Conus Medullaris Stimulation With 5 Columns Lead Versus Medical Treatment in Refractory Pudendal Neuralgia

Pudendal neuralgia is a frequent diagnosis in pain clinics. This perineal pain has devastating effects on patient's quality of life. Today, 30% of patients are refractory to pain management and surgical procedure.

The neuropathic characteristics of the pain in these patients lead us to test the efficiency of spinal cord stimulation at conus medullaris level.

In our published preliminary study involving 27 patients with refractory pudendal neuralgia, we demonstrated that 74% of patients implanted with stimulation electrodes at the conus medullaris responded to stimulation.

The primary objective of the present trial is to assess through a randomized, parallel group design, the effectiveness of spinal cord stimulation at the conus medullaris using pentapolar surgical lead ((TM)Penta, St Jude medical ANS) versus medical treatment alone on sitting time in refractory pudendal neuralgia.

In this national multicenter prospective open label trial, patients will be randomized 1:1 to experimental group (CMS group : Conus Medullaris Stimulation using pentapolar surgical lead, plus optimal medical management) or to control group (OMM group : optimal medical management alone) and followed for 12 months, in intention to treat.

42 patients suffering of refractory pudendal neuralgia will be included. Optimal medical management will be prescribed by algologists in both groups according to patient pain relief.

Eligibility Criteria:
PRE-SCREENING CRITERIA:

* Male or female aged 18 years or over
* Pudendal neuralgia according published Nantes criteria
* History of failure medical management : defined by HAS such as intractable pain after failure (by side effect, ineffective, or contraindication) at effective dose and combination of following treatment:

  * Pain treatment OMS analgesics Level I or II
  * Tricyclicantidepressant
  * Antiepileptics
  * Nerve block
  * Muscle relaxants
  * Physiotherapy
  * TENS (Transcutaneus electric nerve stimulation)
  * Psychobehavioral approach
* Failure of pudendal nerve decompression surgery performed more than 12 months ago
* Neuropathic pain according to criteria of the Neuropathic Pain Diagnostic Questionnaire (DN4).
* Subjects able of giving informed consent
* Affiliation with French social security system.
* Average or maximum pain experienced greater than or equal to 5/10 on a visual analogue scale

INCLUSION CRITERIA:

* Average or maximum pain experienced greater than or equal to 50/100 on a visual analogue scale (average of data collected 7 days prior to the inclusion visit and recorded by the patient on the clinical diary)
* Evaluation by multidisciplinary team including neuro-surgeons, algologists and psychologists performed, (if not already done in the previous year for algologists and psychologists)
* Given informed consent.

EXCLUSION CRITERIA:

* Pregnant, or planning to become pregnant during the study (12months)
* Adults under guardianship or trusteeship
* Being treated or has been treated with spinal cord stimulation, subcutaneous or peripheral nerve stimulation, intrathecal drug delivery system.
* Had pudendal nerve decompression surgery less than 12 months ago
* Is suspected of substance abuse
* Has unresolved major issues of secondary gain
* Exhibits major psychiatric morbidity
* Has life expectancy inferior to 5 years
* Implant spinal cord stimulation surgery contraindication :

  * Magnetic resonnance imaging contraindication
  * History of coagulation disorder
  * Severe immunodepression, systemic, due to medicine drug intake or not (AIDS, transplanted, under anti TNF alpha treatment, ...)
  * Current infection
* Would be unable to operate the spinal cord stimulation equipment, undergo the study assessments or complete questionnaires or clinical diary, based on the opinion of the investigator
* Unwilling to be treated with spinal cord stimulation, comply with study requirements.
* Suffering from another neuropathic pain, or chronic pain, cancer, diabetic neuropathy
* Patient with cardiac sentry stimulator or planned to be implanted with one