Central Nervous System Pain

Central nervous system pain is an unpleasant emotional experience due to abnormal processing of information due to a lesion or disease affecting the processing of somatosensory information. Sensation of pain is continuously modulated at the spinal cord level by descending influences and at the brain stem and cortical levels via interconnected pain networks. Neuroplasticity is central to pathological pain, may be initiated by pathology anywhere in the CNS, and occurs at molecular, neuronal, and network levels. Common causes of CPS include central poststroke pain (CPSP), spinal cord injury, and multiple sclerosis. Central pain syndromes are difficult to diagnose as they often coexist with other types of pain and may occur months or years after the initial injury, and there is lack of a clear, widely accepted diagnostic criteria. Diagnosis requires a history consistent with central nervous system pathology and neurologic signs of abnormal pain processing such as allodynia and hyperalgesia. Medications used for treatment of CPS aim to target different pathophysiological mechanisms and include antidepressants, anticonvulsants, cannabinoids, and other drugs. Management of CPS can be challenging as patients often require combinations of medications attained through slow titration and a process of trial and error. Despite this, most patients still experience incomplete pain relief. Neuromodulatory techniques such as transcranial magnetic stimulation, spinal cord stimulation, and deep brain stimulation are promising treatments in select patients. Ultimately, management of CPS requires a multidisciplinary approach with the aggressive treatment of other causes of pain, optimal management of depression and other psychosocial factors, and use of cognitive behavioral therapy, medications, and if needed, neuromodulatory techniques.