Meningeal Irritation Signs

Definition and EtiologyTop

Signs of meningeal irritation are nonspecific reactions that may occur in a patient with meningeal irritation.

Meningism is defined as signs of meningeal irritation occurring without other features of meningitis or noninflammatory meningeal involvement (eg, in a patient with high-grade fever unrelated to a central nervous system [CNS] disorder).

Causes: Infectious meningitis (bacterial or viral), subarachnoid hemorrhage, neoplasms of the brain and meninges, extensive stroke affecting an area adjacent to the spaces with cerebrospinal fluid.

DiagnosisTop

1. Physical examination:

1) Neck stiffness: Make sure the patient does not have cervical spine instability (eg, due to trauma or rheumatoid arthritis) and is not at risk of cerebral herniation. Place the patient in the supine position. Support the patient’s chest with one hand, slide your other hand under the patient’s occiput, and try to move their chin towards the sternum. In patients with neck stiffness, the reflex contraction of the muscles of the neck prevents the patient’s chin from touching their chest, causing resistance and pain. The distance between the chin and the sternum is a measure of the severity of neck stiffness. In extreme cases, tension of the long paraspinal muscles is high enough to cause spontaneous posterior flexion of the neck and anterior arching of the trunk (opisthotonus). Neck stiffness needs to be differentiated from other causes of limited neck flexion (cervical spine degeneration, parkinsonism, cervical lymphangitis, severe throat infection). Neck stiffness has a sensitivity of ~70% for meningitis, although this is based on low-certainty evidence.

2) Brudzinski sign:

a) Upper: Movement of the chin towards the chest while assessing for neck stiffness causes reflex flexion of the lower limbs at hips and knee joints.

b) Lower: The same lower limb flexion is produced upon exerting pressure on the pubic symphysis.

c) Contralateral leg sign: Reflex leg flexion when the contralateral leg is flexed at the knee and hip in supine position.

3) Kernig sign: Place the patient in the supine position. Flex the patient’s hip to 90 degrees, then attempt to extend a knee. In patients with a positive Kernig sign, reflex muscle contraction prevents extension of the knee, which manifests as resistance and pain. Kernig sign is bilateral (as opposed to Lasègue sign in sciatica).

The sensitivity of signs of meningeal irritation in diagnosing meningitis is moderate, although lower in infants and elderly patients. Brudzinski sign has good sensitivity but poor specificity while Kernig sign has good specificity and poor sensitivity. Because of the implications of misdiagnosis and the ability to perform lumbar puncture to definitively confirm or exclude meningitis in those with moderate to high likelihood of this disease, the degree to which the presence or absence of those signs dictates further management is limited. For those with low pretest probability, the absence of these signs may provide a degree of reassurance, whereas their presence should dictate further investigations.

Other manifestations of meningitis: see Meningitis.

2. Other diagnostic tests: Lumbar puncture (measurement of the opening pressure; cytologic, biochemical, and microbiologic examination of cerebrospinal fluid [direct microscopy, cultures, polymerase chain reaction]); neuroimaging (computed tomography [CT], magnetic resonance imaging [MRI]).