letters, and some could read letters but not words. Even more striking, “a complete text-blindness may exist, although the power of sight, the intellect and the power of speech are intact” (p 775) [25]. Kussmaul devised a complex diagram that included centers for visual images of words, sound images of words, motor coordination of spoken words, and motor coordination of written words (Fig. 1). Kussmaul thought it was premature to assign discrete anatomical locations to these functional centers [25].
Fig. 1. Kussmaul’s 1877 diagram [25] of centers and tracks involved in spoken and written language (labeling added). J, ideational (concept) center. B, center for the sound images of words. B’, center for the visual, or text, images of words. C,motor center for spoken words. C’, motor center for written words. a, acoustic (auditory) nerve. o, optic nerve. o–p–q–p–r,pathway for copy of written text. o–p–r, pathway for copying words that are not understood. q–p–r, pathway for writing spontaneously. c–x–q, pathway for writing to dictation by associating sound images with text images within the concept center. Pathway p–q–p is obstructed in word blindness (alexia) with agraphia. Pathway p–q is obstructed in word blindness without agraphia. Original image modified by V.W. Henderson.
Born in Russia in 1852 and working in Paris, Nadine Skwortzoff wrote a medical thesis on word blindness (alexia) and word deafness in 1881 [26]. Word blindness represented the “failure to comprehend signs of thoughts represented by writing” (p 33). Her thesis included 14 cases with prominent reading impairments. She was influenced by the Scottish neurologist and physiologist David Ferrier (1843–1924). Working in England, Ferrier had mistakenly identified the angular gyrus of the parietal lobe as the primate visual center [27], and Skwortzoff suggested that the angular gyrus in the inferior left parietal lobe was damaged in cases of word blindness.
Also in 1881, Sigmund Exner (1846–1926) in Vienna reviewed literature cases where clinical and autopsy findings permitted inferences on cortical localization [28]. In his chapter on cortical fields for speech, 4 cases mentioned writing disturbances; lesions in these cases included the posterior part of the left middle frontal gyrus. This region is immediately in front of the part of the motor cortex involved with hand movement and immediately above Broca’s area in the inferior frontal gyrus. In one patient, only this area was involved. Exner suggested that this region, later referred to as Exner’s area, played a role in written expression similar to that played by Broca’s area in spoken expression.
The identification of specific centers for reading and writing were a logical extension of ideas advanced by Broca and Wernicke. Bastian, in 1887, produced a new brain diagram that now included “word centres” for auditory impressions, visual impressions, “glosso-kineasthetic” impressions (based on speech movements; Broca’s area), and “cheiro-kinaesthetic” impressions (based on writing movements; Exner’s area) [29]. Damage of the visual word center led to word blindness, and damage of the cheiro-kinaesthetic center led to isolated agraphia. Word blindness and agraphia occurred together when the visual word center and the white matter pathway connecting it to the cheiro-kinaesthetic center were affected all together. Agraphia resulted when this pathway was damaged in isolation.
Jean-Martin Charcot (1825–1893), first recipient of the chair in Clinical Diseases of the Nervous System at the Salpêtrière hospital in Paris, was intensely interested in problems of aphasia [19]. His center-pathway model was based on component memories. Word memories consisted of an auditory image, a visual image, a motor image for articulatory movements, and a motor image for movements required for writing (Fig. 2) [30]. Charcot was interested in partial forms of memory loss, which he believed provided convincing evidence for the existence of independent cerebral centers. Charcot used word blindness (alexia) and agraphia to illustrate 2 of the partial forms of aphasia [31].
Fig. 2. Charcot’s diagram of cortical centers for oral and written language, prepared by Marie in 1888 [30]. CAM, auditory word center. CLA, motor center for articulate language; CLE, motor center for written language; CVM, visual word center; CVC, common visual center; CAC, common auditory center. Original image modified by V.W. Henderson.
Charcot’s student Albert Pitres (1848–1928) in Bordeaux provided the first detailed description of isolated agraphia [32]. Like Charcot, he accepted that the posterior part of the left second frontal convolution (Exner’s area) played a role in graphic memory similar to the role of the posterior part of the third frontal convolution (Broca’s area) in phonetic memory. Pitres described a patient with “pure motor agraphia” affecting the right hand. He had developed aphasia 18 months before, but speech, speech understanding, reading, and spelling aloud were normal when Pitres examined him. He wrote legibly with his left hand. With his right hand, he wrote neither words nor letters, but he easily drew geometric figures. He could copy printed text with his right hand, albeit, as if copying a design; he could not copy cursive text. Pitres interpreted the problem as the written counterpart of motor aphasia (Broca’s aphasia); that is, the loss of memory for movements needed to guide the right hand in writing.
Alexia with and without Agraphia
Jules Dejerine (1849–1917) is linked to syndromes of alexia with agraphia and alexia without agraphia. His seminal work occurred at the Bicêtre hospital in Paris, and later he became the third person to hold the chair in Clinical Diseases of the Nervous System at the Salpêtrière hospital.
Dejerine, like Charcot and others, recognized alexia and agraphia as distinct and dissociable manifestations of aphasia. However, he rejected the existence of a separate specialized writing center near Broca’s area. Agraphia was a feature of damage that caused motor (Broca’s) or sensory (Wernicke’s) aphasia. In addition, reading and writing were selectively impaired by injury to the left angular gyrus [33].
In 1891 and 1892, Dejerine published 2 highly influential case reports in which he provided the anatomical and theoretical basis for word blindness (alexia) with agraphia and word blindness without agraphia [34, 35]. Dejerine’s first case was a 63-year-old man who suddenly discovered that he could not read his morning newspaper [34]. In contrast to relatively preserved spoken language, he could not read or write (p 198; translation from [3]):
When one gives him a newspaper or a written phrase, he looks at the newspaper or the paper for a moment, then faces the examiner, stating, “I do not
