Burning pain in the thigh is a common presentation in active sportspeople. Generally, burning means pain coming from the nervous system, also called neurogenic pain. What causes nerve pain in the thigh, and how do we diagnose and treat burning thigh nerve pain?
Causes of nerve pain in thigh
Common causes of thigh nerve pain are due to nerve entrapment or pinching and include the following:
Meralgia paresthetica
Meralgia paraesthetica is caused by pressure on the lateral femoral cutaneous nerve at the front of the pelvis. Compression of this nerve can occur from weight gain, pregnancy, wearing tight belts or clothing, or surgery to the front of the hip.
Generally, people with meralgia paraesthetica report burning pain on the outside of the thigh, often with numbness and pins and needles. The pain never crosses over to the inner thigh.
Femoral nerve entrapment
The femoral nerve follows the blood vessels of the front of the thigh. It supplies the quadriceps muscle and the skin on the inside of the lower leg.
Pressure on the nerve can be caused by surgery, direct trauma, wearing tight belts or growths in the pelvis. Generally, people feel numbness, pins and needles in the lower front of the thigh (near the knee) and weakness in the leg. Sometimes, the knee can give way due to weakness in the quads.
Genitofemoral nerve pain
This nerve arises from the large hip flexor and passes into the inguinal area. It splits into two branches – the genital branch, which supplies the genitals, and the femoral branch, which supplies the skin at the front of the thigh.
Genitofemoral pain often causes sharp stabbing or burning pain at the front of the thigh or in the genital area.
Obturator nerve pain
The obturator nerve arises from the pelvis and enters the thigh through a small hole in the pelvic bone called the obturator foramen. It passes into the inner thigh, where it divides into two branches. It supplies the inner thigh’s muscles and skin.
Compression of this nerve causes pain in the inner thigh, especially during sports. Sometimes, numbness and pins and needles can follow. Obturator nerve pain often occurs with pubic overload or osteitis pubis. Less commonly, it happens after trauma to the inner thigh or surgery to the pelvis or hip.
Saphenous nerve pain
The saphenous nerve comes from the femoral nerve. It supplies the skin near the front of the knee (below the knee cap) and the inside of the lower leg. Compression of the saphenous nerve occurs from abnormal muscles in the thigh or blunt trauma to the lower thigh or inside of the knee. Surgery to the knee can also be a precipitating factor.
Generally, people report vague pain on the inside of the knee. Pain can be burning or throbbing, and sensation inside the knee is often abnormal.
Nerve pressure from pinched nerve in lumbar spine
Pressure on the nerves from the lumbar spine can cause pain in the thigh. Generally, pressure on the nerves in the upper part of the lumbar spine (L1 to L3) can cause pain radiating to the front of the thigh and the knee.
How to make a diagnosis of thigh nerve pain
Thigh nerve pain is a challenging diagnosis as it overlaps many conditions in the pelvis and thigh. Often, the clue to diagnosis is the history of burning or sharp stabbing pain in the thigh. Imaging tests such as X-rays or MRIs are often normal in thigh nerve pain. Sometimes, pins and needles, numbness and leg weakness are present depending on the nerve affected. Also, your doctor will ask you about other medical problems, such as diabetes or hormonal issues that might cause the problem. In women, asking about matters gynaecological as ovarian cysts or endometriosis is critical.
Your doctor should perform a thorough assessment, including nerve testing and pelvic and hip movements, to ensure the pain is not from other structures.
Sometimes, we use investigations such as blood tests or nerve conduction studies to confirm nerve pain in the thigh or exclude other causes.
Other causes of burning pain in thigh
Your doctor should exclude other causes of thigh pain, including local quadriceps muscle tears, femoral shaft stress fractures, bone growths, and referred pain from the thigh. Your doctor should also exclude localised nerve inflammation from medical conditions such as diabetes, hormonal imbalances, and vitamin deficiencies.
Treatment of burning pain in thigh
There are various treatment options if you suspect a pinched nerve in the thigh.
Physiotherapy
Your physical therapist can help with nerve thigh pain. Soft tissue treatments such as massage may relieve discomfort and tightness. Neural stretches can improve nerve movement or gliding in the soft tissue. Topical products such as capsaicin cream or lidocaine patches are often helpful.
Nerve medications
Simple pain-relieving medication like ibuprofen or paracetamol is often ineffective for nerve-related pain. Alternatively, we use medication that settles nerve excitability. We usually call these medications ‘neuromodulators’. These medications are used for depression or seizures. However, at lower doses, they work to improve nerve pain in the thigh. Examples include Amitriptyline, Duloxetine, Gabapentin, and Pregabalin. While they each have pros and cons, Duloxetine has shown better evidence.
Nerve blocks
Injecting the trapped nerve with a small dose of local anaesthetic and cortisone can confirm the diagnosis and relieve symptoms. Targeting the nerve-trapping site with ultrasound is essential to improve accuracy and reduce side effects. In some cases, such as meralgia paraesthetica, a targeted injeciton can be a cure. Doctors can target other nerves, including femoral, saphenous, obturator and genitofemoral.
Also, if the nerve block relieves symptoms but the pain returns, we can use more definitive treatments, such as radiofrequency ablation (nerve burning).
Surgery
A surgical ‘nerve release’ is an option for persistent pain from trapped nerves. However, surgery is often unpredictable and may not relieve symptoms. So, you should ensure you’ve tried other less invasive options first.
Final word from Sportdoctorlondon regarding nerve pain in thigh
Thigh nerve pain is a common cause of chronic thigh pain. You must consider a nerve cause if tests reveal no apparent focal abnormalities in the thigh or hip. You should see a doctor with experience assessing nerve pain in the thigh.
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