Speak of the devil
The reason you see a picture of Keanu Reeves along with this post is that it clearly illustrates the difficulties faced by aphasic patients with language production. Unfortunately, the issue gets complicated because Neo was obviously delirious in this scene from The Matrix–machines aren’t taking over the world… That being said, this episode was adapted from a blog I wrote for ditchdocem back in March in order to help emergency medical providers recognize language dysfunction. And this question comes up all the time in the hospital: Is the patient delirious, or are they aphasic? So hopefully, in this BrainWaves episode, you’ll know a little more about how to distinguish these two signs.
Why would anyone care about this? The reason you would want to recognize aphasia from delirium is because their causes and management are polar opposites. Aphasia is caused by a focal cortical lesion—like a stroke, tumor, or a neurodegenerative syndrome [For more info on aphasia, refer to our Quanta series on the subject]. In contrast, delirium is caused by a systemic disturbance—like sepsis, hypoglycemia, or uremia—which causes global cerebral dysfunction. You wouldn’t give a septic patient who is delirious tPA would you?
The episode opens with the story of a patient I saw who appeared confused in the ED. She was 71 years old, hypertensive, with mild cognitive impairment, but was fully independent at baseline. She was brought in by her family because that evening after dinner she was not acting like herself. Her son, with whom she lives, found her sitting alone in the study and staring at the wall. When he asked her if she was ok, she responded, “Oh, yeah, the wall needs new paint.” But there was more to it than that, she her son brought her to our emergency room.
So how does a neurologist go about this? The first thing that is immediately obvious to the examiner is how the language is produced. Describe the features of a patient’s language. Are the words clearly enunciated (favoring aphasia) or slurred (favoring delirium)? Is the patient’s speech grammatically correct (delirium) or lacking in appropriate syntax (aphasia)? Is the patient’s prosody—or pattern of speech—fluent (delirium) or irregular (aphasia)? Can the patient understand spoken language (delirium) or is there a major difficulty with following simple verbal/written commands (aphasia)?
Recall that delirium is defined by its (1) fluctuating course and (2) inattention whereas aphasia lacks both of these features. But in the acute setting where the patient is not following commands, it could be either. In an acutely altered patient, the provider has to identify whether the patient can maintain attention or not. This can be evaluated using a number of tasks that may rely on spoken language (assessing serial 7’s, spelling “WORLD” backward) or won’t (giving the patient a drawing task). The motor evaluation of inattention in a delirious patient involves testing for asterixis, either with arms and wrists fully extended or having the patient squeeze the fingers of the examiner (the “milk maid’s sign”). A delirious patient will struggle with these tasks. The aphasic patient, in contrast, is likely to be able to carry out most of these commands.
Thirdly, know that misery loves company. Neurologic deficits don’t often occur in isolation. Consider language lateralization for this aspect. In nearly every right-handed patient, language localizes to the left cerebral hemisphere. I don’t always count on this for left-handed patients, where
a quarter of patients are right hemisphere dominant or even have a more “distributed” language function. Assuming the examiner has this information in the acute setting—the patient likely will not be the one to state his or her handedness, so family or friends may be helpful here—it could prove useful. In knowing the patient’s handedness, the examiner might attend more closely to functions of neighboring brain regions in order to distinguish a focal neurologic deficit from a global cerebral impairment. That is the third pearl. For instance, in a right-hand dominant patient, one might really try to tease out a pronator drift of the right hand (signifying corticospinal tract injury), or relatively slower tapping of the right fingers or feet (also indicating subtle corticospinal tract dysfunction). In the left-handed patient, one might look for those subtle signs on either hemibody.
Knowing this, what should we make about the 71-year-old woman I saw back in the emergency department? Did she have aphasia or delirium? Her words were clearly enunciated although her speech was not perfectly grammatically correct, and she made inappropriate comments to questions and commands—in keeping with the first clinical pearl. She was able to maintain attention well—the second pearl—and on further neurologic assessment, she had mild weakness in her right face and arm. The final pearl. A beautiful localization to the left posterior frontal and parietal lobes for all the neurologists out there. Final diagnosis: Aphasia.
And speaking of aphasia, be sure to check out the episode for some great clips of Johnny Depp accepting an award. Try to figure out if he is aphasic or delirious!