Language Disorders Case File

Language Disorders Case File

EUGENE C.TOY, MD, RAHUL JANDIAL, MD, PhD, EVAN YALE SNYDER, MD, PhD, MARTIN T. PAUKERT, MD

CASE 44

A 72-year-old male presents to the emergency room following a sudden onset of headache, weakness, and inability to speak. His family says 2 hours ago he was out in the yard gardening when he complained of a severe headache. He began to experience weakness on the right side of his body, and eventually could not respond verbally to his family. His daughter states that the patient has a history of high cholesterol and high blood pressure. The patient is righthanded. On examination he has a left facial droop, his eyes look to the right, and he does not spontaneously move the left arm. The patient, while awake, does not follow commands and does not communicate with the physician or his family members. The physician diagnoses the patient as having a cerebrovascular accident (CVA).

• What is the most likely artery affected in this patient?
• What are the treatment options for this patient?

ANSWERS TO CASE 44: LANGUAGE DISORDERS

Summary: A 72-year-old right-handed male presents with sudden-onset hemiplegia and global aphasia, diagnosed with a stroke.

• Artery most likely affected: As mentioned above, this patient has suffered an ischemic stroke of the middle cerebral artery (MCA). The occlusion of this vessel at the trunk leads to contralateral hemiparesis, global aphasia, and ipsilateral eye deviation (secondary to injury to the lateral gaze center). In 70%-90% of right-handed people, the left cerebral hemisphere controls language.
• Treatment options for MCA stroke: In patients with depressed levels of consciousness, one must first ensure the airway is protected. Blood pressure control is important to maintain perfusion to the brain, and the parameters depend upon if the patient is a candidate for tPA. Treatment with tPA is most successful if given within 3 hours from the onset of symptoms. It is important to monitor for brain edema and resulting increases in intracerebral pressure. Treatment with mannitol or hyperventilation may be necessary.

CLINICAL CORRELATION

Death from stroke continues to be the third highest cause of mortality in the United States, with an incidence of 750,000 new strokes each year. For the nearly 80% of people who survive the initial insult, the morbidity is significant, making strokes the leading neurological cause of long-term disability. The most common vessel to be affected is the middle cerebral artery (MCA). The language centers of the brain are supplied by this vessel, the occlusion of which leads to difficulties in speech and/or interpretation of language. In fact the most common cause of aphasia is stroke.

APPROACH TO LANGUAGE DISORDERS

Objectives

1. Understand the neuroanatomy of language.
2. Be familiar with multiple language disorders.
3. Be familiar with the terminology of speech, language, and the resulting disorders.

Definitions

Affective agnosia: The inability to perceive or comprehend emotional intonation of speech, occurring as a result of injury to the right temporoparietal region.

Agraphia: Acquired inability to write, or express oneself in written language; may occur without aphasia, but generally seen in association.

Alexia: Acquired, complete inability to recognize or comprehend written language, seen in association with aphasia.

Anomia: Word-finding difficulty or inability to name an object. Affected patient may describe the function of the object rather than provide the name. Patient may recognize the name when given.

Anosognosia: Disabled patient unaware of his or her disability.

Aphasia: Acquired lack of comprehension or expression of language, which may include speech, writing, and signing.

Apraxia: Normal muscle function, but an inability to coordinate voluntary movements, such as in speech formation.

Aprosody: Lack of intonation or emotion in speech. Occurs as a result of injury to the right hemisphere (temporoparietal) and basal ganglia, or in Parkinson disease.

Auditory agnosia: The loss of ability to interpret auditory stimuli, despite having knowledge of the characteristics of the stimuli. For example, one may know what a car is and what it sounds like, but when presented with the sound of a car, it cannot be identified.

Broca area: Injury to this area in the inferior frontal lobe leads to an inability to formulate speech, with intact comprehension (expressive aphasia).

Dysarthria: Weakness of the muscles required for speech production, or damage to the lower brain functions that control speech.

Dyslexia: Developmental disorder of perception of written language.

Dysphagia: Difficulty swallowing.

Dyspraxia: Inability to organize movement.

Jargon aphasia: Meaningless sentences filled with neologisms, incoherent arrangement of standard words, or a combination of both.

Neologistic distortions: A recently created term or phrase. In neurologic disease, this may include words where the definition is only known by the patient.

Paraphasic errors: Instead of the desired word, the patient produces wrong word or wrong wordlike sounds, substitution or addition of inappropriate sounds, syllables, or words in efforts to speak. Includes literal (phonological), neologistic, and semantic (verbal).

Wernicke area: Injury to this area in the superior temporal lobe leads to an inability to comprehend language (fluent/receptive aphasia).

DISCUSSION

Interpersonal communication is essential for an independent existence. Language disorders limit a patient’s ability to communicate and, therefore, carry significant morbidity. Language disorders occur as a result of mechanical or cognitive problems and can be either receptive (input) or expressive (output). The main areas of understanding and composing language are Wernicke and Broca areas, respectively. Deeper brain structures including the thalamus, also appear to be heavily involved.

The right and left superior temporal lobes (primary auditory area) receive auditory input from the eighth cranial nerve (vestibulocochlear). Bilateral lesions to these areas lead to cortical deafness. Patients with cortical deafness are able to “hear” sound (thalamus, amygdala), but these sounds cannot be processed, and therefore, they cannot perceive or comprehend sounds or language. This auditory agnosia is because of a disconnection between the bilateral primary auditory areas and the auditory association areas. Patients with global auditory agnosia cannot transfer external auditory stimuli to Wernicke area for language comprehension, and as a result they are still able to speak, but cannot perceive their own speech.

Examples of mechanical problems include damage to the anatomy required for speech formation and damage to the nerves innervating the musculature. For example, prolonged intubation can injure the vocal cords, leading to difficulty in phonation. Amyotrophic lateral sclerosis or Lou Gehrig disease leads to a selective attack of central nervous system motor neurons that control voluntary muscles. Therefore, many patients present with “thick speech” secondary to weakness of the muscles required to speak. This type of language disorder is referred to as dysarthria. Additional causes of dysarthria include brain injury to the motor cortex (stroke, traumatic, tumors, cerebral palsy), developmental disorders (dyspraxia, spasmodic dysphonia), and other neurodegenerative disorders (Parkinson’s, Huntington’s, Multiple Sclerosis).

A significant amount of knowledge about the function of certain regions of the brain has been derived from stroke patients. The limitations of a patient after a stroke can be correlated with the area of the brain affected by an ischemic incident. An infarction of the dominant inferior frontal lobe (insula and frontoparietal operculum, Broca area), leads to an expressive or motor aphasia. If the patient has a Broca aphasia secondary to stroke, frequently this will be accompanied by a motor weakness, because of the fact that Broca area and the motor strip are adjacent. In Broca aphasia, the patient is able to understand language; however, he or she has great difficulty producing language. These patients speak in short phrases without intonation, using agrammatic or “telegraphic speech.” For example, if a patient wanted to say “I would like to eat dinner out on Friday,” she instead may say, “dinner eat.” The inability to put into context these two words makes it difficult to convey the meaning of the phrase. Patients with Broca aphasia can hear and understand their own speech impediments, and therefore, may become frustrated with their inability to effectively communicate. If the right frontal-temporal emotional-melodic speech areas are functional, the patient may retain the ability to swear and sing. Deep frontal or cingulate gyrus lesions leads to the loss of prosody.

Damage to Wernicke area (posterior temporal, inferior parietal, lateral temporo-occipital regions), leads to a fluent or receptive aphasia. This may result from the occlusion of the lower division of the MCA bifurcation or one of its branches. The patient creates speech easily and with inflection, however, the string of words lacks meaning. These strings of nonsensical gibberish may include neologistic and phonetic distortions, word and sound substitution, confusion of semantic and phonetic information, perseveration, and the loss of normal conversation pauses. Language structure (eg, grammar) remains intact. Rather than saying, “I would like to eat dinner out on Friday,” patients with Wernicke aphasia would say, in a pressured sentence, “you see with seeds on the day to donsumit that I wanted you to know I like schwaddle for the eating of that porridge so what’s up do you see.” This can deteriorate into jargon aphasia. Unfortunately, patients with Wernicke aphasia cannot understand their own speech, and as a result are unaware of their own limitations.

Information is transmitted from Wernicke to Broca areas via the arcuate fasciculus. Lesions involving the supramarginal gyrus, angular gyrus, insula, auditory cortex, or left temporal lobe may injure these axonal fibers connecting the two regions. This leads to conduction aphasia, where patients cannot repeat words or read out loud and have difficulty naming. The ability to comprehend language (both oral and written) would remain intact. These patients understand that they have some difficulty with language and if they make a mistake, will attempt to self-correct.

Whereas in conduction aphasia the language areas are separated from each other, in transcortical aphasia the speech areas are connected to each other but not to the rest of the cerebral axis. This isolation of the speech area occurs because of ischemia of the surrounding cortex, disconnecting the process of language from any meaningful association or interpretation by higher brain functions. The patient has the ability to create and absorb language; however, because of the disconnect, has nothing to say and cannot interpret what is said. The patient does have the ability to generate automatic responses of previously learned phrases, prayers, or songs.

As in the initial case example, injury to both Broca and Wernicke areas leads to a global aphasia. Global aphasia means the patient can neither understand nor formulate meaningful language. This is a devastating condition, as the patient has no means to communicate with the outside world, nor can the world communicate with the patient. Generally, patients with global aphasia also have a corresponding hemiplegia.

All of the above examples generally result from an insult to the dominant hemisphere for language (left, for the majority of the population). Language disorders also occur with injury to the right or nondominant hemisphere. For example, patients with right language area lesions may have difficulty organizing their speech, leading to difficulties in communication. Likewise, reasoning disorders lead to an inability to understand abstract language (parables, sarcasm, metaphors, humor) and pragmatics (intonation, body language, facial expression). Finally, social judgment may be impaired, leading the patient to say inappropriate things without realization that he or she has done so.

COMPREHENSION QUESTIONS

[44.1] A 56-year-old, right-handed woman presents to the clinic because of difficulty speaking. Over the past few months she has had increasing difficulty expressing herself. She knows what she wants to say, but can only express herself in short, agrammatic phrases. She is capable of understanding what others are saying to her, and seems very frustrated with her inability to speak properly. A lesion to which area of the brain best accounts for these findings?

A. The dominant pars opercularis and triangularis of the inferior frontal gyrus

B. The nondominant pars opercularis and triangularis of the inferior frontal gyrus

C. The dominant posterior aspect of the superior temporal gyrus

D. The nondominant posterior aspect of the superior temporal gyrus

[44.2] A 42-year-old left-handed man is brought to the clinic by his family because of bizarre speech. They state that 2 days ago, he suddenly began speaking in sentences that do not make any sense, and that he does not appear to understand what they are telling him. On examination the man speaks easily, and his speech seems to have normal structure and intonation, but the combinations of words simply do not make sense. He is also completely unable to follow any commands that the physician tells him. Damage to what area of the brain is mostly likely responsible for these findings?

A. The right pars opercularis and triangularis of the inferior frontal gyrus

B. The left pars opercularis and triangularis of the inferior frontal gyrus

C. The right posterior aspect of the superior temporal gyrus

D. The left posterior aspect of the superior temporal gyrus

[44.3] A 56-year-old woman comes into your clinic complaining of difficulties with speech. Most notably, she says, she cannot read out loud, and also occasionally has difficultly naming objects. You do a full speech evaluation and in addition to the complaints that she has, you find that she cannot repeat words or phrases that you ask her to, and she also replaces words with incorrect words that sound similar. Based on these findings, a lesion in what location is most likely responsible for the production of her symptoms?

A. The nondominant arcuate fasciculus

B. The dominant arcuate fasciculus

C. The dominant pars opercularis and triangularis of the inferior frontal gyrus

D. The dominant posterior aspect of the superior temporal gyrus

Answers

[44.1] A. The lesion is most likely in the dominant pars opercularis and triangularis of the inferior frontal gyrus. This woman is presenting with Broca aphasia, also known as a productive aphasia. She is able to understand speech, but has difficulty in producing it. Because she can understand her own speech, she is able to recognize that it is deficient, which commonly causes a great deal of frustration in these patients. Broca area is located in the inferior frontal gyrus of the dominant hemisphere, adjacent to the motor cortex responsible for controlling speech organs.

[44.2] D. This man is presenting with Wernicke’s aphasia (fluent or receptive aphasia) caused by a lesion in the Wernicke’s area, which is located in the dominant hemisphere’s (left in this patient) posterior aspect of the superior temporal gyrus. This area is responsible for comprehending speech and generating comprehensible speech. Damage to this area results in an aphasia where the patient has no problem creating speech (it is fluent), it simply does not make sense. Although this man is left handed, there is still a 70% likelihood that he is left hemisphere dominant.

[44.3] B. This patient is presenting with a conduction aphasia secondary to a lesion in the dominant arcuate fasciculus, the fiber tract connecting the Wernicke and Broca areas. Because this disorder affects the communication between Wernicke and Broca areas, common findings include difficulties with reading aloud and the inability to repeat words and phrases.

NEUROSCIENCE PEARLS ❖ In 70%-90% of right-handed people, the left cerebral hemisphere controls language. ❖ Broca area (inferior frontal lobe) and Wernicke area (posterior temporal lobe) have distance (output vs comprehension) yet integrated and essential functions. ❖ The nondominant hemisphere contributes to the nuances of language, such as intonation and emotion.

REFERENCES

Antonucci SM, Beeson PM, Rapcsak SZ. Anomia in patients with left inferior temporal lobe lesions. Aphasiology. 2004;18(5-7):543-554. 

Carandang R, Seshadri S, Beiser A, et al. Trends in incidence, lifetime risk, severity, and 30-day mortality of stroke over the past 50 years. JAMA. 2006, Dec 27;296(24):2939-2946. 

Delazer M, Semenza C, Reiner M, Hofer R, Benke T. Anomia for people names in DAT: evidence for semantic and post-semantic impairments. Neuropsychologia. 2003;41(12):1593-1598.

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