Inclusion Criteria:  Signed written informed consent Adult patients (age 18-75 years old) suffering from chronic (duration > 12 months) unilateral neuropathic pain caused by a ischemic or haemorrhagic cerebral stroke or Adult patients (age 18-75 years old) suffering from chronic (duration > 12 months) unilateral neuropathic facial pain due to one of the following causes: a) post-herpes-zoster-neuralgia, b) posttraumatic, neuropathic facial pain, c) atypical trigeminal neuralgia after surgical intervention Severe baseline pain intensity (VAS score >6/10) Considered as resistant to medication specific to neuropathic pain at sufficient doses and durations (including at least antiepileptics and antidepressants)  Exclusion Criteria:  Significant cognitive impairment (MMSE score <22), DSMIV axis I or II psychiatric disorder Relevant psychosocial risk factors (any of): history of other chronic pain syndrome, pain catastrophizing, substance abuse, secondary gain Contra-indication to surgery, anesthesia or MRI