Dorsal Root Entry Zone Operation Research Articles

Neuropathic pain relief and altered brain networks after dorsal root entry zone microcoagulation in patients with spinal cord injury.

Spinal cord injury (SCI) below-level neuropathic pain is a difficult condition to treat both pharmacologically and surgically. Successful treatment using surgically created lesions of the spinal cord dorsal root entry zone (DREZ), guided by intramedullary monitoring of neuronal electrical hyperactivity, has shown that DREZs both cephalad and caudal to the level of injury can be the primary generators of SCI below-level pain. Below-level pain perception follows a unique somatotopic map of DREZ pain generators, and neuronal transmission to brain pain centres can occur primarily through sympathetic nervous system (SNS) pathways. This study evaluated changes in brain resting-state and task-based functional magnetic resonance imaging responses before and after neuroelectrically guided DREZ microcoagulation surgery. Eight persons with clinically complete SCI who suffered chronic, severe and unrelenting below-level neuropathic pain refractory to all pharmacological management were investigated before and after the surgical intervention. Baseline differences between DREZ subjects, group-matched low pain SCI and healthy controls were observed in medial primary somatosensory and motor cortex connectivity to the hippocampus, amygdala and medial prefrontal cortex. The DREZ surgery led to short-term (12 days) almost complete pain relief in all participants and long-term (1+ year) pain relief in all participants receiving DREZ lesioning both cephalad and caudal to the level of injury (six out of eight participants). Follow-up 12 days post-operatively indicated that DREZ surgery normalized prior negative functional coupling between primary sensory (S1) and motor (M1) cortices to the hippocampus, amygdala and the medial prefrontal cortex, increased M1 to putamen and amygdala connectivity and decreased limbic to cerebellar connectivity. DREZ hyperactivity was found both cephalad and caudal to the level of injury. The regional distribution of hyperactive regions corresponded not to classical dermatomes but rather mapped on to intermediolateral (IML) cell column end organ innervation of body regions of below-level pain perception, consistent with a non-classical SNS-mediated somatotopic map of DREZ below-level pain generators. The results indicate that neuroelectrically guided DREZ microcoagulation alters a medial prefrontal-somatosensory-limbic network that is separate from classical pain pathways. This provides further evidence that below-level SCI pain originates in hyperactive DREZs and can be relayed to the brain via the SNS.

Split-Cord Malformation of the Cervical Spinal Cord Following Dorsal Root Entry Zone Lesioning Surgery

The authors report a rare case of a 54-year-old man who developed an asymptomatic cleft within the cervical spinal cord at C7-T1 following Dorsal Root Entry Zone (DREZ) lesioning surgery. The patient presented to the authors’ institution with neuropathic pain from a left brachial plexopathy resulting from a lower trunk avulsion. The initial MRI at 6 months post-injury confirmed preganglionic avulsions of the left C7, C8 and T1 nerve roots. Of note, there was a prominent anterior median fissure at the C7-T1 spinal level. He underwent a DREZ lesion 8 months after the injury. Subsequent MRI studies showed a progressive near complete split within the cervical cord at C7- T1. The patient did not develop any new neurological deficits. It remains unclear whether this observation was a sequela of the root avulsion or the DREZ surgery.

Dorsal Root Entry Zone Operation for Brachial Plexus Neuropathic Pain

Dorsal Root Entry Zone Operation for Brachial Plexus Neuropathic Pain

193 The Morphology of the Cod Dorsal Horn

193 The Morphology of the Cod Dorsal Horn

Anatomy of the spinal dorsal root entry zone: its clinical significance.

The posterolateral sulcus (PLS) is an important surgical landmark, especially for DREZ (dorsal root entry zone) operations. The present study aimed to show the variations of the PLS using human spinal cord histological sections and report the variability in the number of dorsal rootlets of the spinal nerves in each the spinal cord segment. Further, measure the height and width of the dorsal horn on histological sections for cervical, thoracic, and lumbar levels. The results of the present study showed various patterns of PLS 1.clearly present PLS, 2. short PLS, 3. absent PLS or 4. irregular PLS. Height and width measurements of the dorsal horn showed that the average width was greatest at lower cervical (0.48 ± 0.04 mm) and least at lower thoracic levels (0.41 ± 0.04 mm), whereas the average height was greatest at upper cervical (3.0 ± 0.06 mm) and smallest at lower lumbar levels (1.8 ± 0.08 mm). The average number of rootlets varied considerably, at cervical level it was 7.6 ± 1.4 mm, at thoracic 6.6 ± 0.8 mm and at lumbar 6.1 ± 0.4 mm. The detailed anatomy of the variations of the PLS and the average number of rootlets at each spinal level can increase the success of regional surgery. Further, fine measurements on histological sections can give detailed knowledge on the size necessary for lesioning in DREZ operations.

A curative treatment option for Complex Regional Pain Syndrome (CRPS) Type I: dorsal root entry zone operation (report of two cases).

Complex Regional Pain Syndrome Type I (CRPS-I) is a debated health problem concerning its pathophysiology and treatment strategies. A 12-year-old boy and a 35-year-old woman were diagnosed with CRPS-I at different times. They had previously undergone various types of interventions with no success. After one year of follow-up and observation, DREZ lesioning operation was performed. Afterwards, both cases had transient lower extremity ataxia. The first case was followed for 60 months with no recurrence and total cure. The second case was pain-free until the 6th month, when she required psychological support; she was followed for 33 months with partial satisfactory outcome. Although not a first-line option, DREZ lesioning procedure can be chosen and may be a curative option in selected cases of CRPS-I who are unresponsive to conventional therapies.

Microsurgical anatomy of the dorsal thoracic rootlets and dorsal root entry zones

For successful DREZ (dorsal root entry zone) surgery, optimal neuroanatomical orientation and precise microsurgical dissection are required. Although cervical, lumbar, and sacral spinal segments have been studied in detail, such information is not available for thoracic segments. The objective of this anatomical study is to comprehensively illustrate the microanatomical features of the thoracic DREZs and their variations. Fifteen formalin-fixed adult cadaveric spinal cords from T1 to T12 were used. The dorsal rootlet numbers, distance between the posteromedial and posterolateral sulcus, length of each DREZ, length of each segment, and mean length of the dorsal rootlets were measured under a surgical microscope. The longest DREZs were observed at the T6, T7, and T8 segments with mean values of 15.3 mm, 15.6 mm, and 15.4 mm, respectively. The longest segment was observed at the T10 segment with a mean value of 21.0 mm, and the shortest segment was observed at the T1 segment with a mean value of 13.5 mm. The highest dorsal rootlet density is at the T1 segment of the spinal cord, can be easily distinguished visually, and may be a useful surgical landmark. The DREZs in T6-7 segments are longest, while these two segments have the least number of rootlets. Because the dorsolateral tract is remarkably narrow and the dorsal horn is exceedingly deep, DREZ surgery at the thoracic level may be difficult and risky for the dorsal column and corticospinal tract. Acquaintance with the microanatomy of the DREZ in the thoracic spinal cord is crucial to DREZ surgery.

Nucleus caudalis lesioning: Case report of chronic traumatic headache relief

Background:The nucleus caudalis dorsal root entry zone (DREZ) surgery is used to treat intractable central craniofacial pain. This is the first journal publication of DREZ lesioning used for the long-term relief of an intractable chronic traumatic headache.Case Description:A 40-year-old female experienced new-onset bi-temporal headaches following a traumatic head injury. Despite medical treatment, her pain was severe on over 20 days per month, 3 years after the injury. The patient underwent trigeminal nucleus caudalis DREZ lesioning. Bilateral single-row lesions were made at 1-mm interval between the level of the obex and the C2 dorsal nerve roots, using angled radiofrequency electrodes, brought to 80°C for 15 seconds each, along a path 1 to 1.2 mm posterior to the accessory nerve rootlets. The headache improved, but gradually returned. Five years later, her headaches were severe on over 24 days per month. The DREZ surgery was then repeated. Her headaches improved and the relief has continued for 5 additional years. She has remained functional, with no limitation in instrumental activities of daily living.Conclusions:The nucleus caudalis DREZ surgery brought long-term relief to a patient suffering from chronic traumatic headache.

Neurosurgical Advances in Cancer Pain Management

Neurosurgical procedures to treat pain are mainly destructive and involve the spinal cord and occasionally the brain. Targets include the spinothalamic tract, the trigeminal tract nucleus, the midline ascending visceral pain pathway, the brainstem spinal lemniscus, the thalamus, and the cingulate gyrus. Since the introduction of intrathecal opioids, the need for neurosurgical destructive procedures has been in decline. In recent years, cordotomy, trigeminal tractotomy, and dorsal root entry zone (DREZ) operations are the neurosurgical procedures most often utilized to treat cancer pain. The addition of CT guidance to spinal cord pain pathway ablation was a major addition and refinement to the procedure. Here the authors review the latest techniques and recently published results for CT-guided cordotomy, CT-guided trigeminal tractotomy, and DREZ operations utilized to treat cancer pain.

High cervical spinal cord stimulation after failed dorsal root entry zone surgery for brachial plexus avulsion pain

High cervical spinal cord stimulation after failed dorsal root entry zone surgery for brachial plexus avulsion pain

Minimally Invasive Dorsal Root Entry Zone Operation

Minimally Invasive Dorsal Root Entry Zone Operation

High cervical spinal cord stimulation after failed dorsal root entry zone surgery for brachial plexus avulsion pain

Background Many patients had intractable pain after brachial plexus avulsion. This article describes a feasible method of high cervical SCS for a patient who failed in DREZ surgery to treat the pain. Case Description A 70-year-old man had right brachial plexus avulsion after a car accident 15 years ago. He complained of chronic spontaneous pain over his right upper limb since then. Two DREZ surgeries failed to relieve the pain. The pain was successfully controlled by high cervical SCS. Conclusion Stimulating the high cervical spinal cord is effective for treating intractable pain after brachial plexus avulsion, which the DREZ surgery failed to relieve.

SPINAL AND NUCLEUS CAUDALIS DORSAL ROOT ENTRY ZONE OPERATIONS FOR CHRONIC PAIN

Dorsal root entry zone (DREZ) operations came into medical practice after the demonstration of increased electrical activity in the dorsal horn of the spinal cord and brainstem in patients with deafferentation of the central nervous system after injury to these areas. The aim of the study was to describe the technique and the effectiveness of spinal DREZ and nucleus caudalis (NC) DREZ operations, which may be the treatments of choice in unique chronic pain conditions that do not respond to medical therapy or any other surgical methods. Fifty-five patients (44 spinal, 11 NC DREZ) underwent 59 (48 spinal, 11 NC DREZ) operations. There were 44 men and 11 women with a mean age of 46.4 years (range, 24-74 yr). The mean follow-up period was 72 months (range, 6 mo-20 yr). Follow-up assessments were performed with clinical examination on the first day and in the sixth and twelfth months postoperatively. Patients' pain scores and Karnofsky Performance Scale scores were also evaluated pre- and postoperatively. The initial success rates for spinal and NC DREZotomy procedures were 77 and 72.5%, respectively. In the spinal DREZotomy group, mortality occurred in one patient (2.2%). There were two cases of transient muscle weakness (4.4%) and two of cerebrospinal fluid fistulae (4.4%). In the NC DREZotomy group, mortality occurred in one patient (9%). There were two cases of transient ataxia (18%) and two of transient hemiparesis (18%). Spinal and trigeminal NC DREZ operations are effective in the treatment of intractable pain syndromes, especially in traumatic brachial plexus avulsions, segmental pain after spinal cord injury, postherpetic neuralgia, topographically limited cancer pain, and atypical facial pain.

PAIN SYNDROMES AFTER MISSILE-CAUSED PERIPHERAL NERVE LESIONS

To analyze treatment procedures and treatment outcomes of painful missile-caused nerve injuries and factors influencing the outcome. The study included 326 patients with clinically significant pain syndromes, including complex regional pain syndrome Type II, deafferentation pain, reinnervation pain, and neuralgic pain. Treatment modalities included drug therapy, nerve surgery, sympatholysis, and dorsal root entry zone operation. Pain intensity was assessed before and after the treatment using a visual analog scale, and treatment outcome was defined as successful (pain relief >70%), fair (pain relief between 50 and 69%), or poor (pain relief <50%). The outcome was compared between different pain syndromes and different treatment modalities. A successful outcome was achieved in 28.6% of patients with deafferentation pain, in 76.9% of patients with complex regional pain syndrome Type II, and in 87.9 to 100% of patients with other pain syndromes (P = 0.002). Each type of pain syndrome required a specific treatment algorithm, but average pain relief was similar for all definitive treatment modalities (range, 81-88%; P > 0.05). Ten factors were found to significantly influence the treatment outcome, but only three factors were independent predictors of a successful outcome: type of pain syndrome (P < 0.001), severity of nerve injury (P < 0.001), and absence of pain paroxysms (P = 0.03). The treatment outcome of painful nerve injury depends on several factors, including the type of pain syndrome, severance of nerve injury, and absence of pain paroxysms. Drug therapy (carbamazepine, amitriptyline, or gabapentin) should be recommended, at least as a part of treatment, for patients with reinnervation pain, deafferentation pain, and complex regional pain syndrome Type II. Nerve surgery should be recommended for patients with posttraumatic neuralgia, either as the first treatment choice (acute nerve compression or intraneural foreign particles) or after unsuccessful pharmacological treatment (other causes of neuralgic pain).

Neurosurgical treatment of pain

Surgical treatment of chronic pain includes destructive procedures (neurectomy, rhizotomy, sympathectomy), often referred to as ablative, and accompanied by high morbidity and mortality rates. During the past three decades, thanks to current knowledge on chronic pain mechanisms and technological developments, such as improved microsurgical and stereotactic techniques, guided by computerized tomography, magnetic resonance imaging and neural tissue impendance monitoring, the majority of ablative procedures have been replaced by new methods. Among them, a few can be considered as selectively and minimally ablative (microsurgical spinothalamic cordotomy, dorsal root entry zone lesions, limited midline myelotomy) and others as neuroaugumentative procedures for neuromodulatory proceses (deep brain structures and spinal cord stimulation, drug-delivery systems). Cordotomy is very effective in pain treatment and it may produce complete abolishment of pain, especially in patients suffering from neoplastic invasion of the brachial plexus (Pancoast's syndrome) or lumbosacral plexus. Dorsal root entry zone operation is generally the only treatment option for pain due to root avulsion and segmental pain in spinal cord injury. Spinal cord stimulation is useful in management of pain following peripheral nerve injury. Deep brain stimulation is a promising treatment of central pain. The purpose of this review is to draw attention to neurosurgical approaches to treatment of chronic and opioid-resistant pain.

The trigeminal tract and nucleus procedures in treatment of atypical facial pain

Background Atypical facial pain (AFP) is a throbbing pain situated deep in the eye and malar region, often radiating to the ear, neck, and shoulders. The pain generally is not within any dermatomal or anatomical boundaries. Atypical facial pain is distinct from trigeminal neuralgia and its variants. Therefore, the treatment of AFP should be specified. There is also no consensus in the treatment of AFP. Two different treatment procedures on the trigeminal tract and nucleus in a series of cases with AFP are presented. Methods Between 1989 and 2005, 17 patients with AFP, in whom previous therapies had failed, underwent computed tomography (CT)-guided percutaneous trigeminal tractotomy-nucleotomy (TR-NC). One patient with unfavorable response to TR-NC underwent trigeminal dorsal root entry zone (DREZ) operation. Results In the series with AFP, pain relief was achieved in all of the 17 cases. TR-NC provided maximum to inadequate degrees of pain relief in 16 of 17 patients. Dorsal root entry zone operation provided partial relief in 1 case. Neither mortality nor serious permanent complication was observed in the series. Conclusion Neurosurgical procedures such as TR-NC or trigeminal DREZ operation may be effective in the treatment of intractable AFP. The primary choice of operation should be TR-NC because this procedure is minimally invasive. Trigeminal DREZ operation, which affects a larger spread area, may follow if TR-NC fails. The indications and procedure of choice should be individually tailored, depending on the type of pain, underlying pathology, and experience of the surgeon.

Cancer pain: Neurosurgical management

The management of cancer pain represents a difficult diagnostic and therapeutic problem for the clinician. In a multidisciplinary approach to the management of cancer pain, neurosurgical methods are an essential part of the therapy. Frequently, patients with advanced cancer suffer from an increasing pain, requesting ever-higher dosage of narcotics, and finally seeming to respond only to high dosage of intravenous narcotics. Gradually, the opioids produce less satisfactory analgetics effects an more serious side manifestations. These patients can be considered for surgical management of pain. Historically, surgery for cancer pain began with destructive procedures (neurectomy, rhizotomy, sympathectomy), often referred to as ablative. In past two decades, with the help of the current knowledge of cancer pain mechanisms and some of the technological developments, such as microsurgical and stereotactic techniques, computerized tomography and magnetic resonance imaging, the majority of ablative procedures have been replaced by new methods. Among them a few are selectively and minimally ablative (microsurgical spinothalamic cordotomy, dorsal root entry zone operation, limited midline myelotomy) and the others ones are neuroaugumentative operations (deep brain structures and spinal cord stimulation, drug-delivery systems).

Neurophysiological monitoring for the nucleus caudalis dorsal root entry zone operation.

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. 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. 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. 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.

Computed tomography-guided trigeminal tractotomy-nucleotomy in the management of vagoglossopharyngeal and geniculate neuralgias.

Vagoglossopharyngeal and geniculate neuralgias are less frequently seen types of cranial neuralgias. Their causes and symptomatology are similar to those of trigeminal neuralgia; however, the complex anatomic relationship between the intermedius, vagal, and glossopharyngeal nerves leads to difficulties in the diagnosis and management of neuralgias originating from these cranial nerves. Numerous procedures have been used to treat intractable neuralgias of the VIIth, IXth, and Xth cranial nerves: 1) extracranial sectioning of the cranial nerves, 2) percutaneous thermal rhizotomy, 3) intracranial glossopharyngeal and vagal rhizotomies, 4) microvascular decompression, and 5) percutaneous trigeminal tractotomy-nucleotomy (TR-NC) or nucleus caudalis dorsal root entry zone operation. We propose that computer-guided TR-NC may be the first-choice operation for patients with glossopharyngeal, vagal, or geniculate neuralgia. Nine patients suffering from idiopathic vagoglossopharyngeal neuralgia (six patients) and geniculate neuralgia (three patients) were managed at our clinic. Computed tomography-guided percutaneous trigeminal TR-NC was performed for these nine patients. Excellent (six patients) or good (three patients) pain control was obtained in each patient. Complications included temporary ataxia in two patients after TR-NC. The risk:benefit ratio should be evaluated individually to select the appropriate treatment procedure for patients with vagoglossopharyngeal and geniculate neuralgias. Computed tomography-guided percutaneous TR-NC is an effective and minimally invasive procedure for such patients.

Ablative spinal cord surgery for the treatment of chronic pain

Percutaneous cordotomy can be a successful short-term procedure if performed by an experienced neurosurgeon. The procedure should be reserved for patients with intractable pain secondary to malignant disease that is resistant to conservative treatment and pain that is not of a dysesthetic type. Dorsal root entry zone (DREZ) lesions can be highly effective in eliminating certain previously intractable pain syndromes by eliminating the pathologic discharge of neurons in the dorsal horn following injury. DREZ surgery is of proven value in treating pain following brachial plexus avulsion injury and certain pain syndromes following spinal cord injury. DREZ lesions are less effective in treating postherpetic pain along with a higher prevalence of postoperative neurologic deficits, which may be due to the advanced age of patients suffering from this condition. This article reviews various aspects of anterolateral cordotomy and DREZ lesioning.