Dement Neuropsychol 2014 September;8(3):236-242
241Rodrigues JC, et al. Acquired dysgraphia in adults
some patients may appear to recover from aphasia, but
not from writing impairments, suggesting that these
disturbances are caused by dierent lesions.
48
LHD4 made predominantly mirrored and inclined
writing errors, although graphemic errors were also ob-
served (omission, addition and substitution of letters).
e patient also displayed length and regularity eects,
since fewer errors were observed in short and regular
words. ese features are characteristic of peripheral
dysgraphia.
2,6
Mirrored writing (writing some letters or the entire
word in mirrored form) is a spatial error caused by im-
pairments in the motor representation of letters, which
is also observed in adults who are asked to write with
their left hand.
49
e motor sequences used for letter
writing are associated with the right hands of right-
handed individuals, so that a new motor program must
be learned when individuals attempt to write with their
left hands. Due to stroke-associated motor decits, pa-
tient LHD4 performed the TEPPs with her non-domi-
nant hand, which may explain the presence of mirrored
writing in her responses to the task.
Patient LHD4 also had diculty maintaining letter
sequences while writing, possibly due to graphemic buf-
fer damage.
2
It is possible that these errors were caused
by dysfunctions in working memory (namely, in the buf-
fer component) during word writing.
23,24
e graphemic
buer is also sensitive to word length eects, since lon-
ger words take up more of its capacity.
2,6
Furthermore,
patient LHD4 also displayed regularity eects, suggest-
ing that the graphemic buer may be more sensitive to
certain letter sequences, such as those found in irregu-
lar words. is nding has been previously observed in
a case of non-uent aphasia by Gvion and Friedmann
(2010).
50
e errors exhibited by patient LHD4, which con-
sisted mostly of the omission, addition and substitution
of letters, are often observed in cases of graphemic buf-
fer impairment. Graphemic paragraphias, consisting of
phonologically plausible letter substitutions, were also
observed. Although these are usually considered phono-
logical errors, it is possible that in the case of this spe-
cic patient, they may have been caused by damage to
the graphemic buer. Similar errors have been reported
in patients who suered extensive LHD25, akin to that
seen in patient LHD4.
In conclusion, the fact that dysgraphia was diag-
nosed in half the participants with LHD suggests that
this hemisphere plays an important role in word writ-
ing. e presence of lexical dysgraphia in a patient with
RHD also underscores the need for further studies of
the role of the right hemisphere in word processing.
e fact that two patients with LHD displayed poor
performance and made several errors in the TEPPs, in
spite of an absence of aphasia, suggested that the cogni-
tive mechanisms involved in spoken language are distinct
from those responsible for writing. On the other hand,
patients with aphasia made similar errors on both spoken
and written tasks, suggesting that, in more severe cases,
both spoken and written language may be impaired, cor-
roborating the hypothesis of a continuum of severity in
dysgraphia. Results such as those of the present study
help advance knowledge on written word processing,
and may serve as a basis for neuropsychological inter-
ventions which focus specically on the dierent pat-
terns of impairment observed in each type of dysgraphia.
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