Marc A. Huntoon

Anatomy of the cervical intervertebral foramina: vulnerable arteries and ischemic neurologic injuries after transforaminal epidural injections.

&NA; Cervical transforaminal epidural steroid injections are performed for the treatment of radicular pain. Multiple recent case reports have raised safety concerns regarding neurologic deficits such as anterior spinal artery syndrome and cerebellar injury after these injections. To investigate the potential causes of these injuries, an anatomic study was conducted. In this study of 10 embalmed cadavers, the cervical intervertebral foramina were examined to determine if the ascending or deep cervical arteries supplied radicular or segmental medullary arteries potentially susceptible to cannulation or needle trauma during transforaminal injection. In two specimens, dissection was carried down to the spinal cord, demonstrating the anterior spinal, radicular, and segmental medullary arteries. Of 95 intervertebral foramina dissected, 21 had an arterial vessel proximal to the posterior aspect of the foraminal opening. Seven of these 21 were spinal branches that entered the foramen posteriorly, potentially forming radicular or segmental medullary vessels to the spinal cord. One additional ascending cervical artery formed a segmental medullary artery that joined the anterior spinal artery. This would only be injured by anterior needle misplacement. Of the seven foraminal branches, three were included in the deep dissections. Two contributed to segmental medullary arteries and one to a radicular artery. Variable anastomoses between the vertebral and cervical arteries were found. Therefore, it is possible to introduce steroid particles into the vertebral circulation via the cervical arteries. Critical arteries are located in the posterior aspect of the intervertebral foramen and may be vulnerable to injection or injury during transforaminal epidural steroid injection.

Paralysis after transforaminal epidural injection and previous spinal surgery.

Objective This case discusses a rare but devastating complication of transforaminal epidural injection. Elements in the patients history that may be risk factors are discussed. Case report A 64-year-old man was evaluated for chronic low-back pain after multiple spine surgeries. After the most recent surgery, he suffered transient cauda equina symptoms. Because conservative therapy was not helpful for spinal stenosis and neuroclaudication, a left L2 transforaminal epidural injection was attempted, but a posterolateral fusion mass made this procedure impossible. A left L1 transforaminal approach was successful, and 1 mL of iopamidol (Isovue) contrast was injected, followed by 5 mL of a solution of 0.125% bupivacaine and 40 mg of triamcinolone. Approximately 1 to 2 minutes after injection, the patient described discomfort in the lower abdomen, and 1 minute later, he was unable to move his lower extremities. An MRI showed T2 signal change in the conus medullaris gray matter at T11-12, consistent with an acute vascular infarct. Spinal shock protocol with high-dose methylprednisolone was begun without change. More than 4 years later, the patient continues to be troubled by persistent paraparesis and chronic pain. Conclusions This case report is part of a new and growing body of literature that demonstrates the potential risk of transforaminal injection. Further study is necessary to ensure that spinal vascular injuries can be kept to an acceptably rare level.

Epidural Abscess and Meningitis After Epidural Corticosteroid Injection

Epidural abscess with and without associated meningitis after epidural corticosteroid injections for radicular back pain is a rarely reported complication. We report the occurrence of an epidural abscess and meningitis in a 70-year-old man after 2 epidural corticosteroid injections for treatment of acute radicular lumbar back pain. At the time of diagnosis, cerebrospinal fluid cultures grew Staphylococcus aureus, and the patient was treated with intravenous antibiotics. Possible predisposing factors for the development of an epidural abscess and meningitis in this patient include a 2-year history of neutropenia and an accidental dural puncture that occurred during performance of the first epidural injection. A literature search identified 11 reported cases of epidural abscess, 2 of epidural abscess and meningitis, and 1 of meningitis attributed to epidural corticosteroid injections. Eight of the 14 reported patients were immunocompromised, and 8 (67%) of the 12 in whom cultures of blood, cerebrospinal fluid, or epidural pus were performed had results positive for S. aureus. Antibiotic prophylaxis for S. aureus should be considered for immunocompromised patients undergoing epidural corticosteroid injections.

Ultrasound‐Guided Permanent Implantation of Peripheral Nerve Stimulation (PNS) System for Neuropathic Pain of the Extremities: Original Cases and Outcomes

OBJECTIVE Our objective is to describe our experience applying a minimally invasive, ultrasound-assisted technique for peripheral nerve stimulation (PNS) trial and permanent implantation in patients with neuropathic extremity pain. DESIGN Retrospective case series and review of the literature. Setting. Tertiary referral center and academic medical center. PATIENTS Patients with upper or lower extremity neuropathic pain resistant to other therapies who responded to an ultrasound-guided peripheral nerve block at a proximal location. Interventions. Ultrasound-assisted through-the-needle placement of percutaneous neurostimulation electrodes on target major peripheral nerves for fully percutaneous trial, staged trial or permanent implantation of PNS system. A PNS trial period of 3-7 days was used. OUTCOME MEASURES Pain relief at last follow-up, complications, therapeutic limitations due to technique as applied. Results. Six of eight (75%) patients and 7/9 (78%) peripheral nerves had a successful trial and underwent permanent PNS system implantation using a minimally invasive, ultrasound-assisted technique from November 2007 to December 2008. All but one patient with an implanted PNS system had > or =50% pain relief at last follow-up and 3/7 (43%) permanent systems were associated with > or =80% relief. Loss of paresthesia required revision to dual-lead systems in upper extremity radial nerve PNS. Infection led to explant in one case. CONCLUSIONS In a small series of patients, a minimally invasive, ultrasound-assisted technique for PNS trial, and permanent PNS implantation proved feasible. Patients without adequate analgesia during neurostimulation trial avoided surgical incision and those undergoing permanent implantation were not subjected to the potential morbidity associated with nerve dissection.

4. Cervical radicular pain.

Cervical radicular pain is defined as pain perceived as arising in the arm caused by irritation of a cervical spinal nerve or its roots. Approximately 1 person in 1,000 suffers from cervical radicular pain. In the absence of a gold standard, the diagnosis is based on a combination of history, clinical examination, and (potentially) complementary examination. Medical imaging may show abnormalities, but those findings may not correlate with the patients pain. Electrophysiologic testing may be requested when nerve damage is suspected but will not provide quantitative/qualitative information about the pain. The presumed causative level may be confirmed by means of selective diagnostic blocks. Conservative treatment typically consists of medication and physical therapy. There are no studies assessing the effectiveness of different types of medication specifically in patients suffering cervical radicular pain. Cochrane reviews did not find sufficient proof of efficacy for either education or cervical traction. When conservative treatment fails, interventional treatment may be considered. For subacute cervical radicular pain, the available evidence on efficacy and safety supports a recommendation (2B+) of interlaminar cervical epidural corticosteroid administration. A recent negative randomized controlled trial of transforaminal cervical epidural corticosteroid administration, coupled with an increasing number of reports of serious adverse events, warrants a negative recommendation (2B−). Pulsed radiofrequency treatment adjacent to the cervical dorsal root ganglion is a recommended treatment for chronic cervical radicular pain (1B+). When its effect is insufficient or of short duration, conventional radiofrequency treatment is recommended (2B+). In selected patients with cervical radicular pain, refractory to other treatment options, spinal cord stimulation may be considered. This treatment should be performed in specialized centers, preferentially study related.

Subcutaneous peripheral nerve stimulation with inter-lead stimulation for axial neck and low back pain: case series and review of the literature.

Objectives:  While pain in the extremities often responds to treatment using spinal cord stimulation (SCS), axial pain is notoriously refractory to SCS. Interest in subcutaneous peripheral nerve stimulation (SQ PNS) as an alternative to SCS has emerged, but the most appropriate electrode locations and neurostimulator programming techniques are not yet clear.

The Vertebral Artery is Unlikely to be the Sole Source of Vascular Complications Occurring during Stellate Ganglion Block

Introduction:  Stellate ganglion block (SGB) is commonly performed for upper extremity complex regional pain syndrome and other conditions. Known complications of stellate block include Horners syndrome, hoarseness, hematoma formation, airway compromise, immediate seizure (presumably from vertebral artery injection), and death. A previous arterial anatomy study demonstrated other vessels, eg, the ascending and deep cervical arteries, reinforcing the blood supply of the spinal cord and brain stem. The potential role of these vessels in the pathogenesis of seizures or hematoma during SGB has not been studied.

Review of spinal cord stimulation in peripheral arterial disease.

Ever since its initial development in the late 1960s, spinal cord stimulation (SCS) has been used to treat a number of painful conditions. European practice, in contrast to that in North America, has used peripheral arterial disease (PAD) as a primary indication for SCS. First employed in patients with PAD in 1976, SCS was shown by Cook et al. to heal chronic leg ulcers. Numerous subsequent retrospective studies of SCS in PAD show improvements in multiple outcomes such as exercise tolerance, limb salvage, and pain. Previous retrospective studies are likely flawed with respect to author bias, inadequate sample size, and possible placebo effects. Further, they have not identified clinical criteria for selecting SCS therapy. Recent randomized prospective studies have questioned some of the conclusions from these preceding retrospective data. In addition to the questions related to outcomes, theories regarding exact mechanisms by which SCS improves circulatory parameters remain unclear. A thorough Medline literature review on the subject of SCS in peripheral vascular disease was thus undertaken to attempt to clarify questions regarding which patients are best suited for SCS therapy, pinpoint possible methodologic flaws in previous studies, and to review the background, outcomes, mechanisms of action, complications, and alternatives for SCS in patients with PAD.

Intrinsic spinal cord catheter placement: implications of new intractable pain in a patient with a spinal cord injury.

We present a case of new intractable flank pain after intrathecal infusion system placement in a 45-yr-old man with a history of a T12 spinal cord injury with dysesthetic leg pain. Pain after intrathecal infusion system placement was evaluated by magnetic resonance imaging and the catheter was found to be intraparenchymal. The patient was treated by cessation of infusion and surgical removal of the system. Before surgical removal, the pump was turned off and the patients flank pain resolved. Increased vigilance is warranted when caring for paraplegic patients. When new pain persists, intrathecal medication tapering should be considered.

Thoracic spinal cord stimulation for post-ablation cardiac pain in a patient with permanent pacemaker.

Background:  Spinal cord stimulation (SCS) is increasingly utilized for inoperable, intractable chest pain because of ischemia. Because patients with ischemic heart disease commonly have permanent cardiac pacemakers (PPM) or automated implantable cardio‐defibrillators (AICD), concurrent use of SCS and PPM or AICD may grow. Interference between SCS and PPM or AICD devices is potentially dangerous and has been previously reported.