Bacterial meningitis affects more than 1 million people per year globally and ranks as one of the top ten most deadly infectious diseases. Bacterial meningitis has a high frequency of neurologic sequelae and mortality and is treatable with antibiotics, which makes the diagnosis extremely important and time-sensitive. As compared with other febrile illnesses, bacterial meningitis is relatively rare. Because of this, many clinical tests have been described to help providers differentiate meningitis from other causes of fever and headache. Two of the most commonly used are Kernig's and Brudzinski's signs. The original report of Brudzinski's sign was in the late 1800s by Dr. Josef Brudzinski. At that time, he described four maneuvers to aid in the clinical diagnosis of meningitis. The four maneuvers he described included the Brudzinski's reflex, the cheek sign, the nape of the neck sign and the symphyseal sign. The most popular of the maneuvers is the nape of the neck sign, currently known as Brudzinski's sign.
Brudzinski's sign is characterized by reflexive flexion of the knees and hips following passive neck flexion. To elicit this sign, the examiner places one hand on the patient's chest and the other hand behind the patient's neck. The examiner then passively flexes the neck forward and assesses whether the knees and hips flex. Upon passive neck flexion, a positive test results when the patient flexes his knees and hips. During the process of performing the test, the hand on the chest prevents the patient from reflexively lifting his chest off the bed which decreases the specificity of the test. While the pathophysiology for the hip/knee flexion is not completely understood, the theory is that hip and knee flexion occurs as an involuntary reflex to compensate and help reduce meningeal irritation. Passive neck flexion causes spinal cord movement and stretching of the meninges, resulting in pain for patients with meningitis. The thinking is that the involuntary hip/knee flexion occurs to create maximal relaxation of the meninges, reducing pain.