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Importance of the field:Hyaluronidase for injection is an adjuvant that increases the absorption and dispersion of other injected drugs or fluids (hypodermoclysis); and improves absorption of radiopaque agents in subcutaneous urography. Ovine hyaluronidase is approved for the treatment of vitreous hemorrhages.Areas covered in this review:We review approved indications for injectable hyaluronidase and off-label uses as well as safety, efficacy and dosing information. We compare formulations made using animal tissue extracts versus the novel human recombinant type. Emphasis is on the human recombinant form and off-label uses in patients with chronic pain.What the reader will gain:Hyaluronidase reduces the obstacle that the interstitial matrix presents to fluid and drug transfer. It is a mucolytic enzyme derived from mammalian tissue or synthesized in vitroin pure form (rHuPH20) using recombinant technology. Hyaluronidase is used off-label in chronic pain management to facilitate removal of epidural adhesions with mechanical and/or hydrostatic forces and to treat edema.Take home message:The recently introduced rHuPH20 formulation obviates any risk of allergic reaction or prion-related illnesses. Reduction of edema by hyaluronidase and facilitation of epidural adhesioloysis may be beneficial in treating certain chronic painful conditions.

Lumbar radicular pain is a common and often difficult condition to treat. Current literature supports the theory that radicular pain is at least in part due to an inflammatory process involving cytokines, including tumor necrosis factor alpha and interleukins. This review summarizes some of the most recent research concerning the use of tumor necrosis factor alpha antagonists and interleukin receptor antagonists in the treatment of lumbar radicular pain.

Background: Ziconotide is the only N-type calcium channel blocker approved by the US FDA for the treatment of chronic pain. The approved indication is for the management of severe chronic pain in patients for whom intrathecal therapy is warranted and who are intolerant of or refractory to other treatments such as systemic analgesics, adjunctive therapies or intrathecal morphine. Objective: The purpose of this article was to review the available safety, efficacy and dosing information for ziconotide. Methods: The sources searched for literature from 1980 to January 2008 included Pub Med, MEDLINE and PREMEDLINE using the words ziconotide, conotoxins and pain. Results/conclusion: Ziconotide is administered intrathecally by infusion pump to block nociceptive signal transmission in the spinal cord. It is a synthetic neuroactive peptide equivalent to the omega conotoxin MVIIA, a constituent of the venom of the fish-hunting marine snail Conus magus. It is highly potent, has a steep dose–response curve, a slow onset of action and a narrow margin of safety and responses to dose adjustments are slow. Patients receiving ziconotide should be under the care of physicians experienced in the management of intrathecal infusion therapy for pain control and should have convenient access to medical facilities.

Daily head and neck pain is the bain of existence for thousands of people every day. The economic burden is immense. The treatment of migraine headaches alone amounts to billions of dollars per year in direct and indirect costs. Conservative measures help many, but for the unfortunate few their search continues. Thankfully, therapeutic options exist in the hands of invasive pain management physicians. Minimally to highly invasive pain procedures can provide relief that allows the patient some aspect of normality. This article will review available options and support them with recent studies.

Abstract:This study retrospectively investigated the predictive value of intrathecal narcotic trials for long‐term drug utilization via implantable pumps in chronic non‐cancer patients. Data were derived from 86 patients who were categorized according to the intrathecal narcotic dose that resulted in the optimal trial response. The response during the trial period and the pattern of long‐term utilization of morphine was studied, as was the impact of age, gender and diagnosis. The analysis revealed that low dose responders had lower daily dose requirements at 18 months than standard dose and high dose responders. It also showed that women had lower total daily dose requirements at 18 and 24 months and that individuals over 65 years of age had lower total daily dose requirements at 18 months. A trend toward a disproportionately higher use of adjuvant drugs and narcotic substitutions was found among high dose responders, while a trend toward a disproportionately higher total daily dose was found among cervicalgia patients. The findings indicate that the responsiveness to an intrathecal narcotic during a trial, along with the diagnosis at the time of implantation, and the patient's age and gender can shed light on the long‐term utilization of intrathecal analgesics in chronic non‐cancer patients. This information may be used to better select patients and design trials that more closely reflect long‐term drug utilization.

Abstract:A CSF leak that persists despite conservative therapy may significantly increase the morbidity associated with implantable intrathecal drug delivery systems. This report presents 2 cases where the application of a subdural blood patch led to the satisfactory resolution of a persistent CSF leak after previous epidural blood patches had failed.

Abstract:Facial pain of trigeminal and sphenopalatine ganglion origin is the bain of existence for thousands of people. Treatment protocols typically begin with oral medication, usually anticonvulsants, and may progress to percutaneous and open surgical procedures. Several new medications show promise as alternatives to carbamazepine, which has been the standard first‐line treatment (trigeminal neuralgia), while electromagnetic pulsed radiofrequency and gamma knife surgery are new options when the surgical route is warranted.

Coagulation abnormalities and bleeding disorders are frequently encountered in patients undergoing invasive procedures. These are of particular importance in the pain management setting where even small amounts of excessive bleeding can result in devastating complications. It is imperative that physicians treating those patients understand the basic concepts of coagulation and be able to identify and manage the common bleeding disorders. This article provides a brief overview of the coagulation system and describes the use of appropriate screening tests and management strategies to limit bleeding in pain management procedures.

Spinal cord and peripheral nerve stimulation for relief of chronic intractable pain have been used since the mid-1960s. Multiple mechanisms of action have been theorized without a clear-cut winner. The early frustrations with patient selection criteria and equipment difficulties have diminished secondary to carefully controlled studies and improvements in equipment designs. Efficacy studies consistently show an overall 50% improvement in long-term pain control in patients who have failed conservative or other invasive modalities. With improvements in today’s technology, one hopes that better analgesia will be attainable.

The sphenopalatine ganglion and its involvement in the pathogenesis of pain has been the subject of debate for the last 90 years. The ganglion is a complex neural center composed of sensory, motor, and autonomic nerves, which makes it difficult to determine its pathophysiology. Current indications for blockade of the sphenopalatine ganglion include sphenopalatine and trigeminal neuralgia, migraine and cluster headaches, and atypical facial pain. Methods of blockade use local anesthetics, steroids, phenol, and conventional radiofrequency and electromagnetic field-pulsed radiofrequency lesioning. The techniques for blockade range from superficial to highly invasive. Efficacy studies, though few and small, show promise in patients who have failed pharmacologic or surgical therapies.

This article describes the development of a technique for radiofrequency lesioning of the splanchnic nerves. It features point neurolysis and improvement in safety from previously described techniques with the use of a curved, blunt needle. After extensive anatomic studies, the site of entry has been identified 4 cm lateral to the spinous process at the costovertebral angle of either the T11 or T12 vertebral body, and the placement of the needle tip at the junction of posterior two thirds to the anterior one third of the vertebral body. The use of a sharp, straight needle has been discouraged to prevent pneumothorax, and bowel, kidney, or nerve root injury. The radiofrequency lesion permits a point neurolysis, thus decreasing the rate of complications. Our experience of 22 patients treated with this technique has been complication-free, and the outcome was effective for all 10 patients with cancer. In the nonmalignancy group, some patients needed a second neurolysis (radiofrequency) procedure 4 months apart. There were also no secondary complications in these patients. We expect multicenter data accumulation in the coming years, which will determine the true efficacy of the radiofrequency of splanchnic nerves.