Interventional pain management is defined as ‘the discipline of medicine devoted to the diagnosis and treatment of pain and related disorders by the application of interventional techniques in managing subacute, chronic, persistent and intractable pain, independently or in conjunction with other modalities of treatments.’1 The treatment of chronic pain has undergone a revolution in the past 25 years.2–4 The development and further refinement of new technology and devices, coupled with an improved understanding of the pathologic processes associated with musculoskeletal degeneration and pain mechanisms, has led to the definition and implementation of new interventions for patients with spinal pain conditions (Table 1).4,5 Evidence-based recommendations have been developed based on available data, but more randomised clinical trials, long-term studies and head-to-head comparisons among different interventional and noninterventional treatments are needed.4,5
Limitations of surgery and conservative approaches
In recent years, we have witnessed controversies around spinal surgery for the treatment of spinal pain, usually focused on the use of spinal fusion for the large proportion of patients, a small but non-negligible percentage of patients have unsatisfactory results with surgery and present a complex problem.6
Conservative treatment of chronic pain has often included the use of opioids as a part of the pharmacological approach. The many drawbacks of inappropriate chronic opioid use for chronic non-malignant conditions have recently become apparent, such as dependence, addiction, chronic unwanted effects and the phenomenon of opioid-induced hyperalgesia.7,8
Lumbar discogram showing dispersion of contrast agent consistent with annular degeneration at L3/4 and L4/5. Discography is a valuable diagnostic tool in cases of discogenic pain
©Living Art Enterprises/SciencePhotoLibrary
Diagnostic interventional procedures
Based on medical history, physical examination, imaging and nerve conduction studies in non-radicular pain, a specific cause of pain may be identified in only approximately 15% of spinal pain patients.9 However, through the use of controlled diagnostic interventional techniques, a diagnosis may be achieved in 85% of patients.5 Various diagnostic techniques with proven accuracy include diagnostic facet joint nerve blocks,5 sacroiliac joint injections,10 selective nerve root injections9 and provocation discography.9
Discography used as a diagnostic technique can predict, to a great extent, the relief of discogenic pain because this method can reproduce the original pain and allow visualisation of the pathology of the disc, thus enabling the appropriate determination of treatment.
Injection of local anaesthetics in the autonomous nervous system (sphenopalatine, cervical, thoracic, lumbar, hypogastric or coccygeal) can help to establish the diagnosis of sympathetically maintained pain and it has prognostic value. Blockade of peripheral nerves with local anaesthetics can also help to elucidate the cause of pain and to predict the response to further interventions.11
Therapeutic interventional procedures
Patients with chronic pain disorders may improve with short-term rest, supported self management, physical therapy and temporary pharmacological control of symptoms.12 However, for patients in whom this conservative regimen fails, the use of interventional therapies can be effective.3 Surgery is usually performed in patients with refractory symptoms.
Craniofacial pain syndromes unresponsive to conservative treatments can be a challenge for many experienced neurologists and pain specialists. Trigeminal neuralgia can be successfully treated with percutaneous radiofrequency thermocoagulation of the Gasserian ganglion.13 Other treatment modalities include percutaneous retrogasserian glycerol injection and percutaneous balloon compression of the Gasserian ganglion. Procedures directed to the sphenopalatine ganglion such as sphenopalatine block and pulsed radiofrequency (PRF) treatment14 are usually employed in cluster headache and other vascular headaches, as well as refractory migraine, sphenopalatine neuralgia and atypical facial pain. Other interventional procedures in the craniofacial region include glossopharyngeal nerve PRF treatment for glossopharyngeal neuralgia, PRF of trigeminal nerve branches and treatment of occipital neuralgia with procedures targeting the C2 dorsal root ganglion and C2 and C3 medial branch, as well as C1-C2 joint injection and/or PRF.13
The aetiopathogenic diagnosis of chronic spinal pain is essential to establish an appropriate indication with regard to an invasive procedure. Patients who have pain predominantly originating from the posterior compartment of the spine (zygapophyseal joints) can benefit from posterior facet blocks or radiofrequency thermocoagulation of the medial branch of the posterior nerve. If the sacroiliac joints are the source of the problem, sacroiliac injection and several modalities of sacroiliac denervation are available as well as various percutaneous fusion modalities, which have recently been introduced.
Radicular pain can be successfully treated with epidural injections of corticosteroids and local anaesthetics. PRF treatment of the dorsal root ganglion may provide relief.15 PRF of the dorsal root ganglion of C2 can be performed, should occipital neuralgia and cervicogenic headache be present.14
The intervertebral disc has been described as a source of chronic low back pain and discogenic pain accounts for 39% of patients complaining of low back pain.5,16 Conservative therapeutic approaches are usually unsuccessful in this group of patients and several percutaneous intradiscal procedures are available. Techniques that involve heating discal tissue are used when discogenic pain is predominant over pain radiating to the extremities. Devices such as IDET and Disctrode were designed to provide denervation of the outer annulus fibrosus, when fissures and nerve ingrowth is presumed. Due to safety issues and a poor evidence base, other techniques have been developed such as transforaminal radiofrequency annuloplasty, cooled radiofrequency technology and directional field radiofrequency. Percutaneous disc decompression is indicated in the presence of a herniated disc. It can be achieved by a number of minimally invasive techniques.
Lumbar and cervical spinal stenoses are a manifestation of end-stage spinal degenerative processes. Surgery is not always effective and has inherent complications and risks. Techniques such as epidurolysis or lysis of adhesions (Racz’s technique), through the insertion of a specially designed steerable catheter, can provide some success, preventing patients undergoing unnecessary surgeries. Also, the so-called failed back surgery syndrome, often due to the presence of epidural fibrosis or adhesions, can be treated with adhesiolysis.
Vertebral augmentation techniques, such as vertebroplasty or kyphoplasty, are indicated in patients with painful acute or subacute vertebral fractures.
Percutaneous access to autonomous nervous systems provides an opportunity to treat painful conditions that would otherwise be very resistant to treatment. Patients with complex regional pain syndrome (CRPS) type I and II can be treated with percutaneous sympathetic blocks to the cervicothoracic chain or the lumbar sympathetic chain.4 If the anaesthetic blocks are helpful, percutaneous sympatholysis is used by some authors in order to achieve a prolonged analgesic effect. Interstitial cystitis and other pelvic pain syndromes can be treated with procedures directed to the superior hypogastric plexus and neurolysis.11
Many cancer pain syndromes can be managed through interventional pain techniques, such as splanchnic nerve radiofrequency ablation or coeliac plexus block and neurolysis.
Spinal infusion of drugs is an established technique of interventional pain medicine.17 It is indicated in the presence of severe disabling pain when pharmacological treatment and other approaches fail to provide relief, or in the presence of unbearable and/or unwanted effects of analgesic medication. Spinal infusion can be epidural or intrathecal. Implantable programmable infusion pumps are now widely used for several pain conditions as well as for spasticity of central nervous system origin. Several types of medication can be used for infusion, namely opioids (morphine or hydromorphone), bupivacaine, baclofen, clonidine or ziconotide, among others.
Spinal cord stimulation (SCS) represents a great advancement in the treatment of refractory chronic pain conditions, such as spinal pain radiating to the extremities that can occur after surgery, CRPS, painful ischaemic diseases of the extremities, neuropathic pain syndromes and others. However, it is important to carefully select those patents who may do well receiving this therapy. Recent developments such as high-frequency SCS and burst SCS are capable of relieving pain, including axial pain, more effectively and without producing paraesthesia, resulting in better comfort for patients.
Contemporary societies have redefined patients’ needs in pain management, and as a consequence, there is an ongoing search for innovative techniques and devices that provide increased effectiveness and reduce approach-related morbidity by sparing normal anatomic spinal structures. Invasive pain management is associated with risks and not all patients will respond well. Successful management may require an overlapping of two disciplines, namely interventional pain management and minimally invasive spinal surgery. This is an ever-growing field of investigation and evidence-based medicine, through systematic reviews and meta-analysis, will allow the most appropriate algorithms of clinical practice to be established.
- Dr Carmen Pichot and Professor Ricardo Ruiz-López are from Clinica Vertebra – Barcelona Spine & Pain Surgery Center, Barcelona, Spain
Date of preparation: May 2015. Item code: MINT/PAEU-15001a