Loss of sensory discrimination after median nerve injury does not decrease activation in the primary somatosensory cortex in fMRI
(English)Manuscript (preprint) (Other academic)
The aim of this study was to assess functional effects of median nerve injnry and regeneration on the primary somatosensory cortex in adults. Activation in the somatosensory cortex was studied in 6 injured adult men and 12 healthy volunteers with functional magnetic resonance imaging (fMRI) and somatosensory evoked potentials. Examination 15 to 55 months (mean 38 ± 18) after a total transection of the median nerve at the wrist repaired with epineural suture showed a persistent loss of two point discrimination in digit II-III and a decrease in sensory nerve conduction velocity (-29 %) and amplitude (-84 %) in the median nerve segment at the wrist. The cortical somatosensory potential evoked by electrical nerve stimulation proximal to the lesion was normal in latency and amplitude. fMRl performed during tactile stimulation of dig II-III (distal to the lesion) resulted in all patients in activation near the contralateral central sulcus (n=4, two patients and one control were excluded because of movement artifacts). The activated area was increased by 48 %relative to stimulation of the unaffected hand (p<0.05) but not significantly different from controls. It is concluded that a loss of sensory discrimination in the hand following median nerve injury is associated with a normal or even elevated activation in the somatosensory cortex as measured with fMRI during tactile stimulation.
functional magnetic resonance imaging, nerve injury, plasticity, regeneration, somatosensory
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:liu:diva-79483OAI: oai:DiVA.org:liu-79483DiVA: diva2:542798