (FTD)</a> is used inconsistently in the literature, sometimes synonymously with behavioural variant frontotemporal dementia and other times to denote frontotemporal lobar degeneration (FTLD) more generally <sup>2-3</sup>. As such it is also best avoided.</p><p>A convenient division based on clinical presentation is into behavioural and language variants. The former demonstrates predominantly frontal lobe changes whereas the latter has a predilection for the temporal lobe, and is further subdivided into a number of clinical distinct entities. As such frontotemporal lobar degeneration can be divided as follows <sup>3-4</sup>:</p><ul>- +<p><strong>Frontotemporal lobar degeneration (FTLD)</strong> is the pathological description of a group of <a href="/articles/neurodegenerative-disease">neurodegenerative disorders </a>characterised by focal atrophy of the frontal and temporal cortices. The conditions grouped under this term vary from publication to publication, depending on whether clinical, pathological or genetic factors are used in the classification.</p><p>The term <a href="/articles/pick-disease">Pick disease</a> should probably be avoided when discussing clinical presentation. Rather it should be reserved for the pathological entity characterised by Pick bodies.</p><p>It should also be noted that the term <a href="/articles/frontotemporal-dementia-ftd">frontotemporal dementia (FTD)</a> is used inconsistently in the literature, sometimes synonymously with behavioural variant frontotemporal dementia and other times to denote frontotemporal lobar degeneration (FTLD) more generally <sup>2-3</sup>. As such it is also best avoided.</p><p>A convenient division based on clinical presentation is into behavioural and language variants. The former demonstrates predominantly frontal lobe changes whereas the latter has a predilection for the temporal lobe (particularly the left), and is further subdivided into a number of clinical distinct entities. As such frontotemporal lobar degeneration can be divided as follows <sup>3-4</sup>:</p><ul>
-<a href="/articles/behavioural-variant-fronto-temporal-lobar-degeneration-bvftld">behavioural variant fronto-temporal lobar degeneration dementia (bvFTLD)</a>, (behavioural variant frontotemporal dementia)<sup>1</sup>- +<a href="/articles/behavioural-variant-fronto-temporal-lobar-degeneration-bvftld">behavioural variant fronto-temporal lobar degeneration dementia (bvFTLD)</a>, (behavioural variant frontotemporal dementia)<sup>1</sup>
-<a href="/articles/agrammatic-variant-primary-progressive-aphasia">agrammatic variant primary progressive aphasia</a>, (progressive non-fluent aphasia (PNFA)</li>- +<a href="/articles/agrammatic-variant-primary-progressive-aphasia">agrammatic variant primary progressive aphasia</a>, (progressive non-fluent aphasia (PNFA)</li>
-</ul><h4>Epidemiology</h4><p>The majority of cases are sporadic, however 20-40% may relate to an autosomal gene. Typically FTLDs occur in younger patients than Alzheimer's, usually with onset between 40-60 years of age.</p><p>Given the difficulty in clearly defining this group, the incidence is similarly fuzzy, however it is thought to be the fourth most common cause of progressive dementia (after <a href="/articles/alzheimer-disease">Alzheimer disease</a>, <a href="/articles/vascular-dementia">vascular dementia</a> and <a href="/articles/dementia-with-lewy-bodies">Lewy body dementia</a>) accounting for up to 20% of cases.</p><h4>Clinical presentation</h4><p>Due to the prominent frontal lobe involvement, there tends to be more pronounced and earlier involvement of behaviour and language, whereas the decline in short term memory seen prominently in Alzheimer is seen much later in FTLD.</p><h4>Radiographic features</h4><p>Although, as the name suggests, the frontal and temporal lobes are predominantly affected, there is often striking asymmetry both of involvement of frontal vs temporal lobes, and involvement of left and right hemispheres.</p><p>In addition the degree of frontostriatal dysfunction varies between the different FTLD subgroups, with behavioural variant frontotemporal dementia (bvFTD) having the greatest involvement. As a result the caudate heads tend to be reduced in size in these patients, to a much greater degree than in the language variants of frontotemporal dementia <sup>5</sup>.</p>- +</ul><p>As if this wasn't complicated enough, in addition to a broad division into behavioural (frontal) and language (temporal) variants, an anatomical variant of <a title="right temporal frontotemporal dementia" href="/articles/right-temporal-frontotemporal-dementia">right temporal frontotemporal dementia</a> has been described with relatively distinct clinicopathological presentation <sup>7</sup>. </p><h4>Epidemiology</h4><p>The majority of cases are sporadic, however 20-40% may relate to an autosomal gene. Typically FTLDs occur in younger patients than Alzheimer's, usually with onset between 40-60 years of age.</p><p>Given the difficulty in clearly defining this group, the incidence is similarly fuzzy, however it is thought to be the fourth most common cause of progressive dementia (after <a href="/articles/alzheimer-disease">Alzheimer disease</a>, <a href="/articles/vascular-dementia">vascular dementia</a> and <a href="/articles/dementia-with-lewy-bodies">Lewy body dementia</a>) accounting for up to 20% of cases.</p><h4>Clinical presentation</h4><p>Due to the prominent frontal lobe involvement, there tends to be more pronounced and earlier involvement of behaviour and language, whereas the decline in short term memory seen prominently in Alzheimer is seen much later in FTLD.</p><h4>Radiographic features</h4><p>Although, as the name suggests, the frontal and temporal lobes are predominantly affected, there is often striking asymmetry both of involvement of frontal vs temporal lobes, and involvement of left and right hemispheres.</p><p>In addition the degree of frontostriatal dysfunction varies between the different FTLD subgroups, with behavioural variant frontotemporal dementia (bvFTD) having the greatest involvement. As a result the caudate heads tend to be reduced in size in these patients, to a much greater degree than in the language variants of frontotemporal dementia <sup>5</sup>.</p>
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