With Broca aphasia, the lesion is in or near the Broca area (inferior frontal cortex near the motor strip). Speech is nonfluent (halting), produced with great effort, and poorly articulated. There is marked reduction in total speech, which may be “telegraphic” with the omission of articles (the, an) or word endings. Comprehension of written and verbal speech is good, except where grammar is required. For example, a patient may have difficulty with a question such as, “If a tiger is eaten by a lion, which one is
still alive?” Repetition of single words may be good, although it is done with great effort. Phrase repetition is poor, especially phrases containing words such as “if,” “and,” or “but.” The patient always writes in an aphasic manner, and writing is affected even in a subtle aphasia. Object naming is usually poor, although it may be better than spontaneous speech. Hemiparesis (usually greater in the face and arm than the leg) is present in larger lesions because the motor cortex is close to the Broca area. The patient is aware of this deficit, but is frustrated and frequently depressed. Interestingly, the patient may be able to hum a melody normally. However, a musician may have deficits in producing music. Curses or other ejaculatory speech may be well articulated. These exceptions are the result of right-hemisphere mechanisms for such emotional speech. Buccolingual apraxia, which is difficulty producing facial movements to command, not caused by poor comprehension or paralysis, may be present. It is demonstrated by having the patient try to protrude the tongue, blow out the cheeks, or whistle.

With Wernicke aphasia, the lesion is in or near the Wernicke area of the dominant temporal lobe. Speech is fluent with normal rhythm and articulation, but it conveys information poorly, because of meandering, indirect phrases (circumlocutions), use of nonsense words (neologisms), and incorrect words (paraphasic errors). The patient uses wrong words and sounds. For example: “letter” for “ladder” (phonemic paraphasia), or “orange” for “apple” (semantic paraphasia). The patient is unable to comprehend written or verbal speech. The content of writing is abnormal, as is speech, although the penmanship may be good. Repetition is poor. Object naming is poor. Hemiparesis is mild or absent, because the lesion is far from the motor cortex. A hemianopsia or quadrantanopsia may be present owing to involvement of optic radiations passing through the affected temporal lobe. Patients do not realize the nature of their deficit, and usually are not depressed in the acute stage. They may exhibit elements of paranoia for this reason. This type of aphasia is commonly the result of an embolic event to the superior temporal gyrus.

Conduction aphasia is caused by a lesion in the posterior part of the superior temporal gyrus or supramarginal gyrus. It functionally disconnects the anterior and posterior speech areas. Speech is
fluent, but conveys information imperfectly. Paraphasic errors are common. The patient can comprehend spoken or written phrases containing small grammatical words. Repetition is the most severely affected, especially for phrases containing grammatical words and nonsense syllables. There is difficulty naming objects. Written language is impaired, although penmanship is preserved. Hemiparesis, if present, is mild.