Dynamic Ultrasound Examination for Asymptomatic/Bilateral Peroneus Brevis Muscle Hernias

A 30-yr-old male patient presented with chronic/intermittent palpable bulging in the lateral sides of both legs. He had complaints (e.g., pain and spasm) only after strenuous activities of the calf during sports. He had no history of trauma or surgery, and the medical history was otherwise unremarkable. Physical examination revealed bilateral and symmetric palpable fusiform masses (with a longitudinal diameter of 15–20 mm) on the lateral side of the calf regions—only during squatting not in normal position. Neurological examination was normal. Dynamic ultrasound imaging (during squatting) uncovered bilateral peroneus brevis muscle herniations. The fascial defects were very small, and the mass lesions had no compression on any nerve (Fig. 1).FIGURE 1: Ultrasound imaging clearly visualizes the herniation of peroneus brevis muscle during squatting (A). Note the defective area of the fascia (white arrows) and the herniated muscle part (asterisk). Contralateral side is also imaged during resting/normal position where hernia is not evident at all (B).A muscle hernia (also known as a myofascial herniation) is a focal protrusion of the muscle tissue through a defect in its fascia. The muscle bulging usually ensues to the subcutaneous tissue, especially in some positions that cause volume constriction.1 Muscle hernias are most common in the leg (i.e., tibialis anterior muscle).2 Involvement of peroneus brevis and longus, extensor digitorum longus, and gastrocnemius muscles have also been reported in the literature. Muscle hernias can be (a)symptomatic and congenital or secondary to trauma.1,2 Ultrasound and magnetic resonance imaging are used in the diagnosis. Herein, taking into account the appearance/mechanism of the problem, dynamic examination is paramount.3 Likewise, we present a case of peroneus brevis muscle herniation diagnosed by dynamic ultrasound examination. Unless promptly diagnosed, this simple pathology (i.e., muscle hernia) can mimick other (benign) mass lesions, such as hematoma, angioma, epidermoid cyst, lipoma, schwannoma, or traumatic muscle rupture. Accordingly, the diagnostic procedures might even end up with biopsy and/or surgery.1,3 Herein, a substantial ultrasound examination (including dynamic manuevers/positioning and Doppler imaging) plays a crucial role.3 However, most patients are asymptomatic and respond to conservative treatment.