Second edition

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64 ‘Cortical’ signs and symptoms
Bedside testing for motor neglect may be accomplished
by asking patients to clap their hands or fasten a button:
when motor neglect is present, the arm on the neglected
side will either not participate in the task or do so only
minimally. Importantly, this is not the result of a lack of
strength or coordination: with strong urging, patients are
generally able to bring the affected arm into play such that
there is more or less full bimanual cooperation in the task
at hand.
Etiology
As indicated earlier, left neglect, due to a lesion in the right
hemisphere, is clinically far more prominent than right
neglect. Although right neglect certainly does occur, it is
less common, less severe, and, in the case of stroke, less
enduring (Beis et al. 2004; Stone et al. 1991).
Although neglect may occur secondary to both cortical
and to subcortical lesions, in the great majority of cases, it
is a lesion of the cortex that is responsible (Vallar and
Perani 1986; Vallar et al. 1994). Cortical lesions capable of
causing neglect may be found in the frontal lobe (primarily
in the posterior portion of the inferior frontal gyrus
[Daffner et al. 1990; Husain and Kennad 1996; Heilman
and Valenstein 1972; Maeshima et al. 1994; Stein and
Volpe 1983]), the parietal lobe (Bender 1945; Cherington
1974; Critchley 1949; Frantz 1950) (primarily in the inferior
parietal lobule [Mort et al. 2003; Vallar and Perani
1986]), and in the temporal lobe (primarily the medial
aspect of the parahippocampal gyrus [Mort et al. 2003]).
Subcortical structures implicated include the caudate
nucleus (Caplan et al. 1990; Kumral et al. 1999), the putamen
(Hier et al. 1977), and the thalamus (Kumral et al.
1995; Motomura et al. 1986; Watson et al. 1981). Rarely,
neglect has been noted with a lesion of the posterior limb
of the internal capsule (Bogousslavsky et al. 1988c; Ferro
and Kertesz 1984) and with a combined lesion of the
medial aspect of the occipital lobe and the splenium
(Chung Park et al. 2005).
Although neglect is most commonly seen as part of a
stroke syndrome, it may also occur with other focal lesions
(such as tumors) and may also be seen as but one sign in a
dementing disorder such as Alzheimer’s disease.
Differential diagnosis
Visual neglect must be distinguished from hemianopia and
constructional apraxia. Hemianopic patients, of course,
will fail to attend to objects in the hemianopic field, given
that they simply do not see them. Confrontational testing
for visual fields, done with sufficient vigor, however,
reveals full fields in patients with neglect. In constructional
apraxia, drawing a clock face or daisy may be very difficult;
however, here one sees a random pattern of errors, rather
than a ‘bunching up’ on the unneglected side.
Motor neglect must be distinguished from hemiparesis,
and this distinction is made, as indicated earlier, on the
basis of the response to vigorous encouragement. Patients
with neglect eventually respond to vigorous direction,
whereas patients with hemiparesis simply cannot.
Treatment
Various rehabilitation techniques are helpful for visual
neglect, including prism adaptation (Frassinetti et al. 2002;
Keane et al. 2006), neck muscle vibration (Schindler et al.
2002), and visual scanning training.
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