What is the treatment for psoas myositis?

From the Guidelines

Treatment for psoas myositis should prioritize rest, pain management, and antibiotics, with vancomycin recommended for initial empirical therapy, especially in cases where community-acquired MRSA is suspected 1. When treating psoas myositis, it's essential to start with rest and avoid activities that aggravate the pain. Non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen (400-600mg three times daily) or naproxen (500mg twice daily) can be used to reduce inflammation and pain.

• If the myositis is bacterial in origin, antibiotics such as vancomycin are recommended for initial empirical therapy, given the prevalence of community-acquired MRSA 1.
• In cases where the causative agent is identified as MSSA, cefazolin or antistaphylococcal penicillin is recommended for definitive therapy 1.
• Physical therapy should be initiated once acute pain subsides to restore strength and flexibility to the psoas muscle.
• Applying heat to the affected area for 15-20 minutes several times daily can improve blood flow and reduce muscle tension.
• In severe cases, especially if an abscess has formed, drainage guided by CT or ultrasound may be necessary, as prompt treatment is crucial to prevent complications like sepsis 1. Key considerations in treatment include:
• The use of MRI as the recommended imaging modality for establishing the diagnosis of pyomyositis, with CT scan and ultrasound studies also being useful 1.
• The importance of obtaining cultures of blood and abscess material to guide antibiotic therapy 1.
• The need for early drainage of purulent material and repeat imaging studies in patients with persistent bacteremia to identify undrained foci of infection 1.

From the Research

Treatment Options for Myositis of the Psoas

• The treatment for myositis of the psoas can vary depending on the underlying cause and severity of the condition.
• In a case report, etidronate treatment was initiated for a patient with myositis ossificans in bilateral psoas major muscles, which improved pain after 4 days 2.
• For idiopathic inflammatory myopathies, such as polymyositis and dermatomyositis, glucocorticoids are considered the mainstay of treatment, with some patients requiring add-on immunosuppressive therapy 3.
• Biological therapies, such as B-cell blockade by rituximab, have shown promise in treating polymyositis, dermatomyositis, and juvenile dermatomyositis 4.
• Exercise has also been shown to be beneficial in improving aerobic capacity and reducing disability in patients with polymyositis and dermatomyositis 4.
• In cases of iliopsoas disorders, conservative treatment options include activity modification, physical therapy, nonsteroidal anti-inflammatory drugs, and corticosteroid injections, with surgical treatment considered if conservative measures fail 5.

Specific Treatment Approaches

• Etidronate administration may be effective in treating myositis ossificans, as seen in a case report where it improved pain after 4 days 2.
• Rituximab has been shown to be effective in treating polymyositis, dermatomyositis, and juvenile dermatomyositis, particularly in patients with anti-Jo or anti-Mi-2 antibodies 4.
• Exercise has been shown to improve aerobic capacity and reduce disability in patients with polymyositis and dermatomyositis, and is well-tolerated in patients with juvenile dermatomyositis 4.
• Surgical treatment for iliopsoas disorders typically involves arthroscopic lengthening of the musculotendinous unit and treatment of concomitant intra-articular abnormality 5.