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The neurologic approach
Published in Stanley Berent, James W. Albers, Neurobehavioral Toxicology, 2012
Stanley Berent, James W. Albers
The most important grading of abnormality on the neurologic examination is distinguishing normal from abnormal function. This information is used in the initial step of localizing the problem within the nervous system. The magnitude of abnormality can be graded for many components of the neurologic examination. The standard approach is to use a qualitative grading system of the magnitude of impairment consisting of five levels, from ‘0’, which is no impairment, to ‘+ 4’, which is maximal impairment or absent function. The three steps in between correspond to the subjective levels of mild, moderate, and severe abnormality. More quantitative levels exist for some measures, such as measurement of strength, sensation, or reflexes. The most commonly used scale for grading strength is based on the Medical Research Council (MRC) (1943) guidelines. The MRC scale is based on whether or not the limb has antigravity function. Unfortunately, this scale emphasizes the very weak limb and is therefore best at scoring severe impairments. Sensory functions such as light touch can be clinically quantified using different calibre Von Frey hairs. The individual hairs are sequentially applied to the skin and, based on their size, they deliver different amounts of pressure before they bend. Numerous devices are available to measure sensation more quantitatively (discussed in Chapter 7). Muscle stretch reflexes are graded on a five-level scale: 2+, which equals normal, 0, which equals absent, 1+, which equals diminished or present only with reinforcement (Jendrassik maneuver), 3+, which equals normal but brisk, and 4+, which equals abnormal with clonus.
The early history of the knee-jerk reflex in neurology
Published in Journal of the History of the Neurosciences, 2022
It was in the context of variability that Buzzard mentioned Jendrassik’s (Ernö Jendrassik, 1858–1921), Hungarian neurologist) discovery of an enhanced knee jerk if the patient attempted to pull apart clinched fists simultaneous with the occurrence of the tendon blow. Such a maneuver enhanced the occurrence of the knee jerk, making its absence more reliable (Anonymous 1885; Fearing 1928). Jendrássik (1883) generally discussed the association of upper arm tension and enhancement of the reflex twitching of the quadriceps muscle. In 1885, he specifically discussed the disturbingly large variability of failures to elicit the knee jerk in people without debilitating pathologies. They varied from .04% to 4.8%—a factor of about 100 (Jendrássik 1885). It was in that paper that he explicitly described what was to become the Jendrassik maneuver.6“… während ich auf seine Patellarsehne klopfe, fordere ich es auf, die gebeugten Finger der rechten und linken Hand in einander zu hängen und sie bei nach vorne ausgestreckten (horizontal) Armen so stark als möglich auseinander zu ziehen.” (“… while I knock on his patellar tendon, I ask him to hang the bent fingers of the right and left hands together and pulling them apart as much as possible with arms stretched forward [horizontally])” (Jendrássik 1885, 413). The Jendrassik maneuver is taught today as a neurologist’s tool to enhance weak knee jerk (Fine and Darkhabani 2009).