Kernig's sign
A reliable early indicator and tool used to diagnose meningeal irritation, Kernig’s sign elicits both resistance and hamstring muscle pain when the examiner attempts to extend the knee while the hip and knee are both flexed 90 degrees. However, when the patient’s thigh isn’t flexed on the abdomen, he’s usually able to completely extend his leg. (See Eliciting Kernig’s sign, page 194.) This sign is usually elicited in meningitis or subarachnoid hemorrhage. With these potentially life-threatening disorders, hamstring muscle resistance results from stretching the blood- or exudate-irritated meninges surrounding spinal nerve roots.
Kernig’s sign can also indicate a herniated disk or spinal tumor. With these disorders, sciatic pain results from disk or tumor pressure on spinal nerve roots.
Act Now: Because Kernig’s sign may signal meningitis or subarachnoid hemorrhage, both life-threatening central nervous system disorders, take the patient’s vital signs at once to obtain baseline information. Then test for Brudzinski’s sign to obtain further evidence of meningeal irritation. Next, ask the patient or his family to describe the onset of illness. Typically, the progressive onset of headache, fever, nuchal rigidity, and confusion suggests meningitis. Conversely, the sudden onset of a severe headache, nuchal rigidity, photophobia and, possibly, loss of consciousness usually indicates subarachnoid hemorrhage.
If you elicit a positive Kernig’s sign and suspect life-threatening meningitis or subarachnoid hemorrhage, immediately prepare for emergency intervention.
Assessment
History
If you suspect meningitis, ask the patient about recent infections, especially tooth abscesses. Ask about exposure to infected persons or places where meningitis is endemic. Meningitis is usually a complication of another bacterial infection, so blood cultures are needed to determine the causative organism. If subarachnoid hemorrhage is the suspected diagnosis, ask about a history of hypertension, cerebral aneurysm, head trauma, or arteriovenous malformation. Check the patient’s pupils for dilation, and assess him for signs of increasing intracranial pressure, such as bradycardia, increased systolic blood pressure, and widening pulse pressure.
If you don’t suspect meningeal irritation, ask the patient if he feels any back pain that radiates down one or both legs. Does he also feel leg numbness, tingling, or weakness? Ask about other signs and symptoms, and find out if he has a history of cancer or back injury.
Physical examination
Perform a physical examination, concentrating on motor and sensory function. Assess motor function by inspecting the muscles and testing muscle tone and strength. Perform cerebellar testing. Cerebellar deficits affect the patient’s voluntary movements, equilibrium, integration of sensations, and sense of position. Assess sensory function by checking the patient’s sensitivity to pain, light touch, vibration, position, and discrimination.
Pediatric pointers
Kernig’s sign is considered ominous in children because of their greater potential for rapid deterioration.
Medical causes
Lumbosacral herniated disk
A positive Kernig’s sign may be elicited in patients with lumbosacral herniated disk, but the cardinal and earliest feature is sciatic pain on the affected side or on both sides. Associated findings include postural deformity (lumbar lordosis or scoliosis), paresthesia, hypoactive deep tendon reflexes in the involved leg, and dorsiflexor muscle weakness.
Meningitis
A positive Kernig’s sign usually occurs early with meningitis, along with fever and, possibly, chills. Other signs and symptoms of meningeal irritation include nuchal rigidity, hyperreflexia, Brudzinski’s sign, and opisthotonos. As intracranial pressure (ICP) increases, headache and vomiting may occur. In severe meningitis, the patient may experience stupor, coma, and seizures. Cranial nerve involvement may produce ocular palsies, facial weakness, deafness, and photophobia. An erythematous maculopapular rash may occur in viral meningitis; a purpuric rash may be seen in those with meningococcal meningitis.
Spinal cord tumor
Kernig’s sign can be elicited occasionally, but the earliest symptom is typically pain felt locally or along the spinal nerve, commonly in the leg. Associated findings include weakness or paralysis distal to the tumor, paresthesia, urine retention, urinary or fecal incontinence, and sexual dysfunction.
Subarachnoid hemorrhage
Kernig’s sign and Brudzinski’s sign can both be elicited within minutes after the initial bleed. The patient experiences a sudden onset of severe headache that begins in a localized area and then spreads, pupillary inequality, nuchal rigidity, and decreased level of consciousness. Photophobia, fever, nausea and vomiting, dizziness, and seizures are possible. Focal signs include hemiparesis or hemiplegia, aphasia, and sensory or vision disturbances. Increasing ICP may produce bradycardia, increased blood pressure, respiratory pattern change, and rapid progression to coma.
Nursing considerations
Prepare the patient for diagnostic tests, such as a computed tomography scan, magnetic resonance imaging, spinal X-ray, myelography, and lumbar puncture. Closely monitor his vital signs, ICP, and cardiopulmonary and neurologic status. Ensure bed rest, quiet, and minimal stress.
If the patient has a subarachnoid hemorrhage, darken the room and elevate the head of the bed at least 30 degrees to reduce ICP. If he has a herniated disk or spinal tumor, he may require pelvic traction.
Patient teaching
Teach the patient the signs and symptoms of meningitis. Discuss measures to prevent meningitis. Explain the activities that a patient with a herniated disk should avoid. Teach the patient how to apply a back brace or cervical collar, as needed.
Pictures
Book Source Details
- Book Title: Alarming Signs and Symptoms: Lippincott Manual of Nursing Practice Series
- Author(s): Springhouse
- Year of Publication: 2007
- Copyright Details: Alarming Signs and Symptoms: Lippincott Manual of Nursing Practice Series, Copyright © 2007 Lippincott Williams & Wilkins.
Other Book Chapters Related to Encephalitis
Read excerpts from these other book chapters related to Encephalitis:
Medical Books Excerpts
- Meningitis
- "Professional Guide to Diseases (Eighth Edition)" (2005)
- [ read ]
- Kernig's sign
- "Alarming Signs and Symptoms: Lippincott Manual of Nursing Practice Series" (2007)
- [ read ]
Copyright Details: Alarming Signs and Symptoms: Lippincott Manual of Nursing Practice Series, Copyright © 2008 Williams & Wilkins.
More About Causes of Encephalitis
» Next page: Brudzinski's sign (Signs & Symptoms: A 2-in-1 Reference for Nurses)
Rate This Website
What do you think about the features of this website?
Take our user survey and have your say:
Website User Survey
Medical Tools & Articles:
Next articles:
Tools & Services:
Medical Articles:
Forums & Message Boards
- Ask or answer a question at the Boards:
