Sensory examination is a part of the neurological examination carried out as large, small fibres and cortical sensations.
Depends upon the following 3 types sensory examination can be explained.
Two types of sensation are seen in the case of nerve injury
- Positive Symptoms
- Negative Symptoms
Positive Symptoms
- Nerve is intact
- Added symptoms
- Burning sensation, pin and prick, tinglings
Negative Symptoms
- > 50 % of fibres are generally lost
- absence of things that should have been present
- Numbness, loss of cold, warm sensations etc
Small fibres
Small fibres will access for pain, temperature, fine touch and crude touch:
Pain:
In all examinations, first, explain to the patient the whole procedure
Sterilize the pin
First, prick in the normal areas and tell the patient that the pain sensation will be like this.
Prick in all the dermatomes
Check symmetrically in dermatomes
Temperature:
37±7′ C [30’C (cold) + 44’C (warm)]
Ideally, a test tube (30′ C to 44′ C) is taken
First, test in the normal areas and tell the patient that the temperature sensation will be like this.
Check in all the dermatomes
Check symmetrically in dermatomes
Fine touch:
By cotton fibres
Avoid hairy areas
Like pain, first check in normal and then symptomatic side
Check symmetrically in dermatomes
Crude touch:
With pen touch all dermatomes
Like pain, first, check in normal and then symptomatic side
Check symmetrically in dermatomes
Large Fibres
Position (EYE CLOSED)
Teach the patient by opening the eye
Move the great toe up and down (15°), and ask the patient where is his toe, up or down
Hand movements and shoulder movements are assessed in the upper limb
Vibration
128 Hz Tuning fork
Check-in bony prominences
Great toe–> lateral / Medial Malleolus –>knee –>ASIS –>Costal Margin –>Clavicle
Compare both sides with the normal
Normal is assessed by placing the tuning fork on the forehead
In Diabetic Neuropathic predominately large fibres are involved, So the first to lost is Vibration
If small fibres + large fibres = Both sensation problems–>DO NOT DO Cortical Sensation
If small fibres + large fibres = Both sensation Intact –> Proceed to Cortical Sensation
Cortical Sensation
Cortical Sensation signifies the functions of the parietal lobe
- Point localization
- 2 Point discrimination
- Stregnosis
- Graphesthesia
Point Localization
Identify at which point the stimulus is provided in the skin
Use of paper clip/ divider
2-Point discrimination
Normal 2-point discrimination points distances:
Palm : 3 cm
Sole: 4 cm
Other body parts: <5 cm
Pulp: 2-3 mm (Highly sensitive)
Stregnosis
Identify the geometry of the object
Astreognosis: Unable to identify the objects by size and shape
Graphesthesia
Generally done in the trunk
Shapes and numbers are drawn and asked the patient to identify
Also can be done in palms/ soles
See also: Motor examination
