In a Word - Aphasia

In this episode, Dr. O'Leary discusses a word that he has struggled to understand since medical school.  The word is aphasia.  The root “phasia” comes from the Greek phanai which means “to speak.”  When aphasia is used medically, it refers to an inability to speak, although not always.  More generally it is often used to mean a failure to understand or produce language, but it gets complicated.  Dr. O'Leary reviews the brain regions responsible for various kinds of aphasia and how to identity them.

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Welcome to PsyDactic.  I am your host, Dr. O’Leary.  This is a podcast about psychiatry and about neuroscience.  I do it out of a love for what I do, which is psychiatry.  Trying to figure out even a little bit about how the brain works, for some reason just gets me going.  So thank you for nerding out with me today.  I need to warn you that this podcast is my own venture and mine alone.  Although I might quote other people or make reference to institutions, everything I say here should not be mistaken for what anyone else might think.  These are my opinions and mine alone.

Today, I am going to discuss a word that I have struggled to understand since medical school.  The word is aphasia.  Google Bard tells me that the root “phasia” comes from the Greek phanai which means “to speak.”  I didn’t double check that fact, but it was consistent with what I know: that when aphasia is used medically, it refers to an inability to speak, although not always.  More generally it is often used to mean a failure to understand or produce language.  It also sounds like another word, aphagia, which means to be unable or unwilling to swallow.  Anorexia is being unable or unwilling to eat. Aphagia is being unable or unwilling to swallow, so they have some overlap. Phage is also Greek-to-me and refers to consuming things, so aphagia could result in anorexia.  Cells that eat other cells or cellular debris are called macrophages.  But although aphasia and aphagia both utilize the mouth, they are not the same thing, unless possibly, when we are required to eat our own words. [Here I am going to pause for laughter].

Those who have been listening for a while know that my nerdiness does not end with bad jokes and the brain. I also love me some history.  Digging through PubMed, I found a case report from 1867.  The article internally is referred to as “Dr. Scoresby-Jackson’s case of typhus fever followed by aphasia.”  I like these old articles especially because they are so readable, so human, so poetic, so unlike the current scientific literature.  The inefficiency of this article is formidable, but the humanity makes it worth the work.  Let me just quote some of the introduction, which I am sure was intended to be read with a British accent, but I am going to spare you mine.

“It would be simply a waste of time and space to repeat what has already been so ably written in the various journals respecting that condition of the body which is now commonly expressed by the word Aphasia… [he goes on] In relating the following narrative, therefore, I shall not enter upon the consideration of its physiological or pathological bearings, but merely describe the facts as they occurred.”

He starts the case report by describing having dinner with [quote] “the gentleman,” Mr. A.B.X.  Mr. X reported he had been ill with what he thought was a cold and had [quote], “treated himself accordingly.  He had been freely purged with Henry’s solution of salts, and had taken one or more doses of Jame’s powder.”  I do not know what Henry’s solution of salts is, but given the word “purged” was used, I assume it was a laxative or emetic agent or both.  I found a picture of a bottle of Jame’s Fever Powder at the Royal Museum at Grenwich’s website and they described it as “one of the most ubiquitous patented medicines from the mid-eighteenth century to the early twentieth century” and likely contained antimony potassium tartrate (a highly toxic emetic agent) and calcium phosphate.  So Mr. X, to treat what he thought was a cold, gave himself diarrhea and made himself vomit as a cure.

Dr. Scoresby-Jackson decides it is not a cold, but a case of typhoid fever, and then follows the patient for many weeks and takes daily, excruciatingly detailed notes of the case.  He reports that after a 3-day headache terminating on the 11th day, [quote] “his remarks were somewhat incoherent, and although he was not deaf, he did not answer questions so promptly as he had previously done.”  The doctor believed that the patient was not delirious during this time, so that could not explain his speech or slow response, but this seemed to improve.  The only typhus symptom that seemed severe otherwise was something he called “muscular prostration” which I think means exhaustion or weakness.

After what appears to be the 20th day, Mr. X is responding appropriately to questions and even responds with “Oh, I feel charming” when asked about his condition.  When Dr. Scoresby-Jackson returns the next day, he notices the patient's tongue is dry and grey and he has a right facial palsy and difficulty forming words.  He describes his speech like this, “His attempts to speak are like those of a man who has something important to communicate in a language in which he has command of but a few words, with perhaps this exception, that he is amused and not irritated by his inability to proceed.” [unquote] Mr. X is able to eat.  His facial palsy, but not speech seemed to improve throughout the day after they gave him castor oil to make his bowels move.  It seems that moving the bowels was something of a cure-all in 1867.  Dr. Scoreby-Jackson also ordered nurses to make, quote, “...two large mustard poultices which were wrapped around the calves of the legs, and the application of iodine liniment to the left side of the head.” Despite this cutting edge treatment, the next day, Mr. X’s whole right side was paralyzed, his facial weakness was much worse and he produced no speech whatsoever.

Although Dr. Scoresby-Jackson has not mentioned this yet, and seems oblivious to this fact, it is obvious to me that Mr. X has had at least two strokes, most likely in the territory of his left middle cerebral artery.  Over the next week or so, he slowly regained some control of his right arm and leg, was able to grasp and move things and even able to walk with assistance.  Within a couple months he could walk without assistance.  His language skills, however, remained more impaired.  He was utterly speechless and responded to questions only with a nod of the head or other movement.  He often appeared confused by words and did not respond.  He did not initiate communication with anyone else.

Over some weeks, Mr. X slowly gained the ability to write his name and he responded to commands to move his body appropriately.  He even, on occasion audibly laughed, but produced no speech.  Over time, his writing, though impaired, improved and when prompted he could invent and write very basic sentences that were tolerably legible but with poor spelling.  He also began to stutter syllables and with great difficulty could form a single word.

After a couple months, Dr. Scoresby-Jackson got the idea to challenge Mr. X to a game of backgammon, which he immediately recognized and played skillfully.  They found that he could with some effort write numbers and was able to do calculations.  However, he remained mostly mute except for some syllabic utterances, his spelling was atrocious and he tended to mix up words while writing.  For example, he would write “match” instead of “watch,” even after having successfully followed instructions to take out his watch.  He was even able to search and find references to hymns in his Bible, given a chapter and verse.

Another interesting part of the story is that Mr. X almost always was pleasant and appeared motivated.  He never appeared particularly bothered by his deficits, and seemed to accept them as a matter of fact, almost as if he was unaware that they were deficits.  Overall, Dr. Scoresby concluded that Mr. X had suffered from an unfortunate aphasia but maintained his intellectual capacity.

What do we call it when a patient cannot speak?  Aphasia.  What do we call it when a patient can speak, but can’t form grammatically correct sentences? Aphasia.  What do you call it if a patient makes frequent mistakes when speaking, like replacing the word flower with star, or cat with dog, or read with write?  Aphasia.  What do we call it when someone is not able to say prepositional phrases, but can make simple sentences?  Aphasia.  What do we call it when someone cannot recognize written words as having any particular meaning?  Alexia.  Did I get you?  Alexia is a different thing.  Being able to recognize that something is a word, but not be able to understand what a sentence means is aphasia.  Not being able to recognize words as meaningful things is alexia and it is far more rare than aphasia.

More than a problem with speaking, neurologically aphasia is a problem either understanding or producing language, but that does not mean that all kinds of aphasia are created equal.  Various parts of your brain may be malfunctioning to impair speech, writing, or language comprehension, and so to use the word aphasia refers to a broad category of things with different pathophysiology.  Alexia will impair the ability to read, but not to communicate with language otherwise.

Knowing the characteristics of an aphasia can help us determine where in the brain the dysfunction likely is.  Let's say you have a patient who can follow instructions both written or verbal, can write, but lacks the ability to speak.  We know they have language comprehension abilities intact, that is they have receptive language abilities, but they cannot produce language.  This is a non-fluent aphasia.  A clinician might be tempted to write down “global aphasia” when a patient produces no recognizable words, but this would be an error.  In a global aphasia, the patient cannot understand or speak language.

Non-fluent aphasias can vary in severity from complete loss of language production and writing, to minor or moderate impairments.  Fluent aphasias are those in which patients appear to produce speech without difficulty but that that speech does not make sense, except maybe when they are repeating things back.  A patient who doesn’t understand may or may not be able to repeat something back, and this is where a clinician needs to be careful.

Maybe a better way to talk about this, is to imagine that a particular part of the brain malfunctions for some reason.  It might be a stroke or focal epilepsy, traumatic brain injury, local inflammation, neuronal degeneration, compression like when there is a mass of abnormal tissue or a hematoma, just pick your poison.

Let's think about brain anatomy for a moment.  

There are two classical areas that are recognized as brain-centers for language comprehension and production.  By comprehension here, I don’t mean subtle meanings or inferred meaning, I mean the concrete meanings of words, their identity.  By production, I mean the ability to make your mouth, glottis, tongue, breath, etc do what it needs to do to form single words and strings of words, like sentences or lists.  I don’t mean the ability to write a novel or an epic poem.

Broca’s area is part of our frontal lobe.  It is on the dominant side of the brain, which is the left side for most folks.  Its center is on the inferior frontal gyrus just anterior to the motor cortex.  You can think of Broca’s area as our speech making center.  Damage to Broca’s area always results in a non-fluent aphasia.  It takes information being fed forward from places like Wernicke’s area, which I will get to in a moment, and creates a motor plan for making those ideas into words, either written or spoken.  Without Broca’s our ability to produce language is broken.  However, we still likely have the capacity to understand speech or writing.  When Broca’s area is completely off-line, we will not be able to even repeat simple things back.  It is our premotor language planning center.

In most cases where Broca’s is broken, it is not entirely off-line.  Fluency is compromised, but some words can be formed.  Speech may be halting, with long pauses, a lot of ums, or it might be diminished in things like multisyllabic words, use of synonyms, complex grammar or prepositional phrases.  “Dog… um… out.  Umm… poop now.”  So a non-fluent aphasia is an expressive aphasia.  I should point out that there may be many other reasons why someone might not be able to speak that have nothing to do with Broca’s area.  They could have damage to lower motor neurons, they may be catatonic, or have akinetic mutism.  They may have selective mutism, damage to the cerebellum, damage to motor neurons, or a functional neurological disorder.  Pts with Broca’s aphasia my not be fluent, but they are not necessarily mute.  They can still produce sounds, but these are not what we would recognize as words.

An example of a relatively pure fluent aphasia, an aphasia where speech is produced, is called Wernicke aphasia.  This is a result of damage to the superior and posterior part of the temporal lobe.  The temporal lobe is often involved in ascribing identity to sensory information, especially visual and auditory.  “Word salad,” is typically used to describe the kind of speech folks with a Wernicke aphasia make.  They say a lot of words, but these words appear randomly strung together.  They cannot understand what is said to them and they cannot understand what they are saying.  While nothing they say appears to make sense, they appear blissfully ignorant of this.  They don’t try to correct themselves, because they don’t know that what they say doesn’t make sense.  They cannot even repeat words or phrases back because they cannot identify what is being said to them.  When this is happening, there may also be other issues.  A person may be psychotic, intoxicated, or delirious.  Someone who is catatonic may also have verbigeration, where they repeat words over and over that don’t appear to make sense.  Speech that does not make sense is not necessarily a Wernicke aphasia.

I wish aphasia was as simple as this: you either can’t produce language or you can’t understand language, but purely Broca’s or Wernicke’s aphasias would require damage to the brain of a surgical precision.  Most brain damage is not so neat.  There may also be damage to only part of Broca's or Wernicke’s area or to other surrounding cortical areas that support them.  This would result in a transcortical aphasia.

Remember that Broca’s is our language motor coordinator and Wernicke’s is our language meaning maker, so there can be a transcortical motor aphasia (you might also call a transcortical non-fluent or a transcortical expressive aphasia), and there can be a transcortical sensory aphasia (you might also call a transcortical fluent or transcortical receptive aphasia).

A lesion located around Wernickes that effectively isolates it from its support areas, can result in an inability to make meaning out of speech, but preserve the ability to repeat speech. It might also result in something less severe like semantic paraphasia where someone will substitute one word for another, especially similar sounding words or words with similar meanings.  Think substituting ship for car, or stink for shrink.  This second substitution overlaps with something called phonemic paraphasia, where similar sounding syllables are substituted, for example cat instead of cab, when referring to a taxi, or “phelatone” instead of telephone.  They will not catch their own errors because it is also difficult for them to understand speech or the written word.  A similar phenomenon (do, do, do, do, do), is when the angular gyrus is damaged.  The angular gyrus is just posterior to the main part of Wernicke’s area and damage to it may impair a person’s ability to name something, though they could identify it otherwise.  This is similar to one of the common deficit in Alzheimer’s dementia, when someone starts to have word finding difficulties and frequently describes what they want instead of saying it straight.

A lesion located around Broca’s area is analogous except that it affects the motor functions.  Patients are less able to produce speech spontaneously, but may be able to repeat something back, even a relatively long phrase.  When they produce speech, it is generally limited to 1 or 2 words.  They have no difficulty understanding speech.

So I have discussed Broca’s aphasia and Wernicke aphasia which are pure deficits in either producing or understanding language. Broca’s is non-fluent, because they can’t say anything and Wernicke’s is fluent, because they can speak, they just can’t make sense of anything.  Then there are the transcortical aphasias where Broca’s and Wernicke’s are relatively isolated from nearby supporting regions.  In transcortical motor aphasia, a patient may be able to repeat a long phrase back, but when producing spontaneous speech it is limited to 1-2 words.  In a transcortical sensory aphasia, either language understanding is impaired or some aspect of phonetics or semantics is impaired, like naming, or confusing one similar word for another.

There is also something called conduction aphasia, which is specifically a disconnect between Broca’s and Wernicke’s area without direct damage to either of them.  This results when the arcuate fasciculus is damaged.  The arcuate fasciculus is the wiring or white matter tracts between the posterior portions of the temporal lobe and the frontal lobe.  This means that the motor area cannot communicate with the receptive area for language.  A patient may not be able to repeat back something, not because he didn’t understand it or cannot say the word, but because he cannot send the information forward.  In less severe cases patients can repeat things back, but make frequent errors.  Unlike in a pure Wernicke’s or transcortical sensory aphasia, patients can hear and understand their errors.  They just struggle to be able to correct them.  How annoying must that be?  In conduction aphasia, patients are perfectly capable of understanding what is being said, they lack the ability to communicate, not because Broca’s area is damaged, but because it either cannot be induced into speech, or it is induced erroneously or incompletely.

I think it is very helpful to think about this in terms of anatomy, because simple tests can rule out a lot of things.  If someone can understand speech as evidenced by their ability to produce sensical speech, or to follow directions then you can rule out a lesion in or around Wernicke’s area.  If someone can produce language fluently, whether it makes sense or not, you can rule out a lesion in or around Broca’s area.

The others are a tiddly-bit more complex.  All of the transcortical aphasias retain the ability to merely repeat something back (as opposed to making spontaneous speech), so the ability to repeat means that it is localized to regions around Wernicke’s or Broca’s areas or both.  A conduction aphasia cannot repeat, because the signal cannot be conducted from Wernicke’s area to Broca’s area.  If the only deficit is in naming things, such that someone has to describe most things instead of giving the name, the lesion is likely in the angular gyrus.

Now let’s look back at Mr. X’s deficits.  The morning after the second stroke, Dr. Scoresby-Jackson describes him like this, “His attempts to speak are like those of a man who has something important to communicate in a language in which he has command of but a few words, with perhaps this exception, that he is amused and not irritated by his inability to proceed.”

It is hard to parse what is going on here.  It could be that the primary motor cortex is affected, which would mean that he could still attempt to form words, but not be able to initiate the motor movement.  Whether Broca’s area is affected or not, his motor cortex almost certainly is because he is hemiplegic on his right side.  However, over time, his right side gains back a substantial amount of strength, but he does not gain back a substantial amount of speech.  It is mostly monosyllabic utterances, and over time can stutter a series of syllables and with great difficulty can form a word.  His writing improved and when prompted he could invent and write very basic sentences that are tolerably legible but with poor spelling.  He also begins to stutter syllables and with great difficulty can form a word.

-Bells-

What can we rule out here?  Mr. X is able to follow commands, and appears to understand what is being said to him.  He can even learn the rules of a game.  However, he can barely write or speak.  This sounds a lot like an expressive aphasia where a substantial portion of Broca’s area has been damaged.  There may also be some transcortical aspects, but when Broca’s is damaged, a transcortical aphasia would not be able to get through enough to be identified.  He cannot repeat anything back.  When asked to write certain words or names, he is able to, even though it requires extraordinary effort, so we can rule out a conduction aphasia, which would limit this ability completely.

We also know that the external signs of his stroke were obviously in the left motor cortex because it affected motor abilities on the right side of his body.  The left motor cortex is, in most cases, just next to Broca’s area.  Mr. X had Broca's aphasia.

Thank you for listening.  I am Dr. O and this has been an episode of PsyDactic.



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