Microsurgical DREZotomy (MDT) for pain, spasticity, and hyperactive bladder: a 20-year experience.

Since 1972, micro-DREZ-tomy has been performed in 367 patients: with cancer pain in 81, neurogenic pain in 139, hyperspasticity in 135, and hyperactive neurogenic bladder in 12. MDT consists of an incision and bipolar coagulations performed ventro-laterally in the Dorsal Root Entry Zone (DREZ) at the entrance of the rootlets into the dorso-lateral sulcus. The lesion is directed at 45 degrees ventro-medially, and 2-3 mm deep according to the pre-operative neurological status and the desired effects. MDT 1 degree interrupts the small (nociceptive) fibres regrouped laterally and the large (myotatic) afferents which runs centrally, whilst sparing part of the large medial (lemniscal) fibres. 2 degrees destroys the (excitatory) medial part of the Lissauer's tract, 3 degrees and the cells of the dorsalmost layers of the dorsal horn, which can be the site of hyperactivity, as we were able to record in patients with deafferentation pain. Best indications are: 1) well localized cancer pain, such as Pan-coast syndrome; 2) neuropathic pain due to: brachial plexus injuries, cauda equina and/or spinal cord lesions especially for pain corresponding to segmental lesions, peripheral nerve injuries-amputation-herpes zoster-(especially when the predominant component of pain is of the paroxysmal type and/or corresponds to provoked hyperalgesia/allodynia); 3) excess of spasticity and 4) neurogenic hyperactive bladder.