Brudzinski's "new sign" in meningitis is probably one of the best signs in the diagnosis of this disease, although it does not differentiate between the various forms. It consists of reflex actions manifested in what are called the neck-sign and the leg-sign. It comprises two reflex phenomena, the identical reflex (réflexe identique) and the contralateral reflex (réflexe contralatérale).
The identical reflex is elicited by forcibly flexing the head on the chest, when the arms and legs regularly assume the positions shown in Figures 2 and 3.
The contralateral reflex is produced by passive flexion of one leg, which causes the fellow limb to draw up and remain in the position shown in Figure 4.
Of the two signs the neck-sign is the more constant and is really a refinement of the ordinary "stiff-neck," "rigidity," etc., mentioned in the descriptions of the physical signs in meningitis.
Brudzinski1 in forty-two
NORTHRUP WP. NEW REFLEX SIGNS IN MENINGITIS DIAGNOSIS. JAMA. 1911;LVI(2):114-115. doi:10.1001/jama.1911.02560020030010