PMC8249134_01
(a) Magnetic resonance (MR) images on day 0. Axial diffusion weighted images demonstrating a very new infarction in the right cerebellar hemisphere. Rt: right, Lt: left. (b) MR images on day 148. Axial FLAIR (fluid attenuated inversion recovery) MR images demonstrating no evidence of supratentorial damage without current infarction in the right cerebellar hemisphere. (c) A MR image 3 years after stroke onset. An axial FLAIR MR image demonstrating still no structural damage on the left posterior middle temporal gyrus.
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fig1
HDxt 1.5T) revealed a new infarction in the right cerebellar hemisphere involving cortex and the medullary core due to the obstructions of the right superior cerebellar artery and the right posterior inferior cerebellar artery (Figure 1(a)). He underwent subtentorial open decompressive craniectomy for brain edema. He was transferred to our rehabilitation hospital on day 35. Although no evidence of supratentorial damage was found on MRI (General Electric Company; Sigma Excite 1.5T) (Figure 1(b)), SPECT using 123I-N-isopropyl-p-iodoamphetamine (123I-IMP SPECT) perfusion scans (Toshiba Medical Systems Corporation; Symbia E) on day 98 revealed lower levels of perfusion, mainly in the left posterior middle temporal gyrus, left superior and middle temporal gyrus, and right cerebellar hemisphere (the current infarct area), than those observed in normal individuals (normal database findings) (Figure 2(a)). Follow-up MRI did not show any additional damage (Figure 1(c)) and previous hypoperfused areas were attenuated on SPECT study after 3 years (Figure 2(b)).
(a) A single photon emission computed tomography using 123I-N-isopropyl-p-iodoamphetamine (123I-IMP SPECT) perfusion scans on day 98. Compared with a standard normal database in perfusion findings, the Z-scores (SD) were calculated for each region and a regional Z-score of >2.0 was considered significant and indicated in green to red (compatible with the side color bar). The decreased perfusion was mainly observed in the left posterior middle frontal gyrus (pointed by red circles and arrows). (b) A following SPECT 3 years after stroke onset. The previous hypoperfusion showed an attenuation in both the area and degree on the left side view of this study.
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fig2
Although no evidence of supratentorial damage was found on MRI (General Electric Company; Sigma Excite 1.5T) (Figure 1(b)), SPECT using 123I-N-isopropyl-p-iodoamphetamine (123I-IMP SPECT) perfusion scans (Toshiba Medical Systems Corporation; Symbia E) on day 98 revealed lower levels of perfusion, mainly in the left posterior middle temporal gyrus, left superior and middle temporal gyrus, and right cerebellar hemisphere (the current infarct area), than those observed in normal individuals (normal database findings) (Figure 2(a)). Follow-up MRI did not show any additional damage (Figure 1(c)) and previous hypoperfused areas were attenuated on SPECT study after 3 years (Figure 2(b)).
Samples of the patient's handwriting in the dictation ability between 4th and 12th month after onset. Kanji characters were chosen from the screening writing under the 4th grade test, (A) (  ) ([Tokyo], Tokyo), (B) (  ) ([kyoshitsu], classroom), (C)(  ) ([sakubun], essay), (D) (  ) ([sansu], mathematics), (E) ( ) ([kao], face), (F)(  ) ([shakai], society), (G)(  ) ([kokugo], national language), (H)(  ) ([kyodai], brother), (I)(  ) ([daiku], carpenter), and (J)(  ) ([rika], science). Underlined letters are kanji. Japanese pronunciation and meaning in English are noted. X is incorrect kanji letters. Red strokes are additional handwriting by a speech therapist. Phonologically related errors: D-2, G-1, H-1, and H-2; orthographically related errors: A-1, B-2, C-1, D-1, D-3, E-2, E-3, F-2, F-3, G-1, H-1, and I-1; semantically related errors: B-1 and E-1 (some were classified in combinations of these two types). Nonreal letters were as follows: A-1, B-2, C-1, D-1, D-3, E-2, E-3, F-3, G-1, and H-1.
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His dysgraphia in the poor kanji writing constituted difficulty to recall correct letters with morphological, orthographical, or semantical errors, most of which resulted in nonwords (Figure 3). And when we reassessed his writing kanji ability using the same kanji screening test that was previously used 4 months after the onset, the correct numbers of kanji characters improved to 14/20 (Figure 3).
(a) Fusion map (lower photo) was comprised of left lateral side view of SPECT (upper left) and the patient's head photo in the fiber cap-type holder (upper right). The measurements were obtained from areas on both sides of the prefrontal and temporooccipital cortex (upper right). No. 10 and No. 13 channels (in a yellow circle) were considered to be receiving signals from the region of interest that corresponded to the hypoperfused area in the left posterior middle temporal gyrus. (b) Schematic figure of numbered channel arrangements that was indicated between the light detector (blue circle) and light source (red circle) on the left temporooccipital gyrus on fNIRS. (c) The procedure of tasks. The patient was instructed to empty his mind without movement for 20 sec, and then the operator prompted the patient to start a task. After a 20 sec task period, the patient was ordered to relax for another 20 sec: 5 cycles of 20 sec of rest, 20 sec of task, and 20 sec of rest were performed for averaging. For example, for the 5 times' task, we showed the patient the picture of curry, miso soup, ramen, a combination meal of rice and hamburger steak, and sukiyaki, respectively. R: rest period.
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We concluded that No. 10 and No. 13 channels were recording signals from the regions of interest that corresponded to the hypoperfused area in the left posterior middle temporal gyrus; this conclusion was based on a fusion map generated using an image of the patient's head inside the fiber cap-type holder and a left-side SPECT view (Figure 4(a)). Channels corresponding to the left temporooccipital cortex are shown in Figure 4(b). Before and after the 20 sec tasks, the patient was instructed to clear his mind and not move for 20 sec, and each 20 sec rest-task-rest cycle was repeated 5 times for averaging (Figure 4(c)).
(a) Raw data after merging 5 continuous trials of the picture card task on fNIRS. Relative change in hemoglobin (Hb) (a.u.) is shown on the vertical axis, and a task was ongoing during the time period between the orange and yellow lines in the horizontal axis. The red, green, and blue lines indicate changes in oxy-Hb, total-Hb, and deoxy-Hb, respectively. No. 10 and No. 13 channels (surrounded by a red frame) were allocated to the region of interest according to the fusion map in Figure 4(a). (b) Group-averaged fNIRS recordings at No. 10 and No. 13 channels in response to the picture card task stimulation showing a rapid activation and deactivation corresponding to the picture task.
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After trying several tests such as word imaging tasks or difficult kanji recalling tasks over a few days, we finally identified a workable picture card task that could increase blood perfusion in the hypoperfused area of the left posterior middle temporal gyrus, where we presumed to be the anatomical location of pure agraphia of kanji (Figure 5).