Coding note: For probable major neurocognitive disorder due to frontotemporal lobar de- generation, with behavioral disturbance, code first 331.19 (631.09) frontotemporal dis- ease, followed by 294.11 (F02.81) probable major neurocognitive disorder due to frontotemporal lobar degeneration, with behavioral disturbance. For probable major neu- rocognitive disorder due to frontotemporal lobar degeneration, without behavioral distur- bance, code first 331.19 (631.09) frontotemporal disease, followed by 294.10 (F02.80) probable major neurocognitive disorder due to frontotemporal lobar degeneration, without behavioral disturbance.
For possible major neurocognitive disorder due to frontotemporal lobar degeneration, code 331.9 (631.9) possible major neurocognitive disorder due to frontotemporal lobar degen— eration. (Note: Do not use the additional code for frontotemporal disease. Behavioral distur- bance cannot be coded but should still be indicated in writing.)
For mild neurocognitive disorder due to frontotemporal lobar degeneration, code 331.83 (631.84). (Note: Do not use the additional code for frontotemporal disease. Behavioral disturbance cannot be coded but should still be indicated in writing.)
Major or mild frontotemporal neurocognitive disorder (NCD) comprises a number of syn- dromic variants characterized by the progressive development of behavioral and personality change and/ or language impairment. The behavioral variant and three language variants (se- mantic, agrammatic/nonﬂuent, and logopenic) exhibit distinct patterns of brain atrophy and some distinctive neuropathology. The criteria must be met for either the behavioral or the lan- guage variant to make the diagnosis, but many individuals present with features of both.
Individuals with behavioral—variant major or mild frontotemporal NCD present with varying degrees of apathy or disinhibition. They may lose interest in socialization, self- care, and personal responsibilities, or display socially inappropriate behaviors. Insight is usually impaired, and this often delays medical consultation. The first referral is often to a psychiatrist. Individuals may develop changes in social style, and in religious and political beliefs, with repetitive movements, hoarding, changes in eating behavior, and hyperoral- ity. In later stages, loss of sphincter control may occur. Cognitive decline is less prominent, and formal testing may show relatively few deficits in the early stages. Common neuro- cognitive symptoms are lack of planning and organization, distractibility, and poor judg- ment. Deficits in executive function, such as poor performance on tests of mental ﬂexibility, abstract reasoning, and response inhibition, are present, but learning and mem- ory are relatively spared, and perceptual motor abilities are almost always preserved in the early stages.
Individuals with language-variant major or mild frontotemporal NCD present with pri- mary progressive aphasia with gradual onset, with three subtypes commonly described: semantic variant, agrammatic/nonﬂuent variant, and logopenic variant, and each variant has distinctive features and corresponding neuropathology.
”Probable” is distinguished from ”possible” frontotemporal NCD by the presence of causative genetic factors (e.g., mutations in the gene coding for microtubule—associated pro- tein tau) or by the presence of distinctive atrophy or reduced activity in frontotemporal re- gions on structural or functional imaging.
Extrapyramidal features may be prominent in some cases, with an overlap with syn- dromes such as progressive supranuclear palsy and corticobasal degeneration. Features of motor neuron disease may be present in some cases (e.g., muscle atrophy, weakness). A subset of individuals develop visual hallucinations.