The patient was a 48-year-old, right-handed Japanese man educated up to the 12th grade and with a history of type 2 diabetes mellitus, hypertension, and dyslipidemia. Additionally, the patient had nasopharyngeal cancer and had received chemoradiation therapy, with no problems with activities of daily living. The patient was skilled at texting messages using a smartphone with toggle input. The patient was also skilled at typing using Romaji input, and the patient’s typing speed was considerably faster than that of writing.
The patient suddenly realized the clumsiness of the right hand, difficulty in articulation, and word-finding difficulty. Furthermore, the patient unconsciously tapped the key, either more or less than correctly, while texting a message on a smartphone. Additionally, the patient was unable to correctly type with the keyboard and required more than 1 min to input one word.
Twenty-nine days after onset, the patient was admitted to our hospital with a diagnosis of cerebral infarction. A neurological examination revealed that the patient was fully alert, cooperative, and mentally stable. Furthermore, slight dysarthria, clumsiness of the right hand, and abnormal sensations on the right side of the body were observed. After admission, dysarthria and clumsiness of the right hand improved; however, difficulties in texting and typing did not completely recover.
On admission, brain magnetic resonance imaging revealed a cerebral infarction extending from the lateral side of the left thalamus to the left corona radiata (Fig. 1A). Single photon emission tomography (SPECT) with Technetium-ethyl cysteinate dimer (99Tc-ECD) 41 days after onset revealed decreased cerebral blood flow (CBF) in the left dorsolateral frontal lobe, right occipital lobe, subcortical area of the right cerebral hemisphere, and the right cerebellar hemisphere, in addition to the infarct area (Fig. 1B).
Neuropsychological evaluations were performed 30–40 days after onset. Table 1 shows the detailed data of the standard neuropsychological tests. Although the patient experienced word-finding difficulty at disease onset, the Japanese version of the Western Aphasia Battery revealed no signs of aphasia, alexia, or agraphia. The patient showed no signs of spatial neglect, constructional disabilities, short-term memory impairment, or general intelligence deficit. During Part B of the Trail Making Test, Japanese edition (TMT-J), he took slightly more time than the average and had one connection error, suggesting slight executive dysfunction.
Table 1
Performance on standard neuropsychological tests
| Tests | | Score |
| General intelligence |
| J-RCPM | | 35/36 |
| HDS-R | | 30/30 |
| Attention and Executive function |
| Digit span | Forward, Backward | 6, 4 |
| TMT-J | Part A | 29 s |
| | Part B | 65 s |
| Language |
| WAB | Spontaneous speech | |
| | Fluency | 10/10 |
| | Comprehension | |
| | Auditory word recognition | 60/60 |
| | Sequential commands | 80/80 |
| | Repetition | 100/100 |
| | Object naming | 60/60 |
| | Written word stimulus-picture choice matching | 6/6 |
| | Writing | |
| | Writing of dictated words (Kanji, Kana) | 6/6, 6/6 |
| | Copying a sentence | 10/10 |
| Praxis |
| WAB | Praxis (right hand, left hand) | 60/60, 60/60 |
| Visual perception |
| BIT | Line crossing | 36/36 |
| | Letter cancellation | 38/40 |
| | Star cancellation | 54/54 |
| | Line bisection | 9/9 |
| Figure copy | Crossed pentagon, Necker cube | Normal, Normal |
| J-RCPM: Japanese Raven’s Coloured Progressive Matrices, HDS-R: Revised Hasegawa Dementia Scale, TMT-J: Trail Making Test, Japanese edition, WAB: Western Aphasia Battery, BIT: Behavioural Inattention Test |
[Table 1]
Furthermore, we investigated texting and typing difficulties by presenting 100 auditory words 39–40 days after onset [5]. The patient was required to write in Kana, text and type the same material. Errors were not detected in writing. However, the number of texting errors per 100 words was 11. We classified texting errors into three categories: consonant errors, vowel errors, and errors in both consonants and vowels. All consonant errors were tapped to keys adjacent to the target, possibly caused by the clumsiness of the right hand, whereas vowel errors are not thought to be caused by clumsiness. The number of typing errors per 100 words was 12. We also classified typing errors into four categories: spatial error (mistyping the key adjacent to the target), phonological error (mistyping the key not adjacent to the target), omission, and order inversion. Phonological errors and omissions are not thought to be present in healthy individuals skilled at typing. (Table 2).
Table 2
Error distribution of the word dictation task
| Tests | Error patterns | Example | Number of errors |
| Writing in Kana | | | 0 |
| Texting | Consonant | wa→ya | 1 |
| Vowel | su→si | 10 |
| Consonant and vowel | ko→na | 1 |
| Typing | Spatial | ya→ys | 4 |
| Phonological | ha→ka | 2 |
| Omission | ta→t | 5 |
| Order inversion | so→os | 1 |
Next, we assessed the patient’s Romaji conversion ability. We randomly presented 60 auditory syllables one at a time; subsequently, the patient was required to write the same material in Kana and Romaji. The number of errors and the time required to write every five syllables were recorded. The number of errors was zero (writing in Kana), and one (written in Romaji). However, the average time required for writing in Kana was 15.7 ± 4.5 s, and that for writing in Romaji was 21.0 ± 6.8 s. An unpaired t test revealed a significant difference between the two conditions (p = 0.035).