The result of the DREZotomy procedure used for the treatment of chronic intractable neuropathic pain caused by injuries at the T9-L4 spine level in 26 patients has been reported. For the purpose of identifying the most favorable pain pattern for DREZ surgery we retrospectively analyzed the effectiveness of surgical treatment on different forms of pain in the follow-up period of 13-50 months, 37 months on average. All pain forms were classified according to subjective sensory pain expression including the rhythm and topography of the pain. Three groups of pain were formed according to subjective sensory equivalents: pain of thermal quality (burning, boiling, baking, warm etc.), pain of mechanical-nonthermal quality (shooting, cutting, stabbing, sharp, incisive, cramping, constriction, distraction, throbbing etc.). The third group was the combination of the previous two. Success in pain relief has been defined as a 50% or greater reduction in pain after surgery such that pain no longer interferes with patient activities of daily living and sleeping pattern and no longer requires routine analgesic pain medication. Our results revealed that the pain of mechanical-nonthermal nature and intermittent rhythm, confined to segmental topography was the most responsive to the DREZ surgical treatment so that 90% patients suffering from this pain pattern experienced a good long-term pain relief (70% had complete long term pain relief). Neuropathic pain of thermal quality with the diffuse infralesional distribution and steady rhythm was the most resistant to the DREZ surgical treatment: neither patient had long-term relief of this pain pattern. In the group of patients suffering from pain consisting of combined mechanical and thermal sensory components with confined pain territory, 75% experienced a good long-term pain relief (50% had complete long-term pain relief). Immediate pain relief was obtained in 88% of patients and was long lasting in 69% of the total series. Our results pointed to confined territory, intermittent rhythm and mechanical nature of the pain as the most relevant predictors of the expected pain relief achieved by the DREZ surgery.

The results of DREZlesioning procedure used for the treatment of chronic intractable pain due to deafferentation caused by gunshot injuries at the thoracolumbar (T10-L1) spine level are reported in six patients. The specificity of these cases arises from the fact that all the patients underwent, after decompressive laminectomy, an implantation of vascularized omental graft on the injured cord segments, 4-17 months after injury. Because of the failure of this method, which did not improve spinal function nor hinder the development of pain, surgery in the DREZ was performed 2-5 years after implantation. The results of the microsurgical DREZotomy procedure in those patients, 7-12 months after the surgery were: 4 patients with complete pain relief and 2 patients with pain relieved of 80%. All the patients with well-confined segmental pain were completely cured.

The relationship between the neonataltestes and the functional development of the hypothalamo-hypophysial system of the male rat was studied. Males were castrated on day 3, 4, 5, 8 or 10 of life. At 40 days of age one-half of an ovary from a littermate was grafted under the kidney capsule. 20 days after transplantation into males castrated on days 3 to 8, the histology of the ovarian grafts showed a relative abundance of corpora lutea, indicating the development of the female-specific functional pattern of the hypothalamo-hypophysial system. After 10 days, in spite of castration, the hypothalamo-hypophysial system was of the male-specific type. Castration and the simultaneous transplantation of ovaries in the abdominal region caused a significant increase in the weights of the anterior pituitary and the seminal vesicles.

The chronic neuropathic pain of spinal cord injury origin has been shown to be related to permanent neurochemical changes in the dorsal horn neurons thus producing spontaneous discharges of central nociceptive neurons resulting in chronic pain. There is a doubt, however, regarding the possible supraspinal neurogenic mechanism contributing to the generation of this chronic neuropathic pain phenomenon. To address this issue we determinated the functional condition of the thalamocortical transsmission by obtaining somatosensory evoked potentials from the stimulation of median nerves in the group of 23 paraplegics suffering from chronic posttraumatic neuropathic pain. We prospectively collected and analysed data from 23 patients, 21 males and 2 females, aged from 22 to 59 years (mean age, 35.8 y) suffered from chronic neuropathic pain of the spinal cord and cauda equina injury origin who underwent neurophysiological investigation by obtaining somatosensory evoked potentials from the stimulation of median nerves. Somatosensory evoked potentials were defined according to three-grade scale: normal findings (C), slightly abnormal (B), abnormal findings (A). Our findings revealed pathological somatosensory evoked potentials in 17 patients (73.9%). Only 3 (13%) patients had normal findings, and 3 (13%) slightly abnormal according to our criteria. Pathological findings in a majority of our patients, with changes in the primary cortical complex N20-P25, could be indicative for the dysfunction of thalamocortical afferences in patients with paraplegic pain.

No abstract