The Neurological Exam: Evaluating the Master Organ
by Gary Cordingley, MD, PhD
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It might seem old-fashioned, but the neurological physical exam is
still the best starting-point for investigating symptoms related to the
brain and other parts of the nervous system.
How does a mind contemplate itself? That's a philosophical question
I'll leave to minds smarter than mine, but what I can tell you is
how to examine the brain and other parts of the nervous system.
Most people are familiar with how doctors examine a heart or set of
lungs. The physical exam of these organs consists mainly of using a
stethoscope to listen to them in action. But when it comes to examining
components of the nervous system—consisting of the brain, spinal cord,
peripheral nerves and muscles—a stethoscope is pretty useless. The nervous
system doesn't make sounds that the doctor can listen to (though the
arteries in the neck that deliver blood to the brain can be usefully
listened to). But because people can have medical disorders that damage
the nervous system, it is every bit as important to have a method for
evaluating this organ as for any other.
The method is called the neurological exam. Because different parts of
the nervous system do different things, the basic idea of the neurological
exam is to put the patient through a number of mini-exams, each evaluating
the function of a different component. And what a variety of functions
there are! In fact, apart from exposure to an inspiring teacher, this is
what drew me into the study of neurology in the first place—the sheer
diversity of the neurological exam. This is an organ responsible for jobs
as diverse as thinking, remembering, smelling, tasting, seeing, hearing,
speaking, moving, walking, balancing, feeling and, yes, even contemplating
itself—though I confess that my neurological exam doesn't include an
assessment of self-contemplation. Moreover, the nervous system handles
many infrastructure tasks like controlling body-temperature, pulse,
blood-pressure, breathing and enabling a person to urinate at a time and
place of their choosing. What's not to admire about an organ system that
can do so many things!
The many mini-tests of the neurological exam are bundled together in
the following sub-groupings: mental status exam, cranial nerve exam, motor
exam, sensory exam and evaluation of stance and walking. I'll provide a
brief overview of each.
The mental status exam focuses on the cerebrum which has a wrinkly,
gray, outer surface usually shown in pictures of the brain. The cerebrum
is divided into eight lobes which includes pairs of frontal lobes,
parietal lobes, temporal lobes and—bringing up the rear—the occipital
lobes. Each handles different mental tasks. In fact, even within a lobe,
many different jobs are handled. So the usual mental status exam consists
of observing the patient's behavior in the exam room and using a variety
of standard tests to check the patient's orientation to time and place,
attention, memory, speech, comprehension of language, memory, calculation
and ability to track the relative positions of objects in space.
The next grouping of mini-tests, the cranial nerve exam, also assesses
the functioning of parts of the cerebrum, but additionally focuses on the
brainstem. The brainstem is located at the base of the brain and connects
the cerebrum above to the spinal cord below. The cranial nerve exam
includes tests of smelling, vision, constriction of the pupils,
eye-movement, facial sensation, facial movement, hearing, and action of
certain muscles in the throat, tongue, neck and shoulders. I'll single out
one item on the cranial nerve exam as deserving special mention, and that
is the visual field exam. The visual fields are evaluated one eye at a
time. While the patient stares at an unmoving object, the doctor asks if
the patient can see objects (like the doctor's fingers) appearing in
different locations of the patient's peripheral vision. In order to detect
objects in the four corners of each eye's vision, the patient must have
proper functioning of each of six lobes of the brain—both parietal lobes,
both temporal lobes and both occipital lobes. In fact, this is the only
portion of the entire neurological exam that checks the right temporal
lobe. Despite its importance, the visual field exam sometimes gets skipped
by medical students (in which case the ones under this author's
supervision must endure hearing an earful).
The motor exam includes some pretty obvious things like checking the
strength of different muscles in the arms and legs, but also includes less
obvious components like muscle tone, coordination, and the presence of
involuntary movements. It also includes an inspection of muscles for loss
of size or the presence of spontaneous twitches. Additionally, this is the
part of the exam in which the doctor pulls out his or her rubber hammer
and checks reflexes in the arms and legs. The motor exam also includes a
briefly painful maneuver—called the Babinski test—in which the bottom of
the foot is scraped with a metal object while the doctor observes for a
reflexive response in certain foot-muscles.The sensory exam focuses on the
processing of inputs from sensory nerve-endings in the patient's skin and
joints. It can include awareness of light touch, pain, warmth, coldness
and vibration. In addition, the doctor examines position-sense by moving
the patient's toes and fingers up or down and asking the patient to say,
without looking, which way they moved.
Finally, we have those portions of the exam related to stance and
walking, but also including the patients' ability to transfer in and out
of their chair. While on their feet, patients are asked to walk in their
usual fashion, as well as on tiptoes. They are also observed while doing a
"tandem gait," known more commonly as the "state trooper test," in which
they walk flat-footed in a straight line with the heel of the leading foot
touching the toes of the trailing foot. Last, the doctor checks the
patients' ability to remain standing after closing their eyes. This is
called the Romberg test.
That's about it. In the hands of experienced clinicians the
neurological exam doesn't take much longer to perform than to describe,
and yet provides a wealth of information about the functioning of the
patient's nervous system. In this age of high-tech imaging devices the
neurological exam might seem archaic or old-fashioned, but it is still
indispensable, and provides diagnostic information that even a battery of
CT or MRI scans might miss.
(C) 2005 by Gary Cordingley
ABOUT THE AUTHOR
Gary Cordingley, MD, PhD, is a clinical neurologist, teacher and
researcher who works in Athens, Ohio. For more health-related articles,
see his website at: http://www.cordingleyneurology.com/
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