Spinal Cord Injury and Loss of Touch Sensation: Mechanism and Consequences

Normal Touch Pathway

1. Mechanoreceptors in skin (Merkel, Meissner, Ruffini, Pacinian).
2. Dorsal root ganglion (pseudounipolar neuron).
3. Dorsal column (fasciculus gracilis/cuneatus) → medulla.
4. Decussation (internal arcuate fibers) → medial lemniscus.
5. Thalamus (VPL nucleus).
6. Primary somatosensory cortex (postcentral gyrus).

Effect of Spinal Cord Injury (SCI)

• Complete transaction: All sensory/motor function below level lost (ASIA A).
• Incomplete: Partial preservation (ASIA B–D); depends on tracts spared (e.g., dorsal columns vs. spinothalamic).
• Level determines distribution: Cervical → tetraplegia (all 4 limbs + trunk); thoracic/lumbar → paraplegia (legs + trunk below level).

Clinical Syndromes

Syndrome	Lesion	Sensory Loss	Motor
Complete	Full transection	All modalities below level	Complete paralysis
Central cord	Central gray matter (hyperextension)	Burning dysesthesias (cape); sacral sparing	UE > LE weakness
Brown-Séquard	Hemisection	Ipsilateral proprioception/vibration loss; contralateral pain/temp loss (1–2 levels below)	Ipsilateral paralysis
Anterior cord	Anterior spinal artery	Pain/temp loss; proprioception spared	Paralysis below level
Posterior cord	Rare	Proprioception/vibration loss	Intact

Rehabilitation

• Neuroplasticity-based training, sensory re-education, FES, BMI.
• Psychosocial support critical.