Anarthria is the complete inability to articulate words (cf. dysarthria). This is most commonly seen in bulbar motor neurone disease.
A motor disorder of speech production with preserved comprehension of spoken and written language has been termed pure anarthria; this syndrome has also been called aphemia, phonetic disintegration, apraxic dysarthria, cortical dysarthria, verbal apraxia, subcortical motor aphasia, pure motor aphasia, and small or mini Broca’s aphasia. It reflects damage in the left frontal operculum, but with sparing of Broca’s area.
A pure progressive anarthria may result from focal degeneration affecting the frontal operculum bilaterally (so-called Foix-Chavany-Marie syndrome).
Lecours AR, Lhermitte F. The "pure" form of the phonetic disintegration syndrome (pure anarthria): anatomo-clinical report of a single case. Brain and Language 1976; 3: 88-113