Dejerine–Roussy Syndrome - Causes and Pathophysiology - Proposed Mechanism

Proposed Mechanism

The imbalance in sensation characterized by Dejerine–Roussy syndrome can be argued through a model addressing a system of inputs and outputs that the brain must constantly process throughout life, suggesting latent plasticity. The right and left hemispheres of the brain both play important roles in the sensory input and output. When a stroke damages one hemisphere, it is proposed that the other hemisphere will cope with the discrepancies in a specific manner. The left hemisphere tends to "gloss over" discrepancies from inputs, eliciting either denial or rationalization defense mechanisms in order to stabilize said discrepancy. In contrast, the right hemisphere does the opposite, and will focus on the discrepancy, and motivate action to be taken to restore equilibrium. Therefore, damage to the left hemisphere can cause both an indifference to pain and hypersensitivity to pain (dysaesthesia or allodynia), while damage to the right hemisphere can cause denial as a defense mechanism (anosognosia and somatoparaphrenia).

The insular cortex, part of the cerebral cortex, is responsible for self-sensation, including the degree of pain perceived by the body, and for self-awareness and defense mechanisms. The insular cortex is often lesioned by a stroke. Particularly, the posterior insula has been mapped to correlate to pain experienced by an individual. In addition, is has been proven that the posterior insula receives a substantial amount of the inputs of the brain, and can be treated with visual, kinesthetic, and auditory inputs.