Preserved somatosensory conduction in complete spinal cord injury: Discomplete SCI

Spinal cord injury (SCI) disrupts the communication between brain and body parts innervated from below-injury spinal segments, but rarely results in complete anatomical transection of the spinal cord. The aim of this study was to investigate residual somatosensory conduction in clinically complete SCI, to corroborate the concept of sensory discomplete SCI.

We used fMRI with a somatosensory protocol in which blinded and randomized tactile and nociceptive stimulation was applied on both legs (below-injury level) and one arm (above-injury level) in eleven participants with chronic complete SCI. The experimental design accounts for possible confounding mechanical (e.g. vibration) and cortico-cortical top-down mechanisms (e.g. attention/expectation).

Somatosensory stimulation on below-level insensate body regions activated the somatotopically corresponding part of the contralateral primary somatosensory cortex in six out of eleven participants.

Our results represent afferent-driven cortical activation through preserved somatosensory connections to the brain in a subgroup of participants with clinically complete SCI, i.e. sensory discomplete SCI.

Identifying patients with residual somatosensory connections might open the door for new rehabilitative and restorative strategies as well as inform research on SCI-related conditions such as neuropathic pain and spasticity.