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

Review of the Treatments for Central Neuropathic Pain

Central neuropathic pain (CNP) affects millions worldwide, with an estimated prevalence of around 10% globally. Although there are a wide variety of treatment options available, due to the complex and multidimensional nature in which CNP arises and presents symptomatically, many patients still experience painful symptoms. Pharmaceutical, surgical, non-invasive, cognitive and combination treatment options offer a generalized starting point for alleviating symptoms; however, a more customized approach may provide greater benefit. Here, we comment on the current treatment options that exist for CNP and further suggest the need for additional research regarding the use of biomarkers to help individualize treatment options for patients.

Ablation Procedures

Although ablation has a limited role in the management of chronic noncancer pain, ablation continues to help patients with treatment of refractory cancer-related pain. Interdisciplinary treatment involving supportive care, pain medicine, oncology, and neurosurgery is critical to optimizing the timing and outcome of neurosurgical ablative options for pain management. In this review, 3 targets for ablative surgery-the spinothalamic tract, the dorsal column's visceral pain pathway, and the anterior cingulate cortex-are discussed with a focus on patient selection and key aspects of surgical technique.

Dorsal root entry zone procedure and other surgeries for pain

Pain is a very common symptom that often serves a protective function. It is typically treated medically. When pain becomes chronic and intractable, it no longer serves a protective function and often requires more aggressive forms of treatment. Many types of surgeries can be performed for the management of pain. These surgeries can involve ablation (destruction) or augmentation (stimulation or facilitation) of some part of the nervous system. In many of these surgeries, neurophysiologic intraoperative monitoring (NIOM) is not needed, however, in others neuromonitoring serves a mapping and monitoring purpose. The prototype of pain surgery for this chapter is the dorsal root entry zone (DREZ) procedure. Both mapping and monitoring can help improve lesioning precision and outcomes in this surgery. In this chapter, the DREZ procedures and other surgeries for primarily pain relief in which NIOM is used are discussed. Surgeries, such as spinal stenosis, in which pain relief is important but not the sole purpose, are not discussed here and are covered elsewhere.

Intrathecal Baclofen Monotherapy and Polyanalgesia for Treating Chronic Pain in Patients with Severe Spasticity

PURPOSE OF REVIEW

Intrathecal drug delivery is a well evidenced strategy for the treatment of many chronic pain syndromes. While opioids, anesthetics, and ziconotide are the most commonly used agents, intrathecal baclofen (ITB), which is indicated to treat spasticity, is also thought to have some analgesic properties that are poorly understood. These analgesic benefits have been reported with ITB use in treating patients with central neurological disorders who suffer from severe spasticity and chronic pain. Our review aims to characterize ITB's effects on pain, function, and quality of life in patients with severe spasticity. We performed a systematic review based on the Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) guidelines. The primary outcome parameters were analgesic relief and functional improvements. Secondarily, quality of life and adverse effects were also recorded.

RECENT FINDINGS

After an initial survey identified 393 studies, 20 studies met final inclusion criteria. Of these, 16 utilized ITB monotherapy and 4 utilized ITB polyanalgesia. Overall, there was a paucity of high-powered studies. Mean titrated ITB doses ranged from 140 to 627.9 μg daily. Nineteen studies reported improved pain and spasticity. Seven studies reported improved functional outcomes and quality of life. Our results show that ITB may be an effective agent in treatingfor the treatment of chronic pain in patients with severe spasticity independent of its spasmolytic effects. Although this evidence was largely derived from studies lacking clearly defined outcomes of pain relief, ITB is reasonable to consider for concurrent spasticity and pain management. Well-designed studies are still needed to characterize ITB's analgesic efficacy when used in patients with severe spasticity.

Focused Ultrasound (FUS) for Chronic Pain Management: Approved and Potential Applications

Chronic pain is one of the leading causes of disability and disease burden worldwide, accounting for a prevalence between 6.9% and 10% in the general population. Pharmacotherapy alone results ineffective in about 70-60% of patients in terms of a satisfactory degree of pain relief. Focused ultrasound is a promising tool for chronic pain management, being approved for thalamotomy in chronic neuropathic pain and for bone metastases-related pain treatment. FUS is a noninvasive technique for neuromodulation and for tissue ablation that can be applied to several tissues. Transcranial FUS (tFUS) can lead to opposite biological effects, depending on stimulation parameters: from reversible neural activity facilitation or suppression (low-intensity, low-frequency ultrasound, LILFUS) to irreversible tissue ablation (high-intensity focused ultrasounds, HIFU). HIFU is approved for thalamotomy in neuropathic pain at the central nervous system level and for the treatment of facet joint osteoarthritis at the peripheral level. Potential applications include HIFU at the spinal cord level for selected cases of refractory chronic neuropathic pain, knee osteoarthritis, sacroiliac joint disease, intervertebral disc nucleolysis, phantom limb, and ablation of peripheral nerves. FUS at nonablative dosage, LILFUS, has potential reversible and tissue-selective effects. FUS applications at nonablative doses currently are at a research stage. The main potential applications include targeted drug and gene delivery through the Blood-Brain Barrier, assessment of pain thresholds and study of pain, and reversible peripheral nerve conduction block. The aim of the present review is to describe the approved and potential applications of the focused ultrasound technology in the field of chronic pain management.

An overview of interventional strategies for the management of oncologic pain

Pain is a ubiquitous part of the cancer experience. Often the presenting symptom of malignancy, pain becomes more prevalent in advanced or metastatic disease and often persists despite curative treatment. Although management of cancer pain improved following publication of the WHO's analgesic ladder, when used in isolation, conservative approaches often fail to control pain and are limited by intolerable side effects. Interventional strategies provide an option for managing cancer pain that remains refractory to pharmacologic therapy. The purpose of this review is to investigate these strategies and discuss the risks and benefits which must be weighed when considering their use. Therapies anticipated to have an increasingly important role in the future of cancer pain management are also discussed.

Early neurological care of patients with spinal cord injury

PURPOSE

Considering the major clinical challenges of managing patients with spinal cord injury (SCI), we summarized the relevant aspects of the early (within 1 year after SCI) neurological care emphasizing common standards.

METHODS

This review was performed according to the methodology recommended by the Joint SIU-ICUD International Consultation. Embase and Medline databases were used to identify literature relevant to the early neurological care of SCI patients. Recommendations were developed by consensus and graded using a modified Oxford system which identifies level of evidence (LOE) and grade of recommendation (GOR).

RESULTS

Emergency health care providers must address altered mental status, evidence of intoxication, suspected extremity fracture/distracting injury, focal neurological deficit and spinal pain/tenderness to determine the risk of SCI in a trauma patient [LOE 1, GOR A]. Neurogenic shock must be recognized and treated [LOE 3, GOR A]. Spine surgeons should consider early decompression and spine fixation/stabilization, where indicated, and should promote early active rehabilitation to improve functional recovery [LOE 2, GOR B]. Clinicians should refer SCI patients to specialized SCI rehabilitation centers [LOE 4, GOR B], must apply interventions to prevent venous thromboembolism (i.e., compression devices and low-molecular weight heparin/unfractionated heparin) after acute SCI respecting contraindications [LOE 1, GOR A]. Contemporary guidelines to manage pain must be employed [LOE 1, GOR A] and methods to reduce the risk of pressure ulcers should be used [LOE 3, GOR B].

CONCLUSIONS

Early treatment, prevention of associated complications and individualized patient-targeted rehabilitation programs provided by a specialized interdisciplinary team are crucial to optimize the outcome after SCI.

Central Neuropathic Pain Syndromes

Chronic pain is common in patients with neurologic complications of a central nervous system insult such as stroke. The pain is most commonly musculoskeletal or related to obligatory overuse of neurologically unaffected limbs. However, neuropathic pain can result directly from the central nervous system injury. Impaired sensory discrimination can make it challenging to differentiate central neuropathic pain from other pain types or spasticity. Central neuropathic pain may also begin months to years after the injury, further obscuring recognition of its association with a past neurologic injury. This review focuses on unique clinical features that help distinguish central neuropathic pain. The most common clinical central pain syndromes-central poststroke pain, multiple sclerosis-related pain, and spinal cord injury-related pain-are reviewed in detail. Recent progress in understanding of the pathogenesis of central neuropathic pain is reviewed, and pharmacological, surgical, and neuromodulatory treatments of this notoriously difficult to treat pain syndrome are discussed.

Microendoscopy-guided percutaneous cordotomy for intractable pain: case series of 24 patients

OBJECTIVE

The aim of this study was to show that microendoscopic guidance using a double-channel technique could be safely applied during percutaneous cordotomy and provides clear real-time visualization of the spinal cord and surrounding structures during the entire procedure.

METHODS

Twenty-four adult patients with intractable cancer pain were treated by microendoscopic-guided percutaneous radiofrequency (RF) cordotomy using the double-channel technique under local anesthesia. A percutaneous lateral puncture was performed initially under fluoroscopy guidance to localize the target. When the subarachnoid space was reached by the guiding cannula, the endoscope was inserted for visualization of the spinal cord and surrounding structures. After target visualization, a second needle was inserted to guide the RF electrode. Cordotomy was performed by a standard RF method.

RESULTS

The microendoscopic double-channel approach provided real-time visualization of the target in 91% of the cases. The other 9% of procedures were performed by the single-channel technique. Significant analgesia was achieved in over 90% of the cases. Two patients had transient ataxia that lasted for a few weeks until total recovery.

CONCLUSIONS

The use of percutaneous microendoscopic cordotomy with the double-channel technique is useful for specific manipulations of the spinal cord. It provides real-time visualization of the RF probe, thereby adding a degree of safety to the procedure.

Dorsal root entry zone lesion, midline myelotomy and anterolateral cordotomy

This review encompasses the most common spinal cord lesioning procedures used for the treatment of pain: dorsal root entry zone lesioning, open cordotomy, percutaneous cordotomy, and midline myelotomy. A literature review and summary of each technique regarding relevant anatomy, patient selection, surgical technique, outcomes, and complications are discussed. A general review of somatic and visceral pain pathways of the spinal cord is included, as each procedure requires an understanding of the advantages and disadvantages of various approaches to lesioning the spinal cord for pain. Neurosurgical education of these rarely used procedures needs to be included in residency and fellowship training.

A palliative care intervention for pain refractory to a percutaneous cordotomy

Background:

Intrathecal analgesia and radiofrequency techniques for tumor ablation are employed for palliation of symptoms. These interventions are efficacious in a select number of patients for controlling pain and improving quality of life. Careful selection of an appropriate candidate must be performed to prevent needless, invasive, and costly interventions, as interventional pain management alone will not treat total pain in cancer patients. We describe here a patient who experienced intractable pain and unsuccessfully underwent cordotomy but responded to the interdisciplinary (IDT) palliative care approach in an acute palliative care unit (APCU).

Case:

A middle-aged female with ovarian cancer metastatic to the left psoas muscle and the supraclavicular and retroperitoneal lymph nodes was admitted with severe left thigh and flank pain. She had been unsuccessfully treated with different opioid regimens, hypogastric nerve block, epidural steroid injection, and cordotomy. The palliative care team was consulted while awaiting placement of an intrathecal pump. The patient was subsequently transferred to the APCU for symptom management and transition to hospice. On admission, her morphine equivalent daily dose (MEDD) was 660 mg. Our IDT—composed of a physician, fellow, nurse practitioner, counselor, chaplain, social worker, and physical and occupational therapists—was able to identify several sources of distress that likely contributed to her expression of pain. Our IDT focused on frequent counseling, improving her function, provided medication education, discussed goals of care, and educated about hospice. She was discharged to hospice care with good pain control and an 85% reduction in her MEDD.

Conclusion:

An APCU approach involving an IDT alleviated the need for invasive interventions by diagnosing and treating the psychosocial, emotional, and spiritual distress contributing to the patient's total pain expression. Successful management must be reflective of rigorous assessment of the physical, psychological, spiritual, social, and practical aspects before consideration of more invasive treatments.

Bilateral open thoracic cordotomy for refractory cancer pain: a neglected technique?

At least 10% of patients with cancer have pain that is refractory to systemic analgesics. For most of these patients, interventional techniques may be of benefit but are often not considered or are difficult to access. Of these techniques, spinal analgesia is most commonly used in Australia and the United Kingdom, and neurosurgical procedures, such as open cordotomy with sectioning of the spinothalamic tract, are rarely used. We describe a case illustrating the successful use of bilateral open thoracic cordotomy in a patient with refractory mixed nociceptive and neuropathic pain secondary to a lumbosacral tumor. We discuss the various interventional options and review the recent literature regarding the use of both percutaneous and open cordotomy for cancer pain.

Computed tomography-guided percutaneous cordotomy for intractable pain in malignancy

OBJECTIVE

Pain, usually a response to tissue damage, is accepted as an unpleasant feeling generating a desire to escape from the causative stimulus. Although, in the early stages of malignant diseases, pain is seen in 5% to 10% of cases, this rate reaches nearly 90% in the terminal stage, and pain becomes a primary symptom. Cordotomy is one of the treatment choices in pain caused by malignancies localized unilaterally to the extremities as well as the thorax and the abdomen.

METHODS

The target of computed tomography (CT)-guided percutaneous cordotomy is the lateral spinothalamic tract located in the anterolateral region of the spinal cord at the C1-C2 level. Between 1987 and 2007, CT-guided percutaneous cordotomies were performed in 207 patients; most (193 patients) suffered from intractable pain related to malignancy. The patients' pain scores and Karnofsky Performance Scale scores were evaluated pre- and postoperatively.

RESULTS

The initial success rate of CT-guided percutaneous cordotomy was 92.5%. The success rate was higher in the malignancy group. In the cancer group, selective cordotomy (pain sensation denervated only in the painful region of the body) was achieved in 83%. In 12 cases, bilateral selective percutaneous cordotomy was successfully applied.

CONCLUSION

In the treatment of intractable pain, CT-guided cordotomy is an option in specially selected cases with malignancy. In this study, anatomic and technical details of the procedure and the experience gained from treating 207 patients over a 20-year period are discussed.

Percutaneous destructive pain procedures on the upper spinal cord and brain stem in cancer pain: CT-guided techniques, indications and results

In the century of science and technology, the average life span has increased, bringing with it an increase in the incidence of degenerative and cancer disease. Intractable pain is usually the main symptom of cancer. With the advancement in technology, there is a large group of patients with intractable pain problems who can benefit from special help medically or surgically. Destructive pain procedures are necessary to control the cancer pain and are based on the lesioning of the pain conducting pathways. Percutaneous cordotomy, trigeminal tractotomy and extralemniscal myelotomy are special methods based on lesioning of the pain conducting pathways. The procedure consists of obtaining direct morphological appearance of the upper spinal cord and surrounding structures by computed tomography (CT). The next step is functional evaluation of the target and its environment by impedance measurement and stimulation. The final step is terminated with controlled lesioning obtained by a radiofrequency system (generator, needles, electrode system). In the last two decades, CT-guided destructive procedures were used as minimally invasive procedures as follows: percutaneous cordotomy (207 patients), trigeminal tractotomy-nucleotomy (65 patients), and extralemniscal myelotomy (16 patients). Most of these patients had cancer pain. Minimally invasive CT-guided destructive pain procedures are still safe and effective operations for relieving intractable cancer pain in selected cases.

Modern concepts of acute and chronic pain management

Both, acute and chronic pain should be treated using appropriate pain management as they may cause several negative reactions and jeopardise the health or at least the quality of life of the patients. Nowadays there are many analgesics and treatment tools available to provide sufficient pain relief for almost all patients. Unfortunately there are still patients suffering from pain due to inadequate or/and inconsequent pain therapy.