What is the Lasegue mark?
The Lasègue sign is a clinical sign that belongs to the neurological and orthopedic examination methods. It was named after the French doctor Ernest-Charles Lasègue. The Lasègue sign, or Lasègue test, is based on the triggering of stretch pain in the spinal nerve roots L4 to S1 and the sciatic nerve. A positive Lasègue sign is an indication of inflammation in the area of these nerve roots or the sciatic nerve. Since it is also positive in the case of meningeal irritation, it is also carried out if meningitis (meningitis) is suspected.
Causes of a positive Lasègue sign
Many orthopedic and neurological diseases require examination of the Lasègue sign. Possible causes for a positive Lasègue sign are inflammation in the area of the spinal nerve roots L4 to S1 and inflammation or irritation of the sciatic nerve, also known as the sciatic nerve.
A common cause of such nerve damage in the area of the spinal nerve roots is a herniated disc. The sciatic nerve itself can be damaged in its course and trigger sciatica / sciatica, also known as lumbago or lumbago, or when it emerges as the spinal nerve S1, it can be damaged as part of a herniated disc. Theoretically, the S1 nerve is damaged, which by definition is not yet referred to as the sciatic nerve. This means that a positive Lasègue sign indicates the localization of a possible disease. Furthermore, the Lasègue sign can be positive for meningitis. The meninges are irritated and are stretched by the movement, so that they cause a sharp pain.
Causes of a negative Lasègue sign
A negative Lasègue sign occurs in principle in healthy individuals and in those patients who do not suffer from a nerve root compression syndrome in the area of the nerve roots L4 to S1 or from meningeal irritation. Herniated discs that affect higher spinal nerve roots are not detected with this clinical examination sign.
What is a crossed Lasègue sign
If there is a crossed Lasègue sign, the unaffected leg is examined. The affected person lies on his back and the examiner lifts the unaffected leg in a straight line. A positive Lasègue sign with the crossed Lasègue sign means that a pain suddenly shoots in the opposite leg that is lying on the bed and has not been lifted, which can spread to the motor / sensitive area of the affected nerve root. This means that the crossed Lasègue test works like the "normal" Lasègue test, with the difference that the unaffected leg is raised and symptoms are caused in the affected leg. A positive Lasègue sign in the crossed Lasègue test means that there is irritation of the spinal nerve roots L4 to S1, the sciatic nerve or irritation of the meninges on the opposite side.
How do you test the Lasègue sign?
The Lasègue sign is tested by first lying down on a couch. The affected person lies on their back. The examiner lifts the patient's affected leg in an extension. While the leg is raised in a stretched manner, passive flexion occurs in the hip joint. The Lasègue sign is positive if further flexion is no longer possible from an angle in the hip joint of 70 - 80 ° due to sudden shooting pain. Typically the pain kicks in at 40 to 60 degrees of flexion in the hip. The examiner notes the angle at which pain occurs. With a positive Lasègue sign, pain suddenly kicks in and can spread to the motor and sensitive area of the affected nerve root. A positive Lasègue sign thus provides an indication of root irritation in the range from L4 to S1, damage to the sciatic nerve or irritation of the meninges. The Lasègue sign is negative if there is no pain.