(Re)organisation of the somatosensory system after early brain lesion: A lateralization index fMRI study - 13/03/19

Doi : 10.1016/j.rehab.2019.02.001

Jean-Michel Lemée ^a,^⁎ , Eva Chinier ^b, Pauline Ali ^b,^c, Matthieu Labriffe ^d, Aram Ter Minassian ^c,^e, Mickael Dinomais ^b,^c
^a Département de neurochirurgie, CHU Angers, 49933 Angers, France
^b Département de médecine physique et de réadaptions, CHU Angers-Capucins, 49933 Angers, France
^c EA7315, laboratoire Angevin de recherche en ingénierie des systèmes (LARIS), université d’Angers, 49000 Angers, France
^d Département de radiologie, CHU Angers, 49933 Angers, France
^e Pôle d’anesthésie réanimation, CHU Angers, 49933 Angers, France

^⁎Corresponding author.

Sous presse. Épreuves corrigées par l'auteur. Disponible en ligne depuis le Wednesday 13 March 2019
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Highlights

•	In children with unilateral cerebral palsy, shifting of the sensory function to the contralesioned hemisphere seems uncommon.
•	Shifting of the sensory function to the contralesioned hemisphere seems ineffective.
•	Inter-hemispheric plasticity can occur but is unable to compensate for tactile discrimination.
•	Structural preservation of ipsilesioned primary sensory and secondary sensory cortices is critical in somatosensory processing.
•	fMRI and lateralization index calculation are well suited to study the reorganization in sensory system.

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Abstract

Objective

To evaluate the relationship between neural (re)organization of the somatosensory cortex and impairment of sensory function (2-point discrimination [2PD]) in individuals with unilateral cerebral palsy.

Methods

We included 21 individuals with unilateral cerebral palsy. 2PD thresholds were evaluated on thumb pads, and activation of the somatosensory cortex was recorded by functional MRI (fMRI) during passive movements of the affected hand. A lateralization index (LI) was calculated for the primary sensory (S1) and secondary sensory (S2) cortices and the correlation between the LI and 2PD thresholds was analysed.

Results

We found a significant negative correlation between the 2PD thresholds and the S2 LI (r=−0.5, one-tailed P-value=0.01) and a trend towards a negative correlation with the S1 LI (r=−0.4, one-tailed P-value=0.05).

Conclusion

High levels of activation in the contralesional hemisphere were associated with high levels of sensory impairment in individuals with unilateral cerebral palsy. The interhemispheric (re)organization of the somatosensory system may not effectively compensate for somatosensory impairment.

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Keywords : Cerebral palsy, Sensory function, Plasticity, Functional MRI, Lateralization index, Brain lesion