Diagnostic Nerve Blocks Research Articles

The Origin and Course of the Infrapatellar Branch of the Saphenous Nerve: An Anatomical Study

Introduction: Nerve injury of the saphenous nerve or infrapatellar branch seems to be a frequent complication following knee surgery or trauma. Denervation results vary and in some cases no pain relief is achieved. This might be due to anatomic variation. The purpose of this anatomical study is to identify variation in the course of the infrapatellar branch and saphenous nerve. Materials and Methods: We dissected 18 cadavers from adult donors. Medial to the knee, the saphenous nerve and infrapatellar branch were identified and followed proximally to the point where the infrapatellar branch branched from the saphenous nerve. The location where the infrapatellar branch came off from the saphenous nerve relative to the knee joint and where the branch and nerve passed the knee joint were measured. Results: A total of 23 infrapatellar branches were found. We identified 10 branches that came off the saphenous nerve between 0-10 cm proximal to the knee joint, 3 branches at 10-20 cm, and 9 branches at >20 cm. Between the patella and semitendinosus tendon, the knee joint was crossed by 5 branches in the anterior, 15 in the middle, and 2 in the posterior one-third. 13 of the 18 saphenous nerves crossed the knee joint in the posterior one-third and 5 in the middle one-third of the line. Conclusion: The origin of the infrapatellar branch and the location at which it passes the knee are highly variable. This, in addition to people having multiple branches, might explain why denervation is frequently unsuccessful. Based on the anatomical findings, we propose a more proximal diagnostic nerve block to help differentiate between a distal-middle, or proximal origin of the infrapatellar branch. Appropriate placement of the nerve block might help identify people who benefit from denervation.

Recommendations for Ultrasound Guidance for Diagnostic Nerve Blocks for Spasticity. What Are the Benefits?

The diagnostic nerve block (DNB) for spasticity is the percutaneous application of an anesthetic to an individual peripheral nerve trunk (mixed motor sensory nerve), nerve branch to a muscle or an intramuscular branch. The DNB causes a temporary paralysis to assess the contribution of muscle(s) on the spastic pattern and may unmask a fully or partially increased joint range of motion. The anesthetic literature supports the use of ultrasound (US) guidance to improve nerve blocks for sensory targets. This communication summarizes the potential advantages that support the use of US to improve DNB technique. Nerves are much smaller than muscle targets and have various known innervation patterns. US allows for rapid localization of the target before injection, particularly in complex anatomy patterns. The nerve trunks are typically found adjacent to or encapsulating blood vessels, which can be quickly identified with or without color Doppler, allowing the clinician to scan from the vessels to the target and avoid intravascular injection. Lower stimulation levels can be used as the targeted muscle(s) can be seen stimulating rather than only on the surface. A shorter needle insertion time and lower stimulation levels should cause less discomfort to the patient. Smaller volumes of anesthetic may be used as the fluid is seen reaching its target and cessation of stimulation is observed. Further study is needed to identify evidence supporting US utilization with electrical stimulation in DNBs for spasticity management, as US use during nerve blocks for perineurial anesthesia has demonstrated improved patient safety and procedural efficiency.

Occipital neuralgia in multiple sclerosis: Successful ultrasound-guided diagnostic occipital nerve block and treatment with cryoablation

Occipital neuralgia in multiple sclerosis: Successful ultrasound-guided diagnostic occipital nerve block and treatment with cryoablation

Medico-Surgical Management of the Spastic Equinovarus Foot Deformity in Adults: A Retrospective Series of 622 Patients

Objective: This study aimed to determine the frequency of spastic equinovarus foot (SEF) treatments. Materials and Methods: the medical files of 622 patients treated for SEF were reviewed. Results: SEF resulted from stroke in 66%. The most frequent pattern was equinovarus in 56%, knee recurvatum in 55%, and claw toes in 41%. Patients benefited from surgical treatment in 59%, including neurotomy in 22%, tendon surgery in 12%, and a combined surgery in 25%. Conclusion: Surgery was performed in 59% of the cases. The type of treatment was influenced by the preoperative diagnostic nerve block assessment.

The origin and course of the infrapatellar branch of the saphenous nerve: An anatomical study

SummaryNerve injury of the saphenous nerve or infrapatellar branch seems to be a frequent complication following knee surgery or trauma. Denervation results vary, and in some cases, no pain relief is achieved. This might be due to anatomic variation. The purpose of this anatomical study is to identify the variation in the course of the infrapatellar branch and saphenous nerve.We dissected 18 cadavers from adult donors. Medial to the knee, the saphenous nerve and infrapatellar branch were identified and followed proximally to the point where the infrapatellar branch branched from the saphenous nerve. The location where the infrapatellar branch came off from the saphenous nerve relative to the knee joint and where it passed the knee joint were measured.A total of 23 infrapatellar branches were found. We identified 10 branches between 0–10 cm proximal to the knee joint, 3 branches at 10–20 cm, and 9 branches at >20 cm. Between the patella and semitendinosus tendon, the knee joint was crossed by 5 branches in the anterior, 15 in the middle, and 2 in the posterior one-third.The origin of the infrapatellar branch and the location at which it passes the knee are highly variable. This, in addition to people having multiple branches, might explain why denervation is frequently unsuccessful. Based on the anatomical findings, we propose a more proximal diagnostic nerve block to help differentiate between a distal-middle or proximal origin of the infrapatellar branch. Appropriate placement of the nerve block might help identify people who benefit from denervation.

Evidence-Based Clinical Guidelines from the American Society of Pain and Neuroscience for the Use of Implantable Peripheral Nerve Stimulation in the Treatment of Chronic Pain.

The objective of this peripheral nerve stimulation consensus guideline is to add to the current family of consensus practice guidelines and incorporate a systematic review process. The published literature was searched from relevant electronic databases, including PubMed, Scopus, Cochrane Central Register of Controlled Trials, and Web of Science from database inception to March 29, 2021. Inclusion criteria encompassed studies that described peripheral nerve stimulation in patients in terms of clinical outcomes for various pain conditions, physiological mechanism of action, surgical technique, technique of placement, and adverse events. Twenty randomized controlled trials and 33 prospective observational studies were included in the systematic review process. There is Level I evidence supporting the efficacy of PNS for treatment of chronic migraine headaches via occipital nerve stimulation; chronic hemiplegic shoulder pain via stimulation of nerves innervating the trapezius, supraspinatus, and deltoid muscles; failed back surgery syndrome via subcutaneous peripheral field stimulation; and lower extremity neuropathic and lower extremity post-amputation pain. Evidence from current Level I studies combined with newer technologies facilitating less invasive and easier electrode placement make peripheral nerve stimulation an attractive alternative for managing patients with complex pain disorders. Peripheral nerve stimulation should be used judiciously as an adjunct for chronic and acute postoperative pain following adequate patient screening and positive diagnostic nerve block or stimulation trial.

Surgical Treatment Strategies for Injuries of the "Unforgiving" Superficial Branch of the Radial Nerve.

Neuropathic pain caused by adhesions or neuroma formation of the superficial branch of the radial nerve (SBRN) is difficult to treat. The authors evaluated the effectiveness of different routinely used surgical techniques for SBRN neuralgia to provide a basis for future studies on SBRN neuralgia and explored the prognostic value of a preoperative diagnostic nerve block. The authors performed a retrospective cohort study by reviewing surgical records for procedures to treat SBRN neuralgia. Patient satisfaction was scored as satisfied or unsatisfied, and pain intensity was scored with a numeric rating scale. The authors included 71 patients who had 105 surgeries on the SBRN. Patients with a neuroma ( n = 43) were most satisfied after proximal denervation with burying into the brachioradialis muscle compared with burying elsewhere (53 versus 0 percent; p < 0.001). Adhesions of the SBRN ( n = 28) were treated with neurolysis (39 percent satisfied). If neurolysis or denervation did not suffice, an additional denervation of the lateral antebrachial cutaneous nerve or posterior interosseous nerve led to satisfaction in 38 percent. A decrease of less than 3.5 points on the numeric rating scale score after diagnostic nerve block led to higher postoperative pain scores (4.0 versus 7.5; p = 0.014). The authors found that the outcome of the diagnostic nerve block can predict the outcome of SBRN denervation and burying into brachioradialis muscle. The most effective burying technique is burying the SBRN into the brachioradialis muscle. Future studies on the treatment of SBRN neuralgia should therefore compare newer techniques, with burying the SBRN into the brachioradialis muscle as the control group.

A Novel Approach to New Onset Hemiplegic Shoulder Pain With Decreased Range of Motion Using Targeted Diagnostic Nerve Blocks: The ViVe Algorithm

A Novel Approach to New Onset Hemiplegic Shoulder Pain With Decreased Range of Motion Using Targeted Diagnostic Nerve Blocks: The ViVe Algorithm

Radiofrequency Ablation for the Knee Joint: A Survey by the American Society of Pain and Neuroscience.

BackgroundGenicular nerve radiofrequency ablation (RFA) is an effective, minimally invasive procedure often used to treat patients with intractable knee pain secondary to knee osteoarthritis and failed knee replacements. The prevalence of knee pain in adults has been estimated to be as high as 40% and is continuously increasing with an aging population. Over the past two decades, proceduralists have adopted variations in patient preparation, procedural steps, and post-operative care for genicular nerve RFA procedures. A survey was dispensed via the American Society of Pain and Neuroscience (ASPN) to gain a popular assessment of common practices for genicular nerve RFA.MethodsA 29 question survey was dispensed via SurveyMonkey to all members of ASPN. Members were able to respond to the survey a single time and were unable to make changes to their responses once the survey was submitted. After responses were compiled, each question was assessed in order to determine common practices for genicular nerve RFA.ResultsA total of 378 proceduralists responded to the survey. There was high consensus with the three most commonly targeted nerves. The inferomedial, superomedial, and superolateral genicular branches were treated by 95–96% of respondents, while other targets were less commonly treated. There remains some debate among proceduralists regarding the need for a second diagnostic nerve block and the type of steroid used for diagnostic nerve blocks.ConclusionPain physicians use a wide variety of methods to perform genicular nerve ablations. The data offered by the survey show that there is no standardized protocol when it comes to treating knee pain via genicular nerve block and ablation and highlights controversies among proceduralists that ought to serve as the targets of future clinical research aimed at establishing a standardized protocol.

CT-Guided Cooled Radiofrequency Denervation for Chronic Arthritis Pain of the Hip and Shoulder.

The paradigm in the treatment of arthritis pain is shifting for previously open surgical denervations of the hip and shoulder, as it already has for the geniculate nerves in knee arthritis. Interventional radiology is poised to contribute to this space with the use of CT guidance to provide safe, fast, and effective targeting of the target nerves for unequivocal diagnostic nerve block and definitive cooled radiofrequency denervation. The authors provide the background of which nerves are targeted for hip and shoulder denervation and the normal CT appearance of these blocks.

Is the Outcome of Diagnostic Nerve Block Related to Spastic Muscle Echo Intensity? A Retrospective Observational Study on Patients with Spastic Equinovarus Foot.

To investigate the relationship between spastic calf muscles echo intensity and the outcome of tibial nerve motor branches selective block in patients with spastic equinovarus foot. Retrospective observational study. Forty-eight patients with spastic equinovarus foot. Each patient was given selective diagnostic nerve block (lidocaine 2% perineural injection) of the tibial nerve motor branches. All patients were evaluated before and after block. Outcomes were: spastic calf muscles echo intensity measured with the Heckmatt scale; affected ankle dorsiflexion passive range of motion; calf muscles spasticity measured with the modified Ashworth scale and the Tardieu scale (grade and angle). Regarding the outcome of tibial nerve selective diagnostic block (difference between pre- and post-block condition), Spearman's correlation showed a significant inverse association of the spastic calf muscles echo intensity with the affected ankle dorsiflexion passive range of motion (p = 0.045; ρ = 00-0.269), modified Ashworth scale score (p = 0.014; ρ = -0.327), Tardieu grade (p = 0.008; ρ = -0.352) and Tardieu angle (p = 0.043; ρ = -0.306). These findings support the hypothesis that patients with spastic equinovarus foot with higher spastic calf muscles echo intensity have a poor response to selective nerve block of the tibial nerve motor branches.

Subthreshold Peripheral Nerve Stimulation with a High Frequency Electro-Magnetic Couple Powered Implanted Receiver for the Treatment of Chronic Shoulder Pain

BACKGROUND: Shoulder pain has an estimated population prevalence of up to 26%. The most common source of shoulder pain is the rotator cuff, which is a group of muscles and tendons that surround the shoulder joint, accounting for over two-thirds of cases. CASE REPORT: A 65-year-old man presented with sharp, localized pain on abduction of the left shoulder due to a left rotator cuff tear. A diagnostic nerve block provided 100% short-term pain relief. Subsequently a peripheral nerve stimulator trial was offered to the patient, which was successful. The permanent peripheral nerve stimulator was implanted at the supraspinous fossa with the middle electrodes at the suprascapular notch. A receiver was inserted into the inner lumen of electrode array and the neurostimulator was coiled and fixated to the fascia. The following stimulation settings were used: frequency at 1.5 kHz, pulse width at 30 µs, and amplitude of 3.5 mA. CONCLUSION: At one year after implant, the patient had close to 100% pain relief and reported excellent mobility of the shoulder. Wirelessly powered peripheral nerve simulation was a successful option for this patient suffering from debilitating left shoulder pain due to a left rotator cuff tear. KEY WORDS: Chronic shoulder pain, glenohumeral osteoarthritis, peripheral nerve stimulator, suprascapular neuralgia

Sixty-Day Pudendal Nerve Stimulation: A Potential Therapy for Refractory Pudendal Neuralgia Case Report

BACKGROUND: Pudendal neuralgia (PN) can cause severe, disabling chronic pain. Though common, PN is frequently unrecognized and misdiagnosed. Historically, the last-resort treatment for PN has been permanent implantation of spinal cord stimulation (SCS), but SCS for PN carries high risk of complications and explantation. We report the first case of temporary (60-day) peripheral nerve stimulation (PNS) treatment for refractory PN. CASE REPORT: A 63-year-old woman presented with one year of chronic bilateral suprapubic vaginal pain radiating to the bilateral proximal medial thighs with concomitant dysuria, urinary frequency, and pain with intercourse. PN was confirmed via diagnostic pudendal nerve block. Using fluoroscopic guidance, we implanted PNS leads on the left and, subsequently, the right pudendal nerves, with explantation at 60 days for each lead. The patient reported continuing pain reduction with 80% improvement in the Visual Analog Scale score at 6 months, resumption of normal activity and functionality, discontinued use of opioids, and high satisfaction with treatment. This case is notable for the sustained pain relief provided by this temporary and minimally invasive treatment. CONCLUSIONS: This case suggests that 60-day PNS with fluoroscopic guidance is a viable treatment for refractory PN in correctly selected patients. This treatment is low-risk, minimally invasive, and may be used early in the care continuum, potentially sparing patients multiple failed treatments and the risks associated with permanently implanted devices. KEY WORDS: Pudendal nerve, peripheral nerve stimulation, neuromodulation, chronic pain, pelvic pain, perineal pain, case report

The Role of Diagnostic Nerve Blocks in Headache Surgery

The Role of Diagnostic Nerve Blocks in Headache Surgery

Anococcygeal Nerve and Sitting Pain: Differential Diagnosis and Treatment Results.

The plastic surgeon is often asked to reconstruct the sacral area related to pilonidal cysts or a tumor, or after other surgery, such as coccygectomy. When sitting pain is not due to the pudendal or posterior femoral cutaneous nerve injury, the anococcygeal nerve (ACN) must be considered. Clinically, its anatomy is not well known. Rather than consider coccygectomy when the traditional nonoperative treatment of coccydynia fails, resection of the ACN might be considered. A review of traditional anatomy textbooks was used to establish classical thoughts about the ACN. A retrospective cohort of patients with sitting pain related to the coccyx was examined, and those operated on, by resecting the ACN, were examined for clinicopathologic correlations. When the ACN is described in anatomy textbooks, it is with varying distributions of innervated skin territory and nerve root composition. Most include an origin from sacral 5 and coccygeal 1 ventral roots. Most agree that the ACN forms on the ventral side of the sacrum/coccyx, alongside the coccygeus muscle, to emerge laterally and travel dorsally to innervate skin over the coccyx and lower sacrum. A review of 13 patients with sitting pain due to the ACN, from 2015 to 2019, demonstrated a mean age of 54.6 years. Eleven were female. The etiologies of ACN injury were falls (9), exercise (3), and complication from surgery (1). Six of the 9 patients who had surgery were able to be followed up with a mean length of 36.3 months (range, 11-63 months). Overall, 3 had an excellent result, 2 had a good result, and 1 was not improved. The one with a failed result showed improvement with coccygectomy. The ACN must be included in the differential diagnosis of sitting pain. It is most often injured by a fall. The ACN can be evaluated with a diagnostic nerve block, can be identified at surgery, and can be resected, and its proximal end can be implanted into the coccygeus muscle. This surgery may prove an alternative to coccygectomy.

Pulsed Radiofrequency of the Occipital Nerves: Results of a Standardized Protocol on Chronic Headache Management.

BackgroundPulsed radiofrequency (PRF) of the occipital nerves has neuromodulative properties and is used for chronic pain management. However, its role in various types of chronic headaches has not been adequately investigated so far.ObjectivesΤhis was an observational, open-label, prospective study aiming to assess the efficacy of PRF of occipital nerves on various types of chronic headache management.MethodsPatients with chronic headaches followed up at the pain management unit were scheduled for PRF of both occipital nerves after a positive diagnostic nerve block. PRF was applied following a standardized protocol at 42°C, and the number of headaches per month was assessed as a primary outcome at baseline (before treatment), as well as after 1, 3, and 6 months. Pain intensity during headache crises was recorded using the Numeric Rating Scale (NRS, 0 - 10),ResultsFifty-seven patients suffering from chronic migraines, cluster headaches, tension-type headaches, and occipital neuralgia were studied. PRF significantly improved the number of headache episodes per month, as well as the pain intensity of the crises. The median number of headache episodes per month was significantly reduced in patients with migraine, from 14.5 to 4 after 1 month, and to 6.5 after 6 months. The same was seen for patients with clusters, who were also improved. A statistically significant reduction in NRS values over time was seen for all types of headaches.ConclusionsPRF of the occipital nerves can lead to a reduction of the number of headache episodes per month, improving the intensity of pain during each episode.

Bipolar Radiofrequency Neurotomy of the Genicular Nerves for Chronic Pain Due to Knee Osteoarthritis.

Background: The current treatments for chronic knee osteoarthritis (OA), a disabling and costly healthcare condition in the United States, vary in their level of supporting evidence. Although total knee replacement is one of the best-supported interventions, its associated risks should not be taken lightly, especially in older patients with comorbidities. Genicular nerve block with subsequent genicular nerve radiofrequency neurotomy (GN-RFN) has emerged as a promising intervention for refractory pain in knee OA. Purposes/Questions: We sought to assess the pain and functional outcomes of genicular nerve bipolar radiofrequency neurotomy (B-RFN) for the treatment of chronic pain due to knee OA. Methods: A total of 21 patients who underwent unilateral genicular nerve B-RFN after positive diagnostic genicular nerve block (50% or greater pain relief) treated between July 2018 to December 2018 were included. Pain numeric rating scale (NRS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were collected at baseline, 3 months, and 6 months post-B-RFN. Changes at each time point were compared to baseline scores using paired sample t tests. Results: At 3 months, 62% of patients had a greater than 50% improvement in NRS scores and 57% of patients had a greater than 50% improvement in WOMAC scores. At 6 months, 81% of patients had a greater than 50% improvement in NRS scores and 67% had a greater than 50% improvement in WOMAC scores. The absolute change in mean NRS (± standard deviation) at 6 months went from 7.5 ± 1.9 to 2.5 ± 1.2. The absolute change in mean WOMAC scores at 6 months went from 46.9 ± 8.0 to 19.0 ± 6.2. Conclusion: Of 21 patients, 14 (67%) saw greater than 50% improvements in both NRS and WOMAC scores at 6 months after genicular nerve B-RFN. Further prospective studies are needed to determine the selection criteria of patients most likely to benefit from this procedure.

Diagnostics of infrapatellar saphenous neuralgia\u2014a reversible cause of chronic anteromedial pain following knee surgery

ObjectivesTo evaluate the impact of diagnostic nerve block and ultrasound findings on therapeutic choices and predict the outcome after concomitant surgery in patients with suspected neuropathy of the infrapatellar branch of the saphenous nerve (IPBSN).MethodsFifty-five patients following knee surgery with suspicion of IPBSN neuralgia were retrospectively included. Ultrasound reports were assessed for neuroma and postsurgical scarring (yes/no). Responders and non-responders were assigned following anesthetic injection of the IPBSN. The type of procedure (neurectomy/interventional pain procedure/other than nerve-associated therapy) and pain score at initial follow-up were recorded and patients were assigned as positive (full pain relief) or negative (partial/no pain relief) to therapeutic nerve treatment. Factors associated with a relevant visual analog scale (VAS) reduction were assessed using uni- and multivariate logistic regression models and chi-square for quantitative and qualitative variables (p ≤ 0.05).ResultsResponders (37/55) more often had an entrapment or an evident neuroma of the IPBSN (97% vs. 6%). A positive Hoffmann-Tinel sign (p = 0.002) and the absence of knee joint instability (p = 0.029) predicted a positive response of the diagnostic nerve block (90%; 26/29). In the follow-up after therapeutic nerve treatment, all patients with full pain relief showed neuromas or entrapment of the IPBSN. Patients negatively responding to therapeutic nerve treatment more frequently showed an additional knee joint instability (25% vs. 4%).ConclusionSelective denervation for neuropathic knee pain is beneficial in selected patients with significant VAS reduction after diagnostic nerve block. Non-responders following diagnostic nerve block but sonographic evidence of IPBSN pathologies need to be evaluated for other causes such as knee joint instability.Key Points• Sonographic diagnosis of neuroma or entrapment of the IPBSN is frequently seen in patients with anteromedial knee pain and leads to a good response to diagnostic nerve block following knee surgery.• The vast majority of patients with clinical signs of IPBSN neuropathy and response to a diagnostic nerve block sustained full pain relief following therapeutic nerve treatment.• Patients not responding to therapeutic IPBSN treatment have to be evaluated for other causes of anteromedial knee pain such as knee joint instability.

Dermatosensory Peripheral Nerve Interfaces: Prevention of Pain Recurrence Following Sensory Neurectomy.

Chronic pain is a significant health care problem. Many patients' pain can be linked to a neuropathic origin, diagnosed with a thorough history and physical examination, and confirmed with a diagnostic nerve block. There are new procedures designed to address neuropathic pain from symptomatic neuromas by providing physiologic targets for regenerating axons following neurectomy. Dermal wrapping of the end of a sensory nerve following transection, a technique called dermatosensory peripheral nerve interface, may provide an optimal environment to prevent neuroma pain and reduce chronic neuropathic pain.

Resolution of post-traumatic chronic testicular pain in a pediatric patient after microsurgical denervation of the spermatic cord: a case report

Chronic scrotal content pain, chronic orchialgia, or testicular pain can present after trauma, vasectomy, and hernia repair, among other triggers. Microsurgical denervation of the spermatic cord is an option for definitive pain control. While this practice is established in adult urology, access to diagnostic intervention and definitive denervation surgery is limited in the pediatric population. We report a case of definitive resolution of testicular pain with microsurgical denervation of the spermatic cord in a pediatric patient with post-traumatic chronic orchialgia that significantly reduced his daily activities and worsened his anxiety prior to this treatment. The patient underwent attempts at conservative medication-based management, followed by diagnostic spermatic cord nerve block before definitive denervation surgery. The incidence of chronic pain in pediatrics is substantial and is estimated to be around 20%. Orchialgia remains difficult and problematic to treat. Mental health diagnoses such as anxiety and depression are also significantly associated with chronic pain. Following consideration and implementation of steps for all these concerns, a diagnostic block and microsurgical denervation led to successful resolution of chronic testicular pain in a pediatric patient.