When one tells the patient to write, he holds the pen or pencil quite awkwardly … and if sometimes he wishes to write spontaneously, to dictation or copy, he always writes [only] his name. [34].
Autopsy 10 months later revealed a small area of cortical softening that involved the left angular gyrus, extending inward from the surface [34] (Fig. 3a). Dejerine inferred that alexia and agraphia were caused by the angular gyrus softening, which resulted in the “loss of optical images of letters” (p 200) [34].
Fig. 3. Horizontal sections through the left cerebral hemisphere, which depict softenings caused by stroke affecting angular gyrus cortex and subcortical white matter (thin arrows) in Dejerine’s patient with word blindness (alexia) with agraphia [34] (a, top) and with word blindness without agraphia followed by word blindness with agraphia [35] (b, bottom). The thick arrow in b indicates the occipital lobe site of the first stroke. Original images modified by V.W. Henderson.
The following year, Dejerine established the theoretical basis for pure word blindness. He described the remarkable case of a 68-year-old man who had 2 strokes. The first caused pure word blindness and the second caused word blindness with agraphia [35]. According to Dejerine, the critical lesion of pure word blindness isolated the left angular gyrus from visual input, required for letters and words to be perceived as linguistic symbols. After the first stroke, Dejerine’s examination revealed no weakness or sensory loss. Speech was normal and writing nearly so, except that the patient wrote as if he were copying a drawing. He could not read (Fig. 4a–c; pp 67–69; translation from [3]):
Fig. 4. Writing samples from Dejerine’s 1892 patient after his first (a–c) and second (d) stroke [35]. a Spontaneous writing. b Writing to dictation. c1 and c2Model text (c1) and patient’s copy (c2). d Illegible writing after second stroke. Original image modified by V.W. Henderson.
His spoken language is very correct, even carefully selected; he always uses appropriate terms and shows no trace of paraphasia. … The patient understands perfectly all that one says to him. … Writing spontaneously and to dictation is perfectly preserved. … Spontaneously, the patient writes as well as he speaks. In comparing the many writing specimens that I had him write, one notices no mistakes, no spelling error, no transposition of letters. … Writing to dictation is executed equally easily and fluently, but reading what the patient has written is absolutely impossible. Here it is indeed a question of a case of absolutely pure word blindness. The patient recognizes not a letter, not a word except, however, his name.” [35].
The second stroke caused slurred speech and right-sided weakness. Although he soon regained his strength, his speech contained naming errors, and he could not write (Fig. 4d). He died soon after the second stroke, and the autopsy showed 2 lesions (Fig. 3b). Dejerine summarized the case as follows (pp 83–84; translation from [3]):
During the first phase, which lasted 4 years, the patient presented the purest clinical picture that one can imagine of … pure word blindness without any alteration in spontaneous writing or [writing] to dictation. During the second phase, which lasted only 10 days, complete agraphia with paraphasia came to complicate word blindness. In this second phase, the clinical picture then corresponded to … word blindness with marked alteration of writing. To these two clinical phases correspond, as the autopsy shows, two anatomically distinct lesions in the left hemisphere: one old, occupying the occipital lobe and more particularly the convolutions at the occipital point, the base of the cuneus, as well as those of the lingual and fusiform lobules.… The other lesion of a recent date occupies the angular gyrus and inferior parietal lobule, that is to say the region that we are accustomed to see lesioned in the case of word blindness with writing difficulties. It perfectly explains symptoms observed during the last days of this patient’s life. [35].
The key consequence of the first stroke was to interrupt tracts coursing from visual cortex in the occipital lobes to the left angular gyrus. For Dejerine, the left angular gyrus was a center interposed between visual cortex and the auditory center for words (Wernicke’s area) in the temporal lobe, wherein “the visual image of letters simultaneously arouses the auditory image and the articulatory image” (p 87) [35]. The auditory word center was linked to the frontal lobe center for motor articulation (Broca’s area). Angular gyrus destruction led to both alexia and agraphia. Dejerine suggested that letters of a specific word evoked meaning through connections between the left angular gyrus and other parts of a left hemisphere “language zone.”
Deconstruction
In 1906, the dominant Broca-Wernicke-Dejerine paradigm was unexpectedly and doggedly assailed by Pierre Marie (1853–1940) [36, 37]. Marie had trained with both Broca and Charcot, and later he succeeded Dejerine to Charcot’s neurology chair at the Salpêtrière. Marie did not accept the dogma of cerebral centers specialized for language. He pointed out that during the long course of human evolution and culture, reading and writing were relatively recent developments. It was illogical to presume that specialized centers had evolved for these purposes [38]. Marie acknowledged but one variety of aphasia. This was Wernicke’s aphasia, which occurred after lesions within a broadly defined left hemisphere Wernicke’s “zone” that included cortex and white matter tracts of the angular and supramarginal gyri and the posterior superior and middle temporal gyri [36]. Broca’s aphasia was simply mild Wernicke’s aphasia from a Wernicke zone lesion, coupled with dysarthria when the lesion extended beneath Broca’s area to the lenticular nucleus (caudate and putamen). Because it lay within the same vascular territory, the left third frontal convolution was often affected by a stroke that caused symptoms of Broca’s aphasia. However, injury to Broca’s area was incidental and irrelevant.
Wernicke zone lesions affected not just language but all aspects of intelligence dependent on didactic learning [37]. Alexia and agraphia did not exist apart from aphasia. Like Broca’s area, the angular gyrus had no special role: “One cannot recognize in the [angular gyrus] the role of the center for visual images of words” (p 500) [37].
Marie’s iconoclasm resonated with English neurologist Henry Head
