Definition and Pathophysiology

Brudzinski’s sign refers to the involuntary flexion of the hips and knees in response to passive flexion of the neck, and is a classical indicator of meningeal irritation. This reflex occurs due to the stretch and irritation of the inflamed meninges and spinal nerve roots, which leads to a protective motor response. A positive sign often suggests meningitis or subarachnoid hemorrhage (SAH) — conditions with significant morbidity and mortality if not promptly recognized and treated.

Clinical Significance

While not routinely assessed during a general physical exam, Brudzinski’s sign is crucial in neurologic assessments when meningeal inflammation is suspected. It has moderate sensitivity but high specificity for meningeal irritation, particularly when used in combination with other signs like Kernig’s sign and nuchal rigidity.

Emergency Interventions

In patients presenting with a positive Brudzinski’s sign, evaluate for elevated intracranial pressure (ICP) and other life-threatening complications:

• Assess for headache, neck stiffness, photophobia, diplopia, nausea, and vomiting.

• Observe for signs of raised ICP: altered level of consciousness (e.g., confusion, stupor, coma), Cushing’s triad (hypertension, bradycardia, and irregular respiration), papilledema, and pupillary abnormalities.

• Initiate neuroprotective measures: elevate head of bed to 30–60°, administer mannitol or hypertonic saline, and ensure airway protection.

• Prepare for potential intubation, CSF drainage, and mechanical ventilation if ICP remains uncontrolled.

History and physical examination

A detailed neurologic and systemic history is essential. Inquire about:

• Recent infections, especially otitis media, sinusitis, or dental abscesses

• Head trauma, neurosurgical procedures, or intravenous drug use

• Recent symptoms: sudden severe headache (thunderclap), fever, seizures, photophobia, and focal neurologic deficits

• In the neurologic exam, assess cranial nerves, motor and sensory function, and signs such as:

  • Kernig’s sign

  • Papilledema

  • Nuchal rigidity

  • Opisthotonos (in severe cases)

Differential Diagnosis and Causes

1. Meningitis (Bacterial, Viral, Fungal, TB)

• Positive Brudzinski’s and Kernig’s signs are often present 12–24 hours after symptom onset.

• Common symptoms: fever, neck stiffness, altered mental status, and seizures.

• May show CSF pleocytosis, hypoglycorrhachia, and elevated opening pressure.

2. Subarachnoid Hemorrhage (SAH)

• Brudzinski’s sign may appear minutes to hours after aneurysmal rupture.

• Classic presentation: "worst headache of life", nuchal rigidity, photophobia, nausea, focal deficits.

• Diagnosis: CT brain ± lumbar puncture if imaging is inconclusive.

3. Severe Cervical Arthritis or Spinal Pathology

• May mimic Brudzinski’s response due to limited neck mobility and mechanical irritation of the spinal canal.

Diagnostic evaluation

• Lumbar puncture: critical to confirm meningitis or SAH (if CT is negative).

• Blood, urine, and CSF cultures

• Neuroimaging: CT/MRI brain, angiography for vascular causes

• Electrolytes, CBC, renal function, and inflammatory markers (CRP, ESR)

Special Considerations

• Pediatrics: Brudzinski’s sign may be unreliable in infants; look instead for bulging fontanelles, lethargy, hypotonia, and poor feeding.

• Geriatrics: Presentation may be atypical; altered LOC or falls may be initial findings.

• Immunocompromised patients may lack classical signs but still have life-threatening pathology.

Patient management and counseling

• Educate on symptoms of meningitis and when to seek urgent care.

• Instruct high-risk patients (e.g., with shunts, immunodeficiency) to present early.

• Emphasize the importance of meningococcal and pneumococcal vaccinations.

References

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