Dorsal root entry zone lesions for the treatment of brachial plexus avulsion injuries: a follow-up study

Dorsal root entry zone (DREZ) lesions have been shown to yield short term relief from the pain associated with a brachial plexus avulsion injury. Because of the propensity of pain to recur after neuroablative procedures, 39 patients with pain after a brachial plexus avulsion injury were observed for 14 months to 10 years after DREZ lesions were made. Fifty-four per cent of these patients were afforded good pain relief. Of 21 patients who had multiple small lesions made within the DREZ, 15 (72%) were afforded good pain relief.     

Dorsal root entry zone lesions for the treatment of post-herpetic neuralgia

Post-herpetic pain was treated in 12 patients using dorsal root entry zone ( DREZ ) lesions. All patients had failed to receive adequate pain relief from conservative therapy consisting of transcutaneous nerve stimulation, carbamazepine, and/or amitriptyline. Dorsal root entry zone lesions were made to include the involved dermatomes plus one-half of the dermatomes above and below the painful areas. Eight patients reported good pain relief with follow-up periods ranging from 6 to 21 months. A ninth patient obtained satisfactory pain relief, but the superior 1 cm of the original painful area was not included in the distribution of the DREZ lesions. Patients whose lesions were performed using a thermally controlled lesion probe suffered no significant postoperative neurological deficit. Dorsal root entry zone lesions appeared to be a satisfactory treatment for post-herpetic neuralgia in patients who have failed to respond to more conservative modes of therapy.     

Microsurgical junctional DREZ coagulation for treatment of deafferentation pain syndromes

BACKGROUND: In the treatment of intractable deafferentation pain, different procedures in the DREZ have proved most effective. For most of the spot-like techniques special equipment is mandatory. In this study the technique and the results of junctional DREZ coagulation for treatment of different pain syndromes with the help of bipolar forceps is presented. METHODS: In 40 patients with intractable deafferentation pain syndromes a junctional DREZ coagulation lesion along the entire dorsolateral fissure of the involved spinal cord segments was made using bipolar forceps. Etiologies of the pain included avulsion of the brachial plexus (21 cases), postherpetic pain (4 cases), phantom pain (3 cases), peripheral nerve injury (3 cases), reflex sympathetic dystrophy (2 cases), spinal cord transsection (1 case), and syringomyelia (6 cases). RESULTS: Of 21 patients who underwent junctional DREZ surgery for pain because of brachial plexus avulsion 10 (47.6%) had complete, 7 (33.3%) excellent, 3 (14.3%) good, and 1 (4.7%) fair pain relief (follow-up 20 to 120 months). In the group of 19 patients (follow-up 6 to 84 months) with pain syndromes other than postavulsion pain we achieved excellent results in 10 cases (52.6%), good in 8 (42.1%) and no pain relief in 1 case (5.3%). Transient sensory neurological disturbances lasting up to 8 weeks were observed in 6 (15%) cases; permanent sensory and motor deficit in 1 (2.5%) case. CONCLUSIONS: Clinical results of junctional coagulation DREZ lesion for the treatment of deafferentation pain syndromes are promising. There is no need for special equipment for creating DREZ lesions. The lesions are precisely placed with only a bipolar electrode. Postoperative complications are rare and transient. We believe that the junctional coagulation includes the entire dorsolateral sulcus and DREZ structures important for deafferentation pain.     

Pain and spinal cysts in paraplegia: treatment by drainage and DREZ operation

About 10% of paraplegics suffer from intractable pain. The onset of pain may be immediate or delayed for months to several years after the injury. The delayed onset of pain is highly suggestive of the development of a spinal cyst. This is a report of 18 paraplegics who developed a delayed onset of intractable pain who were found at the time of surgery to have associated spinal cord cysts. Treatment consisted of the dorsal root entry zone (DREZ) operation in addition to evacuation of the cyst. Burning pain was the most common complaint occurring years after the trauma. In this study we compared the relationship between the onset and character of the pain, the time of the spinal injury, the operative findings, and the results of the DREZ procedure and evacuation of the traumatic spinal cyst. We believe that the combination of paraplegia, pain and spinal cyst has not been emphasized in the neurosurgical literature although it is well known that cystic formation can follow spinal trauma. Two patients developed spinal cysts with nontraumatic lesions of the spinal cord. A single cyst was found in 14 patients while four had two separate cysts. The diagnosis was made on the basis of history and clinical examination with radiographic confirmation using delayed CT scan and myelography and more recently magnetic resonance imaging. Intraoperative ultrasound was employed in the study of some patients. All patients were treated with combined DREZ lesions and evacuation of the cysts with good pain relief in 77.7%.     

The effect of DREZ (dorsal root entry zone) lesions on intractable pain in patients with spinal cord injury

Some patients with spinal cord injury complain of a severe intractable pain. This intractable pain places new hurdles on the road to return to the ordinary daily life in these patients. The effective therapy for the intractable pain has not been established. Dorsal root entry zone (DREZ) lesion was originally reported by Nashold et al to alleviate deafferented pain syndrome. Three male and one female patients with intractable pain following spinal cord injury were treated with DREZ-lesions. One month after operation, all 4 patients obtained good pain relief. However, at a follow-up period till February 1989 (ranging 11 months from 2 years and 6 months), 2 patients had subjective pain relief. When other therapies on intractable pain following spinal cord trauma are not effective, the DREZ-lesion might be considered.     

Clinical experience with radiofrequency and laser DREZ lesions.

Dorsal root entry zone (DREZ) lesions were used to treat intractable pain due to deafferentation in 78 patients managed between 1981 and 1988. Etiology of pain included avulsion of brachial or lumbosacral plexuses (27 cases), spinal cord injury (20 cases), amputation (nine cases), post-herpetic neuralgia (16 cases), and cauda equina injury (six cases). Three different lesioning techniques were employed: a radiofrequency (rf) method using a 0.5 X 2-mm stainless steel electrode with control of electric current and duration (Group 1: 21 cases); the CO2 laser (Group 2: 20 cases); and an rf method, using a 0.25 X 2-mm stainless steel electrode with control of electrode temperature and duration (Group 3: 37 cases). Overall, 48 (61.5%) of 78 patients received satisfactory pain relief, defined as a 50% or greater reduction in pain intensity, cessation of narcotic analgesic usage, and improvement in functional capacity. Fourteen (67%) of the 21 Group 1 patients obtained effective pain relief, compared to nine (45%) of the 20 Group 2 patients and 25 (68%) of the 37 Group 3 patients. Neurological complications including mainly ipsilateral leg weakness or loss of proprioception occurred in 52.3% of the patients in Group 1, 15% of the Group 2 patients, and 8.1% of the Group 3 patients. These results support the view that DREZ lesions may be made most effectively and safely with the rf lesioning technique associated with control of electrode temperature and duration.     

Results of DREZ coagulations for pain related to plexus lesions,spinal cord injuries and postherpetic neuralgia

Summary The results of 58 dorsal root entry zone (DREZ) thermocoagulation procedures in 51 patients are reported. The postoperative analgesic effect was judged by the patients as being good (more than 75% pain reduction), fair (25–75% pain reduction) or poor (less than 25% pain reduction). Of the 14 patients who underwent surgery for pain due to cervical root avulsion, 10 (77%) had permanently good (8) or fair (2) pain relief after a mean follow up period of 76 months, another 2 (15%) experienced recurrence to the pre-operative level (initially 1 good, 1 fair) after more than 2 and 4 years, respectively. Twenty two paraplegics were operated upon, 3 of whom twice, for intractable pain. After a mean observation time of 54 months, continuing pain relief was reported by 12 (55%) patients (11 good, 1 fair), and one (initially fair) had recurrent pain after 8 months. All 3 (early) re-operations remain successful for an average period of 75 months. Poor results were seen especially in cases of associated spinal cord cysts (5 out of 7), despite combined drainage, and in patients with diffuse pain distribution (5 out of 6). Continuous marked improvement for longer periods (mean follow up: 52 months) after DREZ lesions was reported only by 2 out of 10 patients with postherpetic neuralgia (12 procedures) and by 1 out of 5 with painful states due to radiation-induced brachial plexopathy (2), previous surgery (2) and malignant tumour infiltration of the brachial plexus (1). Three patients died postoperatively due to acute cardiac failure (2) and pulmonary embolism (1). Major complications, especially permanent gait disturbances were observed in 6 patients (12%) following primary procedures and in 2 out of 7 patients after re-operations, most of them suffering from postherpetic neuralgia. Minor neurological deficits were noted in 9 cases (18%). DREZ lesions revealed to be an effective procedure in patients with pain related to root avulsion and paraplegia. In contrast, it seems to be less successful for painful states due to other plexus lesions or postherpetic neuralgia.     

Trigeminal nucleus caudalis dorsal root entry zone: a new surgical approach.

New radiofrequency lesion dorsal root entry zone (DREZ) electrodes for relief of facial pain were designed based on a neuroanatomic study in man of the trigeminal nucleus caudalis at the cervicomedullary junction. The human brainstems of 3 normal postmortem specimens were sectioned with measurements and relationships of the trigeminal nucleus caudalis, segmental tracts, spinocerebellar tracts and dorsal columns. Two right-angle DREZ electrodes were made by Radionics for producing DREZ lesions in the trigeminal nucleus caudalis to treat deafferentation facial pain.     

外科手术治疗幻肢痛的临床研究

目的研究立体定向脑内靶点毁损术和脊髓后根入髓区（DREZ）毁损术治疗幻肢痛的临床应用。方法共15例幻肢痛患者,男性14例,女性1例。按手术方式不同分为两组,A组4例,为同期联合毁损对侧中脑脊髓丘脑束加双侧扣带回前部,B组11例,采用患侧对应脊髓节段的DREZ毁损术,包括颈5～胸1 10例,腰2～骶1 1例。采用直观模拟疼痛量表（VAS）和McGill疼痛问卷量表（MPQ）分别在术前和术后进行疼痛状况评分,采用自身配对t检验将术前、术后不同时间的评分进行比较。结果15例患者术后疼痛均消失,A组3个月之内止痛效果稳定,VAS评分和MPQ评分较术前显著降低（P〈0．01）;长期随访患者分别在术后4、6、12和18个月疼痛复发。B组1例术后2个月死于严重肺部感染,另10例随访12～24个月,平均14．5个月,止痛效果稳定,VAS评分和MPQ评分较术前均显著降低（P〈0．05）。结论一侧中脑加双侧扣带回前部联合毁损术和脊髓DREZ毁损术均能有效消除幻肢痛,近期疗效确切,DREZ毁损术的长期疗效更为稳定。     

Dorsal root entry zone lesions (Nashold's procedure) in brachial plexus avulsion

Dorsal root entry zone coagulation (DREZ) lesions for pain were made in 41 patients at the National Hospitals during 1980 through 1983. In 34 patients the operation was an attempt to relieve pain due to avulsion of the brachial plexus. Of these patients, 95% were male and 91% had received their injury in road traffic accidents. The follow-up period is 4 to 44 months. Pain relief was good in 62%, fair in 24%, and poor in 14%. Postoperative motor or sensory changes occurred in 50% of the patients, but these were significant in only 12%. In later patients in this series, pre-, peri-, and postoperative monitoring of somatosensory evoked potentials was used. Evoked potential monitoring indicated subclinical posterior column damage ipsilateral to avulsion before DREZ lesion making in about 50% of the cases; in some cases, postoperative changes were detected.     

Neurophysiological monitoring for the nucleus caudalis dorsal root entry zone operation

OBJECTIVE: The purpose of this report is to describe a neurophysiological monitoring technique that can decrease the incidence of complications while maintaining the effectiveness of the nucleus caudalis dorsal root entry zone (DREZ) operation. METHODS: Needle electrodes were used to stimulate the supraorbital, infraorbital, mental, and median nerves after the nucleus caudalis was surgically exposed. The DREZ electrode was used to record responses from the various areas in and near the nucleus. The target site was localized. Before lesioning, the site was stimulated with the DREZ electrode and electromyographic activation was sought. If no activation was observed, a lesion was made. RESULTS: Five patients underwent a total of seven nucleus caudalis DREZ procedures with complete neurophysiological monitoring. The mean number of lesions per procedure in this series was 5.4. Six procedures (86%) resulted in immediate pain relief, and five (71%) produced persistent benefit after a mean follow-up period of 12 months. Only one patient (20%) (one of seven procedures) who underwent a unilateral DREZ procedure had ataxia, which resolved within a few days. No complications were noted at follow-up. CONCLUSION: Despite patients in this series receiving fewer lesions, the efficacy of the DREZ operation was comparable to that reported in earlier studies. There were fewer complications when neurophysiological monitoring was used. Such monitoring should be considered for nucleus caudalis DREZ operations.     

Dorsal root entry zone lesions for post-amputation pain

Chronic pain following an amputation may involve the stump, the phantom limb, or both. Operations such as rhizotomy, cordotomy, stump revision, and dorsal column stimulation have been unsuccessful in treating this condition. This study evaluates the effectiveness of dorsal root entry zone (DREZ) coagulation for this pain problem. The authors studied 22 patients with amputations due to trauma, gangrene, or cancer. All developed post-amputation pain, underwent a DREZ procedure, and were followed from 6 months to 4 years after surgery. Overall, only eight (36%) of these 22 patients had pain relief. However, good results were obtained in six (67%) of nine patients with phantom pain alone, and in five (83%) of six patients with traumatic amputations associated with root avulsion. Poor results were obtained in patients with both phantom and stump pain, or stump pain alone. The DREZ procedure has a limited, but definite, place in the treatment of post-amputation pain.     

Current status of the DREZ operation: 1984

The DREZ operation was introduced in 1976 as a method to control deafferentation pain associated with brachial plexus injury. Since then, 250 DREZ operations have been done at Duke Medical Center. At present, the best results of pain relief occur in brachial and lumbosacral root avulsions, paraplegia, and postherpetic pain. Post-DREZ complications have been reduced by the introduction of new lesion techniques, including the recent use of the laser. The neural basis of deafferentation pain is still not solved, nor is the therapeutic effect of the DREZ lesion known.     

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.     

The DREZ procedure: an update on technique

The DREZ operation was first done in 1975 on a patient with arm pain following a brachial plexus avulsion. Since then approximately 500 patients have undergone the DREZ procedure under our care for treatment of various pain syndromes including deafferentation pain, post-herpetic neuralgia, and post-paraplegia pain. We report several modifications in instrumentation and technique. Currently, we use two types of electrodes for lesion production. The first is the standard 0.25 mm diameter, thermocouple, temperature monitoring electrode which has a 2 mm long tip for introduction into the spinal cord. A second type, recently modified from the original, is used only for lesioning the nucleus caudalis in patients with trigeminal post-herpetic neuralgia. Its tip is 3 mm long with insulation along the first 1 mm. This allows lesioning of the caudalis nucleus while sparing the more superficial spinocerebellar tracts. We no longer lesion only the dorsal root entry zones at each root level but include all the contiguous substantia gelatinosa between roots. With lesions only 1 mm apart this greatly increases the number of lesions and decreases the incidence of incomplete postoperative pain relief. In patients undergoing caudalis lesioning, we make two rows of lesions, one above the other, from C2 to slightly above the obex. This prevents sparing of the facial midline with resultant residual pain. Finally, lesions are made by heating the electrode tip to 75 degrees C for exactly 15 sec, thus allowing for a more uniform lesion. With these modifications, we have a decreased incidence of incomplete pain relief as well as a decreased incidence of complications, especially in patients undergoing caudalis lesioning.     

Microsurgical lesioning in the dorsal root entry zone for pain due to brachial plexus avulsion: a prospective series of 55 patients

OBJECT: Most patients with preganglionic lesions after brachial plexus injuries suffer pain that is hard to control through medication or neuromodulation. Lesioning in the dorsal root entry zone (DREZ) is undeniably effective. Fifty-five patients who had undergone the so-called microsurgical DREZotomy (MDT) procedure were studied with the two following objectives: 1) to describe the anatomical lesions observed during MDT in correlation with sensory deficits and pain features; and 2) to analyze the results in the 44 patients who were followed for more than 1 year (mean 6 years). METHODS: The observed lesions were severe: 79.6% of ventral and 78.2% of dorsal roots from C5-T1 were impaired. Damage extended to all five roots in 42% of patients. Strong arachnoiditis was present in 38.2%, pseudomeningoceles in 31%, spinal cord distortion and/or atrophy in 49%, and abundant gliotic tissue and/or microcavitations within the dorsal horn at the avulsed segments in 36.4% of cases. Sensory deficit corresponded to the entire territory of the dorsal root lesions in 52% of patients, but was larger in 30% most certainly due to the associated extrarachidian lesions. At the last evaluation after MDT, 66% of patients showed excellent (total relief without medication) or good (total relief with medication) pain relief and 71% experienced an improvement in activity level. CONCLUSIONS: Apart from other indications not addressed in this article, MDT can be performed to treat refractory pain due to brachial plexus avulsions. The long-term efficacy of this procedure strongly indicates that pain after brachial plexus avulsion originates from the deafferented (and gliotic) dorsal horn.     

Dorsal root entry zone lesions for the control of deafferentation pain: experiences in ten patients

Experiences with radiofrequency lesions of the dorsal root entry zone in 10 patients are reported. All of these patients suffered from central (deafferentation) pain. The early postoperative results were poor in the 2 patients with traumatic paraplegia and good in all 8 patients with pain in the cervical segments. Two patients treated with cervical DREZ lesions died. In 2 of the remaining 6 patients with cervical lesions, pain recurred. Four had a good result up to 30 months after operation.     

Microsurgical DREZotomy for pain of spinal cord and Cauda equina injury origin: clinical characteristics of pain and implications for surgery in a series of 26 patients

Summary.  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.     

Subpial spinal evoked potentials in patients undergoing junctional dorsal root entry zone coagulation for pain relief

Summary Seven patients with complete avulsion of the brachial plexus underwent junctional coagulation lesions of the dorsal root entry zone (DREZ) for relief of intractable pain in the paralyzed arm. Intra-operative monitoring by recording spinal cord somatosensory evoked potentials (SEP) resulting from tibial nerve stimulation was done using subpial recording electrodes situated dorsal to the posterior median sulcus at the C4 and T2 segment. SEP on the normal side showed an initial positive wave and two negative waves followed by a group of high frequency waves of relatively high amplitude which continued into high frequency, low amplitude potentials. The conduction velocity of the fastest spinal evoked potential components were, on average, 86 m/s. Recordings from the side of avulsion revealed a steep positive potential of high amplitude which appeared in five patients prior to the creation of the DREZ lesion. This effect was assumed to be secondary to spinal cord damage caused by avulsion. During the DREZ coagulation the SEP from the unaffected side did not change. On the side of DREZ coagulation the velocity of the fastest fibres decreased. Four patients reported sensory deficits after the operation, which were transient in three. In one of these patients, the first two negative potentials disappeared. In the fourth patient, who had permanent sensory deficits, the positive steep potential appeared after generation of the lesion. Our results point to the usefulness of the subpial SEPs monitoring during microneurosurgical procedures on the spinal cord to provide further insight into evoked electrical activity of the normal and injured spinal cord, and to minimize post-operative neurological morbidity.     

Thermocoagulation of the dorsal root entry zone for the treatment of intractable pain

The authors report the results of DREZ thermocoagulation in 35 patients since March 1980. This technique was applied not only in patients with deafferentation pain after brachial plexus avulsion, but also for postamputation phantom limb pain and pain caused by injury to the spine and spinal cord, by peripheral nerve lesions, and by multiple sclerosis. Independent of etiology, the duration of the pain syndrome, and the quality and projection of the pain, the overall results have been satisfactory and long-lasting.