Disclosures: Evan A. Plunkett, MD: No financial relationships or conflicts of interest

Case Description: The patient was referred for ultrasound assessment of chronic left posterior ankle pain and possible mass. She described burning pain exacerbated by prolonged standing or walking. She also reported intermittent paresthesias affecting the lateral ankle and foot. Lyrica helped control the pain. Her symptoms started with an inversion ankle sprain requiring surgical repair of her anterior talofibular ligament. Subsequent to this, she developed posterior leg pain and focal enlargement that would fluctuate in size. She had unremarkable testing with Doppler studies and electrodiagnosis prior to presentation. Examination revealed tenderness at the gastroc-soleus junction and focal enlargement that increased with ankle plantar flexion and decreased with dorsiflexion. Her neurologic examination was unremarkable.

Setting: Outpatient PM&R office.

Patient: A 30 year-old female with focal posterior leg swelling and pain following previous ankle surgery. Assessment/

Results: Ultrasound showed a large muscle herniation through a fascial defect in the distal gastroc-soleus junction, located where the sural nerve exits from the posterior compartment to the subcutaneous fascia. There was also high-grade Achilles tendinosis. Relative rest and use of a heel lift were recommended for initial treatment. The patient was referred to a surgeon for fascial defect repair with a detailed description to allow for decompression and protection of the sural nerve.

Discussion: Muscle hernias are a rare cause of lower limb pain but are in the differential for localized discomfort, particularly in the presence of a palpable lump. Other conditions to consider include varicose veins, hematomas, vascular malformations, muscle strains, and tumors. Ultrasound is an excellent modality for assessing muscle herniations given its high resolution and capability of assessing tissue movement. Caution should be used to avoid excessive transducer pressure, which could potentially mask herniation.

Conclusion: Muscle herniation is a rare but important diagnosis to consider when evaluating a patient with posterior leg pain. Ultrasound is an excellent modality for this assessment.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/use-of-ultrasound-to-diagnosis-a-gastrocnemius-muscle-herniation-and-sural-neuritis-a-case-report/