Usefulness of Ultrasound for Detecting Suspected Peripheral Nerve Lesions in Diagnosis of Peripheral Neuropathy : Case Report and Brief Review of the Literature
A 55-year-old male presented to the outpatient department complaining of left foot drop that had developed 4 days previously. He had neither back pain nor leg pain. He first noticed the symptom after mountain climbing. He was initially seen by a spine specialist and had undergone a lumbar MRI, which showed only mild central disc bulging at the L3-L4 intervertebral space. The findings were not concordant with the patient's symptoms. Sensation over the anterolateral aspect of the left lower leg and dorsum of the left foot was decreased to light touch and there was weakness of left ankle dorsiflexion with a grade of 2 on the Medical Research Council scale for muscle strength. The presumptive diagnosis was a left peroneal neuropathy, and ultrasound scanning along the left peroneal nerve was performed from the distal sciatic nerve, revealing a mucoid cystic lesion compressing the left common peroneal nerve near the fibular head (). The cyst was connected to the posterolateral aspect of the knee joint ().