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A selective nerve root block is a procedure where a small amount of corticosteroid medication and a local anesthetic agent is injected around a very specific nerve root or spinal nerve that exits out of the spinal cord. The areas of the back where this procedure can be performed include the neck (cervical), mid-back (thoracic), and lower back (lumbar) regions.
An epidural steroid injection is a similar type of treatment for pain caused by conditions such as spinal stenosis and spinal disc herniation.
In a recent study, researchers looked at the selective nerve root block success in patients who had this procedure performed to reduce nerve-related (radicular) pain caused by intervertebral disc prolapse affecting a particular lumbar nerve root.1
The conclusion that was made here is that selective nerve root blocks offer short-term relief of pain caused by conditions such as spinal disc herniation. Mild and moderate pathologies seem to respond well to this treatment, whereas more severe spinal cord conditions affecting the nerves and causing problematic symptoms do better with surgical interventions.
Selective nerve root blocks are safe procedures with minimal side effects caused and even fewer complications. It is a safer procedure than an epidural steroid injection for the fact that the latter has to be performed by injecting through the epidural sac which can lead to complications that wouldn&#;t occur with a selective nerve root block.
All content has been reviewed and approved by orthopedic specialist Dr. Zvezdomir &#;Zed&#; Zamfirov. Dr. Zed&#;s practice &#; All Star Pain Management and Regenerative Medicine &#; proudly serves the Annapolis, Greater Baltimore and Washington D.C. areas. For more, contact Dr. Zed or call 443-808-.
Reference
Lumbar radicular Syndrome (LRS) is a common spinal pathology and is attributed to complex interplay of mechanical, inflammatory and immunological processes. Epidural injection of steroids has a significant therapeutic role in mitigating the inflammatory component of LRS. Trans-foraminal approach under image guidance enables a targeted drug delivery. The current narrative review discusses the various aspects related to lumbar trans-foraminal epidural injection of steroid (LTFIS).
An elaborate search on PubMed, Google and Medline databases was made using keywords &#;lumbar selective nerve root block&#;, &#;lumbar trans-foraminal epidural steroid injection&#;, &#;selective nerve root block in lumbar disc prolapse&#;, &#;trans-foraminal epidural steroid injection in lumbar prolapse&#;, &#;selective nerve root block in lumbar radiculopathy&#;, and &#;trans-foraminal epidural steroid injection in lumbar radiculopathy&#; The articles were selected based on specific inclusion criteria.
Our search identified 539 articles. All articles discussing alternate procedures, LTFIS in other pathologies, diagnostic roles of LTFIS, not pertaining to concerned questions, in non-English language and duplicate articles were excluded. Review articles, randomised controlled trials or level 1 studies were given preference. Overall, 108 articles were included. Being a focussed narrative review, further screening [Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) or Methodological Index for non-randomized studies (MINORS) criteria] was not performed to select articles. Based on the evidence, LTFIS is an effective and useful treatment modality. It is offered to patients with lumbar disc herniation (LDH) presenting with persistent, unilateral, radiculopathy after a course of conservative measures for around 6 weeks&#; duration. It has been reported to yield better results than caudal or inter-laminar epidural injections. The anti-inflammatory and nociceptive signal stabilization actions of steroids, as well as mechanical effects of washout of inflammatory mediators and neural lysis contribute to its efficacy. The three different approaches include sub-pedicular, retro-neural and retro-discal. The procedure is performed under image guidance using a water-soluble contrast under fluoroscopy. The four described radiculogram patterns include &#;arm&#;, &#;arrow&#;, &#;linear&#; and &#;splash&#;. Computerised tomography, ultrasonography and magnetic resonance imaging are other modalities, which may be helpful in performing LTFIS. The use of particulate versus non-particulate steroids is controversial.
The overall success rate of SNRB is reported to be 76&#;88%. The majority of benefits are observed during immediate and early post-injection period. Clinical factors including duration and severity of symptoms, and radiological factors like presence of osteophytes, location, size and type of disc prolapse influence outcomes. The radiculogram &#;splash&#; pattern is associated with poor outcomes.
Keywords:
Lumbosacral radicular syndrome, Selective nerve root block, Trans-foraminal epidural steroid injection, Radiculogram
&#;Lumbosacral Radicular Syndrome&#; (LRS), commonly known as sciatica, is described as a radiating-type of lower extremity pain that follows a specific dermatomal pattern and may be accompanied by sensory or motor deficits.1 Following the landmark description of intervertebral disc (IVD) herniations by Mixter and Barr in , there was a growing perception that mechanical compression of neural elements was the sole etiological factor causing such a manifestation of symptoms.2 Subsequent studies have provided sufficient evidence that the pathophysiology of LRS is not only attributable to pressure over nerve roots, but rather comprises a complex interplay of mechanical, inflammatory and immunological processes.3
Considering that multiple pathophysiological mechanisms underlie LRS, diverse modalities of treatment have been developed over the years.4 Steroids have been demonstrated to have a therapeutic role, owing to their anti-inflammatory and nociceptive signal stabilising properties.5, 6, 7 Lumbar trans-foraminal epidural injection of steroids (LTFIS) or trans-foraminal epidural steroid injection (TFESI) is a technique that enables precise delivery of corticosteroid in close proximity to dorsal root ganglion (DRG) and nerve root under radiological guidance, thereby optimising the therapeutic effect.4,8
The current article broadly discusses various factors related to LTFIS [or selective nerve root block (SNRB), as per the older nomenclature], including different techniques, medications administered, outcome, complications, and current treatment status as compared to other management strategies.
An elaborate search was made using keywords &#;lumbar selective nerve root block&#;, &#;lumbar transforaminal epidural steroid injection&#;, &#;selective nerve root block in lumbar disc prolapse&#;, &#;transforaminal epidural steroid injection in lumbar prolapse&#;, &#;selective nerve root block in lumbar radiculopathy&#;, and &#;transforaminal epidural steroid injection in lumbar radiculopathy&#; on Pubmed, Google and Medline databases. We identified crucial questions regarding LTFIS and included relevant articles pertaining to those subjects for this narrative review.
Our search identified a total of 539 articles. All articles discussing alternate procedures such as, LTFIS in other pathologies (like lumbar stenosis, degenerative scoliosis), diagnostic roles of LTFIS, not pertaining to the concerned questions, in non-English language and duplicate articles were excluded. Review articles, randomised controlled trials, level 1 studies or other large clinical trials were given preference. Overall, 108 articles were included in this review. We did not perform any screening [Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) or Methodological Index for non-randomized studies (MINORS) criteria] for including articles.
With our growing understanding of LRS, it has been well-known in the medical community that biomechanical nerve root compression by a prolapsed disc is not the singular cause for symptoms.9 The two major clinical observations which support this notion include a) on many occasions, there is minimal correlation between inter-vertebral disc (IVD) size and the severity of radiculopathy, and b) significant mitigation of symptoms may occur without concurrent resolution of the disc herniation.10,11 In , Mixter and Ayers12 reported that lumbar radicular pain was possible without significant IVD herniation. Lindahl and Rexed,13 through histopathological evaluation of specimens, demonstrated the causal role of inflammation in IVD-related radiculopathies. As this association between local inflammatory pathology and lumbar radicular pain was substantiated by later studies, targeted corticosteroid delivery modalities have been progressively promulgated as useful treatment options.14,15
Robecchi and Capra14 in reported the first use of peri-radicular hydrocortisone injection around the S1 root as treatment for sciatica. A year later, Lievre et al.15 published successful results in a series of patients treated with peri-radicular corticosteroids for lumbo-sacral radiculopathy. Since then, there has been a growing body of evidence supporting the utility of image-guided SNRB with the injection of steroids or local anesthetic (LA) agents.16, 17, 18 Previous studies have demonstrated superiority of trans-foraminal delivery of corticosteroid over alternate epidural approaches.9,19 ( ) This narrative review comprehensively discusses our current understanding on various aspects of TFESI for management of LRS.
Open in a separate windowThere are no strict guidelines for use of SNRB in lumbar disc herniations (LDH). Riew et al.17 had recommended TFESI in patients with LDH not responding to physical therapy and oral anti-inflammatory medications for more than 6 weeks. Based on a systematic review, DePalma et al.9 recommended a trial of up to four SNRBs prior to considering surgical lumbar discectomy. Nevertheless, these decisions may need to be individualized based on symptom severity and patient profile. It may be reasonable to offer the option of SNRB to all patients presenting with severe radicular pain. Similarly, upon failure of one attempt of SNRB, it may be reasonable to offer the option of surgical intervention in patients remaining symptomatic beyond six to twelve weeks.
Several mechanisms have been suggested to explain the role of corticosteroids in LRS. Firstly, IVD herniations enhance local production of prostaglandins (via phospholipase A2), which leads to inflammation around the dorsal root ganglion and pain.20 Corticosteroids inhibit production of arachidonic acid and thereby block this pain-generating pathway. Secondly, steroids have been shown to curtail ectopic discharges from unmyelinated C-fibres.21,22 Thirdly, steroid administration can also directly relieve central pain sensitization.23, 24, 25 Fourthly, injection of substances (even certain volumes of plain fluids) into the epidural space itself can push the dura forward and inward; and thereby stretch nerve roots. This can consequently result in lysis of neural adhesions, thereby allowing for enhanced pain relief.24,25 Other described mechanisms include cell membrane stabilization, improvement in neuronal blood flow and washing out of various inflammatory mediators including interleukin-1 and tumor necrosis factor.
Three different approaches have been described for trans-foraminal injections: sub-pedicular (SP), retro-neural (RN) and retro-discal (RD) ( ). The most frequently-used approach is the SP technique, which was initially described by Bogduk et al. In this technique, the needle is advanced into a &#;safe triangle&#;, just inferior to the pedicle.26 In the RN approach, the optimal target area is more dorsal to the inter-vertebral (IV) foramen, as compared to the SP approach.27 In the RD approach, the needle is placed in the inferior aspect of the IV foramen, thereby providing the closest access to the nerve root irritated by the prolapsed IVD.28 While certain studies have reported better outcomes with the RD approach,29 other studies have revealed no clear benefit of one approach over another.19,30
Open in a separate windowThe major distinction between these approaches lies on the controversy on whether drug yields better outcome when administered pre- or post-ganglionically. Conventionally, TFESI is administered around the involved nerve root, ie. for a L4-5 paracentral disc herniation with L5 radiculopathy, the drug is administered around the exiting L5 root (L5-S1 neural foramen- SP approach).26 However, it has been suggested that this approach may not deliver drug to the ideal location, i.e, cephalad disc in all situations. Therefore, there has been a suggestion that the pre-ganglionic approach [retro-discal (RD) drug delivery at cephalad disc level] may be necessary in certain situations.28 Lee et al.31 reported that in lumbar radiculopathy with primary impingement at the supra-adjacent IVD level, pre-ganglionic TFESI may yield better short-term outcomes. In a randomised controlled study (RCT) by Jeong et al.32 comparing the effectiveness of pre-ganglionic versus post-ganglionic TFESI, pre-ganglionic drug administration revealed statistically improved short-term therapeutic effects, although outcomes at 6-month follow-up were equivalent. In a retrospective cohort study, Singh et al.33 reported significantly greater improvement in pain and function following 2-level TFESI in para-central or sub-articular DH, thereby ensuring both pre- and post-ganglionic drug delivery. At the senior author&#;s (RMK) institution, a single-level, conventional TFESI (SP approach) is preferred with results comparable to the literature.35
Trans-foraminal injections are performed under image guidance, namely fluoroscopic, ultrasound, CT, or MRI-guided. The latter approaches have been purported to have the specific advantage of reducing radiation exposure to health personnel.
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Author&#;s preferred technique (fluoroscopic SP approach): The patient is positioned prone on a radiolucent table, without sedation. By tilting the image intensifier towards the symptomatic side, an oblique view of the spine is obtained to visualize the &#;Scotty Dog&#; for the L3-4 and L4-5 levels. At L5-S1, the image intensifier is tilted to visualize the sacral foramen as a near-perfect oval. After anesthetizing skin with 5 ml of 2% lignocaine, a 23-gauge (3.5 inch/90 mm) spinal needle is inserted end-on towards the safe triangle. The position of the needle tip is confirmed on antero-posterior (AP) and lateral images, following which 1 ml of contrast solution [iohexol (Omnipaque, GE Healthcare, London, United Kingdom)] is injected. This helps us confirm the needle position at the desired site, as well as rule out intravasation, sub-arachnoid, sub-dural, or intra-discal spread of dye. Radicular pain reproduction is expected and after visualizing a good radiculogram, 2 ml of 0.5% bupivacaine and 80 mg triamcinolone are injected in to the IV foramen. The alternate approach is to just perform AP and lateral c-arm images with the needle tip being placed at the 6 o&#;clock position, immediately below the pedicle.
Types of radiculogram: The term &#;radiculogram&#; describes the pattern of dye distribution on AP imaging after foraminal injection. In , Pfirrmann et al.34 described three different types of contrast flows, based on a cadaveric study. Type 1 radiculogram indicates intra-epineural contrast flow (showing tubular appearance), type 2 radiculogram describes extra-epineural flow (where nerve root is visible as a filling defect) and type 3 denotes para-neural flow (where nerve root is not visualized). Intra-epineural injections are painful, with a high risk of chemical neuritis. During SNRB, dye is preferably injected extra-epineurally.
It has been demonstrated that the spread of dye is proportionate to the volume of injectate. Makkar et al.35 reported that whenever 0.4 ml or more of dye is injected, the selectivity for a particular nerve root reduces to only 51.4%. In the study by Makkar et al.,35 the spread of the dye to the contralateral side was observed in 57.5% of patients. They also observed that superior spread of the dye was more common than an inferior spread.
Kanna et al.36 described four patterns visible on extra-epineural radiculograms, namely &#;arm&#;, &#;arrow&#;, &#;linear&#; and &#;splash&#; ( ). The &#;arm&#; pattern is defined as a thick band of dye distribution around the entire nerve root thickness, the &#;arrow&#; pattern describes dye distribution along the medial border of the root and around the thecal sac, the &#;linear&#; pattern is the flow of dye as a streak along the lateral nerve root border, and the &#;splash&#; pattern implies an irregular distribution of dye. Additionally, lateral imaging to evaluate the ventral spread of dye has also been suggested, which is shown by hugging of the contrast medium over the posterior aspect of contiguous vertebral body.19 This classification is yet to be validated.
Open in a separate windowThe mean fluoroscopy time for TFESI is around 11.43&#;46.6 s.37 Mean radiation for transforaminal injections has been reported to be around 101.7 μGy.m2 (101.7 cGy.cm2).38 The primary aim of radiation management is to ensure &#;as low as reasonably achievable (ALARA)&#;, as endorsed by experts so as to ensure the least possible exposure to patients, practitioners, and all operating room (OR) personnel without compromising on procedural safety. Optimisation of patients&#; radiation dose, shorter fluoroscopy time, use of pulsed fluoroscopy and collimation, increasing distance from source and appropriate utilization of protective equipment (aprons, thyroid shield, glasses and gloves) are all important principles to such an approach.39
Computerised Tomography (CT) is a well-accepted tool for spinal injections.40, 41, 42 Conventional CT with or without contrast, as well as intermittent CT fluoroscopy have been described for performing spinal injections. The main benefits of CT technology include improved accuracy, reduction of complications and enhanced patient comfort. These benefits need to be weighed against the potential drawbacks of higher radiation, as well as non-availability of this infrastructure at all centers. Maino et al.43 compared the effective dose (ED) of CT and fluoroscopic guidance for TFESI. They concluded that there was eight times greater patient exposure to radiation in CT -guided injections as compared with fluoroscopic-guided procedures [1.59 mSv (interquartile range [IQR ] 0.78 to 3.09) vs. 0.19 mSv (IQR 0.11 to 0.30]. The importance of strictly following the principles of ALARA cannot be understated.
Ultrasound-guided spinal procedures have been proposed as possible &#;no-radiation alternatives&#; to conventional fluoroscopy- or CT-guided procedures.44, 45, 46, 47 The ultrasonogram is also well-accessible to most centers world-wide; and the procedure may be performed on both an out- and in-patient basis. Nevertheless, the major criticisms against ultrasound-guided LTFIS include greater difficulty in precise needle localization, as well as high operator dependency. There have been reports of coupling this imaging modality with other modalities (like fluoroscopy plus contrast injection, CT or nerve stimulation) for final confirmation of needle tip position. This can help us gain the dual advantage of maintaining accuracy and reducing radiation exposure.45, 46, 47 Interventional MRI has also been recommended for spinal therapeutic procedures, especially in younger individuals and those requiring serial injections. This technology offers advantages including absence of ionizing radiation, better tissue contrast and feasibility of multi-planar imaging, as compared to conventional fluoroscopy.48,49
Various combinations of medications have been tried for TFESI.50,51 The study by Vad et al.50 comparing fluoroscopic trans-foraminal injections of steroids versus control saline revealed 84% success rates in the former group, as compared with 48% in the latter. In a prospective, randomised study by Ghahreman et al.,51 involving 4 groups, trans-foraminal epidural injections of steroid plus LA, LA-only, normal saline, and intramuscular injections, the first group demonstrated statistically greater pain improvement.
The initial radiculogram is obtained by injection of a water-soluble contrast. The most popular contrast agent is iohexol (usual volume of 0.5&#;3 ml). It is a low-osmolality contrast agent (in contrast to the older, high osmolality agents like diatrizoate) with an osmolality ranging between 322 mOsm/kg and 844 mOsm/kg.52
The total volume of injectate (usually steroid plus LA) has varied between 3 and 9 ml (usually around 4 ml). The popular LA agents include 1&#;2% lidocaine and 0.25&#;0.5% bupivacaine. As previously mentioned, we use a standard cocktail of 2 ml of 0.5% bupivacaine and 80 mg triamcinolone at the senior author&#;s institution.
Steroids: The steroid preparations for use in the epidural space are broadly classified into two groups, namely particulate (methylprednisolone, betamethasone and triamcinolone) and non-particulate (dexamethasone phosphate) agents.35,53
The particulate steroids have a longer duration of action (due to local depot effect causing continuous release of active drug) with slightly improved outcomes.35 On the other hand, the non-particulate agents are water-soluble, smaller sized and subjected to limited particle aggregation. Hence, they are rapidly cleared from the spinal canal and have shorter durations of action.35,53
A comparative study on the relative sizes and properties of various steroid agents was performed by Tiso et al.54 in . Dexamethasone and betamethasone are rod-like and lucent, while particles of methylprednisolone and triamcinolone are opaque and amorphous. The particles of methylpednisolone and triamcinolone tend to coalesce into particles larger than 100 μm. Such particles are capable of occluding capillaries, meta-arterioles and even arteries, resulting in ischemia and infarction. These agents have been reported to be associated with higher incidence of cord infarction secondary to embolic events. In contrast, particles of dexamethasone are smaller than 5 μm, with low density and low propensity for aggregation. No serious neurological complications have so far been reported with the use of dexamethasone in TFESI. Despite this favourable safety profile, routine use of dexamethasone has always been questioned, in view of its limited effectiveness and shorter duration of action.35,53, 54, 55
Two systematic reviews in re-emphasized the relatively poorer safety profile of particulate steroidal agents, with only marginally greater benefit as compared with their non-particulate counterparts.35,53 Both these studies concluded in favour of non-particulate steroidal preparations in lumbar TFESI. At the senior author&#;s (RMK) institution, triamcinolone is employed as the standard agent. We have so far not observed any serious neurological complications with this agent.
The overall success rate of SNRB has been reported to be between 76 and 88%.36,56 Most of the available studies report better outcomes with trans-foraminal delivery of medication as compared to other epidural approaches. The trans-foraminal approach enables drug delivery to the epidural space anterior to nerve root, thereby ensuring enhanced local concentration of drug.57,58 A recent RCT described a para-sagittal inter-laminar epidural approach as an alternate option, with apparently significantly improved outcomes as compared to the traditional inter-laminar midline approach and equivalent outcomes as TFESI.19
Most of the evidence in the literature seems to denote good short-term pain improvement following TFESI. However, over the longer term, the disease tends to take its natural course.59,60 Although it has been shown that steroids can be detectable in tissues for the initial 2&#;3 weeks, therapeutic effects far out-last the presence of measurable quantities of drug.61 In general, there is a strong improvement in pain over the first seven days.58 In the study by Kumar et al.,62 82.5% of patients had improvement by 2 weeks. However, as time since the procedure progressed, pain relief was reduced with only 72.5%, 47.5% and 32.5% of patients showing good relief at the end of one, two and three month follow-up time points, respectively. At the end of 6 months, only 20% remained pain-free and all these patients had mild, unilateral LDH. All patients in this series with a large LDH had poor outcomes.
In , Joswig et al.63 reported favourable one-month outcomes in two-thirds of patients following CT-guided lumbar TFESI. They observed that significant (i.e., improvement in VAS leg pain &#;50%) pain relief at the end of the first week was the most important indicator for pain relief at the end of one month. They suggested that patients with clinically meaningful, but transient, responses could be offered repeat TFESI within 2&#;3 weeks. However, patients with no initial pain relief would rather benefit from alternative treatment modalities. In the series by Dhakal et al.,64 there was a significant reduction in disability scores for the first six months after SNRB, following which the response plateaus off.
In the study by Jang et al.65 involving 50 patients after TFESI, at the end of 5&#;7 years after onset of symptoms, mean numerical rating scale (NRS) score for pain had reduced from 5.1 to 2.4. Around 25% of patients reported complete pain resolution and 60% reported NRS &#;2. 50% of patients received additional doses of TFESI, 8% had already undergone surgery and 16% required some form of regular oral analgesic prescriptions. Considering that therapeutic steroidal effects last no longer than a few days to weeks, these results would typically represent the natural course of patients presenting with LDH.66 Previous studies by Lutz et al.,67 Riew et al.68 and Vad et al.50 have also demonstrated good long term outcomes with multiple SNRBs. In one-third of patients in the study by Riew et al.,66,68 who were initially offered the surgical option, surgical intervention could be deferred by 5 years with the administration of multiple SNRBs.
Various studies have also tried to identify clinical and radiological factors that may help to better prognosticate outcomes after SNRBs.19,69, 70, 71 McCormick et al.69 studied 188 patients who underwent TFESI and concluded that higher pre-injection pain, pain pattern not worsening with walking, and patients with positive femoral stretch test had better VAS improvement at two weeks post-injection. Other clinical factors that have been reported to influence outcomes include duration of symptoms (duration less than 3 months is associated with better outcomes), present functional status, socio-economic status, psychological factors like depression and anxiety, and sleep quality.19,70,71Kanna et al.36 reported that clinical factors including significant sensory symptoms, high mean pre-injection ODI score, high mean post-injection score at 3 weeks, and white-collar employment were associated with poor outcomes following SNRB.
Various imaging findings have also been reported to influence the outcome after SNRB. Presence of a transitional vertebra (sacralised L5) has generally been associated with poorer outcomes.38 In a retrospective study, Kim et al.72 concluded that small disc size (cut-off 6.23 mm) was associated with successful outcomes. Ghahreman and Bogduk73 reported better success in patients with low-grade neural compression while Paidin et al.74 demonstrated longer term benefits from SNRB in patients with higher grades of neural compression.
In , Tecer et al.75 analysed the role of different MRI findings including type and location of DH, presence of high intensity zone (HIZ), and nerve root impingement (NRI) in determining the outcome following SNRB. They concluded that SNRB was effective in all patients, irrespective of the type and location of DH. Patients with HIZ showed greater pain improvement early on (second week after SNRB) and those with NRI demonstrated a slower recovery (around third month). Other studies have demonstrated more favourable outcomes in patients with foraminal and extraforaminal DH.76,77 In the study by Lechmann et al.,78 pain reduction was significantly better at the end of one month following TFESI in patients with protrusion and sequestration, grade 3 foraminal stenosis, far-lateral disc herniations, and osteophytic degeneration.
Kanna et al.36 evaluated different radiculogram patterns and outcome after SNRB. The &#;arm&#;, &#;linear&#; and &#;arrow&#; patterns were associated with good results, while the &#;splash&#; pattern was associated with poor results. The &#;splash&#; pattern generally indicates poor spreading of dye, possibly secondary to peri-neural adhesions or vascular engorgements around the inflamed nerve roots.
While TFESIs are fairly safe procedures, devastating complications including neural trauma, vascular trauma, intra-vasation of drug and infection have rarely been reported.19 The most dangerous complication following this procedure is spinal cord infarction, resulting in paraplegia of which there are a few case reports. These major neurological complications have been attributed to
a. Embolisation of particulate steroids causing vascular occlusion
b. Anatomic profile of the &#;safe triangle&#;, which although may be safe with respect to neural elements, can contain radicular arteries. Although arteria radicularis magna or artery of Adamkiewicz usually lies around the thoraco-lumbar region, variants of this vessel can arise anywhere down to the sacral vertebrae and thus an inadvertent injury or dissection of this artery can lead to conus medullaris infarction.
c. Transient vasospasm secondary to needle placement (typically described after SP approach).
d. In addition, patients on chronic anti-platelet or anti-coagulant medications may develop epidural hematomas and neuro-deficits.55,79, 80, 81, 82
Adverse effects related to steroids including pituitary-adrenal axis suppression, Cushing&#;s syndrome, osteoporosis, avascular necrosis of bone, myopathy, weight gain, fluid retention and hyperglycemia, although rare, are theoretical possibilities following these injections. These image-guided procedures can also cause significant radiation exposure to patients, practitioners and OR personnel.19
Based on the available evidence, LTFIS is a safe and effective treatment modality in LRS. The overall success rate has been reported to be around 76&#;88%. In patients with good relief, these injections may even be repeated at regular intervals, thereby obviating or at least postponing the need for surgery. With current day technologies, these procedures are excellent tools in the armamentarium of any spine surgeon involved in the management of LDH.
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