Motor cortex stimulation (MCS) is a form of brain stimulation for patients with neuropathic pain not responsive to medication. An electrode is placed on the surface of the brain and connected to a programmable battery in the chest.

The strength of stimulation can be individually adjusted by changing the voltage of stimulation. A too high voltage will produce side effects (e.g. seizures) while a too low voltage will not provide pain control.

The aim of this study is to analyze the optimal stimulation timing parameters in patients already implanted with MCS and have received good pain relief. The investigators wish to cyclize on/off MCS in order to save the battery life of the stimulator and also decrease stimulus habituation. The investigators hope to determine these timing parameters while maintaining optimal pain relief.

Inclusion Criteria:

• Adult patient more than 18 years of age
• Chronic neuropathic pain effectively treated with motor cortex stimulation
• Stable medication during the trial
• Willing and able to comply with the study protocol and to return per the follow-up visit schedule and able to provide informed consent.

Exclusion Criteria:

• Evidence of an active disruptive psychiatric disorder or other known condition significant enough to impact the perception of pain, compliance to intervention and/or ability to evaluate treatment outcome as determined by the investigator
• Technical malfunction of the MCS device
• History of seizures
• Unable to provide informed consent