How to Perform Brudzinski's Sign
To test for Brudzinski's sign, place the patient supine and passively flex the neck forward; the sign is positive when this maneuver causes involuntary flexion of both hips and knees. 1
Testing Technique
The proper technique is straightforward:
- Position the patient lying flat on their back (supine position) 1
- Passively flex the patient's neck by lifting the head forward toward the chest 1
- Observe the patient's lower extremities during this maneuver 1
- A positive sign occurs when passive neck flexion causes reflexive, involuntary flexion of both the hips and knees simultaneously 1
Critical Clinical Context
While the technique itself is simple, understanding the severe limitations of this sign is essential for proper clinical decision-making:
Poor Diagnostic Performance
- Brudzinski's sign has extremely poor sensitivity of only 9% in adults, meaning it misses 91% of meningitis cases 1
- In pediatric patients, sensitivity improves to 66% but remains inadequate to exclude disease 1
- The sign has low diagnostic accuracy for predicting cerebrospinal fluid pleocytosis 1
Do Not Rely on This Sign
- Brudzinski's sign should not be relied upon for diagnosis of meningitis 2, 1
- The absence of Brudzinski's sign cannot be used to exclude bacterial meningitis 1
- No single clinical sign of bacterial meningitis is present in all patients 1, 3
- The classic triad of fever, neck stiffness, and altered mental status is present in only 41-51% of bacterial meningitis cases 1, 3
Clinical Management Algorithm
Regardless of Brudzinski's sign findings:
- All patients with suspected meningitis require hospital referral and cerebrospinal fluid examination, regardless of whether Brudzinski's sign is present or absent 1
- CSF analysis remains the cornerstone of diagnosis with the highest diagnostic accuracy 1, 3
- Document the presence or absence of headache, altered mental status, neck stiffness, fever, rash, seizures, and signs of shock 2
Common Pitfall to Avoid
The most dangerous error is using the absence of Brudzinski's sign (or any meningeal sign) to rule out meningitis and delay lumbar puncture. Clinical signs have poor sensitivity, and outcome in meningitis depends on early treatment, which requires early diagnosis through CSF examination, not physical examination alone. 1, 3