Modulating the pain network--neurostimulation for central poststroke pain

Central poststroke pain (CPSP) is one of the most under-recognized consequences of stroke, occurring in up to 10% of patients, and is also one of the most difficult to treat. The condition characteristically develops after selective lesions to the spinothalamic system, most often to the ventral posterior thalamus. Here, we suggest that CPSP is best characterized as a disorder of brain network reorganization, and that this characterization offers insight into the inadequacy of most current pharmacological treatments. Accordingly, we review the progress in identification of nonpharmacological treatments, which could ultimately lead to mechanism-based therapeutics. Of the invasive neurostimulation treatments available, electrical motor cortex stimulation seems to be superior to deep brain stimulation of the thalamus or brainstem, but enthusiasm for clinical use of the procedure is limited by its invasiveness. The current preference is for noninvasive transcranial magnetic stimulation, which, though effective, requires repeated application, causing logistical difficulties. Although CPSP is often severe and remains difficult to treat, future characterization of the precise underlying neurophysiological mechanisms, together with technological innovation, should allow new treatments to evolve.