The Bernhardt-Roth syndrome, also known as Meralgia paraesthetica (Greek: mêros = thigh, algos = pain, paraesthetica = unpleasant, sometimes painful physical sensation), is a nerve constriction syndrome of the nervus cutaneus femoris lateralis. This nerve runs through the inguinal ligament and transmits sensations of touch from the outside of the thigh to the spinal cord. When the nerve is constricted, its conduction path is disturbed, which leads to discomfort and pain in the area supplied by the nerve. One of the nerve constriction syndromes is the more common carpal tunnel syndrome.
Symptoms
The Bernhardt-Roth syndrome manifests itself through sensations of discomfort up to burning, tingling, needle-stick-like pain in the front and side of the thigh. As this is damage to a purely sensitive nerve, only sensations, e.g. from the skin, are affected. Muscle movements are not affected.
This nerve damage can also lead to a general increase in sensitivity (hyperaesthesia) in the course of the disease, which can make even the wearing of clothing or light touching unbearable. Furthermore, a reduced sensitivity (hypaesthesia) – the area of the leg feels numb or furry – can also result. It is characteristic that the symptoms are alleviated when the hip joint is bent (for example when sitting).
If the impairment is very severe, vegetative disorders such as hair loss or skin changes are possible. The vegetative (autonomic) nervous system controls the unconscious physical processes that are not deliberately influenced. 10 to 20 percent of patients are bilateral and men are affected by Berhardt-Roth syndrome up to three times more frequently than women.
Causes
The Bernhardt-Roth syndrome is mainly caused by pressure on the nervus cutaneus femoris lateralis in the area of the inguinal ligament. Here, the nerve is particularly at risk, since the course of the nerve runs from an initially horizontal to a vertical direction, resulting in a kink. Another possibility are tensile forces acting on the nerve.
A complication caused by surgical procedures, such as puncture of the iliac crest to extract bone marrow and rarely after complicated abdominal or hip joint surgery, must also be considered as a cause of Bernhardt-Roth syndrome. Furthermore, infections in general (e.g. syphilis) or alcoholism and other nerve toxins can lead to nerve damage. Increased pressure on the nerves can be caused by tight clothing (jeans, belts), overweight (obesity), pregnancy, forced weight training in the area of the thigh, hip and abdomen or even long standing activity with a very stretched hip joint. However, rapid weight loss can also lead to the above-mentioned complaints, as the surrounding connective tissue and fat dwindles here and this can lead to irritation.
Diagnosis
The diagnosis of Bernhardt-Roth syndrome is based on a comprehensive medical interview (anamnesis), physical and neurological examination. Here, above all, the reduced sensation in the area of the lateral outer side of the thigh falls into this category. When the hip joint is hyperextended with the leg stretched, pain is provoked in the area supplied by the pinched nerves.
In addition, the point where the nerve runs under the inguinal ligament is increasingly painful under pressure. This place is located about two transverse fingers medially (i.e. towards the middle of the body) of the upper iliac crest protrusion. An MRI (magnetic resonance imaging) can be used to assess altered anatomical conditions or tumorous masses.
The injection of a local anaesthetic (local anaesthetic) into the inguinal ligament and a subsequent improvement in symptoms can confirm the suspicion of Bernhardt-Roth syndrome. A suspicion of root compression syndrome, i.e. a mechanical irritation of a nerve in the area of the spine where the nerves emerge from the spinal cord, should be excluded in the diagnosis. In contrast to the Bernhardt-Roth syndrome, muscle paralysis, reflex weakening of certain characteristic muscles of the leg (e.g. the patellar tendon reflex – reflex of the anterior large thigh muscle) and discomfort in other skin areas of the upper and lower leg are often conspicuous.
