Interventional pathway in the management of refractory chronic flank pain: Prospective series in 45 patients

Chronic flank pain can pose a therapeutic challenge. Current management centres on visceral pathology affecting the renal system. Acute exacerbations can be severe, requiring emergency admission. Patients usually have well-established visceral pathology including polycystic kidney disease, Fowler's syndrome, and renal calculi disease that often cause recurrent urinary tract infections. However, in many cases, despite negative investigations including imaging, biochemistry and urine analysis, flank pain persists. Abdominal myofascial pain syndrome is a poorly recognized pathology in this cohort. The report describes the underlying pathophysiology and a novel interventional management pathway for patients presenting with refractory flank pain secondary to abdominal myofascial pain syndrome.

Adult patients with refractory chronic flank pain at a tertiary renal unit were included as a part of an on-going prospective longitudinal audit. Patients refractory to standard management were offered the interventional pathway. The pathway included two interventions: quadratus lumborum block with steroid and pulsed radio frequency treatment. Patients completed brief pain inventory and hospital anxiety and depression scale questionnaires at baseline, 3 and 6 months postprocedure. Outcomes collected included ability to maintain employment, change in opioid consumption at 6 months and impact on emergency hospital admissions at 12 months after initiation of the pathway.

Forty-five patients were referred to the pain medicine clinic over a seven-year period between 2014 and 2021. All patients were offered the interventions. Four patients refused due to needle phobia. Forty-one patients received transmuscular quadratus lumborum plane block with steroids. Twenty-seven patients (27/41, 66%) reported durable benefit at 6 months and six patients (6/41, 15%) had clinically significant relief at 3 months. Fifteen patients received pulsed radiofrequency to quadratus lumborum plane and 11 patients (73%) reported > 50% analgesia at 6 months. Treatment failure rate was 10% (4/41). Opioid consumption at 6 months and emergency admission at 12 months were reduced post intervention.

Abdominal myofascial pain syndrome is a poorly recognized cause of chronic flank pain syndrome. The interventional management pathway could be an effective solution in this cohort.