Surgery in the DREZ (dorsal root entry zone) for treatment of chronic pain

Microsurgical drezotomy (MDT) consists of an incision and bipolar coagulati ons performed ventro-laterally in the Dorsal Root Entry Zone (DREZ) at the entrance of the rootlets into the dorso-lateral sulcus. The lesion is direc ted at 35 degrees ventro-medically, and to 2-3 mm deep according to the pre -operative neurological status and the desired effects. MDT i) interrupts t he small (nociceptive) fibres regrouped laterally and the large (myotatic) afferents which run centrally, whilst sparing part of the large medial (lem niscal) fibres, ii) destroys the (excitatory) medical part of the Lissauer' s tract, iii) and the cells of the dorsalmost layers of the dorsal horn, wh ich can be the site of hyperactivity, as we were able to record in patients with deafferentation pain. Best indications are : i) well-localized cancer pain, such as Pancoast synd rome ; ii) neuropathic pain due to : brachial plexus injuries ; cauda equin a and/or spinal cord lesions (especially for pain corresponding to segmenta l lesions) ; peripheral nerve injuries, amputation, herpes zoster - especia lly when the predominant component of pain is of the paroxysmal type and/or corresponds to provoked hyperalgesia/allodynia) ; iii) excess of spasticit y, especially when associated with severe pain.