Understanding Nerve Pain in the Calf

A pinched nerve in calf is a potential cause of pain in the lower leg or foot, especially when imaging is normal. How do we make a diagnosis of a pinched nerve in lower leg, and how do we treat it?

Common pinched nerves in calf 

The common nerves that can become damaged and cause nerve pain in lower leg include the following:

Superficial peroneal nerve entrapment 

The superficial peroneal nerve comes from the common peroneal nerve as it wraps around the fibular head close to the outside of the knee. This nerve passes through the muscles of the outside of the leg. Then, halfway down the lower leg, it pierces the deep fascia to travel just under the skin. It is here that pinching can occur.

Generally, common symptoms of a pinched superficial peroneal nerve include pain in the outer part of the lower leg and the top of the foot. Sometimes, people can also experience numbness and pins and needles in this area.

Usually, ankle sprains or direct trauma to the outside of the lower leg can result in pinching or thickening of the nerve as it passes through the deep fascia.

Tarsal tunnel syndrome

The tarsal tunnel is a space between the long bone called the tibia and the inside of the Achilles tendon. It is covered by a touch retinaculum and contains the posterior tibial nerve, vessels, and tendons.

Tarsal tunnel syndrome occurs when the posterior tibial nerve is compressed in the tarsal tunnel – similar to carpal tunnel syndrome in the wrist.

Generally, symptoms of tarsal tunnel syndrome include burning or shooting pain at the inside ankle and mid arch. Sometimes, numbness or pins and needles can occur in the inside arch.

Overall, compression causes include a ganglion cyst, arthritis spurs, extra muscles in the inside ankle, or twisting of the ankle.

Below is an example of a ganglion in a male runner with pain, paraesthesia, and numbness in the foot.

Trapping of one branch of the tibial nerve close to the heel causes pain in the heel, often mistaken as plantar fasciitis. This condition is called Baxter’s nerve.

Sural nerve entrapment  

The sural nerve comes from the large sciatic nerve at the back of the knee. It pierces the deep facia and travels just under the skin as it passes down. It then follows the outer part of the Achilles tendon down the calf. Finally, just above the ankle, it leaves the outer part of the tendon and travels to the outer part of the foot.

Generally, sural nerve entrapment produces pain down the outer calf and into the outside of the ankle and foot. Sometimes, pain can be accompanied by numbness and pins and needles.

Pinching of the sural nerve can occur as it passes through the deep facia from direct trauma or ankle pain. Also, trapping can occur close to the Achilles tendon from Achilles tendonitis or paratendonitis. In some cases, trapping of the nerve can occur from scar tissue or suture material after repairing the Achilles. See this blog for further information on sural nerve pain. 

Medial plantar nerve entrapment

The posterior tibial nerve splits at the inside part of the ankle to form the medial and lateral plantar nerves. The medial plantar nerve passes inside the medial arch close to the foot’s tendons. At one point, called the Knott of Henry, the nerve can become trapped, causing pinpoint pain in the inside arch. Generally, this condition is called jogger’s foot and is often misdiagnosed as plantar fasciitis.

How to diagnose pinched nerve in calf 

Generally, it is difficult to diagnose as symptoms often overlap with other conditions. In addition, we should suspect a trapped nerve in calf when imaging such as MRI is normal.

Usually, the site of symptoms can give a clue as to which one of the nerves are pinched. Also, pain from a pinched calf nerve often differs from tendon or joint pain. For example, pain from a trapped nerve is switched on by walking or running and off by rest. Finally, tapping the nerve at the trapping site (Tinel’s sign) may produce the symptoms.

In general, tests that are used to confirm a diagnosis include:

• Nerve conduction studies to prove how and why entrapment has occurred. Sometimes, however, these studies may be normal in entrapment.

• MRI scan 

• blood tests to rule out other nerve dysfunction causes such as nerve inflammation occurring in diabetes, an underactive thyroid, or immune system problem.

Recently, more doctors are using ultrasound to follow the course of the nerve to see if there is evidence of trapping at any point. Also, ultrasound allows a method to inject the nerve with a local anesthetic or cortisone. However, improvement in pain after a cortisone injection makes nerve entrapment more likely.

It is essential to exclude other conditions that overlap with a trapped nerve, such as an inflamed nerve from medical diseases, local inflammation from muscles and tendons, and nerve trapping from above (sciatica or piriformis syndrome).

Does tarsal tunnel syndrome show on MRI? 

Sometimes, if the trapping of the nerve is due to a growth, MRI picks up pressure on the nerve. However, MRI will not pick up all cases of tarsal tunnel syndrome.

Treatments of nerve pain in lower leg

Once the diagnosis is confirmed, then simple treatments are started.

Ibuprofen cream or tablets can reduce inflammation of the nerve and improve symptoms. In addition, physical therapy such as soft tissue massage, acupuncture, and neural glides can loosen the nerve. Sometimes, medications such as amitriptyline or duloxetine can reduce nerve symptoms.

Sometimes, we use ultrasound-guided cortisone injection at the site of a pinched nerve to confirm and help the problem.

Finally, surgery to release the pinched nerve can be considered. However, surgery should only be considered when other treatments have been tried and imaging or injection has confirmed the cause.

Final word from Sportdoctorlondon about a pinched nerve in calf

Unexplained pain in the calf, foot, or ankle might be due to nerve damage. If imaging such as X-ray or MRI is normal, consider a pinched nerve as a possible cause. The diagnosis is made by combining an assessment with other tests such as ultrasound, nerve conduction studies, and an injection. Overall, you should see a doctor experienced in picking up these uncommon causes of unexplained pain.

Related topics:

• Pinched nerve: what does it mean?
• Burning pain in the thigh: could it be meralgia paraesthetica?
• CRPS: How to treat it?
• Baxter’s nerve entrapment
• Carpal tunnel syndrome
• Cubital tunnel syndrome
• Sural nerve pain