Frontotemporal lobar degeneration

Dr Dan J Bell and A.Prof Frank Gaillard et al.

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 term frontotemporal dementia (FTD) is used inconsistently in the literature, sometimes synonymously with behavioural variant frontotemporal dementia and other times to denote frontotemporal lobar degeneration (FTLD) more generally 2-3.  As such it is also best avoided.

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 3-4:

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

The majority of cases are sporadic, however 20-40% may relate to an autosomal gene. Typically FTLDs occurs in younger patients than Alzheimer, 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 (after Alzheimer diseasevascular dementia and Lewy body dementia) accounting for up to 20% of cases.

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.

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 dementia 5.

Neurodegenerative diseases

Neurodegenerative diseases are legion and their classification just as protean. A useful approach is to divide them according to underlying pathological process, although even using this schema, there is much overlap and thus resulting confusion.

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Article information

rID: 3969
Synonyms or Alternate Spellings:
  • Frontotemporal lobar degeneration (FTLD)
  • FTLD
  • Fronto-temporal lobar degeneration (FTLD)

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Cases and figures

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    Figure 1: gross pathology
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    Case 1: temporal variant
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    Case 2: frontotemporal dementia
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    Case 3
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    Case 4
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    Case 5
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