DRG Spinal Cord Stimulation as Solution for Patients With Severe Pain Due to Anterior Cutaneous Nerve Entrapment Syndrome: A Case Series.

OBJECTIVES: Anterior Cutaneous Nerve Entrapment Syndrome (ACNES) is a debilitating neuropathic pain condition. A small portion of patients do not respond to any currently available treatment modalities. These patients, often young women, might benefit from targeted spinal cord stimulation of the dorsal root ganglion (DRG). METHODS: This retrospective case series describes five ACNES patients who were referred from a Dutch dedicated tertiary referral center to collaborating sites with extensive experience in DRG stimulation to be implanted with a DRG Axium System (St. Jude/Abbott, IL, USA) in the period of 2013-2016. Numeric pain rating scores at routine 6- and 12-month follow-up visits were analyzed. RESULTS: Three patients experienced >50% pain reduction at 12 months follow-up. Four patients experienced device-related complications, such as lead dislocation, lead breakage, pain at the battery site, and overstimulation. CONCLUSIONS: This case series suggests DRG spinal cord stimulation can be safe and effective for some patients with persistent pain due to ACNES.

Lateral Cutaneous Nerve Entrapment Syndrome (LACNES): A previously unrecognized cause of intractable flank pain.

BACKGROUND AND AIMS: Chronic abdominal pain may occasionally be due to terminal endings of intercostal nerves (ACNES, abdominal cutaneous nerve entrapment syndrome) that are entrapped in the abdominal wall. Spontaneous neuropathic flank pain may also be caused by involvement of branches of these intercostal nerves. Aim is to describe a series of patients with flank pain due to nerve entrapment and to increase awareness for an unknown condition coined Lateral Cutaneous Nerve Entrapment Syndrome (LACNES). METHODS: Patients possibly having LACNES (constant area of flank tenderness, small point of maximal pain with neuropathic characteristics, locoregional altered skin sensation) presenting between January 2007 and May 2016 received a diagnostic 5-10mL 1% lidocaine injection. Pain levels were recorded using a numerical rating scale (0, no pain to 10, worst possible). A >50% pain reduction was defined as success. Long term effect of injections and alternative therapies were determined using a satisfaction scale (1, very satisfied, no pain - 5, pain worse). RESULTS: 30 patients (21 women, median age 52, range 13-78) were diagnosed with LACNES. Pain following one injection dropped from 6.9±1.4 to 2.4±1.9 (mean, p<0.001) leading to an 83% immediate success rate. Repeated injection therapy was successful in 16 (pain free n=7, pain acceptable, n=9; median 42 months follow-up). The remaining 14 patients received (minimally invasive) surgery (n=5) or other treatments (medication, manual therapy or pulsed radiofrequency, n=9). Overall treatment satisfaction (scale 1 or 2) was attained in 79%. CONCLUSIONS AND IMPLICATIONS: LACNES should be considered in patients with chronic flank pain. Injection therapy is long term effective in more than half of the population.

Pulsed radiofrequency or anterior neurectomy for anterior cutaneous nerve entrapment syndrome (ACNES) (the PULSE trial): study protocol of a randomized controlled trial.

BACKGROUND: Some patients with chronic abdominal pain suffer from an anterior cutaneous nerve entrapment syndrome (ACNES). This somewhat illusive syndrome is thought to be caused by the entrapment of end branches of the intercostal nerves residing in the abdominal wall. If ACNES is suspected, a local injection of an anesthetic agent may offer relief. If pain is recurrent following multiple-injection therapy, an anterior neurectomy entailing removal of the entrapped nerve endings may be considered. After 1 year, a 70% success rate has been reported. Research on minimally invasive alternative treatments is scarce. Pulsed radiofrequency (PRF) treatment is a relatively new treatment for chronic pain syndromes. An electromagnetic field is applied around the nerve in the hope of leading to pain relief. This randomized controlled trial compares the effect of PRF treatment and neurectomy in patients with ACNES. METHODS: Adult ACNES patients having short-lived success following injections are randomized to PRF or neurectomy. At the 8-week follow-up visit, unsuccessful PRF patients are allowed to cross over to a neurectomy. Primary outcome is pain relief after either therapy. Secondary outcomes include patient satisfaction, quality of life, use of analgesics and unanticipated adverse events. The study is terminated 6 months after receiving the final procedure. DISCUSSION: Since academic literature on minimally invasive techniques is lacking, well-designed trials are needed to optimize results of treatment for ACNES. This is the first large, randomized controlled, proof-of-concept trial comparing two therapy techniques in ACNES patients. The first patient was included in October 2015. The expected trial deadline is December 2017. If effective, PRF may be incorporated into the ACNES treatment algorithm, thus minimizing the number of patients requiring surgery. TRIAL REGISTRATION: Nederlands Trial Register (Dutch Trial Register), NTR5131 ( http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=5131 ). Registered on 15 April 2015.

Chronic Abdominal Wall Pain: An Under-Recognized Diagnosis Leading to Unnecessary Testing.

Chronic abdominal wall pain (CAWP) refers to a condition wherein pain originates from the abdominal wall itself rather than the underlying viscera. According to various estimates, 10% to 30% of patients with chronic abdominal pain are eventually diagnosed with CAWP, usually after expensive testing has failed to uncover another etiology. The most common cause of CAWP is anterior cutaneous nerve entrapment syndrome. The diagnosis of CAWP is made using an oft-forgotten physical examination finding known as Carnett's sign, where focal abdominal tenderness is either the same or worsened during contraction of the abdominal musculature. CAWP can be confirmed by response to trigger point injection of local anesthetic. Once diagnosis is made, treatment ranges from conservative management to trigger point injection and in refractory cases, even surgery. This review provides an overview of CAWP, discusses the cost and implications of a missed diagnosis, compares somatic versus visceral innervation, describes the pathophysiology of nerve entrapment, and reviews the evidence behind available treatment modalities.

A systematic review of the treatment for abdominal cutaneous nerve entrapment syndrome.

BACKGROUND: Abdominal cutaneous nerve entrapment syndrome (ACNES) is a frequently overlooked cause of chronic abdominal pain. We aim to outline the current available literature concerning the treatment of patients diagnosed with ACNES. DATA SOURCES: A systematic search in PubMed, EMBASE, CINAHL, and Cochrane databases was performed. Seven studies were included; describing trigger point injection (TPI) or anterior neurectomy as stand-alone procedure, TPI followed by anterior neurectomy as stepwise regimen, and nerve stimulation and phenolization. After TPI, 86% of the patients showed successful response, 76% at long-term follow-up. Two other studies report successful treatment in 50% of patients. In the included trial using anterior neurectomy, 73% vs 18% of the patients demonstrate a successful pain response in the neurectomy and sham group, respectively. Two cohort studies showed that 69% and 61% of the neurectomy group reported to be satisfied at 18 months and 32 months follow-up, respectively. CONCLUSIONS: There is significant pain relief after injections and anterior neurectomy. Awareness of the diagnosis is important. The validity of currently used diagnostic criteria needs to be evaluated in additional studies.

Transverse abdominal plane neurostimulation for chronic abdominal pain: a novel technique.

Management of chronic abdominal pain can be challenging. Sometimes patients fail to get adequate response from multiple medications and nerve blocks. We present a patient case report of chronic abdominal pain with a history of multiple surgeries managed successfully by neuromodulation of the transverse abdominis plane (TAP). The TAP block is a procedure in which local anesthetic is injected into the abdominal fascial plane that carries sensory nerves to the abdominal wall in order to block pain sensation. It has been shown to reduce postoperative pain and analgesic dependence after abdominal and gynecological surgeries. A 60-year-old woman presented to us for chronic abdominal pain for which medications provided little relief. She had an extensive history of abdominal surgeries and was also treated for lower back pain with surgery and less invasive procedures in the past. Under our care, she underwent 2 TAP blocks with almost complete resolution of her abdominal pain. Her pain, however, came back within a few of weeks of the procedures. Since our patient found pain relief from the TAP blocks, we proceeded with neurostimulation of the TAP for long-term pain relief. We placed a dorsal column stimulator 16 contact lead for lower back and leg pain and 8 contact leads placed in the TAP under ultrasound guidance. She has had multiple follow-ups since her TAP lead placement procedure with continued and near complete resolution of her abdominal pain. The TAP lead stimulation was helping her abdominal pain and the dorsal column lead stimulation was helping her back and leg pain.

Abdominal wall trigger point case study.

Myofascial trigger points (TrPs) are posited to be an element in the etiology of both musculoskeletal and visceral pain. However, the recognition of TrPs as a causative factor in a patient's pain presentation varies amongst physicians and therapists. When myofascial pain syndrome is responsible for a patient's condition and is not recognized by the patient's medical advisors, the patient may be put through a plethora of testing procedures to find the cause of the patient's pain, and prescribed medications in an effort to treat the patient's symptoms. The case review presented here involves a patient with severe anterior abdominal pain, with a history of Crohn's disease, who experienced a long and difficult medical process before a diagnosis of myofascial pain syndrome was made.

Weight-based volume of injection influences cranial to caudal spread of local anesthetic solution in ultrasound-guided transversus abdominis plane blocks in canine cadavers.

OBJECTIVE: To determine if the volume of injected local anesthetic solution affects cranial to caudal spread when performing ultrasound-guided transversus abdominis plane (TAP) blocks in dogs. STUDY DESIGN: Prospective experimental study. ANIMALS: Adult Beagle cadavers (n = 20) METHODS: Bilateral TAP blocks using ultrasound guidance was performed in 20 Beagle cadavers (mean ± SD weight, 9.3 ± 1.4 kg) using a 1:1 solution of methylene blue/bupivacaine injected at volumes of 0.25, 0.5, 0.75, and 1.0 mL/kg. Cadavers were dissected to determine injectate spread within the transversus abdominis fascial plane. RESULTS: The transversus abdominis fascial plane was adequately identified by ultrasonography, injected, and dissected in 38 beagle hemi-abdominal walls; injectate was not identified in 2 hemi-abdominal walls. Dermatomal spread (number of ventral nerve roots saturated by injected solution) was volume dependent (P = .026, Kruskal Wallis): 2.9 ± 0.74 nerve roots for 0.25 mL/kg; 3.4 ± 1.1 for 0.5 mL/kg; 4.0 ± 0.67 for 0.75 mL/kg; and 4.2 ± 1.2 for 1 mL/kg. CONCLUSION: In Beagle cadavers, the volume of injected local anesthetic solution significantly affects cranial to caudal spread within the TAP during ultrasound-guided TAP blocks. The volume of local anesthetic injected could potentially be used to augment the spread of analgesic coverage for a given surgical procedure in dogs.

Management of anterior cutaneous nerve entrapment syndrome in a cohort of 139 patients.

OBJECTIVE: Anterior cutaneous nerve entrapment syndrome (ACNES) is generally neglected as a source of chronic abdominal pain. The aim of this study was to evaluate the efficacy of a diagnostic workup protocol and treatment regimen in patients with suspected ACNES. METHODS: A cohort of all consecutive patients presenting with chronic abdominal pain suggestive of ACNES between 2003 and 2008 was evaluated retrospectively. Patients were offered a single diagnostic injection of 1% lidocaine into the trigger point followed by subsequent therapeutic injections including corticosteroids. If pain was refractory, an anterior neurectomy was performed. Pain scores were done using a visual analog scale for evaluation of the injection regimen and Verbal Rating Scale (1-5) for long-term efficacy. RESULTS: A total of 139 patients with suspected ACNES (77% women, mean age 47 ± 17 years) were evaluated. Eighty-one percent (n = 94) demonstrated a visual analog scale reduction of at least 50% after the first injection. Some 33% (n = 44) remained permanently pain-free after injection therapy only. Sixty-nine patients underwent a neurectomy, which was successful in 49 (71%). Long-term efficacy revealed in 71% (very) satisfying visual rating scale (1-2) results, whereas an additional 9% reported attenuated levels of pain (visual rating scale 3). CONCLUSION: A regimen of consecutive local trigger point injections is effective in one-thirds of patients with ACNES. Surgical neurectomy is effective in about two-thirds of the injection regimen refractory patients. Eighty percent of the entire ACNES population reports total or substantial pain relief on the long term.

Chronic abdominal wall pain--a diagnostic challenge for the surgeon.

BACKGROUND: Chronic abdominal wall pain (CAWP) occurs in about 30% of all patients presenting with chronic abdominal pain. METHODS: The authors review the literature identified in a PubMed search regarding the abdominal wall as the origin of chronic abdominal pain. RESULTS: CAWP is frequently misinterpreted as visceral or functional abdominal pain. Misdiagnosis often leads to a variety of investigational procedures and even abdominal operations with negative results. With a simple clinical test (Carnett's test), >90% of patients with CAWP can be recognized, without risk for missing intra-abdominal pathology. CONCLUSION: The condition can be confirmed when the injection of local anesthetics in the trigger point(s) relieves the pain. A fasciotomy in the anterior abdominal rectus muscle sheath through the nerve foramina of the affected branch of one of the anterior intercostal nerves heals the pain.

Cortical evoked responses to magnetic stimulation of macaque's abdominal wall in sleep-wake cycle.

EEG and eye movements (magnetic search coil method) were recorded in sleep and wakefulness in a monkey (Macaca fascicularis) while the animal was sitting in a primate chair. Single pulse magnetic stimulation was applied to the monkey's abdominal wall using a circular coil and a Magstim 200 stimulator. Magnetic stimuli did not wake the sleeping animal, and being applied during slow wave sleep evoked clear responses in EEG with a latency of 80-100 ms. These responses disappeared during wakefulness and rapid eye movement sleep. Control experiments confirmed that these responses were not caused by the acoustic clicks produced by the magnetic coil. Results of this study further confirm that during sleep, signals from visceral organs reach the cortical areas which in wakefulness process exteroceptive sensory information. This observation indicates that magnetic stimulation may be a useful tool for researching neural connectivity reorganization within the sleep-wake cycle.

Improving respiration in patients with tetraplegia by functional electrical stimulation: an anatomical perspective.

Patients with tetraplegia often have respiratory complications because of paralysis of the abdominal and intercostal muscles. Functional electrical stimulation (FES) has been used to improve breathing in these patients by applying surface stimulation to the abdominal muscles. We aimed to find the best nerves to stimulate directly to increase tidal volume and make cough more effective. Surface electrodes were placed on a patient's abdominal wall to find the optimum points for surface stimulation. These positions were plotted on a transparent sheet. The abdomino-intercostal nerves were dissected in five male dissecting room cadavers matched for size with the patient. The plastic sheet was then superimposed over each of the dissections to clarify the relationship between optimum surface stimulation points and the underlying nerves. Results show that the optimum surface stimulation points overlie the course of abdomino-intercostal nerves T9, 10, and 11. The success with selecting stimulation points associated with T9, 10, and 11 is probably because of the large mass of abdominal muscle supplied by these nerves. The constant position of the nerves below the ribs makes the intercostal space a possible site for direct stimulation of the abdomino-intercostal nerves.

[Pain originating from the abdominal wall: a forgotten diagnostic option]. / Dolor originado en la pared abdominal: una alternativa diagnóstica olvidada.

Chronic abdominal pain is a common clinical problem in primary care, and is usually referred to gastroenterologists or general surgeons. Although up to 20% of cases of idiopathic abdominal pain arise in structures of the abdominal wall, this is frequently overlooked as a possible cause. It includes pain arising from structures of the abdominal wall including skin, parietal peritoneum, cellular subcutaneous tissue, aponeuroses, abdominal muscles and somatosensorial innervation from lower dorsal roots. The diagnosis is based on anamnesis and physical examination. Carnett's sign is a simple maneuver that discriminates between parietal and visceral pain. Management with topical anesthesia is effective in a majority of patients and can help to confirm the diagnosis.

[The abdominal wall: an overlooked cause of pain]. / La parete addominale: una trascurata fonte di dolore.

Abdominal wall pain is frequently misdiagnosed as arising from visceral source, often resulting in inappropriate diagnostic tests, unsatisfactory treatment and high costs. The Authors describe the various causes of abdominal wall pain with particular regard to abdominal cutaneous nerve entrapment syndrome. They analyze the main features of abdominal wall pain: a localized tender trigger point can be frequentely identified, the Carnett's sign is positive and the local injection of an anesthetic agent into the trigger point can be diagnostic and therapeutic, while image techniques are useful when the pain results from structural conditions. At last they describe the therapeutic options.