Working Diagnosis:
Right sural neuritis of unknown clinical significance complicated by underlying Achilles tendinopathy.

Treatment:
For his sural neuritis, conservative management with relative rest, ice, and topical compound of amitriptyline, gabapentin, and ketoprofen were prescribed. Due to persistence of symptoms, patient underwent ultrasound-guided hydrodissection of the sural nerve for diagnostic and therapeutic purposes. Case Photo #5 , Case Photo #6

For his Achilles tendinopathy, a home eccentric exercise program and referral to physical therapy for gait evaluation and retraining were provided. Additional treatments including iontophoresis, nitrous oxide patches, and platelet-rich plasma injections were discussed. Avoidance of oral NSAIDs was recommended due to his renal dysfunction.

Outcome:
The patient continues to engage in his typical daily routines without functional limitation. The symptoms attributed to his sural neuritis and his Achilles tendinopathy have resolved.

Author's Comments:
With regards to images:
Yellow arrow - indicates sural nerve
Purple arrow - indicates focal inflammation/edema
Red asterick - indicates infiltrated injectate

Editor's Comments:
Sural nerve entrapment is uncommon, even in athletes, but can be a debilitating condition and should be considered in any patient with chronic or recurrent pain and paresthesias of the posterolateral calf, ankle and foot as early diagnosis and treatment is imperative to prevent irreversible nerve damage. Entrapment is typically due to chronic fascial inflammation at the fibrous arcade near the Achilles musculotendinous junction from recurrent microtrauma and injury, often aggravated by activities such as running and jumping. Conservative measures may include activity modification, elimination of external compression forces, physical therapy and use of nonsteroidal anti-inflammatories, vitamin B6, tricyclic antidepressants or topical anesthetics. Ultrasound imaging can be useful for the detection of peripheral entrapment neuropathy and ultrasound-guided hydrodissection can provide a minimally invasive alternative with favorable symptom resolution reported, especially as the surgical options of neurolysis or neurectomy are not without risk or complications and generally should be reserved for refractory cases.

References:
Fabre T, Montero C, Gaujard E, Gervais-Dellion F, Durandeau A. Chronic calf pain in athletes due to sural nerve entrapment: a report of 18 cases. Am J Sports Med. 2000; 28(5):679-682.

Meadows JR, Finnoff JT. Lower extremity nerve entrapments in athletes. Curr Sports Med Rep. 2014; 13(5):299-306.

Fader RR, Mitchell JJ, Chadayammuri VP, Hill J, Walcott ML. Percutaneous ultrasound-guided hydrodissection of a symptomatic sural neuroma. Orthopedics. 2015; 38(11):e1046-e1050.

McCrory P, Bell S, Bradshaw C. Nerve entrapments of the lower leg, ankle and foot in sport. Sports Med. 2002; 32(6):371-391.

Paraskevas GK, Natsis K, Tzika M, Ioannidis O. Fascial entrapment of the sural nerve and its clinical relevance. Anat Cell Biol. 2014; 47(2):144-147.

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