Page 270 - MEGIN Book Of Abstracts - 2023

METHODS Twelve patients with chronic phantom limb University Graduate School of Medicine, Aichi, Japan
pain of the upper limb due to amputation or brachial
plexus root avulsion participated in a randomized BACKGROUND Several studies on carpal tunnel
single-blinded crossover trial. Patients were trained syndrome have reported pain that exists beyond the
to move the virtual hand image controlled by the BCI median nerve territory of the affected hand. However,
with a real decoder, which was constructed to classify the mechanism is unknown.
intact hand movements from motor cortical currents,
by moving their phantom hands for 3 days ("real train- PURPOSE We investigated the cause of extra-territorial
ing"). Pain was evaluated using a visual analogue scale pain by the analysis of clinical assessments and cortical
(VAS) before and after training, and at follow-up for an activity using magnetoencephalography.
additional 16 days. As a control, patients engaged in
the training with the same hand image controlled by METHODS To compare patients with and without
randomly changing values ("random training"). The 2 extra-territorial pain, fourteen patients with carpal tun-
trainings were randomly assigned to the patients. This nel syndrome were assessed using clinical examination,
trial is registered at UMIN-CTR (UMIN000013608). such as patients' profile, paresthesia, physical tests, and
psychological tests. The physical assessment included
RESULTS VAS at day 4 was significantly reduced from tactile threshold and static and moving two-point
the baseline after real training (mean [SD], 45.3 [24.2]- discrimination sensations on digital pulp. Neural activa-
30.9 [20.6], 1/100 mm; p = 0.009 < 0.025), but not after tion in the cerebral cortex was also measured using
random training (p = 0.047 > 0.025). Compared to VAS z-scores calculated by magnetoencephalography.
at day 1, VAS at days 4 and 8 was significantly reduced
by 32% and 36%, respectively, after real training and RESULTS Among fourteen patients, ten patients had
was significantly lower than VAS after random training pain in the affected median nerve territory only and
(p < 0.01). four patients had extra-territorial pain. When com-
paring the groups, the static and moving two-point
CONCLUSION Three-day training to move the hand discrimination sensation values in patients with
images controlled by BCI significantly reduced pain for extra-territorial pain were larger than those of patients
1 week. without the pain (p < 0.05). The supra-marginal gyrus,
mid-part of the precentral sulcus, angular gyrus in the
CLASSIFICATION OF EVIDENCE This study provides left hemisphere, bilateral sensorimotor areas for legs,
Class III evidence that BCI reduces phantom limb pain. and bilateral isthmus-cingulate areas showed larger
z-scores in patients with extra-territorial pain than in
Neurology (2020), Vol. 95, No. 4 (32675074) (5 citations) patients without the pain (p < 0.05).

CONCLUSIONS The static and moving two-point
Disturbance of somatotopic spatial cognition and discrimination sensations signify the ability of tactile
extra-territorial pain in carpal tunnel syndrome spatial acuity. Bilateral sensorimotor areas were acti-
(2020) vated in sites that were not the hand. Furthermore, the
inferior parietal lobule in the left hemisphere, which
Yoshida, Akihito; Iwatsuki, Katsuyuki; Hoshiyama, synthesizes and integrates multiple sensations showed
Minoru; Hirata, Hitoshi high activation. Our findings suggested that the
mechanism of extra-territorial pain was associated with
Department of Rehabilitation Science, Nagoya University dysfunction of spatial cognition.
Graduate School of Medicine, Aichi, Japan; Department of
Hand Surgery, Nagoya University Graduate School of Medi-
cine, Aichi, Japan; Brain and Mind Research Center, Nagoya

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