Hi Mile,

To directly answer your question, Mixed fluent aphasia means that the symptoms are mixed between expressive language and receptive language problems so that the individual with aphasia has both comprehension problems and language output problems due to processing.  The term fluent means that the expressive (output) problems result in utterances (especially phrases and sentences) that are smooth and not limited to one or two word phrases...and that the production is NOT hesitant and labored in terms of word production.  The real problem with "fluent" aphasia is that while the individual may produce fluent and complete utterances, mistakes are made with selection of the content words.  Some examples of such problems are 1) They might produce lengthy articulated utterances which make little or no sense to the listener,2) they might have word finding problems (anomia or paraphasia) where in they produce a wrong word.  If they produce the wrong word but one that is phonologically similar (e.g., house/horse) it is phonemic paraphasia.  If they produce the wrong word but one that is semantically similar (house/office) it is semantic paraphasia. If they produce a complete nonsense word ("ferbis") it is called a neologism....but these are all word finding problems.  The result of this is some fluent aphasics is that their fluent and longer productions may (in severe cases) come out as “Jibberish” of “word salad” in that the utterance may appear to be incoherent, incomprehensible, and lacking in meaning....that is, there is the “disappearance of the very quality that gives signification to speech” (so say the authority Fred Darley). 

A bit more info:  If one has the symptoms of "fluent aphasia" then there is (at least) some damage to the posterior portion of the left hemisphere of the brain...although the term "mixed" suggests a lesion of the brain that includes both anterior portions of the brain (frontal lobe) and well as posterior portions (parietal and/or temporal lobe).  Another four symptoms you may see in fluent aphasia is a lack of awareness of their difficulties or of the severity of their difficulties (anosognosia), An increase in emotional lability, difficulty with turn-taking during conversation ("press for speech"), and the use of verbal stereotypes.  These symptoms do not always occur.

Lots of clinical data suggest that the use of terms or labels like "fluent aphasia" only work as mental shorthand that focuses attention on the primary symptoms... HOWEVER, this clinical data shows that the individual with aphasia has problems in all symbolic modalities (oral language, auditory comprehension, reading, writing, and gestures) with the most severe symptoms depending on where the neurological focal lesion happens to be.  Fred Darley especially pushed this point (I have included a chapter from his 1975 classic text).  Essentially the idea here is that aphasia is a unitary deficit multiple modal in nature.

One other point is that aphasia is a symbolic processing problem that affects language and not a problem with motor-speech productions.  Please see the attached chapter from Darley.  I hope this helps.

Mile

I'm not surprised that you can't find much about "mixed fluent aphasia" because it seems that most authors and clinicians don't differentiate this type of aphasia (check e.g. in Helm-Estabrookes' manual). And it is absolutely understandable because this term lacks logic. Mixed aphasia means that it includes symptoms of Broca's aphasia which is nonfluent by definition (so is global/mixed a.). But yes, sometimes patients with mixed aphasia can produce repeatedly and without control (i.e. persevarate) the same word or phrase (but not a sentence) with little or no flexibility at all. However, in my opinion saying that it is a fluent speach is a misunderstanding. It simply doesn't meet the commonly used criteria such as normal utterance length, grammar and prosody. I agree that patients can exibit more receptive or more expressive symptoms and their language problems are less or more severe but in this case introducing the term "mixed fluent aphasia" seems unnecessary and confusing.