From the Guidelines
Meningitis diagnosis is primarily based on physical exam tests that assess for signs of meningeal irritation, including neck stiffness, Kernig's sign, and Brudzinski's sign.
Physical Exam Tests
- Neck stiffness: assessed by checking for resistance to passive neck flexion 1
- Kernig's sign: pain after the patient's hip is flexed 90° and the knee extended 1
- Brudzinski's sign: flexing the patient's neck causes flexion of the patient's hips and knees 1 These physical exam tests are used in conjunction with other diagnostic methods, such as cerebrospinal fluid (CSF) analysis, to diagnose meningitis.
Importance of CSF Analysis
CSF analysis is a crucial diagnostic tool for meningitis, and it is recommended to perform a lumbar puncture to collect CSF for analysis, unless contraindicated 1. The CSF analysis can help identify the cause of meningitis, such as bacterial, viral, or fungal, and guide treatment decisions.
Limitations and Precautions
It is essential to note that some patients, especially infants and young children, may not display typical signs of meningitis, and a high index of suspicion is necessary to make a timely diagnosis 1. Additionally, cranial imaging may be considered before lumbar puncture in selected patients to evaluate for signs of brain shift, but it should not delay antibiotic treatment 1.
From the Research
Physical Exam Tests for Diagnosing Meningitis
The physical exam tests used to diagnose meningitis include:
- Nuchal rigidity
- Jolt accentuation of headache
- Kernig's sign
- Brudzinski's sign
Diagnostic Characteristics of Physical Exam Tests
The diagnostic characteristics of these physical exam tests are as follows:
- Nuchal rigidity: sensitivity of 40%-60%, specificity of 65%-75% 2
- Jolt accentuation of headache: sensitivity of 40%-60%, specificity of 65%-75% 2
- Kernig's sign: sensitivity of 20%-30%, specificity of 85%-95% 2
- Brudzinski's sign: sensitivity of 20%-30%, specificity of 85%-95% 2
Limitations of Physical Exam Tests
Physical exam tests have limitations in diagnosing meningitis, including:
- No single physical sign can accurately distinguish between patients with and without meningitis 3
- Approximately half of patients with meningitis may not present with typical meningeal signs upon physical examination 2
- Combining multiple physical exam tests may decrease the risk of misdiagnosis 2
- Physical signs of meningeal inflammation may not be reliable in certain patient populations, such as small children and the elderly 4