Figure: area of the thigh where the symptoms of meralgia paresthesiica are located
Meralgia paresthesica is characterized by an "alteration of the sensory perception of the skin at the level of the thigh, without compromising the motor skills of the leg. In fact, the patient feels tingling, numbness and burning pain, but is able to move the affected lower limb without problem." . From these symptoms, the diagnosis is usually made.
The therapy of meralgia paresthesiica foresees, in almost all cases, conservative countermeasures; only in very rare exceptions is surgery necessary.
The inguinal ligament is a strong fibrous bundle and the area in which it resides often coincides with the compression area of the lateral cutaneous nerve.
EPIDEMIOLOGY
Meralgia paresthesiica has a "rather low incidence in the general population: every year, about 4 out of 10,000 people suffer from it.
Figure: Location of the lateral cutaneous nerve of the thigh and area of pain. From the meddic.jp website
Pathological conditions associated with meralgia paresthetic:
- Overweight and obesity
- Diabetes
- Ascites
- Neuromas
- Tumors of the pelvic organs
However, it should be noted that this data is inaccurate, as the disease is often not diagnosed or is considered a consequence of other particular conditions, such as diabetes and obesity. In fact, meralgia paresthetic is particularly common among diabetics and overweight people.
It affects, without distinction, men and women of adulthood. The most frequent cases concern middle-aged people.
(cranial and spinal). This condition is also called diabetic neuropathy.
Seat belts that pass over the inguinal ligament after a strong impact can cause compression of the underlying femoral cutaneous nerve.
A relationship has been shown between meralgia paresthesiica and those who have a habit of wearing clothing that is very close to the waist or that tightens the waistband of their trousers. These habits appear to develop excessive pressure on the femoral cutaneous nerve.
After inguinal hernia surgery, scar tissue can form which creates pressure in the femoral skin nerve.
Neuromas, contrary to what one might think, are not tumors; rather, they are thickenings of fibrous tissue, which press on neighboring nerves.
These are malignant tumors, which affect the organs of the urinary tract (prostate, ureter, kidneys, etc.). Their appearance and the expansion of the neoplastic mass can compress the nerves close to the affected area, such as the femoral skin.
These are circumstances that can stress the nerve endings and, in some cases, compress them.
- Where the burning pain, tingling and numbness are localized.
- Know the exact branches of pain.
- If there are certain movements or circumstances that reduce or increase the intensity.
It is also very significant, during the diagnostic evaluation, to consider the patient's state of health and the possible presence of one or more of the risk factors mentioned above. In other words, the fact that an individual is an overweight person, a woman pregnant, a diabetic, etc., is a further clue to support the diagnosis of meralgia paresthesiica.
WHAT CIRCUMSTANCES ACCENTUATE OR REDUCE THE BURNING PAIN?
It has already been said that walking for a long time or standing for a long time accentuates the symptoms of meralgia paresthesiica.
Similarly, there are some movements of the leg that increase pain, and other movements that reduce it. These gestures have diagnostic significance, so much so that they can be considered real signs of the disease.
What is it about?
- The extension of the hip. It is performed by bringing the affected leg backwards. This movement accentuates the crushing of the femoral cutaneous nerve, aggravating the pain.
- The flexion of the hip. It is done from lying down, bringing the leg towards the abdomen / chest. This movement reduces the compression of the affected nerve, relieving the painful sensation.
DIFFERENTIAL DIAGNOSIS
The differential diagnosis is carried out to exclude the presence of any pathologies characterized by symptoms similar to meralgia paresthetic. It is based on instrumental tests, such as X-rays or electromyography, but also on much simpler tests.
For example, a very quick and fairly significant test is the assessment of the motor skills of the affected leg. If a patient manages to control the movements of his lower limbs, it means that the affected nerve is not motor, but sensitive, as is the cutaneous femoral one. Conversely, if the doctor finds that there is "a" motor inability, it means that the affected nerve is of a motor type and that, probably, it is not a matter of meralgia paresthesiica, but of a "other neurological pathology.
If doubts still remain and more serious neurological damage is suspected, instrumental diagnostics are carried out. However, this is a rare eventuality.
Below is a table with the possible exams and their characteristics:
Instrumental test
When and why to do it
They show the pelvic and abdominal area. They are important tests, for example, for those patients with paresthetic meralgia due to a traffic accident, as they show the health of the internal organs.
If there is no trauma at the "origin of the neuropathy" (diabetes, pregnancy, etc.), they are not essential for the diagnosis.
Using electrodes implanted in the muscles of the leg, the electrical activity is measured. If it is normal, it means that the nerve involved is of a sensory and non-motor type; in these cases, the hypothesis of meralgia paresthetic becomes more than concrete.
Using electrodes, it is possible to observe how the nerve signal travels through the nerve endings. If the femoral cutaneous nerve is compressed or pinched, the detected signal is altered.
If the painful symptomatology, despite these first treatments, persists for more than two months, it is necessary to resort to more effective painkilling and anti-inflammatory drugs, but, at the same time, also with more side effects.
- Injections of corticosteroids.
Features: they serve to reduce inflammation and painful sensation.
Possible side effects: high blood pressure, diabetes, weight gain, aggravation of infections etc. - Tricyclic antidepressants.
Features: relieve pain.
Possible side effects: sluggishness, dry mouth (dry mouth), constipation, reduced libido etc. - Specific drugs for neuropathic treatment.
Features: Gabapentin, Pregabalin or Carbamazepine are some of the drugs used; they serve to relieve pain.
Possible side effects: constipation, nausea, dizziness, sluggishness, etc.
THE SURGICAL APPROACH
Surgery is a very remote hypothesis, which is taken into consideration only if conservative treatments have not had an effect.
The operation consists of the surgical decompression of the lateral cutaneous nerve of the thigh.
