Methadone for Patients with Malignant Psoas Syndrome: Case Series of Three Patients

Malignant psoas syndrome (MPS) is a relatively rare syndrome that accompanies malignancy; the pain associated with MPS is often difficult to control. Methadone is known to be effective in relieving both nociceptive and neuropathic pain.

Herein we describe treatment strategies for three patients with MPS, diagnosed by imaging and clinical findings, who responded to methadone treatment.

Patient diagnoses, pain characteristics, and treatment were analyzed retrospectively. Subjects were three patients with MPS who presented to Hyogo Cancer Center with pain. A numeric rating scale (NRS; 0-10) was used to assess patients' pain levels.

All three patients were diagnosed with malignancies (prostate, cervical, and urachal) and had impaired gait and thigh extension. All had tumor invasion to the iliopsoas muscle, as determined by imaging, and were diagnosed with MPS. After starting methadone, symptoms improved in all patients and they were able to extend the thigh and walk normally. The NRS scores improved by an average of -7.3 points (95% confidence interval [CI] -4.97, -9.69) on Day 14; and the average time until symptom improvement after starting methadone was 2.3 days (95% CI 1.86, 2.80).

Methadone may be considered a treatment choice for MPS patients in whom pain is difficult to control.