Cerebellar Reserve: From Theoretical Framework to Therapeutic Strategy

Abstract

Cerebellum contains the highest number of neurons in the brain and is a site for several pathologies. Cerebellar reserve is defined as the capacity for compensation and restoration following cerebellar pathological changes. When the etiology immediately elicits structural damage in a limited area (e.g., in cases of stroke and traumatic injury), the lost cerebellar functions can be compensated for by other areas not affected by the structural loss (structural cerebellar reserve). On the other hand, when the etiology weakens cerebellar neurons in a diffuse area, gradually leading to cell death (e.g., in cases of metabolic, immune-mediated, and degenerative cerebellar ataxias), the affected lesion itself can replenish vanishing cerebellar functions (functional cerebellar reserve). Cause-cure treatment should be introduced in the very initial phases to minimize damage to the cerebellum, at the stage when cerebellar impairment is still within the frame of sufficient cerebellar reserve. In case of acute and restricted pathologies, extension should be avoided as soon as possible, whereas in case of progressive and diffuse pathologies, the progression should be halted in the early stages to prevent further neuronal loss. When cerebellar reserve is still preserved, subsequent neuromodulation therapies can improve cerebellar ataxias.