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Light
Touch
Light touch (thigmesthesia) is used as a screening test for touch.
Both the spinothalamic and DCML systems serve this sensation so it is not
specific for either one. A cotton tip applicator or fine hair brush is used.
Select areas from different dermatomes and peripheral nerves and compare
right versus left.
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Pain
Upper Extremities
Pain is one of the principle sensory modalities of the spinothalamic system.
The sharp end of a broken wooden cotton tip applicator can be used then
discarded. It is important for the patient to be able to identify the sensation
as sharp and then compare between dermatomes, distal versus proximal and
right versus left for the upper extremities.
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Pain
Lower Extremities
Pain is one of the principle sensory modalities of the spinothalamic system.
The sharp end of a broken wooden cotton tip applicator can be used then
discarded. It is important for the patient to be able to identify the sensation
as sharp and then compare between dermatomes, distal versus proximal and
right versus left for the lower extremities.
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Temperature
Temperature is the other sensory modality that is used to test the spinothalamic
system. Tubes or vials of hot and cold water can be used but this is usually
impractical. Using a tuning fork, which is normally perceived as cool or
cold to the touch, compare between dermatomes and right versus left.
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Vibratory
Vibratory sensation (pallesthesia) is one of the sensory modalities
of the DCML system. It is tested by using a 128 Hz tuning fork and placing
the vibrating instrument over a bone or boney prominence. By varying the
force of vibration and comparing the patient to yourself you can detect
any deficits. Compare distal versus proximal and right versus left.
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Position
Sense
Position sense (proprioception), another DCML sensory modality, is
tested by holding the most distal joint of a digit by its sides and moving
it slightly up or down. First, demonstrate the test with the patient watching
so they understand what is wanted then perform the test with their eyes
closed. The patient should be able to detect 1 degree of movement of a finger
and 2-3 degrees of movement of a toe. If the patient can't accurately detect
the distal movement then progressively test a more proximal joint until
they can identify the movement correctly.
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Tactile
Movement
Tactile movement as well as the remaining sensory tests are discriminatory
sensory tests that examine cortical somatosensory (parietal lobe) function
and require an intact DCML system. Tactile movement tests the patient's
ability to detect the direction of a 2-3 cm cutaneous stimulus.
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Two-Point
Discrimination
Two-point discrimination is tested by using calipers or a fashioned paper
clip. The smallest and most dense sensory units are located in those areas
that have the greatest somatosensory cortical representation. The patient
should be able to recognize two-point separation of 2-4 mm on the lips and
finger pads, 8-15 mm on the palms and 3-4 cm on the shins.
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Graphesthesia
Graphesthesia is the ability of the patient to identify characters that
are written on the skin using a dull pointed object. The examiner demonstrates
the test by writing single numbers on the palm of the hand while the patient
is watching. The patient then closes their eyes and identifies numbers that
are written by the examiner.
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Stereognosis
Stereognosis is the ability to identify objects that are placed in the hand
when the eyes are closed. The patient is given common objects and asked
to identify them without looking at them. The inability to do this called
astereognosis and indicates parietal lobe dysfunction.
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Double
Simultaneous Stimulation
The patient should be able to attend to and identify a tactile stimulus
that is applied to both sides of the body at the same time. Double simultaneous
stimulation (DSS) is tested by touching homologous parts of the body
on one side, the other side or both sides at once with the patient identifying
which side or if both sides are touched with their eyes closed. If the patient
neglects one side on DSS (extinction or simultanagnosia) this
indicates dysfunction of the contralateral posterior parietal lobe.
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Romberg
Test
The Romberg test is a test of proprioception. This test is performed by
asking the patient to stand, feet together with eyes open, then with eyes
closed. The patient with significant proprioceptive loss will be able to
stand still with eyes open because vision will compensate for the loss of
position sense but will sway or fall with their eyes closed because they
are unable to keep their balance.
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