Novel technique for trialing peripheral nerve stimulation: ultrasonography-guided StimuCath trial.

OBJECTIVE Peripheral nerve stimulation (PNS) has been used for the treatment of neuropathic pain for many decades. Despite the specific indications for PNS, clinicians often have difficulty screening for candidates likely to have a good or fair outcome. Given the expense of a permanent implant, most insurance companies will not pay for the implant without a successful PNS trial. And since PNS has only recently been approved by the US Food and Drug Administration, many insurance companies will not pay for a conventional trial of PNS. The objective of this study is to describe a short low-cost method for trialing and screening patients for peripheral nerve stimulator implantation. Additionally, this study demonstrates the long-term efficacy of PNS in the treatment of chronic neuropathic pain and the relative effectiveness of this novel screening method. METHODS The records of all patients who had undergone trialing and implantation of a PNS system for chronic refractory pain at the authors' institution over a 1-year period (August 1, 2012-July 31, 2013) were examined in this retrospective case series. The search revealed 17 patients, 13 who had undergone a novel in-office ultrasonography-guided StimuCath screening technique and 4 who had undergone a traditional week-long screening procedure. All 17 patients experienced a successful PNS trial and proceeded to permanent PNS system implantation. Patients were followed up for a mean duration of 3.0 years. Visual analog scale (VAS) pain scores were used to assess pain relief in the short-term (< 6 weeks), at 1 year, and at the last follow-up. Final outcome was also characterized as good, fair, poor, or bad. RESULTS Of these 17 patients, 10 were still using their stimulator at the last follow-up, with 8 of them obtaining good relief (classified as ≥ 50% pain relief, with an average 81% reduction in the VAS score) and 2 patients attaining fair relief (< 50% relief but still using stimulation therapy). Among the remaining 7 patients, the stimulator had been explanted in 4 and there had been no relief in 3. Excluding explanted cases, follow-up ranged from 14 to 46 months, with an average of 36 months. Patients with good or fair relief had experienced pain prior to implantation for an average of 5.1 years (range 1.8-15.2 years). A longer duration of pain trended toward a poorer outcome (bad outcome 7.6 years vs good outcome 4.1 years, p = 0.03). Seven (54%) of the 13 patients with the shorter trial experienced a good or fair outcome with an average 79% reduction in the VAS score; however, all 4 of the bad outcome cases came from this group. Three (75%) of the 4 patients with the longer trial experienced a good or fair outcome at the last follow-up, with an average 54% reduction in the VAS score. There was no difference between the trialing methods and the proportion of favorable (good or fair) outcomes (p = 0.71). CONCLUSIONS Short, ultrasonography-guided StimuCath trials were feasible in screening patients for permanent implantation of PNS, with efficacy similar to the traditional week-long screening noted at the 3-year follow-up.

An ovine model of spinal cord injury.

OBJECTIVE: To develop a large animal model of spinal cord injury (SCI), for use in translational studies of spinal cord stimulation (SCS) in the treatment of spasticity. We seek to establish thresholds for the SCS parameters associated with reduction of post-SCI spasticity in the pelvic limbs, with implications for patients. STUDY DESIGN: The weight-drop method was used to create a moderate SCI in adult sheep, leading to mild spasticity in the pelvic limbs. Electrodes for electromyography (EMG) and an epidural spinal cord stimulator were then implanted. Behavioral and electrophysiological data were taken during treadmill ambulation in six animals, and in one animal with and without SCS at 0.1, 0.3, 0.5, and 0.9 V. SETTING: All surgical procedures were carried out at the University of Iowa. The gait measurements were made at Iowa State University. MATERIAL AND METHODS: Nine adult female sheep were used in these institutionally approved protocols. Six of them were trained in treadmill ambulation prior to SCI surgeries, and underwent gait analysis pre- and post-SCI. Stretch reflex and H-reflex measurements were also made in conscious animals. RESULTS: Gait analysis revealed repeatable quantitative differences in 20% of the key kinematic parameters of the sheep, pre- and post-SCI. Hock joint angular velocity increased toward the normal pre-injury baseline in the animal with SCS at 0.9 V. CONCLUSION: The ovine model is workable as a large animal surrogate suitable for translational studies of novel SCS therapies aimed at relieving spasticity in patients with SCI.

Sphenopalatine ganglion electrical nerve stimulation implant for intractable facial pain.

Persistent idiopathic facial pain can be extremely difficult and significantly challenging to manage for the patient and the clinician. Pharmacological treatment of these painful conditions is not always successful. It has been suggested that the autonomic reflex plays an important role in the pathophysiology of headaches and facial neuralgia. The key structure in the expression of cranial autonomic symptoms is the sphenopalatine ganglion (SPG), also known as the pterygopalatine ganglion. The role of the SPG in the pathophysiology of headaches and facial pain has become clearer in the past decade. In this case report, we describe a 30 year-old woman with insidious onset of right facial pain. She was suffering from daily pain for more than 9 years prior to her visit at the pain clinic. Her pain was constant with episodic aggravation without a predisposing trigger factor. The patient was evaluated by multiple different specialties and tried multimodal therapy, which included antiepileptic medications, with minimal pain relief. A SPG block using short-acting local anesthetic provided significant temporary pain relief. The second and third attempt of SPG block using different local anesthetic medications demonstrated the same responses. After a thorough psychological assessment and ruling out the presence of a correctable cause for the pain, we decided to proceed with SPG electrical neuromodulation. The patient reported significant pain relief during the electrical nerve stimulation trial. The patient underwent a permanent implant of the neurostimulation electrode in the SPG region. The patient was successfully taken off opioid medication and her pain was dramatically responsive during a 6 month follow-up visit. In this article we describe the SPG nerve stimulation and the technical aspect of pterygopalatine fossa electrode placement. The pterygoplatine fossa is an easily accessible location. This case report will be encouraging for physicians treating intractable facial pain by demonstrating a novel therapeutic option. This report shows a minimally invasive approach to the SPG.

Ultrasound guided peripheral nerve stimulation implant for management of intractable pain after inguinal herniorrhaphy.

BACKGROUND: Inguinal hernia repair is one of the most common operations performed worldwide. Intractable pain following this operation is a potential debilitating complication. The exact etiology of this complex pain is unknown and the treatment of chronic pain after inguinal herniorrhaphy can be a difficult task for both the patient and the clinician. OBJECTIVES: The objectives of this study are to identify the ability of peripheral nerve electrical stimulation to decrease post inguinal herniorrhaphy pain, increase patients' functionality, and decrease pain medication use. STUDY DESIGN: Three patients with intractable pain after inguinal herniorrhaphy were included in this case series. Two patients had right-sided inguinal repair and one had a left-sided repair. Pain in these patients all began after the inguinal repair and had an average pain duration of 3.4 years after surgery. All 3 patients had been treated with multiple pain management modalities without significant pain improvement. We will describe the clinical course of these patients who presented with chronic intractable pain. After a period of failed conservative medical management and repetitive successful nerve blocks, we decided to proceed with utilizing electrical nerve stimulation as a treatment modality. SETTING: This retrospective study was done at the university hospital and has an IRB assigned number. RESULTS: After careful consideration of the patients' history and physical examination and a thorough psychological assessment, we proceeded with a temporary percutaneous electrical neurostimulation that provided significant pain relief. Ultrasound guided permanent percutaneous electrical neurostimulation implant was shown to provide significant pain relief at 12-month follow-ups. We reviewed all existing pertinent medical literature related to the management of post herniorrhaphy pain. This case series adds to our current knowledge for chronic intractable post herniorrhaphy pain management. LIMITATIONS: This study is a retrospective assessment of a new technique that was applied to a limited number of cases. It remains to be determined whether this technique is superior to the classical open surgical technique in the future. Our findings warrant further studies on the utilization of peripheral nerve stimulation with chronic post herniorrhaphy pain.

Neuromodulation of the suprascapular nerve.

The shoulder joint is an enarthrodial or ball-and-socket joint. A complex network of anatomic structures endows the human shoulder with tremendous mobility, greater than any other joint in the body. Many pathologies can been found in those patients with chronic shoulder pain. The painful limitation of shoulder motion affects hand and arm motion as well; therefore, it significantly influences work performance and everyday activities as well as the quality of life. Therefore, the treatment of patients with chronic shoulder pain has major social and health economic implications. In this article we present a patient with a complex history of shoulder pathology including 7 surgeries that left the patient with chronic debilitating shoulder pain. She was suffering from chronic pain and limited mobility of the shoulder joint due to adhesive shoulder capsulitis. She was treated with a multimodality approach with the goals of increasing shoulder range of motion and decreasing her pain. This did not provide significant improvement. The suprascapular nerve supplies motor and sensory innervation to the shoulder, and can be easily accessible in the supraspinatus fossa. A suprascapular nerve block dramatically decreased her pain. This clinical observation along with confirmatory nerve block play an important role during the decision-making process for a trial period of electrical neuromodulation. She was followed for 3 months after the permanent implantation of a suprascapular nerve stimulator. Her pain and shoulder range of motion in all planes improved dramatically. Peripheral nerve stimulation (PNS) of the suprascapular nerve, in addition to multimodality pain management, is one approach to the difficult task of treating adhesive capsulitis with accompanying pain and the inability to move the shoulder. We conducted a literature review on PubMed and found no case describing a similar patient to our knowledge.

Neuromodulation of the great auricular nerve for persistent post-traumatic headache.

Headache is the most frequent reason for referral to an outpatient neurology and pain physician practice, with post-traumatic headache (PTH) accounting for approximately 4% of all symptomatic headaches. Headache following trauma has been reported for centuries. In this unique case report we will discuss the clinical course and successful headache treatment of a 57-year-old man diagnosed with PTHs. He suffered from chronic, intractable headaches resistant to multidisciplinary medical management for 4 years. A trial of electrical neuromodulation of the C2-C3 branches within the great auricular nerve (GAN) distribution was proposed as a potential long-term treatment for his chronic, intractable headaches after having several prior headache attacks successfully aborted with ultrasound-guided GAN blocks. Six months after permanent peripheral neurostimulator implantation, the patient reported a greater than 90% reduction in headache frequency, and was able to wean off all his previous prophylactic and abortive headache medications, with the exception of over-the-counter ibuprofen as needed. Subcutaneous electrode application over the branches of C2-C3-namely greater, lesser, and the least occipital nerves-for the treatment of chronic, intractable headache is not a new concept within pain medicine literature. However, subcutaneous electrode application, specifically over the GAN, is unique. The following case report chronicles the novel application of ultrasound-guided peripheral nerve stimulation of the GAN as an effective and safe long-term treatment for chronic, intractable primary headache. The positive outcome chronicled in this case presentation suggests that peripheral nerve stimulation of the GAN should be considered for highly select cases. To our knowledge, this is the first such case report describing GAN as a target for the management of PTH in the literature.

High cervical epidural neurostimulation for post-traumatic headache management.

Headache following head injuries has been reported for centuries. The majority of post-traumatic headache (PTH) patients will report resolution of their complaints within a few months from the time of the initial injury. PTHs can contribute to disability, lost productivity, and health care costs. In this article we discuss a 40-year-old male with a history of motor vehicle accident and basal skull fracture. The patient had no headache history prior to the accident. He presented with more than 3 years persistent daily headache. The patient described constant throbbing and stabbing quality headaches predominantly on the left hemicranium with constant facial pain. He denies having aura, nausea, or vomiting, but reported occasional neck tightness. An extensive workup was carried out under the direction of the patient's primary neurologist. Secondary to persistent intractable pain, the patient was referred to the pain clinic for further evaluation. As his headaches were resistant to all trialed strategies, we decided to turn our therapeutic focus toward electrical neuromodulation along with continuing multimodal medications and multidisciplinary approach. During 7 days of high cervical dorsal column electrical nerve stimulation trial, he reported almost 90% pain reduction and significant improvement on his quality of life. On 12 months follow-up after he underwent a permanent implant of high cervical dorsal column electrical nerve stimulation, he reported the same level of pain reduction along with 100% satisfaction rate. To the best of our knowledge, there have been no publications to date concerning the application of high cervical nerve stimulation for PTH.