May 30, 2024

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

  1. Positive Symptoms
  2. 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
Dermatomes to access in Sensory examination
Sensory Dermatomes

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

  1. Point localization
  2. 2 Point discrimination
  3. Stregnosis
  4. Graphesthesia

Point Localization

Identify at which point the stimulus is provided in the skin

Use of paper clip/ divider

Divider can be used for  2-Point discrimination
The divider can be used for 2-Point discrimination

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