Non-fluent Primary Progressive Aphasia and Its Association to Motor Neuron Disease

Frontotemporal dementia (FTD) is among the most common forms of dementia, with an average symptom onset in the fifth decade of life. Neuropathologic changes in FTD demonstrate degeneration in the frontal and/or temporal lobes, which is defined as frontotemporal lobar degeneration (FTLD). FTD is categorized into a subset of variants by symptomatic presentation and corresponding clinical workup. Primary progressive aphasia (PPA) is among these variants of FTD and is distinguished by its primary clinical presentation of language impairment with correlating neuropathology in the aforementioned areas of the brain. More specifically, the classification of PPA is further subdivided into three clinical variants, which has allowed for appropriate diagnostic and prognostic considerations within this patient population. Among these variants in PPA are the semantic (svPPA), non-fluent (navPPA), and logopenic (lvPPA) forms. Motor neuron disease (MND) is a progressive and irreversible process of neuronal degeneration that can lead to an upper motor neuron, a lower motor neuron, or a combination of these two symptomologies. FTD and its association with MND is a well-established spectrum, although more rarely among the PPA variant of FTD. Comparatively, there is a significant body of clinical knowledge on the association between the behavioral variant of FTD (bvFTD) and MND. This is the case of a 69-year-old female with navPPA who later presented with clinical symptoms of MND. Although the two clinical diagnoses, PPA and MND, are irreversible and progressive, this case serves to elucidate diagnostic and prognostic considerations in this rare patient population.