Unusual MRI Findings in a Polio Survivor

Abstract

A 63-year-old male consulted our institution due to worsening of right hip pain for approximately one month. The patient had no apparent functional disorders besides rigidity of the right ankle secondary to childhood poliomyelitis. Plain radiographs demonstrated narrowing of the right hip joint space. Magnetic resonance imaging (MRI) showed unusual findings in the right gluteus medius muscle, suspecting a malignant musculoskeletal tumor. Further examinations clarified acute inflammation caused by Staphylococcus aureus with no atypia. After treatment, serum inflammatory markers normalized and MRI showed homogeneous fat signal intensity in the muscle, which was consistent with poliomyelitis. Total hip arthroplasty was performed due to progression of osteoarthritis. Intraoperative findings showed flaccidity of the gluteus medius muscle, and histological examination of the specimen also was compatible with poliomyelitis. Postoperatively there was no hip instability and the patient has been able to resume his previous physical activity. To our knowledge, this is the first report regarding polio survivors combined with septic arthritis, and sole MRI examination was unable to lead to the diagnosis. The current patient demonstrates the possibility that the involved muscles in poliomyelitis exist even in asymptomatic regions, which will be helpful for accurate diagnosis and life guidance in polio survivors.

Figure 1

Initial MRI of the hip: (a and b) coronal T1-weighted and axial T2-weighted images showing inhomogeneous fatty signal changes in the gluteus medius muscle and (c) coronal STIR image showing apparent high signal lesions in both the gluteus medius and minimus muscles and slightly high signal lesions in both the femoral head and the acetabular bone with the joint effusion.

Figure 2

MRI of the hip taken 10 months after the starting of treatment: (a) coronal T1-weighted image showing low signal osteoarthritis change and (a and b) coronal T1-weighted and axial T2-weighted images showing homogeneous fatty signal changes in the gluteus medius muscle and similar appearance even in the other muscles (arrows).

Figure 3

Intraoperative photograph showing yellowish gluteus medius muscle (arrow), which had flaccid tone.

Figure 4

Histological examination of the gluteus medius muscle showing diffuse fat infiltration with a few atrophic muscle fibers, but no acute inflammation and no atypia (H and E, ×40).