Percutaneous cervical cordotomy: a review of 181 operations on 146 patients with a study on the location of "pain fibers" in the C-2 spinal cord segment of 29 cases

Hearing, touching, and multisensory integration during mate choice

Mate choice is a potent generator of diversity and a fundamental pillar for sexual selection and evolution. Mate choice is a multistage affair, where complex sensory information and elaborate actions are used to identify, scrutinize, and evaluate potential mating partners. While widely accepted that communication during mate assessment relies on multimodal cues, most studies investigating the mechanisms controlling this fundamental behavior have restricted their focus to the dominant sensory modality used by the species under examination, such as vision in humans and smell in rodents. However, despite their undeniable importance for the initial recognition, attraction, and approach towards a potential mate, other modalities gain relevance as the interaction progresses, amongst which are touch and audition. In this review, we will: (1) focus on recent findings of how touch and audition can contribute to the evaluation and choice of mating partners, and (2) outline our current knowledge regarding the neuronal circuits processing touch and audition (amongst others) in the context of mate choice and ask (3) how these neural circuits are connected to areas that have been studied in the light of multisensory integration.

Congress of Neurological Surgeons Systematic Review and Evidence-Based Guideline on Neuroablative Procedures for Patients With Cancer Pain

BACKGROUND

Managing cancer pain once it is refractory to conventional treatment continues to challenge caregivers committed to serving those who are suffering from a malignancy. Although neuromodulation has a role in the treatment of cancer pain for some patients, these therapies may not be suitable for all patients. Therefore, neuroablative procedures, which were once a mainstay in treating intractable cancer pain, are again on the rise. This guideline serves as a systematic review of the literature of the outcomes following neuroablative procedures.

OBJECTIVE

To establish clinical practice guidelines for the use of neuroablative procedures to treat patients with cancer pain.

METHODS

A systematic review of neuroablative procedures used to treat patients with cancer pain from 1980 to April 2019 was performed using the United States National Library of Medicine PubMed database, EMBASE, and Cochrane CENTRAL. After inclusion criteria were established, full text articles that met the inclusion criteria were reviewed by 2 members of the task force and the quality of the evidence was graded.

RESULTS

In total, 14 646 relevant abstracts were identified by the literature search, from which 189 met initial screening criteria. After full text review, 58 of the 189 articles were included and subdivided into 4 different clinical scenarios. These include unilateral somatic nociceptive/neuropathic body cancer pain, craniofacial cancer pain, midline subdiaphragmatic visceral cancer pain, and disseminated cancer pain. Class II and III evidence was available for these 4 clinical scenarios. Level III recommendations were developed for the use of neuroablative procedures to treat patients with cancer pain.

CONCLUSION

Neuroablative procedures may be an option for treating patients with refractory cancer pain. Serious adverse events were reported in some studies, but were relatively uncommon. Improved imaging, refinements in technique and the availability of new lesioning modalities may minimize the risks of neuroablation even further.The full guidelines can be accessed at https://www.cns.org/guidelines/browse-guidelines-detail/guidelines-on-neuroablative-procedures-patients-wi.

Cervical Cordotomy for Intractable Pain: Do Postoperative Imaging Features Correlate with Pain Outcomes and Mirror Pain?

BACKGROUND AND PURPOSE

Percutaneous cervical cordotomy offers relief of unilateral intractable oncologic pain. We aimed to find anatomic and postoperative imaging features that may correlate with clinical outcomes, including pain relief and postoperative contralateral pain.

MATERIALS AND METHODS

We prospectively followed 15 patients with cancer who underwent cervical cordotomy for intractable pain during 2018 and 2019 and underwent preoperative and up to 1-month postoperative cervical MR imaging. Lesion volume and diameter were measured on T2-weighted imaging and diffusion tensor imaging (DTI). Lesion mean diffusivity and fractional anisotropy values were extracted. Pain improvement up to 1 month after surgery was assessed by the Numeric Rating Scale and Brief Pain Inventory.

RESULTS

All patients reported pain relief from 8 (7-10) to 0 (0-4) immediately after surgery (P = .001), and 5 patients (33%) developed contralateral pain. The minimal percentages of the cord lesion volume required for pain relief were 10.0% on T2-weighted imaging and 6.2% on DTI. Smaller lesions on DWI correlated with pain improvement on the Brief Pain Inventory scale (r = 0.705, P = .023). Mean diffusivity and fractional anisotropy were significantly lower in the ablated tissue than contralateral nonlesioned tissue (P = .003 and P = .001, respectively), compatible with acute-phase tissue changes after injury. Minimal postoperative mean diffusivity values correlated with an improvement of Brief Pain Inventory severity scores (r = -0.821, P = .004). The average lesion mean diffusivity was lower among patients with postoperative contralateral pain (P = .037).

CONCLUSIONS

Although a minimal ablation size is required during cordotomy, larger lesions do not indicate better outcomes. DWI metrics changes represent tissue damage after ablation and may correlate with pain outcomes.

Percutaneous Cervical Cordotomy for the Treatment of Cancer Pain: A Prospective Case Series of 52 Patients with a Long-Term Follow-Up

AIM

The aim of this study is to describe the effects of percutaneous cervical cordotomy (PCC) on pain, opioid consumption, adverse events, and satisfaction in palliative care patients with cancer pain after PCC until end of life.

METHODS

This is a prospective observational case series of 58 PCCs in 52 consecutive patients. Indication for PCC was unilateral cancer pain with a maximum numeric rating scale (NRS) of pain above 5 despite maximal conservative treatment. The PCC was fluoroscopy guided. A radiofrequency lesion was made at 95°C for 20 seconds. The pain location and pain scores, analgesic medication, the cranial and caudal borders of dermatomes hypoesthetic for pin pricks, dysesthesia, urinary retention, Horner's syndrome, muscle strength, Karnofsky performance scale (KPS) score, patient satisfaction, hospital anxiety and distress score (HADS), and RAND 36 score were evaluated at 1 day; 1 and 6 weeks; and 3, 6, 9, 12 18, and 24 months after PCC, or until death if death occurred during the follow-up period.

RESULTS

Pain relief after PCC was intense (change in median maximum NRS from 9 to 0) and persistent. Median opioid use per day was 240 mg (145 to 565 mg) before PCC and 55 mg (0 to 120 mg) after PCC. The upper and lower borders of dermatomes hypoesthetic for pin pricks were stable over time. The most common side effects were short-term (< 1 week) neck pain (28%), dysesthesia (40%), and mild loss of muscle strength (11%). Approximately 83% of the patients were satisfied or very satisfied with the results of PCC 1 week after the procedure, and this percentage remained high in the long term. There was no significant change in the KPS score, HADS, and RAND 36 score.

CONCLUSION

Percutaneous cervical cordotomy is an effective treatment for unilateral cancer pain. The reduction in pain, reduction in opioid consumption, and hypoesthetic area remain stable until death.

Magnetic Resonance-Based Radiomic Analysis of Radiofrequency Lesion Predicts Outcomes After Percutaneous Cordotomy: A Feasibility Study

BACKGROUND

To date, there is limited data on evaluation of the cordotomy lesion and predicting clinical outcome.

OBJECTIVE

To evaluate the utility of magnetic resonance (MR)-based radiomic analysis to quantify microstructural changes created by the cordotomy lesion and predict outcome in patients undergoing percutaneous cordotomy for medically refractory cancer pain.

METHODS

This is a retrospective interpretation of prospectively acquired data in 10 patients (5 males, age range 43-76 yr) who underwent percutaneous computed tomography-guided high cervical cordotomy for medically refractory cancer pain between 2015 and 2016. All patients underwent magnetic resonance imaging (MRI) of the cordotomy lesion on postoperative day 1. After segmentation of T2-weighted images, 310 radiomic features were extracted. Pain outcomes were recorded on postoperative day 1 and day 7 using the visual analog scale. R software was used to build statistical models based on MRI radiomic features for prediction of pain outcomes.

RESULTS

A total of 20 relevant radiomic features were identified using the maximum relevance minimum redundanc method. Radiomics predicted postoperative day 1 pain scores with an accuracy of 90% (P = .046), 100% sensitivity, 75% specificity, 85.7% positive predictive value, and 100% negative predictive value. The radiomics model also predicted if the postoperative day 1 pain score was sustained on postoperative day 7 with an accuracy of 100% (P = .028), 100% sensitivity, 100% specificity, and 100% positive and negative predictive value.

CONCLUSION

MR-based radiomic analysis of the cordotomy lesion was predictive of pain outcomes at 1 wk after percutaneous cordotomy for intractable cancer pain.

Somatotopy and Organization of Spinothalamic Tracts in the Human Cervical Spinal Cord

BACKGROUND

Understanding spinothalamic tract anatomy may improve lesioning and outcomes in patients undergoing percutaneous cordotomy.

OBJECTIVE

To investigate somatotopy and anatomical organization of spinothalamic tracts in the human cervical spinal cord.

METHODS

Patients with intractable cancer pain undergoing cordotomy underwent preoperative and postoperative quantitative sensory testing for sharp pain and heat pain on day 1 and 7 after cordotomy. Intraoperative sensory stimulation was performed with computed tomography (CT) imaging to confirm the location of the radiofrequency electrode during cordotomy. Postoperative magnetic resonance (MR) imaging was performed to define the location of the lesion.

RESULTS

Twelve patients were studied, and intraoperative sensory stimulation combined with CT imaging revealed a somatotopy where fibers from the legs were posterolateral to fibers from the hand. Sharpness detection thresholds were significantly elevated in the area of maximum pain on postoperative day 1 (P = .01). Heat pain thresholds for all areas were not elevated significantly on postoperative day 1, or postoperative day 7. MR imaging confirmed that the cordotomy lesion was in the anterolateral quadrant, and in this location the lesion had a sustained effect on sharp pain but a transient impact on heat pain.

CONCLUSION

In the high cervical spinal cord, spinothalamic fibers mediating sharp pain for the arms are located ventromedial to fibers for the legs, and these fibers are spatially distinct from fibers that mediate heat pain.

Strategies for interventional therapies in cancer-related pain-a crossroad in cancer pain management

PURPOSE

Interventional therapies are important to consider when facing cancer pain refractory to conventional therapies. The objective of the current review is to introduce these effective strategies into dynamic interdisciplinary pain management, leading to an exhaustive approach to supportive oncology.

METHODS

Critical reflection based on literature analysis and clinical practice.

RESULTS

Interventional therapies act on the nervous system via neuromodulation or surgical approaches, or on primitive or metastatic lesions via interventional radiotherapy, percutaneous ablation, or surgery. Interventional therapies such as neuromodulations are constantly evolving with new technical works still in development. Nowadays, their usage is better defined, depending on clinical situations, and their impact on quality of life is proven. Nevertheless their availability and acceptability still need to be improved. To start with, a patient's interdisciplinary evaluation should cover a wide range of items such as patient's performance and psychological status, ethical considerations, and physiochemical and pharmacological properties of the cerebrospinal fluid for intrathecal neuromodulation. This will help to define the most appropriate strategy. In addition to determining the pros and cons of highly specialized interventional therapies, their relevance should be debated within interdisciplinary teams in order to select the best strategy for the right patient, at the right time.

CONCLUSIONS

Ultimately, the use of the interventional therapies can be limited by the requirement of specific trained healthcare teams and technical support, or the lack of health policies. However, these interventional strategies need to be proposed as soon as possible to each patient requiring them, as they can greatly improve quality of life.

Somatotopic organization of the human spinothalamic tract: in vivo computed tomography-guided mapping in awake patients undergoing cordotomy

OBJECTIVE

The location of the human spinothalamic tract (STT) in the anterolateral spinal cord has been known for more than a century. The exact nature of the neuronal fiber lamination within the STT, however, remains controversial. After correlating in vivo macrostimulation-induced pain/temperature sensation during percutaneous cervical cordotomy with simultaneous CT imaging of the electrode tip location, the authors present a modern description of the somatotopy of the human cervical STT.

METHODS

Twenty patients underwent CT-guided percutaneous cervical cordotomy to alleviate contralateral medication-refractory cancer pain. Patient responses to electrical stimulation (0.01-0.1 V, 50 Hz, 1 msec) were recorded and the electrode location for each response was documented with a contemporaneous CT scan. In a post hoc analysis of the data, the location for each patient's response(s) was measured and drawn on a diagram of their cord. Positive responses were represented only when the lowest possible voltage (≤ 0.02 V) elicited a response. Negative responses were recorded if there was no clinical response at 0.1 V.

RESULTS

Clinically, patients did well with an average reduction in opiates of 75% at 1 week, and 67% were able to leave the palliative care unit. The size of the cervical cord varied between patients, with an average lateral extent (width) of 11 mm and a height of 9 mm. Responses from the lower limb were represented superficially (lateral) and posteriorly within the anterolateral cord. The area with responses from the upper limb was larger and surrounded those with responses from the lower limb primarily anteriorly and medially, but also posteriorly.

CONCLUSIONS

In this study, the somatotopic organization of the human STT was elucidated for the first time using in vivo macrostimulation and contemporaneous CT imaging during cordotomy. In this cohort of patients, the STT from the lower-limb region was located superficially and posteriorly in the anterolateral quadrant of the cervical cord, with the STT from the upper-limb region surrounding it primarily anteriorly and medially (deep) but also posteriorly. The authors discuss how the previous methods of cordotomy may have biased the earlier versions of STT lamination. They suggest that an ideal spinal cord entry site for cordotomy of either the upper- or lower-limb pain fibers is halfway between the equator and anterior pole of the cord.

Minimally Invasive Cordotomy for Refractory Cancer Pain: A Randomized Controlled Trial

BACKGROUND

Up to 30% of patients with cancer continue to suffer from pain despite aggressive supportive care. The present study aimed to determine whether cordotomy can improve cancer pain refractory to interdisciplinary palliative care.

MATERIALS AND METHODS

In this randomized controlled trial, we recruited patients with refractory unilateral somatic pain, defined as a pain intensity (PI) ≥4, after more than three palliative care evaluations. Patients were randomized to percutaneous computed tomography-guided cordotomy or continued interdisciplinary palliative care. The primary outcome was 33% improvement in PI at 1 week after cordotomy or study enrollment as measured by the Edmonton Symptom Assessment Scale.

RESULTS

Sixteen patients were enrolled (nine female, median age 58 years). Six of seven patients (85.7%) randomized to cordotomy experienced >33% reduction in PI (median preprocedure PI = 7, range 6-10; 1 week after cordotomy median PI = 1, range 0-6; p = .022). Zero of nine patients randomized to palliative care achieved a 33% reduction in PI. Seven patients (77.8%) randomized to palliative care elected to undergo cordotomy after 1 week. All of these patients experienced >33% reduction in PI (median preprocedure PI = 8, range 4-10; 1 week after cordotomy median PI = 0, range 0-1; p = .022). No patients were withdrawn from the study because of adverse effects of the intervention.

CONCLUSION

These data support the use of cordotomy for pain refractory to optimal palliative care. The findings of this study justify a large-scale randomized controlled trial of percutaneous cordotomy.

IMPLICATIONS FOR PRACTICE

This prospective clinical trial was designed to determine the improvement in pain intensity in patients randomized to either undergo cordotomy or comprehensive palliative care for medically refractory cancer pain. This study shows that cordotomy is effective in reducing pain for medically refractory cancer pain, and these results can be used to design a large-scale comparative randomized controlled trial that could provide the evidence needed to include cordotomy as a treatment modality in the guidelines for cancer pain management.

Interventional Anesthetic Methods for Pain in Hematology/Oncology Patients

This article reviews anesthetic interventional approaches to the management of pain in hematology and oncology patients. It includes a discussion of single interventions including peripheral nerve blocks, plexus injections, and sympathetic nerve neurolysis, and continuous infusion therapy through implantable devices, such as intrathecal pumps, epidural port-a-caths, and tunneled catheters. The primary objective is to inform members of hematology and oncology care teams regarding the variety of interventional options for patients with cancer-related pain for whom medical pain management methods have not been effective.

Postoperative MRI Evaluation of a Radiofrequency Cordotomy Lesion for Intractable Cancer Pain

BACKGROUND AND PURPOSE

There are limited data on the use of postoperative imaging to evaluate the cordotomy lesion. We aimed to describe the cordotomy lesion by using postoperative MR imaging in patients after percutaneous cordotomy for intractable cancer pain.

MATERIALS AND METHODS

Postoperative MR imaging and clinical outcomes were prospectively obtained for 10 patients after percutaneous cordotomy for intractable cancer pain. Area, signal intensity, and location of the lesion were recorded. Clinical outcomes were measured by using the Visual Analog Scale and the Brief Pain Inventory-Short Form, and correlations with MR imaging metrics were evaluated.

RESULTS

Ten patients (5 men, 5 women; mean age, 58.5 ± 9.6 years) were included in this study. The cordotomy lesion was hyperintense with central hypointense foci on T2-weighted MR imaging, and it was centered in the anterolateral quadrant at the C1-C2 level. The mean percentage of total cord area lesioned was 24.9% ± 7.9%, and most lesions were centered in the dorsolateral region of the anterolateral quadrant (66% of the anterolateral quadrant). The number of pial penetrations correlated with the percentage of total cord area that was lesioned (r = 0.78; 95% CI, 0.44-0.89; P = .008) and the length of T2-weighted hyperintensity (r = 0.85; 95% CI, 0.54-0.89; P = .002). No significant correlations were found between early clinical outcomes and quantitative MR imaging metrics.

CONCLUSIONS

We describe qualitative and quantitative characteristics of a cordotomy lesion on early postoperative MR imaging. The size and length of the lesion on MR imaging correlate with the number of pial penetrations. Larger studies are needed to further investigate the clinical correlates of MR imaging metrics after percutaneous cordotomy.

Usefulness of cordotomy in patients with cancer who experience bilateral pain: implications of increased pain and new pain

BACKGROUND:

Although mirror pain occurs after cordotomy in patients experiencing unilateral pain via a referred pain mechanism, no studies have examined whether this pain mechanism operates in patients who have bilateral pain.

OBJECTIVE:

To assess the usefulness of cordotomy for bilateral pain from the viewpoint of increased pain or new pain caused by a referred pain mechanism.

METHODS:

Twenty-six patients who underwent percutaneous cordotomy through C1-C2 for severe bilateral cancer pain in the lumbosacral nerve region were enrolled. Pain was dominant on 1 side in 23 patients, and pain was equally severe on both sides in 3 patients. Unilateral cordotomy was performed for the dominant side of pain, and bilateral cordotomy was performed for 13 patients in whom pain on the nondominant side developed or remained severe after cordotomy.

RESULTS:

After unilateral cordotomy, 19 patients (73.1%) exhibited increased pain, which for 14 patients was as severe as the original dominant pain. After bilateral cordotomy, 7 patients (53.4%) exhibited new pain, which was located cephalad to the region rendered analgesic by cordotomy and was better controlled than the original pain. No pathological organic causes of new pain were found in any patient, and evidence of a referred pain mechanism was found in 3 patients after bilateral cordotomy.

CONCLUSION:

These results show that a referred pain mechanism causes increased or new pain after cordotomy in patients with bilateral pain. Nevertheless, cordotomy can still be indicated for patients with bilateral pain because postoperative pain is better controlled than the original pain.

Cordotomy for treatment of cancer-related pain: patient selection and intervention timing

Many neurosurgical interventions for the management of cancer-related pain have been tried, but their role in today's advanced supportive and palliative care is not well described. The authors discuss the current knowledge gaps that prevent successful integration of neurosurgical interventions and patients with cancer-related pain.

Two patients underwent percutaneous CT-guided cordotomy for refractory cancer-related pain: one patient had melanoma and the other had ovarian carcinoma. Both patients seemed to have unilateral, somatic, nociceptive cancer-related pain.

Cordotomy was effective for only 1 patient.

Percutaneous CT-guided cordotomy is a low-risk intervention that can benefit carefully selected patients with cancer-related pain. There is a clear need for prospective controlled studies to evaluate the effectiveness of cordotomy for patients receiving optimal medical treatment. A multidisciplinary study design could help to identify factors correlated with a positive outcome.

Flat-panel fluoroscopy O-arm-guided percutaneous radiofrequency cordotomy: a new technique for the treatment of unilateral cancer pain

BACKGROUND

Percutaneous radiofrequency cordotomy (PRFC) involves controlled ablation of the anterolateral quadrant of the spinal cord, thereby relieving pain. Evolving from a morbid open surgery, the procedure has been modernized through the application of physiological target confirmation, well-regulated thermal ablation, and improved intraoperative imaging.

OBJECTIVE

To evaluate the utility in PRFC of a new high-resolution, portable flat-panel fluoroscopic imaging technology, the O-arm Imaging System. The O-arm allows traditional 2-dimensional fluoroscopy in addition to axial and 3-dimensional reconstructed computed tomography imaging.

METHODS

PRFC was performed using the O-arm Imaging System in 6 patients with unilateral cancer pain.

RESULTS

Patients experienced 90% to 100% initial pain relief, with 50% to 100% sustained pain relief at the time of death at 2 to 12 months. There were no complications.

CONCLUSION

Portable flat-panel fluoroscopy allows high-resolution, readily updated computed tomography and fluoroscopic image guidance during PRFC. Use of this new technology may assist neurosurgeons in providing an important analgesic intervention at centers possessing the imaging technology.

Percutaneous cervical cordotomy for the management of pain from cancer: a prospective review of 45 cases

BACKGROUND

Percutaneous cervical cordotomy (PCC) is a well recognized but infrequently performed procedure for the relief of unilateral intractable pain from malignancy. There is a paucity of data regarding efficacy and safety of PCC.

OBJECTIVES

The study's objectives were to demonstrate the efficacy and safety of PCC in cancer pain.

DESIGN

The study was a prospective review of 45 cases undergoing PCC at a tertiary referral center over a three-year period.

SETTINGS/SUBJECTS

All patients were suffering from severe, refractory unilateral pain secondary to malignancy with poor pain relief or intolerable side effects of conventional analgesics including opioids and adjuvants.

MEASUREMENTS

Variables recorded preprocedure, at 2 days, and at 28 days postprocedure were numerical rating scale for maximum and average pain, oral morphine equivalent dose, and global impression of change. Adverse events and survival postprocedure were recorded.

RESULTS

Prospective data was obtained in 45 patients. Survival postprocedure ranged from 7 days to 33 months. There was a significant reduction from baseline in pain scores at 2 days and at 28 days postprocedure. Thirty-two patients experienced significant pain relief--average numerical rating scale (NRS) of zero--on day 2. Improvement in pain scores was sustained at 28 days. There were no serious adverse events observed such as respiratory failure.

CONCLUSIONS

PCC is a safe and highly effective procedure to treat intractable unilateral cancer pain. It offers significant advantages over other pain control methods. Patient selection and attention to detail is paramount for a successful outcome.

Renal denervation therapies for refractory hypertension

The treatment of severe hypertension by the surgical obliteration of the renal sympathetic nerves was proposed almost 80 years ago. This approach, although highly effective in reducing blood pressure was associated with a significant amount of side effects and it was rapidly replaced by better tolerated medical therapy. The rapid progress in catheter based technologies occurring within the last 20 years facilitated the development of the first radio frequency renal artery denervation catheter. At the present time, several small trials have demonstrated the safety and efficacy of this approach among patients with refractory hypertension. Besides its effect on reducing blood pressure, other pleiotropic effects (ie, improving glycemia in diabetic patients) have been proposed. In this review, we discuss the anatomical and physiological rationale for this therapy, provide an update on the latest clinical data available and describe additional emerging technologies in this field.

Cutaneous nerve transection for the management of intractable upper extremity pain caused by invasive squamous cell carcinoma

A recurrent clinical dilemma in the management of patients with painful metastatic lesions is achieving a balance between effective analgesic therapies versus intolerable side effects, in particular altered mental status. We present the case of an immunosuppressed patient post-lung transplant who was suffering from intractable pain caused by widely metastatic squamous cell carcinoma. The patient's progressive, excruciating neuropathic pain was localized to the area of the left wrist and forearm. Additionally, the patient complained of moderate pain at sites of tumor involvement on her right arm and scalp. Attempts to adequately manage her left upper extremity pain included a combination of pharmacologic treatments intended to treat neuropathic pain (gabapentin, SNRI, ketamine, opioids) and focused regional analgesia (infraclavicular infusion of local anesthetic). However, the patient developed intolerable side effects including altered mental status and delirium associated with the systemic agents and suboptimal control with the infraclavicular infusion. Given that the most severe pain was well localized, we undertook a diagnostic block of the cutaneous nerves of the left forearm. As this intervention significantly reduced her pain, we subsequently performed neurectomies to the left superficial radial nerve, lateral cutaneous nerve of the forearm and the posterior cutaneous nerve of the forearm. This resulted in immediate and continued relief of her left upper extremity pain without an altered mental status. Residual focal pain from lesions over her right arm and scalp was successfully managed with daily topical applications of lidocaine and capsaicin cream. Successful pain control continued until the patient's death five months later.

Destructive procedures for control of cancer pain: the case for cordotomy

Object

Historically, destructive procedures for cancer pain were the main line of treatment therapy. However, the use of high-dose opioids has essentially replaced such procedures. Recognition of the limits of medical therapy to treat cancer pain effectively is growing, while conversely, in regions with limited access to pain medications, the importance of destructive surgical techniques is increasing. A critical evaluation of the evidence for destructive techniques is warranted, and the authors review current evidence underlying these procedures.

Methods

A US National Library of Medicine PubMed search for “ablation,” “DREZ,” “dorsal root entry zone,” “cingulotomy,” “cordotomy,” “ganglionectomy,” “mesencephalotomy,” “myelotomy,” “neurotomy,” “neurectomy,” “rhizotomy,” “sympathectomy,” “thalamotomy,” “tractotomy,” and “pain” was undertaken. The search was then limited to human studies, English-language literature, cancer pain, and reports with more than 1 patient.

Results

One hundred twenty papers were identified and reviewed based on the selection criteria described. According to the Canadian and US task forces, classification of clinical research literature only “sympathectomy” was supported by Class I or II studies, with 2 Class I papers and 1 Class II paper identified for cancer pain. All other procedures were supported by Class III studies of variable quality. Cordotomy in particular was the most extensively studied and reviewed procedure. Given the large number of patients studied, consistent results, multiplicity of reports and, even though evidence quality for individual studies was relatively low, cumulative evidence suggests that cordotomy may play an important role in the treatment of cancer pain.

Conclusions

Destructive procedures for cancer pain may play more than a historic role in the management of cancer pain. Cumulative evidence from even the poorest quality studies suggests that some procedures, such as cordotomy, should be included in the armamentarium available to the neurosurgeon today. To renew appropriate interest in these procedures, evidence and studies that meets today's evidence-based research criteria are warranted.

The contribution of neuroimaging techniques to the understanding of supraspinal pain circuits: implications for orofacial pain

The aim of this article was to give an overview of the current knowledge of supraspinal pain mechanisms derived from neuroimaging studies, and to present data related to chronic orofacial pain disorders. The available studies implied that the anterior cingulate cortex plays a role in the emotional-affective component of pain, as well as in pain-related attention and anxiety. The somatosensory cortices may be involved in encoding spatial, temporal, and intensity aspects of noxious input. The insula may mediate both affective and sensory-discriminative aspects of the pain experience. The thalamus appears to be a multifunctional relay system. The prefrontal cortex has been implied in the pain-related attention processing; it does not have intensity encoding properties. Chronic pain conditions were associated with increased activity in the somatosensory cortices, anterior cingulate cortex, and the prefrontal cortex, and with decreased activity in the thalamus. Few neuroimaging studies used experimental stimuli to the trigeminal system or included orofacial pain patients. However, the available studies appeared to be in agreement with those using stimuli to other body parts and those concerning other chronic pain conditions. Overall, the available data suggest that chronic (orofacial) pain states may be related to a dysfunctional brain network and may involve a compromised descending inhibitory control system. The somatosensory cortices, anterior cingulate cortex, thalamus, and prefrontal cortex may play a vital role in the pathophysiology of chronic pain and should be the main focus of future neuroimaging studies in chronic pain patients.

Can Direct Spinal Cord Injury Occur Without Paresthesia? A Report of Delayed Spinal Cord Injury After Epidural Placement in an Awake Patient

We discuss the etiology of a delayed spinal cord injury after epidural anesthesia without paresthesia. The description of such a case in an awake, adult patient who underwent a Whipple resection is provided. An epidural was performed at approximately the T8-9 interspace with the patient in the sitting position after 1 mg of midazolam was administered. On the first attempt, a dural puncture occurred. The patient did not report any paresthesia or pain. The needle was withdrawn and a second attempt was made one interspace lower. At this level, the epidural catheter was advanced into the epidural space uneventfully. Postoperatively, the patient suffered decreased motor function in the right leg. Magnetic resonance imaging revealed high signal intensity within the spinal cord, indicating cord edema compatible with direct needle trauma. An extradural fluid collection consistent with a hematoma was also noted. Although it may be impossible to confirm if the spinal cord injury was a result of direct needle trauma, hematoma, or a combination of needle trauma and hematoma, these events clearly raise the important question of whether an awake patient will always report paresthesia secondary to spinal cord trauma.

IMPLICATIONS

This case reminds anesthesiologists that we should not simply assume paresthesia will always occur and be reported if a needle encroaches on the spinal cord even in an awake patient.

Representation of Somatosensory Modalities in Pathways Ascending from the Spinal Anterolateral Funiculus to the Thalamus Demonstrated by Lesions in Man

Patients with cordotomies (16), and brainstem (17) or thalamic (30) infarcts, all except cordotomies verified by magnetic resonance imaging (MRI), have been subjected to quantitative sensory perception threshold testing (QST) for touch (von Frey), mechanical pain, sharpness, innocuous warmth and cold, and heat pain in the maximally affected body area and its unaffected contralateral mirror image region. Some patients were tested twice at widely spaced time intervals; no qualitative differences were found. Results show that all modalities are dissociable from one another by lesions at all levels tested, so that there must be separable representation for each of the six modalities tested. In the lower (crossed symptoms and signs), but not the upper (uncrossed symptoms), deficits for all modalities (except for touch) were more marked than at higher levels. At the level of the thalamus, deficits for innocuous and noxious thermal modalities but not for mechanical pain were recorded in the case of lesions of the principal somatosensory relay nucleus (VPL/Vc), while more medial thalamic lesions resulted in deficits for mechanical pain but not for heat pain or innocuous thermal modalities; there is a marked deficit for sharpness caused by lesions at both thalamic sites.

The management of neuropathic pain

Although the definitive treatment for neuropathic pain remains elusive, scientific investigation continues to provide the field with better and better therapies. As our understanding of the neurophysiologic mechanisms of pain improves, pharmaceutic therapies have become more effective even as side effects are minimized. Surgical therapies have become more precise and less invasive. Advances in neurophysiology have given rise to new advances in the field of neuro-modulation. As this therapy continues to emerge, ablative procedures recede as therapies offering minimal invasiveness, reversible mechanisms, and long-standing relief emerge to the forefront of treatment for neuropathic pain.

Ablative procedures for chronic pain

The advent of neuroaugmentative techniques has reduced the application of neuroablative procedures, especially as regards pain of functional origin. Although intracranial ablative procedures are now rarely performed, spinal ablative procedures, such as anterolateral cordotomies or midline myelotomies, remain important in the management of cancer pain. These procedures produce immediate and satisfactory pain relief with acceptable complication rates. An important future trend will be the application of radiosurgery guided by functional imaging (eg,fMRI, PET) to place such intracranial lesions as cingulotomies or medial thalamotomies.

The surgical treatment of chronic pain: destructive therapies in the spinal cord

Stereotactic pain surgery is accepted as a group of procedures. These are usually highly sophisticated and technically risky procedures. In practice, the most important part of this discipline is not the technical abilities of the surgeon, but selection of the most appropriate patients for the available procedures. We must remember that we are performing all these procedures with the cooperation of patients. The energy that is used for lesioning can be stopped when desired. The target we want to approach can be definitely and anatomically visualized and demonstrated, and the function of the target is evaluated with neurophysiologic impedance techniques and stimulation. Thus, if we are able to understand the language of the central nervous system, these are available, effective, and safe procedures in neurosurgical practice. We must remember that if intractable pain can be controlled by minimally invasive destructive techniques, the patients will not be dependent on implantable systems, drugs,and medical units. This independent lifestyle is a critical goal central to quality of life for patients having intractable pain.

Association of spinothalamic lamina I neurons and their ascending axons with calbindin-immunoreactivity in monkey and human

The calbindin-immunoreactivity of spinothalamic (STT) lamina I neurons and their ascending axons was examined in two experiments. In the first experiment, lamina I STT neurons in macaque monkeys were double-labeled for calbindin and for retrogradely transported WGA*HRP following large (n=2) or small (n=1) injections that included the posterior thalamus. Most, but not all (78%) of the contralateral retrogradely labeled lamina I STT cells were positive for calbindin. Calbindin-immunoreactivity was not selectively associated with any particular anatomical type of lamina I STT cell; 82% of the fusiform cells, 78% of the pyramidal cells and 67% of the multipolar cells were double-labeled. In the second experiment, oblique transverse sections from upper cervical spinal segments of three macaque monkeys, one squirrel monkey and five humans were stained for calbindin-immunoreactivity. In each case, a distinct bundle of fibers was densely stained in the middle of the lateral funiculus. This matches the location of anterogradely labeled ascending lamina I axons observed in prior work in cats and monkeys, and it matches the location of the classically described 'lateral spinothalamic tract' in humans. This bundle had variable shape across cases, an observation that might have clinical significance. These findings support the view that lamina I STT neurons are involved in spinal cordotomies that reduce pain, temperature and itch sensations.

Neurosurgical approaches to pain treatment

In a multidisciplinary approach to the management of chronic pain, neurosurgical methods are an indispensable part of the therapeutic armamentarium. With the exception of percutaneous interventions for trigeminal neuralgia and facet joint syndromes, most ablative pain surgery procedures (neurotomy, rhizotomy, sympathectomy, etc.) have been replaced by neuromodulatory approaches such as electrical stimulation of the central nervous system (CNS). However, cordotomy is still a valuable operation for certain forms of cancer related pains (Pancoast's syndrome, breakthrough pain) which are relatively resistant to pharmacotherapy. Another example of ablative surgery is the dorsal root entry zone (DREZ) operation, which is generally the only treatment option for pain due to root avulsion and segmental pain in spinal cord injury. Spinal cord stimulation (SCS) has proven to be most useful for the management of pain following peripheral nerve injury (including complex regional pain syndromes) and rhizopathy. For these conditions which are otherwise often therapy resistant, SCS may produce substantial and long-lasting pain relief in 60-70% of the patients. Considering that such pains are common and the fact that SCS has been shown to be cost-effective, this treatment is no doubt at present underused. Complications and side-effects are very rare. SCS has also been found to be useful for pain in peripheral vascular disorders and angina pectoris. In the latter condition the overall results are favorable in about 80% of patients with a significant reduction of the frequency and severity of angina attacks and the need for nitrates. Stimulation of the motor cortex is a novel and promising treatment of central, post-stroke pain and painful trigeminal neuropathy.

New pain following cordotomy: clinical features, mechanisms, and clinical importance

OBJECT

The clinical features, possible causes, and contributing factors associated with novel spontaneous pain following unilateral cordotomy were investigated to clarify the mechanism and clinical importance of this pain.

METHODS

Forty-five patients who underwent cordotomy for severe unilateral cancer pain were included in this study. New pain occurred in 33 (73.3%) of 45 patients. Pathological conditions of tissue demonstrated on imaging corresponded to new pain in eight patients, referred pain in five, and neither of these in 15 patients. New pain was centered opposite the site of the original pain in a mirror-image location in 28 patients and rostral to the original pain in five patients. It was temporary in seven patients, weaker than the original pain in 25, and as severe as the original pain in one patient. The incidence of moderate or severe pain was significantly higher in patients with confirmed tissue disease (six of eight patients) than in those without (six of 20 patients). An important contributing factor to the occurrence of new pain was the achievement of analgesia by performing the cordotomy.

CONCLUSIONS

The present results indicate that new pain occurs frequently after unilateral cordotomy. Nonetheless, cordotomy may still be indicated for unilateral uncontrollable pain because new pain, when present, was weaker and more easily controlled than the original pain in nearly all cases. The authors speculate that new pain may represent a type of referred pain from the original painful area or may arise from sensitization of contralateral spinal nociceptive circuits due to metastasis or tumor infiltration, and that new pain is potentiated by the interruption of descending inhibitory pathways.

Percutaneous chordotomy for managing cancer pain

Pain is a problem frequently encountered by patients with cancer. For more than 30 years, the percutaneous chordotomy procedure has been a nonpharmacological approach to the management of intractable cancer pain. Nursing care of patients before, during, and after the percutaneous chordotomy procedure is challenging. Patients and their family members need to be educated about the intent and outcomes of the procedure, as well as its complications. The purpose of this article is to review the theoretical aspect of pain perception and outline the anatomical background and basic steps of the percutaneous chordotomy procedure. Preoperative patient education and preparation, intraoperative nursing interventions, and postoperative patient care are discussed.

Position of spinothalamic tract axons in upper cervical spinal cord of monkeys

Percutaneous upper cervical cordotomy continues to be performed on patients suffering from several types of severe chronic pain. It is believed that the operation is effective because it cuts the spinothalamic tract (STT), a primary pathway carrying nociceptive information from the spinal cord to the brain in humans. In recent years, there has been controversy regarding the location of STT axons within the spinal cord. The aim of this study was to determine the locations of STT axons within the spinal cord white matter of C2 segment in monkeys using methods of antidromic activation. Twenty lumbar STT cells were isolated. Eleven were classified as wide dynamic range neurons, six as high-threshold cells, and three as low-threshold cells. Eleven STT neurons were recorded in the deep dorsal horn and nine in superficial dorsal horn. The axons of the examined neurons were located at antidromic low-threshold points (<30 microA) within the contralateral lateral funiculus of C2. All low-threshold points were located ventral to the denticulate ligament, within the lateral half of the ventral lateral funiculus (VLF). None were found in the dorsal half of the lateral funiculus. The present findings support our previous suggestion that STT axons migrate ventrally as they ascend the length of the spinal cord. Also, the present findings indicate that surgical cordotomies that interrupt the VLF in C2 likely disrupt the entire lumbar STT.

Locations of spinothalamic tract axons in cervical and thoracic spinal cord white matter in monkeys

The spinothalamic tract (STT) is the primary pathway carrying nociceptive information from the spinal cord to the brain in humans. The aim of this study was to understand better the organization of STT axons within the spinal cord white matter of monkeys. The location of STT axons was determined using method of antidromic activation. Twenty-six lumbar STT cells were isolated. Nineteen were classified as wide dynamic range neurons and seven as high-threshold cells. Fifteen STT neurons were recorded in the deep dorsal horn (DDH) and 11 in superficial dorsal horn (SDH). The axons of 26 STT neurons were located at 73 low-threshold points (<30 microA) within the lateral funiculus from T(9) to C(6). STT neurons in the SDH were activated from 33 low-threshold points, neurons in the DDH from 40 low-threshold points. In lower thoracic segments, SDH neurons were antidromically activated from low-threshold points at the dorsal-ventral level of the denticulate ligament. Neurons in the DDH were activated from points located slightly ventral, within the ventral lateral funiculus. At higher segmental levels, axons from SDH neurons continued in a position dorsal to those of neurons in the DDH. However, axons from neurons in both areas of the gray matter were activated from points located in more ventral positions within the lateral funiculus. Unlike the suggestions in several previous reports, the present findings indicate that STT axons originating in the lumbar cord shift into increasingly ventral positions as they ascend the length of the spinal cord.

Percutaneous cervical cordotomy for the control of pain in patients with pleural mesothelioma

BACKGROUND

Severe chest pain is common in mesothelioma. Percutaneous cervical cordotomy, which interrupts the spinothalamic tract at the C1/C2 level causing contralateral loss of pain sensation, is particularly appropriate in mesothelioma as the tumour is unilateral and systemic analgesia may be ineffective and is limited by harmful side effects.

METHOD

A retrospective review was performed to determine the effectiveness and complication rate of this procedure.

RESULTS

Fifty two patients were using opioids prior to cordotomy. The median daily dose of morphine before and after cordotomy was 100 mg (range 0-1000 mg) and 20 mg (range 0-520 mg), respectively (p < 0.001). Forty three patients (83%) had a reduction in pain such that their dose of opioid could be at least halved. Twenty patients (38%) were able to stop completely. Recurrence of pain requiring an increase in opioid medication was recorded in 18 patients at a median time of nine weeks (range 0.7-26 weeks). Four patients developed mild weakness, two had troublesome dysaesthesia. The median time from cordotomy to death was 13 weeks (range 0.3-52 weeks). Six early deaths within two weeks of cordotomy occurred early in the series and reflect postoperative chest infection and poor selection as the patients were in the terminal stages of mesothelioma.

CONCLUSIONS

Percutaneous cervical cordotomy is successful in treating pain from mesothelioma. There was a low complication rate in this series. Referral to a unit experienced in cordotomy is recommended as soon as pain from chest wall invasion is suspected.

Trigeminal neuralgia: a quantitative sensory perception threshold study in patients who had not undergone previous invasive procedures

The authors investigated 28 patients with "idiopathic" trigeminal neuralgia who had undergone no previous invasive procedures; together these patients had a total of 50 affected trigeminal divisions. Quantitative sensory perception thresholds were measured before operation. Preoperative measurements in the affected divisions indicated raised thresholds for touch (von Frey filaments) and temperature, but not for pinprick or heat pain, in agreement with the findings of Nurmikko. Only the tactile threshold was also significantly affected in the unaffected divisions on the affected side. The authors discuss their findings in relation to the pathophysiology of trigeminal neuralgia, concluding that the origin of the condition is almost certainly central to the gasserian ganglion.

The medullary subnucleus reticularis dorsalis (SRD) as a key link in both the transmission and modulation of pain signals

The involvement of the dorsal part of the caudal medulla in both the transmission and modulation of pain is supported by recent electrophysiological and anatomical data. In this review, we analyse the features of a well-delimited area within the caudal-most aspect of the medulla, the subnucleus reticularis dorsalis (SRD) which plays a specific role in processing cutaneous and visceral nociceptive inputs. From a general viewpoint, the reciprocal connections between the caudal medulla and spinal cord suggest that this area is an important link in feedback loops which regulate spinal outflow. Moreover, the existence of SRD-thalamic connections put a new light on the role of spino-reticulo-thalamic circuits in pain transmission.

Central pain: clinical and physiological characteristics

OBJECTIVES

To study the clinical and pathophysiological features of central pain due to damage to the CNS.

METHODS

156 patients (mostly with ischaemic strokes, some with infarct after subarachnoid haemorrhage and other cerebral conditions; one with bulbar and others with spinal pathology) with central pain have been investigated clinically and varying numbers instrumentally with respect to quantitative somatosensory perception thresholds and autonomic function.

RESULTS

Pain onset was immediate in a minority; and from a week or two up to six years in > 60%. For those with supraspinal ischaemic lesions, the median age of onset was 59; dominant and non-dominant sides were equally affected. Two thirds of the patients had allodynia, including a previously undescribed movement allodynia apparently triggered from group I afferents. Most patients exhibited autonomic instability in that their pain was increased by physical and emotional stress and alleviated by relaxation; cutaneous blood flow and sweating may also be affected. Pain occurred within a larger area of differential sensory deficit. The critical deficit seems to be for thermal and pinprick sensations, which were more pronounced in areas of greatest than in areas of least pain; whereas low threshold mechanoceptive functions, if affected, did not vary between areas of greatest and least pain. Skinfold pinch (tissue damage) pain thresholds were only slightly affected in supraspinal cases, but greatly increased in patients with spinal lesions; thermal (heat) pain did not show this dissociation.

CONCLUSION

The pathogenetic hypothesis which seems best to fit the findings is that there is up regulation or down regulation of receptors for transmitters, possibly mainly noradrenergic, over time.