Fabre, T., et al. (2000). Chronic calf pain in athletes due to sural nerve entrapment. A report of 18 cases. Am J Sports Med, 28(5), 679-682.

BACKGROUND

Entrapment syndromes in the lower extremity are nowhere near as common as they are in the upper extremity. However, there are some cases where nerve entrapment may occur and it is a good idea to be aware of these potential sites of entrapment when encountering lower extremity pain.

The sural nerve is a sensory branch of the tibial nerve. It runs between the heads of the gastrocnemius muscle and then runs down the lateral aspect of the posterior leg. There is a small fibrous tunnel through the fascia in this region that the nerve passes through called the fibrous arcade. It is in this region near the musculotendinous junction where entrapment of the sural nerve is most likely to occur. Sural nerve entrapment symptoms are most likely to be felt in the posterior and distal lateral aspect of the leg

This paper was a review of 18 different cases of sural nerve entrapment in athletes. The primary purpose was to better understand the condition and some of the factors that may play a part in its development. The authors stated that the problem, while not very common, is most likely under diagnosed and often mistaken for other conditions such as musculotendinous complaints or vascular problems.

Symptoms included chronic pain in the posterior aspect of the leg. The pain appeared to get worse with physical exertion so there seemed to be some correlation with activity aggravating the problem. For most of the patients, pain was in the posterior calf region but several of them reported sensations that radiated into the foot and several others reported pain in the upper calf. There was increased tenderness to pressure just posterior and lateral to the musculotendinous junction with the Achilles tendon. This region corresponds to the common fibrous arcade that the sural nerve passes through and it is suggested that this is one of the more common regions of sural nerve entrapment.

Patients described in these 18 different cases were treated surgically for fibrous restrictions to the sural nerve. Surgical treatment was successful in most cases with only one of these cases reporting results that were not favorable.

DISCUSSION

The authors state that the area of tenderness and symptom reproduction is an important factor when evaluating the possibility of sural nerve entrapment. The pain can usually be reproduced with finger pressure in the area near the musculotendinous junction on the lateral aspect of the calf. There are several other conditions that may have pain similar to that of sural nerve entrapment and these conditions should also be considered when evaluating the problem. These problems include posterior exertional compartment syndrome and popliteal artery entrapment.

The authors found that the majority of these cases were with patients who were a little older (average age was 43). There seems to be some indication that decreasing flexibility of the soft tissues may be one of the major contributing factors to the problem. They also suggested that increased training levels by the patients involved in this study may have significantly increased the muscle mass in the area to the point that nerve compression was an issue.

It was also suggested that another reason for this problem might be an absence of proper stretching exercises. It is very likely that proper stretching of the gastrocnemius and soleus muscles would help prevent the nerve entrapment for several reasons. First, increasing the extensibility of these muscles would decrease the likelihood that they would be hypertonic and contribute to nerve compression. Second, the very act of stretching the muscles would also help improve mobility of the nerve as it passes through the fibrous arcade of the posterior calf muscles. Increasing the neural mobility will decrease the chances that nerve entrapment here will ever be a problem.

Since many massage techniques applied to the posterior calf region may put pressure on the sural nerve, it is valuable for massage practitioners to be aware of this problem. If any of these techniques aggravate the pain sensations and the pain pattern appears to be neurological and radiates into the distal and lateral aspect of the foot, it is wise to consider that the technique may be irritating the sural nerve. It is also wise to be aware of this potential nerve entrapment problem since it is likely that most clinicians would assume this is a musculotendinous problem because of the pain location near the musculotendinous junction of the gastrocnemius and soleus with the Achilles tendon.

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