Sign, Kernig
A clinical hallmark of meningitis, inflammation of the meninges, the membranes covering the brain and spinal cord.
The test for Kernig sign is done by having the person lie supine (flat on the back), flex the thigh so that it is at a right angle to the trunk, and completely extend the leg at the knee joint. If the leg cannot be completely extended due to pain, this is Kernig sign.
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“Looking down to sign a hotel register, I felt a spasm like an electric current move along my back from the base of my skull to my toes. Every time I repeated the movement, the spasm recurred.” The causes of Lhermitte sign include multiple sclerosis (MS), radiation damage to the spinal cord), cervical spondylosis (degeneration […]
- Sign, Macewen
A sign to detect hydrocephalus and brain abscess. Percussion (tapping) on the skull at a particular spot (near the junction of the frontal, temporal and parietal bones) yields an unusually resonant sound in the presence of hydrocephalus or a brain abscess. Named for Sir William Macewen (1848-1924), a surgeon in Glascow, Scotland who also described […]
- Sign, Tinel's
An examination test that is used by doctors to detect an irritated nerve. Tinel’s sign is performed by lightly banging (percussing) over the nerve to elicit a sensation of tingling or “pins and needles” in the distribution of the nerve. For example, in a person with carpal tunnel syndrome where the median nerve is compressed […]
- Sign, toe
Joseph Francois Felix Babinski (1857-1932). His name will never be forgotten in medicine, thanks to the toe sign he described.
- Signal transduction
A basic process in molecular cell biology involving the conversion of a signal from outside the cell to a functional change within the cell. A signal (such as a hormone or neurotransmitter) interacts with a receptor on the cell surface; this interaction causes a change in a second messenger (such calcium); and, eventually, a change […]