Novel High-Frequency Peripheral Nerve Stimulator Treatment of Refractory Postherpetic Neuralgia: A Brief Technical Note.

OBJECTIVES: The study aims to describe an ultrasound (US)-guided peripheral nerve stimulation implant technique and describe the effect of high-frequency peripheral nerve stimulation on refractory postherpetic neuralgia. MATERIALS AND METHODS: Following a cadaver pilot trial using US and confirmatory fluoroscopic guidance, a 52-year-old man with refractory left supraorbital neuralgia underwent combined US and fluoroscopic-guided supraorbital peripheral nerve stimulator trial. The patient was subsequently implanted with a percutaneous lead over the left supraorbital and supratrochlear nerve utilizing a high-frequency stimulation paradigm. RESULTS: At 9 months follow-up, the pain intensity had declined from a weekly average of 8/10 to 1/10 on the pain visual analog scale (VAS). After implant, both nerve conduction and blink reflex studies were performed, which demonstrated herpetic nerve damage and frequency-specific peripheral nerve stimulation effects. The patient preferred analgesia in the supraorbital nerve distribution accomplished with high-frequency paresthesia-free stimulation (HFS) at an amplitude of 6.2 mA, a frequency of 100-1200 Hz, and a pulse width of 130 µsec, to paresthesia-mediated pain relief associated with low-frequency stimulation. CONCLUSION: We report the implant of a supraorbital peripheral nerve stimulating electrode that utilizes a high-frequency program resulting in sustained suppression of intractable postherpetic neuralgia.

Patients with a history of spine surgery or spinal injury may have a higher chance of intrathecal catheter granuloma formation.

BACKGROUND GOALS: Intrathecal drug delivery is an effective method to treat intractable pain. However, intrathecal catheter tip granuloma (ICTG) is a devastating complication of intrathecal drug delivery systems. It typically occurs in the thoracic region; particularly, in patients receiving high doses or high concentrations of intrathecal drug infusions. MATERIALS AND METHODS: The PUBMED/MEDLINE and Cochrane databases were also systematically searched for all reports on ICTG published in any language. The key words included "intrathecal," "granuloma," and "spine surgery," and all related publications between the earliest available date (the first granuloma-related chronic complication of intrathecal infusion reported in PUBMED/MEDLINE in 1996) and June (week 1) of 2012 were searched. This case report is unique because it describes the formation of an intrathecal granuloma in the lumbar region of a patient who received a low-dose intrathecal infusion. RESULTS AND CONCLUSION: Cerebrospinal fluid flow dynamics within the spinal canal along with the physical, chemical, and immunological properties of intrathecal medications have been suggested to be responsible for the growth of inflammatory mass lesions at the tips of intrathecal drug delivery catheters. Our literature review supports the possible role of certain factors, specifically previous spine surgery or spinal injury, in granuloma formation. The rate of development of ICTG appears to be higher in patients who have had previous spine surgery or spinal injury (68%) than in a general cohort of patients (48%), with an intrathecal pump. Therefore patients with a history of spine surgery or injury may be at increased risk of ICTG when receiving chronic intrathecal analgesia.

Evidence-based knee injections for the management of arthritis.

OBJECTIVE: Arthritis of the knee affects 46 million Americans. We aimed to determine the level of evidence of intraarticular knee injections in the management of arthritic knee pain. METHODS: We systematically searched PUBMED/MEDLINE and the Cochrane databases for articles published on knee injections and evaluated their level of evidence and recommendations according to established criteria. RESULTS: The evidence supports the use of intraarticular corticosteroid injections for rheumatoid arthritis (1A+ Level), osteoarthritis (1A+ Level), and juvenile idiopathic arthritis (2C+ Level). Pain relief and functional improvement are significant for months up to 1 year after the injection. Triamcinolone hexacetonide offers an advantage over triamcinolone acetonide and should be the intraarticular steroid of choice (2B+ Level). Intraarticular injection of hyaluronate may provide longer pain relief than steroid injection in osteoarthritis (2B+ Level). It can also be effective for rheumatoid arthritis knee pain (1A+ Level). However, it is only recommended for patients with significant surgical risk factors and for patients with mild radiographic disease in whom conservative treatment has failed (2B± Level). Botulinum toxin type A injection is effective in reducing arthritic knee pain (2B+ Level), and so is tropisetron (2B+ Level) and tanezumab (2B+ Level). The new agents, such as rAAV2-TNFR:Fc, SB-210396/CE 9.1, and various radioisotopes have provided various degrees of success, but their long-term safety and efficacy remains to be determined. CONCLUSIONS: We conclude that strong evidence supports the use of intraarticular knee injection as a valuable intervention in the continuum of management of arthritis between conservative treatment and knee surgeries.

Regional anesthesia and co-existing chronic pain.

PURPOSE OF REVIEW: Investigate the rational for incorporation of regional anesthesia techniques into a multimodal approach toward patients with co-existing chronic pain as increasing numbers of chronic pain patients are presenting for surgery. RECENT FINDINGS: There is a growing body of evidence suggesting that regional anesthesia may be superior to opioids for improved pain control along with increased patient satisfaction and decreased perioperative morbidity and mortality comparing to general anesthesia in patients with significant medical disease(s) and may also carry several economic benefits. Despite the prevalence of chronic pain and data suggesting that patients with chronic pain are prone to exacerbation of their condition(s) following surgery, regional anesthesia techniques for these patients is only beginning to be developed. SUMMARY: The systemic condition of chronic pain has important practical and clinical implications for regional anesthesia implementation by anesthesiologists and pain management physicians. Comprehensive preadmission assessment together with a complete medication history and close follow-up management should always be employed in patients with pre-existing chronic pain throughout the perioperative setting. Despite successful implementation of neural blockade, and to avoid opioid withdrawal, at least half the chronic pain patient's daily pre-admission opioid dose should be continued daily throughout the perioperative period. Regional anesthesia is a preferable anesthetic option for perioperative management technique of patients with co-existing chronic pain, even if it requires supplementation with sedation or general anesthesia. The specifics of regional anesthesia performance and practical strategies for regional anesthesia application in chronic pain patients, including implanted pain management devices, are reviewed in this study.

Ultrasound-Guided Percutaneous Cervical and Upper Thoracic Sympathetic Chain Neuromodulation for Upper Extremity Complex Regional Pain Syndrome.

BACKGROUND: Complex regional pain syndrome (CRPS) comprises a group of conditions characterized by severe, debilitating pain that is disproportionate to any inciting event and is not distributed in a specific nerve distribution or dermatome. CASE REPORT: A 42-year-old female with a 2-year history of right upper extremity CRPS type I refractory to conventional management underwent an ultrasound-guided and fluoroscopy confirmed percutaneous peripheral nerve stimulation trial with a lead extending from the C6 to the T3 level to cover the cervical and upper thoracic sympathetic chain. The patient subsequently received a permanent ultrasound-guided lead and implantable pulse generator. At 1-month follow-up, the patient's pain intensity had declined from a weekly average of 8/10 to 1/10 on the verbal pain scale with marked improvement in function. The patient continues to be pain-free or experiences only minimal discomfort 7 years after the implant. She experienced no complications and has discontinued all her pain medications since the implant. CONCLUSION: The placement of a peripheral nerve-stimulating electrode resulted in sustained suppression of intractable pain secondary to CRPS. Ultrasonography guidance enabled the nonsurgical minimally invasive percutaneous approach. Use of ultrasonography may improve the safety of the procedure by permitting direct visualization of the related anatomic structures, thereby reducing the risk of injury to the inferior thyroid artery, vertebral artery, esophagus, intervertebral disc, and pleura.

Obesity and chronic pain: systematic review of prevalence and implications for pain practice.

The combination of obesity and pain may worsen a patient's functional status and quality of life more than each condition in isolation. We systematically searched PubMed/MEDLINE and the Cochrane databases for all reports published on obesity and pain. The prevalence of combined obesity and pain was substantial. Good evidence shows that weight reduction can alleviate pain and diminish pain-related functional impairment. However, inadequate pain control can be a barrier to effective lifestyle modification and rehabilitation. This article examines specific pain management approaches for obese patients and reviews novel interventional techniques for treatment of obesity. The infrastructure for simultaneous treatment of obesity and pain already exists in pain medicine (eg, patient education, behavioral medicine approaches, physical rehabilitation, medications, and interventional treatment). Screening for obesity, pain-related disability, and behavioral disorders as well as monitoring of functional performance should become routine in pain medicine practices. Such an approach requires additional physician and staff training. Further research should focus on better understanding the interplay between these 2 very common conditions and the development of effective treatment strategies.

Chorea in a chronic pain patient using gabapentin.

BACKGROUND: Gabapentin increasingly is being used to treat chronic pain in addition to seizures, anxiety, and bipolar disorder. Chorea has been reported as a potential side effect of gabapentin. CASE REPORT: We report the case of a patient with chronic low back pain who was treated with a host of modalities, including gabapentin. After she increased her dose of gabapentin, she developed chorea of the upper extremities, neck, and head. With cessation of gabapentin, the bulk of her symptoms resolved within 24 hours, and symptoms completely resolved in the following months. CONCLUSIONS: Chorea is thought to appear when the basal ganglia are deregulated. Gabapentin interferes with gamma-aminobutyric acid, the primary inhibitory neurotransmitter in the motor pathway. Chorea associated with gabapentin has been reported in several case studies, but not at a dose as low as the patient took in this case.

Management of thyroid incidentalomas encountered by anesthesiologists and pain physicians.

Unexpected, asymptomatic thyroid lesions incidentally discovered during unrelated diagnostic or therapeutic interventions are called thyroid incidentalomas (TIs). These lesions are extremely common, creating a clinical problem that most anesthesiologists and pain specialists are unfamiliar with. Ultrasonography (US), which allows high-quality real-time visualization of tissues during brachial plexus block, stellate ganglion block, central vascular access, and other interventions, is the imaging modality of choice of many anesthesiologists and pain medicine specialists for therapeutic interventions on the neck. The increasing number of US procedures performed on the neck will eventually result in an upsurge of anesthesiologists and pain specialists encountering a TI. Interventionalists are responsible for acquiring optimal images, accurate needle positioning during interventions, and storage and appropriate labeling of the obtained images. Ignoring the TI or disclosing the presence of a "tumor" can substantially affect the patient's well-being. In this literature review, we discuss 2 clinical cases of incidentalomas, summarize the current evidence-based strategies, and provide readers with practical guidelines-possibly applicable to other abnormal findings-for the management of incidentally found thyroid lesions.

A low-cost, durable, combined ultrasound and fluoroscopic phantom for cervical transforaminal injections.

BACKGROUND: This technical report describes a durable, low-cost, anatomically accurate, and easy-to-prepare combined ultrasound (US) and fluoroscopic phantom of the cervical spine. This phantom is meant to augment training in US- and fluoroscopic-guided pain medicine procedures. METHODS: The combined US and fluoroscopic phantom (CUF-P) is prepared from commercially available liquid plastic that is ordinarily used to prepare synthetic fishing lures. The liquid plastic is heated and then poured into a metal canister that houses an anatomical cervical spine model. Drops of dark purple dye are added to make the phantom opaque. After cooling, tubing is attached to the CUF-P to simulate blood vessels. RESULTS: The CUF-P accurately simulates human tissue by imitating both the tactile texture of skin and the haptic resistance of human tissue as the needle is advanced. This phantom contains simulated fluid-filled vertebral arteries that exhibit pulsed flow under color Doppler US. Under fluoroscopic examination, the CUF-P-simulated vertebral arteries also exhibit uptake of contrast dye if mistakenly injected. CONCLUSIONS: The creation of a training phantom allows the pain physician to practice needle positioning technique while simultaneously visualizing both targeted and avoidable vascular structures under US and fluoroscopic guidance. This low-cost CUF-P is easy to prepare and is reusable, making it an attractive alternative to current homemade and commercially available phantom simulators.

Glossopharyngeal neuralgia secondary to vascular compression in a patient with multiple sclerosis: a case report.

INTRODUCTION: Glossopharyngeal neuralgia is an uncommon, painful syndrome, characterized by paroxysms of pain in the sensory distribution of the 9th cranial nerve. Idiopathic glossopharyngeal neuralgia may be due to compression of the glossopharyngeal nerve by adjacent vessels, while secondary glossopharyngeal neuralgia is associated with identifiable lesions affecting the glossopharyngeal nerve at different levels of its neuroanatomic pathway. Glossopharyngeal neuralgia is rare in the general population, but is more common in patients with multiple sclerosis. CASE PRESENTATION: A 56-year-old Caucasian woman with multiple sclerosis and migraine presented to our facility with intermittent lancinating pain to the right of her throat, tongue, and the floor of her mouth that had been occurring for the past year. The pain was intense, sharp, and stabbing, which lasted two to six seconds with radiation to the right ear. Initially, the attacks were infrequent, however, they had become more intense and frequent over time. Our patient reported weight loss, headache, painful swallowing, and the inability to maintain sleep due to painful attacks. A neurological examination revealed a right-handed woman with trigger points in the back of the tongue and throat on the right side. She also had dysphagia, hoarseness, and pain in the distribution of the right glossopharyngeal nerve. Mild right hemiparesis, hyperreflexia, dysmetria, and an ataxic gait were present. A magnetic resonance imaging scan of the brain was consistent with multiple sclerosis and magnetic resonance angiography demonstrated a loop of the posterior inferior cerebellar artery compressing the right glossopharyngeal nerve. She responded satisfactorily to carbamazepine. Microvascular decompression and Gamma Knife® radiosurgery were discussed in case of failure of the medical treatment; however, she declined these options. CONCLUSIONS: Glossopharyngeal neuralgia in multiple sclerosis may occur due to vascular compressive lesions and it should not be solely attributed to the underlying demyelinating process. Vascular compression of the glossopharyngeal nerve could independently cause glossopharyngeal neuralgia in patients with multiple sclerosis, and vascular imaging to exclude such a diagnosis is recommended.