Randomized controlled trial of percutaneous intradiscal radiofrequency thermocoagulation for chronic discogenic back pain: lack of effect from a 90-second 70 C lesion.

STUDY DESIGN: A prospective double-blind randomized trial in 28 patients. OBJECTIVES: To assess the clinical effect of percutaneous intradiscal radiofrequency thermocoagulation for reducing pain, functional disability, and physical impairment in patients with chronic discogenic low back pain. SUMMARY OF BACKGROUND DATA: Chronic discogenic low back pain is a challenging problem in western countries. A treatment option is radiofrequency heating of the affected disc. Its clinical efficacy has never been formally tested in a controlled trial. METHODS: Twenty-eight patients with a history of at least 1 year of chronic low back pain were selected on the basis of a diagnostic anesthetization of the lower intervertebral discs. Only patients with one putative painful level were selected and randomly assigned to one of two treatment groups. Each patient in the radiofrequency treatment group (n = 13) received a 90-second 70 C lesion of the intervertebral disc. Patients in the control group (n = 15) underwent the same procedure, but without use of radiofrequency current. Both the treating physician and the patients were blinded to the group assignment. Before treatment, physical impairment, rating of pain, the degree of disability, and quality of life were assessed by a blinded investigator. RESULTS: Eight weeks after treatment, there was one success in the radiofrequency group (n = 13) and two in the control group (n = 15). The adjusted and unadjusted odds ratio was 0.5 and 1.1, respectively (not significant). Also, visual analog scores for pain, global perceived effect, and the Oswestry disability scale showed no differences between the two groups. CONCLUSIONS: Percutaneous intradiscal radiofrequency thermocoagulation (90 seconds, 70 C) is not effective in reducing chronic discogenic low back pain.

Differential effects of trigeminal tractotomy on Adelta- and C-fiber-mediated nociceptive responses.

In this study we have tested in the rat, whether trigeminal tractotomy, which deprives the spinal trigeminal nucleus caudalis (Sp5C) of its trigeminal inputs, affected differentially nociceptive responses mediated by C- vs. Adelta-nociceptors from oral and perioral regions. Tractotomy had no effect on the threshold of the jaw opening reflex, induced by incisive pulp stimulation (Adelta-fiber-mediated), but blocked the formalin response (mainly C-fiber-mediated). These results suggest that nociceptive responses mediated by trigeminal C-fibers completely depend on the integrity of the Sp5C, while intraoral sensations triggered Adelta-fibers (especially of dental origin) are primarily processed in the rostral part of the spinal trigeminal nucleus.

DREZ surgery on conus medullaris (after failed implantation of vascular omental graft) for treating chronic pain due to spine (gunshot) injuries.

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.

Surgical interruption of a midline dorsal column visceral pain pathway. Case report and review of the literature.

A punctate midline myelotomy performed in a patient effectively eliminated residual, intractable pelvic pain, which remained after resolution of uterine cervical cancer. The authors describe the case history of the patient, in whom pain assessments were made, and a surgical procedure performed. Despite large doses of opiate analgesic medications, the patient experienced constant pressure pain in the right lower pelvis, with excruciating pain on bowel movement. Severe weight loss necessitated better pain control. A minimally invasive surgical procedure, a 5-mm deep puncture using a 16-gauge needle on either side of the median septum in the dorsal column of the spinal cord (T-8), resulted in no new neurological deficits. Narcotic medication was tapered, no pain was reported, and the patient resumed daily household activity. Midline myelotomy has typically been performed with the intention of eliminating the crossing fibers of the spinothalamic tract in the anterior white matter commissure. The punctate midline myelotomy described here was performed with the specific intention of interrupting a newly described visceral pain pathway that ascends to higher brain centers through the midline of the dorsal column. The effectiveness of the pain relief seen in this patient suggests that visceral pain of the pelvis in humans may be transmitted in the midline of the dorsal column, as has been recently reported in studies using rats. The effectiveness of the punctate midline myelotomy performed in this one case of pelvic visceral pain suggests that the surgery may eventually be effective in greatly reducing or replacing opiate narcotic medication for visceral pain management.

Frontal cingulotomy reconsidered from a WGA-HRP and c-Fos study in cat.

A recent positron emission tomography (PET) study demonstrated that the anterior cingulate cortex (area 24), in addition to SI and SII cortices, was activated by painful stimuli. In order to elucidate the participation of relay nuclei in the ascending pain pathway to area 24, we performed a regrograde labelling study with WGA-HRP injection into area 24 in cats. Area 24 was found to receive pain-related thalamic inputs from the intralaminar nuclei including the central medial nucleus, midline nuclei, modiodorsal nucleus and possibly the submedial nucleus. We then examined the expression of Fos protein in CNS induced by formalin injection into the face in cats. Fos positive neurons were demonstrated in areas 23 and 24, the anterior limbic area, insular cortex, midline and paraventricular nuclei in the thalamus, paraventricular nucleus and other areas in the hypothalamus, and in many nuclei in the brainstem in both the formalin-injected group and the control group (anesthesia only). Labelled regions appeared to correspond to stress-related sites. The sole difference from the control group was the expression of Fos in the coronal gyrus and in the trigeminal caudalis nucleus in the experimental group. Although more Fos positive cells were observed in area 24 in experimental than in control cats, the difference was not significant. Our findings suggest that the demonstrated response of area 24 on PET scan represents stress- and emotion-related events rather than pain. Surgical intervention into the anterior cingulate cortex including cingulotomy thus appears to relieve stress and emotion associated with chronic pain, but not pain itself.

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.

Therapeutic stereotactic procedures on the thalamus for pain.

Thalamotomy and electrical stimulation of a thalamic target as treatment for persistent pain are discussed. Thalamotomy is only rarely performed these days according to a questionnaire, given to some colleagues, about the type and the number of operations they performed in the years 1984, 1985 and 1986. The need for stimulation in the periventricular or periaqueductal grey for nociceptive pain is decreasing due to the advent of intraspinal and intraventricular administration of opioids. Nowadays medial and lateral ventro-posterior thalamic nuclei are frequently stimulated for treatment of deafferentation pain. Of 36 patients with deafferentation pain, 22 initially had benefit from this stimulation, but long-term success was only achieved in 11 (30%) of them. It was a general trend that the patients with an initial high pain relief score obtained the best long-term results.

[Functional neurosurgery of chronic pain: nociceptive tracts ablation at the level of the peripheral nervous system and spinal cord]. / Neurochirurgie fonctionnelle de la douleur chronique: interruptions des voies nociceptives au niveau du système nerveux périphérique et de la moelle épinière.

This article is devoted to ablative neurosurgical procedures used for the treatment of chronic pain. The procedures are classified as those directed to the cranial nerves, the peripheral nerves, the spinal roots, the dorsal root entry zone and the ascending spino-reticulo-thalamic pathways. The rational and neurophysiological effects of these operations are stressed. The actual indications for each procedure are specified.

Indications for neurosurgical treatment of chronic pain.

Guidelines are presented for the neurosurgical treatment of chronic pain. In these guidelines a distinction is made between the pain of cancer and neurogenic pain. In cancer pain the survival time and the location of the lesion are the important guidelines. Possible procedures are: opioids via CSF route, lesions in nociceptive pathways and PV-PAG stimulation of the thalamus. In neurogenic pain, neurostimulation procedures, tailored to the location of the pain are procedures of first choice. There are however specific indications for other procedures depending on the aetiology of the pain. Causalgia and reflex sympathetic dystrophy: sympathetic blockade; Tic douloureux: radio-frequency lesion, glycerol, balloon inflation of the ganglion of Gasser, and microvascular decompression; Plexus avulsion: dorsal root entry zone lesion (D.R.E.Z.). There is a need for controlled prospective neurosurgical trials in which as a minimal rule an independent party should evaluate the results of the surgical procedure.

[The dorsal root entry zone of the spinal cord: the surgical target in the treatment of pain and spasticity]. / La zone d'entrée des racines postérieures dans la moelle: cible chirurgicale pour le traitement de la douleur et de la spasticité.

The large amount of experimental works performed in the 60s and 70s, demonstrating the important role of DREZ in the modulation of the segmental mechanisms of pain and spasticity, drew the author's attention to this site as a possible target for surgery. The anatomical rationale, techniques and results of the procedure, named microsurgical -DREZ-tomy, are developed.