An Infant with Femoral Osteomyelitis Misdiagnosed as Lumbosacral Plexitis / 대한소아신경학회지

ABSTRACT

Pseudoparalysis is defined as immobility of the extremity due to painful limb infection. However, such conditions may be misdiagnosed as nerve palsy when abnormal neurologic findings are present. We report herein a case with femoral osteomyelitis that was misdiagnosed as lumbosacral plexitis. A 7-month-old male infant was brought by his parents to the clinic who noticed that he did not move his left leg since 4 days prior to admission. Four days prior to admission, the parents noticed that he was not moving his left leg. There were no signs of inflammation in the involved limb. The left leg showed a motor weakness with grade 4/5, and it was hypotonic with decreased deep tendon reflexes. No abnormal findings were shown in studies which included lumbar spine magnetic resonance imaging (MRI), abdominal computed tomography (CT), and nerve conduction studies. Lumbosacral plexitis was diagnosed presumptively and intravenous immunoglobulin (IVIG) was given. The patient's symptom did not improve with the IVIG. After the orthopedic consultation, a hip MRI was performed and it showed acute osteomyelitis involving the proximal metaphysis of the left femur. Surgical debridement and intravenous antibiotics were administered. The patient's symptoms improved with treatment and he was fully recovered by the time of discharge. During the 4-year follow-up, the patient is doing well without any complication in the bone growth. During infancy, limb infection may present with nerve palsy that is characterized by hypotonic weakness with hyporeflexia. Pseudoparalysis may be the sole sign of osteomyelitis. In a unilateral limb weakness, musculoskeletal infection should be an initial diagnosis of exclusion with a thorough evaluation.