Sensory Testing

Question 1

What tests can be done within Sensory Testing?

Answer 1

• Gross touch
• soft, pinprick
• Vibration 128Hz
• Joint position sense
• Two point discrimination
• Temperature,
• stereognosis/graphesthesia,
• sensory neglect phenomenon

Question 2

1.

Stereognosis - Definition/Clinical Relevance

Answer 2

Definition: The ability to recognize objects by touch alone, without visual input.

Clinical Relevance: Impairment in stereognosis may indicate parietal lobe damage, specifically involving the somatosensory association areas responsible for integrating sensory information.

Question 3

Graphesthesia - Definition/Clinical Relevance

Answer 3

Definition: The ability to recognize writing on the skin by touch, often used with numbers or letters traced on the palm.

Clinical Relevance:Deficits in graphesthesia can suggest problems with how the brain processes touch information, often due to issues in the parietal lobe, which helps interpret sensory input.

Question 4

What sensory pathway do stereognosis and graphesthesia test?

Answer 4

Dorsal Column-Medial Lemniscus (DCML) pathway

Responsible for fine touch, vibration sense, and proprioception.

Question 5

DCML Pathway Function?

Answer 5

Function: Carries sensory information for fine touch, vibration, and proprioception to the brain.

Clinical Relevance: Damage to this pathway can impair tactile discrimination, impacting abilities like stereognosis and graphesthesia.

Question 6

What is gross touch?

Answer 6

Definition: The ability to perceive that something is touching the skin without identifying fine details like texture or exact location.

Also known as crude touch or light touch.

Question 7

Gross Touch Pathway?

Answer 7

Pathway: Transmitted via the spinothalamic tract, specifically the anterior (ventral) spinothalamic tract.
Carries sensations for general touch awareness rather than detailed information.

Question 8

What is the purpose of the soft touch test?

Answer 8

Purpose: Assesses sensitivity to light (gross) touch.
Helps detect any sensory loss or abnormalities in response to a soft touch.

Question 9

Soft Touch Test Pathway

Answer 9

Pathway Tested: Anterior spinothalamic tract
Transmits sensations for gross touch and light touch.

Question 10

What is the purpose of the pinprick test?

Answer 10

Purpose: Tests the perception of pain.
Helps assess the integrity of pain sensation pathways.

Question 11

Pinprick Test Pathway?

Answer 11

Pathway Tested: Lateral spinothalamic tract
Responsible for pain and temperature sensation.

Question 12

Clinical Relevance of Pinprick Test?

Answer 12

Clinical Relevance: Reduced or absent response to pinprick can indicate damage to the lateral spinothalamic tract, as seen in conditions like peripheral neuropathy or spinal cord lesions.

Question 13

What is the purpose of the Vibration 128 Hz Test?

Answer 13

Purpose: Assesses the ability to sense vibration, a key component of proprioception.
Helps detect sensory loss, particularly in distal areas like toes and fingers.

Question 14

How is the Vibration 128 Hz Test performed?

Answer 14

Procedure: A 128 Hz tuning fork is struck and placed on bony prominences (e.g., fingers, ankles).
The patient is asked to indicate when they feel the vibration and when it stops.

Question 15

Which pathway does the Vibration 128 Hz Test evaluate?

Answer 15

Pathway Tested: Dorsal column-medial lemniscus (DCML) pathway
Responsible for proprioception, fine touch, and vibration sense.

Question 16

Clinical Relevance of the Vibration 128 Hz Test?

Answer 16

Clinical Relevance: Impaired vibration sense may indicate peripheral neuropathy (e.g., in diabetes or Vitamin B12 deficiency) or spinal cord/CNS lesions affecting the DCML pathway.

Question 17

Joint Position Sense - Definition?

Answer 17

The ability to sense the position and movement of joints and limbs, important for knowing your body’s posture and movement without seeing it

Question 18

Joint Position Sense - Physiology

Answer 18

Proprioceptors in muscles, tendons, and joint capsules send signals to the central nervous system about joint position and movement.

Question 19

Joint Position Sense - Pathway?

Answer 19

Primarily conveyed through the dorsal column-medial lemniscus (DCML) pathway, which transmits proprioceptive information from the periphery to the brain.

Question 20

Joint Position Sense - Clinical Relevance?

Answer 20

Impaired joint position sense may indicate conditions affecting proprioception, such as peripheral neuropathy, multiple sclerosis, or spinal cord injuries.

Loss of proprioception can lead to difficulties with balance, coordination, and fine motor skills.

Question 21

Two-Point Discrimination - Definition?

Answer 21

The ability to perceive two separate points of contact on the skin simultaneously, rather than feeling them as a single point.

Question 22

Two-Point Discrimination - Pathway?

Answer 22

Sensory information is carried through the dorsal column-medial lemniscus (DCML) pathway, responsible for fine touch, vibration, and proprioception.

Question 23

Two-Point Discrimination - Clinical Relevance?

Answer 23

Impairment may indicate sensory nerve damage, peripheral neuropathy, or central nervous system lesions affecting the DCML pathway.

Commonly assessed in conditions like diabetes, stroke, or multiple sclerosis.

Question 24

Temperature Sensation - Definition?

Answer 24

The ability to perceive changes in temperature, distinguishing between hot and cold stimuli.

Question 25

Temperature Sensation - Physiology?

Answer 25

Transmitted through free nerve endings in the skin sensitive to temperature changes. Involves two types of thermoreceptors: cold receptors (activated by cooler temperatures) and warm receptors (activated by warmer temperatures).

Question 26

Temperature Sensation - Pathway?

Answer 26

Primarily carried by the lateral spinothalamic tract, part of the spinothalamic pathway, which also conveys pain and crude touch sensations.

Question 27

Temperature Sensation - Clinical Relevance?

Answer 27

Impairment may indicate issues with the lateral spinothalamic tract, peripheral nerve damage, or conditions like diabetes, multiple sclerosis, or spinal cord injuries. Testing can help identify areas of sensory loss or abnormal sensory processing.

Question 28

Sensory Neglect - Definition?

Answer 28

Condition where individuals fail to notice or respond to stimuli on one side of their body or environment, typically following brain damage.

Question 29

What pathway is associated with Sensory Neglect?

Answer 29

The dorsal visual stream, which integrates sensory input for attention and action. Damage to the right parietal lobe disrupts this pathway, leading to sensory neglect.

Question 30

What sensory loss occurs with a lesion above the spinal cord (in the brainstem or higher) in the spinothalamic tract (STT)?

Answer 30

Contralateral loss of pain, temperature, and crude touch sensations.

Question 31

Where does decussation occur for the spinothalamic tract (STT)?

Answer 31

At the spinal level.

Question 32

How does sensory loss in the spinothalamic tract (STT) differ from the dorsal column-medial lemniscus (DCML) pathway?

Answer 32

The STT decussates at the spinal level, while the DCML pathway crosses in the medulla.

Question 33

What is Brown-Séquard syndrome?

Answer 33

A condition where half of the spinal cord is damaged, causing different types of sensory loss on each side of the body.

Question 34

In Brown-Séquard syndrome, what sensory loss is seen on the contralateral side?

Answer 34

Loss of pain, temperature, and crude touch (STT pathway).

Question 35

What type of sensory loss occurs in central canal lesions, such as syringomyelia?

Answer 35

Bilateral loss of pain, temperature, and crude touch at the level of the lesion.

Question 36

Why does a central canal lesion cause bilateral sensory loss in the spinothalamic tract (STT)?

Answer 36

It affects the crossing STT fibers at the lesion level

Question 37

What happens when the DCML pathway is damaged?

Answer 37

The brain loses input from skin receptors and proprioceptors, reducing awareness of surroundings and body position.

Question 38

How does the location of a DCML lesion affect symptoms?

Answer 38

Below the decussation (in the medulla): Symptoms are on the same side as the lesion. Above the decussation: Symptoms appear on the opposite side of the body.

Question 39

What is astereognosis?

Answer 39

The inability to recognize an object by its shape and weight using touch alone.

Question 40

What is agraphesthesia?

Answer 40

The inability to recognize numbers or letters drawn on the skin by touch.

Question 41

How does a DCML lesion affect position and movement sense?

Answer 41

The patient cannot accurately perceive the position of their body in space without visual input.

Question 42

What is a positive Romberg test, and how does it relate to DCML lesions?

Answer 42

A positive Romberg test occurs when the patient is unable to maintain balance with eyes closed, indicating loss of proprioceptive sense.

Question 43

What are common causes of DCML pathway damage?

Answer 43

- Degenerative diseases (e.g, vitamin B12 deficiency) - Trauma - Posterior cord syndrome - Degenerative cervical myelopathy - Multiple sclerosis (MS).

Question 44

What is the difference between stereognosis and astereognosis?

Answer 44

Stereognosis = The ability to recognize objects by touch. Astereognosis = The inability to recognize objects by touch (the "a-" prefix means absence or inability)