Kernig's sign
A reliable early indicator and tool used to diagnose meningeal irritation, Kernig’s sign elicits resistance and hamstring muscle pain when the examiner attempts to extend the knee while the hip and knee are 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.) 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.
History and physical examination
If you elicit a positive Kernig’s sign and suspect life-threatening meningitis or subarachnoid hemorrhage, immediately prepare for emergency intervention. (See When Kernig’s sign signals CNS crisis, page 370.)
If you don’t suspect meningeal irritation, ask the patient if he feels 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. Then perform a physical examination, concentrating on motor and sensory function.
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 a 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 and Brudzinski’s signs can be elicited within minutes after the initial bleed
The patient experiences a sudden onset of a severe headache that begins in a localized area and then spreads, pupillary inequality, nuchal rigidity, and a decreased level of consciousness. Photophobia, a fever, nausea and vomiting, dizziness, and seizures are possible. Focal signs include hemiparesis or hemiplegia, aphasia, and sensory or visual disturbances. Increasing ICP may produce bradycardia, increased blood pressure, respiratory pattern change, and rapid progression to coma.
Special 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 the patient’s 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.
Pediatric pointers
Kernig’s sign is considered ominous in children because of their greater potential for rapid deterioration.
Pictures
Book Source Details
- Book Title: Handbook of Signs & Symptoms (Third Edition)
- Author(s): Springhouse
- Year of Publication: 2006
- Copyright Details: Handbook of Signs & Symptoms (Third Edition), Copyright © 2006 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: Handbook of Signs & Symptoms (Third Edition), Copyright © 2008 Williams & Wilkins.
More About Causes of Encephalitis
» Next page: Nuchal rigidity (Handbook of Signs & Symptoms (Third Edition))
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:
