Nursing care
Why Kernig and Brudzinski signs occur in meningitis: stretching inflamed meninges
Written and reviewed by Dana Whitfield, RN, MSN · 4 min read · Updated October 2026
Short answer
In meningitis, the membranes around the brain and spinal cord and the nerve roots passing through them are inflamed and painful to stretch. Kernig and Brudzinski manoeuvres pull on those structures, so the body guards with pain, hamstring spasm or reflex hip and knee flexion. A positive sign supports meningeal irritation, but many patients with meningitis test negative.
Follow the stretch from the limbs to the meninges
The meninges wrap the brain and spinal cord and extend along the nerve roots as they leave the spine. In meningitis, bacteria or viruses trigger an inflammatory response that makes these tissues swollen and sensitive. Movements that lengthen the spinal canal or pull on the lumbosacral nerve roots stretch inflamed tissue, which hurts and provokes protective muscle contraction.
Neck stiffness works the same way: bending the head forward stretches the meninges from above, so the patient resists. Kernig and Brudzinski signs are bedside tests of this protective response. They do not detect infection directly; they detect irritation of the meninges, which can also come from blood in the subarachnoid space or other causes.
How each sign is produced
For Kernig's sign, the patient lies on their back with the hip and knee both flexed to a right angle. The examiner then tries to straighten the knee. A positive sign is pain in the lower back or the back of the thigh, or resistance to extension, caused by reflex hamstring contraction guarding against traction on inflamed roots and meninges.
For Brudzinski's neck sign, the patient lies on their back and the examiner flexes the neck by lifting the head toward the chest. A positive sign is involuntary flexion of the hips and knees. Neck flexion stretches the spinal meninges along their length, and drawing up the legs relaxes tension on the lower nerve roots, an automatic attempt to reduce pain.
What a positive or negative result can and cannot tell you
Both signs are fairly specific but have low sensitivity. When present, they add weight to the suspicion of meningeal irritation and support urgent investigation. However, most patients with confirmed meningitis do not show a positive Kernig's sign, so a negative result does not exclude the diagnosis. Fever, headache, neck stiffness, photophobia and confusion remain central findings.
Infants are a particular trap. Fever, headache and neck stiffness may be absent in neonates and infants, who instead may be irritable, feed poorly, appear slow or inactive, or have a bulging fontanelle. Paradoxical irritability, where being held makes the baby more upset, is another clue. A rash of petechiae or purpura suggests meningococcal infection and is an emergency.
Turn the finding into isolation and escalation
A positive meningeal sign with fever or altered consciousness calls for immediate escalation to the provider. Antibiotics for suspected bacterial meningitis are started after blood cultures and are not delayed for imaging or lumbar puncture. Prepare for cultures, intravenous access and investigations, and monitor level of consciousness, pupils and vital signs closely for rising intracranial pressure.
Place the patient on droplet precautions as soon as bacterial meningitis is suspected; for meningococcal disease these are commonly continued for the first 24 hours of effective treatment, following local infection control policy. Reduce light and noise for comfort, provide seizure precautions as ordered, and report close contacts to the team so prophylaxis can be considered.
Work through a hypothetical exam-style scenario
Imagine a hypothetical university student with fever, severe headache and sensitivity to light. When the nurse lifts her head toward her chest, her hips and knees bend. The options are to wait for the lumbar puncture result before isolating her, to dim the lights and reassess in an hour, or to start droplet precautions and notify the provider immediately.
Starting droplet precautions and notifying the provider is the strongest answer. Waiting for results delays both protection of others and treatment, and dimming the lights alone addresses comfort, not danger. The tested reasoning is that a positive Brudzinski sign with fever and headache reflects inflamed meninges, which makes bacterial meningitis a time-critical possibility.
Sources and further reading
The diagnostic accuracy of Kernig's sign, Brudzinski's sign, and nuchal rigidity in adults with suspected meningitis (Clin Infect Dis, 2002). Prospective study showing Kernig and Brudzinski signs have high specificity but very low sensitivity, so a negative sign does not exclude meningitis.
MSD Manual Professional: Acute bacterial meningitis. Atypical presentation in infants, bulging fontanelle, petechial rash, antibiotics not delayed for imaging, and droplet precautions for the first 24 hours.
CDC: Meningococcal disease symptoms. Fever, headache, stiff neck, photophobia and infant signs such as poor feeding, irritability and bulging fontanelle.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our neurological practice questions are the closest set to what this page covers.
Common questions
What causes a positive Kernig's sign?
Straightening the knee with the hip flexed stretches inflamed lumbosacral nerve roots and meninges. Reflex hamstring contraction and pain resist the movement, which is the positive finding.
Does a negative Kernig or Brudzinski sign rule out meningitis?
No. Both signs have low sensitivity, so many people with meningitis test negative. Fever, headache, neck stiffness, confusion and, in infants, irritability and a bulging fontanelle still need urgent assessment.
What isolation is used for suspected bacterial meningitis?
Droplet precautions. For meningococcal disease they are generally continued for the first 24 hours of effective antibiotic treatment, according to local infection control policy.