ASRA Pain Medicine Update

Literature Review - August 2020

Aug 1, 2020, 11:03 AM by Sudheer Potru, DO, and Anthony Machi, MD

Editor’s note: “Literature Review” is a new feature of the ASRA News designed to provide you with brief summaries of recent articles of interest, particularly from sources that our readers might not normally consume. 

Ultrasound-Guided Subcostal TAP Block with Depot Steroids in the Management of Chronic Abdominal Pain Secondary to Chronic Pancreatitis: A Three-Year Prospective Audit in 54 Patients”

by Niraj G, Kemal Y. In: Pain Med. 2020;21(1):118-24.

Selection and Summary by Sudheer Potru, DO.

Chronic pancreatitis often results in ongoing chronic abdominal pain. The pain can be because of visceral abdominal pain syndrome (VAPS) from the ongoing pancreatic inflammation or from viscerosomatic convergence that leads to abdominal wall myofascial pain syndrome (AMPS). A total of 38 patients at a tertiary-care institution with chronic abdominal pain from chronic pancreatitis (17 with VAPS and 21 with AMPS) underwent bilateral subcostal transversus abdominis plane (STAP) blocks with depot methylprednisolone 80 mg. Clinically significant pain relief was defined as a two-point change in VAS at 3 months. Durable relief was defined as four-point change at 3 months and two-point change at 6 months. Treatment failure was described as return of pain to baseline within 4 weeks.

Results: 95% (20/21) of patients with AMPS who underwent bilateral STAP had clinically significant pain relief at 3 months, and 62% (13/21) of patients had durable relief. The remaining one patient reported transient pain relief (2 weeks) after STAP and proceeded to have ultrasound-guided trigger point injections, which provided clinically significant relief at 3 months. Of the 17 patients with VAPS who underwent STAP blocks, 100% failed treatment (17/17).

Key point: STAP blocks may be an effective option in the management of abdominal myofascial pain secondary to chronic pancreatitis. The block is ineffective in producing clinically significant pain relief in the presence of visceral pain.

“The Effectiveness of Radiofrequency Ablation of Medial Branch Nerves for Chronic Lumbar Facet Joint Syndrome in Patients Selected by Guideline-Concordant Dual Comparative Medial Branch Blocks”

by Conger A, Burnham T, Salazar F, et al. In: Pain Med. 2020;21(5)902-9.

Selection and Summary by Sudheer Potru, DO.

Radiofrequency ablation (RFA) of the medial branch of the lumbar dorsal spinal nerves is typically performed for lumbar facet joint pain after successful diagnostic medial branch blocks. The threshold for proceeding to RFA has varied; some physicians require a 50% reduction in pain as a threshold, while others recommend an 80% reduction in pain. Previous studies have demonstrated prolonged relief if the 80% threshold is used, but most of these authors have only followed patients to the 1-year mark. 

To ascertain the clinical utility and sustained benefits of the commonly used 80% pain reduction threshold following two comparative medial branch blocks prior to RFA, researchers conducted a telephone survey study of 85 patients from one institution. Outcome measurements included Numerical Rating Scale (NRS), Patient Global Impression of Change (PGIC), and report of 50% or more reduction of index pain. These outcome measurements were also evaluated in the setting of different patient characteristics that included increasing age, duration of pain, presence of scoliosis, degenerative spondylolisthesis, and >75% disc height loss. 

Results: Patients who had undergone lumbar medial branch RFA after 80% relief from two comparative medial branch blocks showed substantial pain relief. Although the results demonstrated were not statistically significant (p = 0.17), this resulted in >50% pain reduction in 63.2% of patients at 6 to 12 months, 65.6% at 12 to 24 months, and 44.1% at >24 months. Patient characteristics including older age and a smaller Cobb angle were associated with >50% pain reduction.

When patients were evaluated at least 6 months following RFA, >70% reported a pain reduction of two or more NRS points and >50% demonstrated a PGIC score that was “much improved” or better.

Key point: Lumbar medial branch RFA is an effective treatment for a substantial proportion of patients (potentially up to 44% of patients 2 years post-treatment) who undergo two sets of diagnostic medial branch blocks and obtain >80% pain relief.

Time to Block: Early Regional Anesthesia Improves Pain Control in Geriatric Hip Fractures”

by Garlich JM, Pujari A, Debbi EM, et al. In: J Bone Joint Surg Am. 2020;102(10):866-72.

Selection and summary by Anthony Machi, MD.

Delay in adequate analgesia for hip fracture in geriatric patients leads to worse outcomes, including increased rate of delirium and increased hospital length of stay. Regional anesthesia is an important effective component of analgesia for hip fracture endorsed by the American Academy of Orthopaedic Surgeons. A single center, prospective cohort study was conducted in 107 patients age 60 or older who presented to the emergency department with a hip fracture and received a fascia iliaca block (FIB) between arrival and 4 hours before transfer to the preoperative holding area. Patients were enrolled from March 1, 2017, to December 31, 2017. The pri mary outcomes were opioid consumption and pain scores on a visual analog scale. Multiple secondary outcomes were investigated, including incidence of delirium and opioid-related adverse events, and hospital length of stay. Time to block (TTB) was defined as time from emergency department arrival to block placement, while time to surgery (TTS) was defined as time from emergency department arrival to surgical start. 

Results: The median TTB was 8.5 hours and served to distinguish the 2 groups into early blockade (<8.5 hours) and late blockade (>8.5 hours). The mean TTS in the early blockade group was 24.9 hours, while the mean TTS in the late blockade group was 32.1 hours. Among all patients, 72% of all opioids were received prior to block placement. Patients with an earlier FIB received fewer opioids (12.0 vs 33.1 morphine milligram equivalents), had lower VAS scores for pain on postoperative day 1 (2.8 vs 3.5) and were discharged earlier (4.0 vs 5.5 days). No difference was found in incidence of delirium (20.0% vs 22.6%) or opioid-related adverse events (17.0% vs 14.8%). 

Key point: Opioid consumption, pain, and hospital length of stay may all be reduced by early preoperative fascia iliaca blockade in geriatric patients with hip fracture.

“An Iliopsoas Plane Block Does Not Cause Motor Blockade—A Blinded Randomized Volunteer Trial”

by Nielsen ND, Madsen MN, Ostergaard HK, et al. In: Acta Anaesthesiol Scand. 2020;64(3):368-77.  

Selection and summary by Anthony Machi, MD.

Use of peripheral nerve blockade techniques for analgesia related to hip surgery has been controversial due to the motor blockade that accompanies common techniques, such as femoral nerve and lumbar plexus blockade. This is particularly important because they can inhibit early mobilization and potentially lead to falls. The iliopsoas plane block (IPB) targets the sensory branches of the femoral nerve to the hip joint; however, it is not known if this leads to motor blockade as well.

A single center, double-blinded randomized volunteer trial was conducted in June 2018 on 22 healthy subjects by performing IPB on each leg, one with a lidocaine 1.8% mixture with gadoteric acid and the other normal saline with gadoteric acid. The primary outcome measure was the decrease in maximal force knee extension 1 hour after IPB compared to baseline. Secondary outcome measures included decrease in maximal force of hip adduction, sensory testing for the distribution of cutaneous blockade, maximal force for active vs sham injectate, and assessment of the spread pattern by MRI.

Results: No significant decrease in maximal force knee extension or hip adduction and no decrease in sensation at the lateral thigh or at the medial patella were found. All subjects had injection in the desired IPB plane confirmed by MRI, while two subjects had evidence of intra-articular spread.

Key point: The iliopsoas plane block may be a technique that provides sensory blockade and analgesia to the hip joint without causing appreciable motor blockade.

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