O UTLINE

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N i n a I a n J o h n “ G ” R a c h e l M a r k I v z J o b e J o c e ll e E d o G i

January 31, 2011S4L4: Sensory Examination by Dr. Alfredo Guzman

Sensory input travels up through the spinal cord along specific paths, with the precise route defined by the type of sensation being transmitted.Nerves carrying pain impulses cross to the opposite side of the spinal cord soon after entering, and travel up to the brain on that side of the cord.Vibratory sensations enter the cord and travel up the same side, crossing over only when they reach the brainstem

Sensory nerves terminate in the brain, where the impulses are integrated and perception occurs.

2 main afferent pathways:

Spinothalamic: Detects pain, temperature and crude touch. Impulse travel from the periphery, enter the spinal cord and then

cross to the other side of the cord within one or two vertebral levels from the entry point

continues up that side to the brain It will terminate in the cerebral hemisphere on the opposite

side of the body from where the impulse initially entered.

Dorsal column Detects position (proprioception), vibratory sensation and light

touch. Impulse travel from the periphery, entering the spinal cord and

then moving up to the base of the brain on the same side of the cord as where the impulse started.

Upon reaching the brainstem it will cross to the opposite side. It will terminate in the cerebral hemisphere on the opposite

side of the body from where they began.

Evaluate the following:

Pain and Temperature (spinothalamic tracts)

Position (proprioception)

Vibration (posterior columns)

Light touch (both spinothalamic and posterior column)

Discriminative Sensations (depend on touch sense, position sense and the cortex)

General Instruction:

a. Explain each test before you do itb. Unless otherwise specified, the patient’s eyes should be closed

during the actual testingc. Compare symmetrical areas on the two sides of the bodyd. Compare distal and proximal areas of the extremities. e. When you detect an area of sensory loss, map out its boundaries

in detail.

Patterns of testing:

Compare the symmetric areas on the 2 sides of the body, including the arms, legs, and trunk

When testing for pain, temperature, and touch sensation, compare the distal with the proximal areas of the extremities.

When testing vibration and position sensation, first test the fingers and toes.

Vary the pace of your testing.

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I. Sensory Function ExaminationA. PainB. Light TouchC. TemperatureD. VibrationE. ProprioceptionF. Discriminative Sensation

1. Stereognosis2. Graphesthesis3. 2 point discimination4. Point localization5. extinction

II. Special TestingA. Monofilament Testing

III. AssessmentA. DermatomesB. Diffused distal sensory lossC. Peripheral Nerve Distribution

SENSORY FUNCTION EXAM

When you detect an area of sensory loss or hypersensitivity, map on its boundaries in detail.

PAIN

Test item: Sterile pin According to Bates, you could also use a sharp safety pin, broken

cotton swab, or other suitable tool.

Procedure: Touch the patient with the sharp or dull end and ask them to

identify “sharp or dull” with the eyes closed. The examiner randomly alternates touching the patient (fingers

and toes) with the sharp and dull ends of a paper clip (or safety pin) while the patient identifies the stimulus.

One can also ascend from the foot upwards and ask the patient to identify the level where appreciation of sharpness occurs or where an appreciable increase in sensation occurs.

Test the following areas: Shoulders (C4) Inner and outer aspects of the forearms (C6 and T1) Thumbs and little fingers (C6 and C8) Front of both thighs (L2) Medial and lateral aspect of both calves (L4 and L5) Little toes (S1)

LIGHT TOUCH

Test item: cotton wisp

Procedure: Close patient’s eyes while fingers and toes are lightly touched Ask the patient to respond whenever a touch is felt.

Test the following areas: Shoulders (C4) Inner and outer aspects of the forearms (C6 and T1) Thumbs and little fingers (C6 and C8) Front of both thighs (L2) Medial and lateral aspect of both calves (L4 and L5) Little toes (S1)

TEMPERATURE

Test item: Cold tuning fork; hot and cold water in a test tube

Procedure: With eyes closed, ask them to identify when touched with hot or

cold. Levels and laterality can also be tested as described for pain and

light touch

VIBRATION

Test item: 128 Hz Tuning fork

Procedure: Test with a non-vibrating tuning fork first to ensure that the patient

is responding to the correct stimulus. Place the stem of the fork over the distal interphalangeal joint of

the patient's index fingers and big toes. Ask the patient to tell you if they feel the vibration. If vibration sense is impaired proceed proximally (bony

prominences): Wrists Elbows Medial malleoli Patella Anterior superior iliac spines Spinous processes Clavicles

PROPRIOCEPTION

Procedure: Grasp the patient's big toe and hold it away from the other toes to

avoid friction. Show the patient "up" and "down." With the patient's eyes closed, ask the patient to identify the

direction you move the toe. If position sense is impaired move proximally to test the ankle

joint. Test the fingers in a similar fashion. If indicated move proximally to the metacarpophalangeal joints,

wrists, and elbows.

DISCRIMINATIVE SENSATION

Since these tests are dependent on touch and position sense, they cannot be performed when the tests above are clearly abnormal.

a. Stereognosisrefers to the ability to identify an object by feeling it.

Test item: Familiar Objects (coin, paper clip, pencil, etc.)

Procedure: Place a familiar object in the patient's hand Ask the patient to tell you what it is.

b. Graphesthesia

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Note: This test is often omitted if pain sensation is normal.

Note: Greater deficits are characterized by having to move a more proximal joint such as ankle, knee or hip for the patient to appreciate the movement.

Note: This test is used as an alternative to graphesthesia

Test item: Blunt end of pen/pencil

Procedure: With the blunt end of a pen or pencil, draw a large number in the

patient's palm. Ask the patient to identify the number.

c. Two-point discrimination

Test item: Opened paper clip

Procedure: Use an opened paper clip to touch the patient's finger pads in two

places simultaneously. Alternate irregularly with one point touch. Ask the patient to identify "one" or "two." Find the minimal distance at which the patient can discriminate.

d. Point localization

Procedure: Briefly touch a point on the patient’s skin Ask the patient to open both eyes and point to the place touched

e. Extinction

Procedure: Simultaneously stimulate corresponding areas on both sides of

the body. Ask where the patient felt your touch.

MONOFILAMENT TESTING

A careful foot examination should be performed on all patients with symptoms suggestive of sensory neuropathy or at particular risk for this disorder (e.g. anyone with Diabetes).

Test item: Disposable monofilaments are small nylon fibers

Procedure: Have the patient close their eyes. Touch the monofilament to 5-7 areas on the bottom of the

patient's foot. Pick locations so that all of the major areas of the sole are

assessed.

Avoid calluses, which are relatively insensate. The patient should be able to detect the filament when the tip is

lightly applied to the skin

Normal patient should be able to feel the ends when they are gently pressed against the soles of their feet.If the force required to provoke a sensory response is strong enough to bend the monofilament, then sensation is impaired.

Neuropathic ulcerLarge ulcer that usually results from severe diabetic neuropathy

Patients should be able to correctly distinguish sharp sensation (pain), indicating normal function of the spinothalamic pathway

Mapping out regions of impaired sensation:

The history or screening examination will suggest a discrete anatomic region that has sensory impairment.

Map out the territory involved, using careful pin testing to define the medial/lateral and proximal/distal boundaries of the affected region.

You may even make pen marks on the skin to clearly identify where the changes occur.

This type of mapping is somewhat tedious and should only be done in appropriate situations.

DermatomesBand of skin innervated by sensory root of a single spinal nerveKnowledge of dermatomes helps you localize neurologic lesions to a specific level of the spinal cord (SCI or spinal cord injury)

Diffuse distal sensory loss:

The most commonly occurring chronic systemic diseases affecting the nerve function is Diabetes

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Note: These stimuli are carried by the Dorsal Column pathway. While not checked routinely, it is useful test if a discrete peripheral neuropathy is suspected (e.g. injury to the radial nerve).

SPECIAL TESTING: EARLY DIABETIC NEUROPHATHY

ASSESSMENT

Manifestation: This first affects the most distal aspects of the nerves and then

moves proximally. The feet are the first area to be affected. It occurs simultaneously in both limbs. Exam reveals loss of ability to detect the sharp stimulus across

the entire foot. The sensory loss does not follow a dermatomal (i.e. spinal nerve

root) or peripheral nerve distribution. As the examiner tests more proximally, he/she will ultimately

reach a point where sensation is again normal. The more advanced the disease, the more proximal this will

occur.

Stocking or Glove distribution impairmentArea involved covers an entire distal region, much as a sock or glove would cover a foot or hand. Hands can be affected, though much less commonly than feet as the nerves travelling to the legs are longer and thus at much greater risk. Such deficits may be associated with neuropathic pain, a continuous burning sensation affecting the distal extremity.

Peripheral nerve distribution:

A specific peripheral nerve can become dysfunctional as the result of trauma or infarction (another complication of diabetes). There will be a pattern of sensory impairment that follows the distribution of the nerve. Testing of the sacral nerve roots, serving the anus and rectum, is important if patients complain of incontinence, inability to defecate/urinate, or there is otherwise reason to suspect that these roots may be compromised.

Radial nerve palsy Can occur if an intoxicated person falls asleep in a position

that puts pressure on the nerve as it travels around the humerus

Intoxication induced loss of consciousness then prevents the patient from reflexively changing position, the normal means by which we prevent nerves from being exposed to constant direct pressure.

The resultant sensory loss would involve the back of the hand and forearm.

Motor function would also be affected.

Cauda Equina syndrome Multiple sacral and lumbar roots become compressed

bilaterally (e.g. by posteriorly herniated disc material or a tumor).

The patient is unable to urinate, as the lower motor neurons carried in these sacral nerve roots no longer function.

There is no way to send an impulse to the bladder instructing it to contract.

They will not be aware that the bladder is full. There will also be loss of anal sphincter tone, which can be

appreciated on rectal exam. Ability to detect pin pricks in the perineal area (a.k.a. saddle

distribution) is also diminished.

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