Case report of isolated rectus femoris atrophy

Introduction: Non-traumatic neuromuscular lesions of only one muscular portion of the quadricepsare rare and poorly described in literature.Aim: The goal of our study was to investigate the possible causes of this pathology and toobjectively quantify the functional consequences of this isolated atrophy from the rectus femoris onthe total muscular performances of the quadriceps.Patient and Method: A male patient, 44 years old, presented an isolated atrophy of the right rectusfemoris without pain nor history of previous traumatic event. He reported occasional paraesthesiason anterior right thigh. Electromyographic exploration of the lower limbs, imagery (echography andMRI) and isokinetic test were undertaken by the patient.Results: Imagery explorations showed the atrophy of the right rectus femoris combined with fattydegeneration but this exam did not allow determining the actual etiology. Therefore, a precisediagnosis was not allowed, even if the EMG confirmed the presence of important signs of specificand isolated denervation only in the right rectus femoris. The isokinetic test, performed in theclassical sitting position, highlighted symmetrical performances for flexors of the knee and amoderately decrease in the right concentric quadriceps torque (-10%). A complementary isokineticassessment, in a lying supine position, demonstrated a more marked deficit of this right quadriceps(higher than -30%).Conclusion: No precise etiology was shown for this isolated atrophy of the right rectus femoris.Nevertheless, we brought back the importance to lay the patient in a lying supine position in orderto preferentially investigate the rectus femoris performances through an isokinetic test.