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Related Subjects: |Neurological History taking |Cortical functions |Motor System |Sensory System |Mental state Examination |Speech and Language Exam |Cranial nerves and examination |Assessing Cognition

Anatomy

• Conscious sensation passes ultimately from sense organ to contralateral parietal lobe
• From sensory receptor passes into the cord through the dorsal root.
• Passes into either through
  • Dorsal columns
    • Carry afferent proprioception, vibration and fine touch.
    • Fibres remain on the same side of the cord
    • Fibres cross over at the foramen magnum
  • Spinothalamic tracts.
    • Cross over to other side of cord very quickly after entering
    • Ascends in spinal cord and passes to ipsilateral thalamus
    • Then crosses over to contralateral parietal lobe
• Minimum exam
  • Cutaneous sensation is pinprick and light touch (cotton wool) over dermatomes comparing right and left
  • Test for temperature as well as proprioception
• Proprioception (Dorsal Column)
  • Testing: Tests dorsal columns which also carry vibration and touch sensation.
  • Choose distal joint and move proximally. Hold joint by side and isolate joints above and below so that only one is moved. Ask the patient to describe the orientation of the digit or toe or foot. With eyes closed get the patient to touch nose.
  • Romberg test: Patient stands with feet together. Push to chest to see if the patient can maintain a stance. If unable to then this is instability which could be for a variety of reasons. Repeat with eyes closed and see and if this makes a marked difference then suggests that visual input vital to maintaining posture and there is a problem with dorsal column function carrying proprioception information
• Vibration (Dorsal Column)
  • Use a 128 Hz tuning fork and apply to distal bony points e.g. bony part of the big toe, medial malleolus, patella
  • See if a vibrating can be distinguished from a non-vibrating fork
• Temperature (Spinothalamic)
  • See if patient appreciates the coolness of the tuning fork
  • Isolated loss can be seen in hemi-cord lesions and lateral medullary syndrome
• Fine touch (Dorsal Column)
  • Use cotton wool ball in each of the dermatomal areas or any area of decreased sensation working to that with normal sensation.
• Pinprick (Pain) (Spinothalamic)
  • Use disposable pins. Move from areas with sensory loss to normal. Spinothalamic

Interpretation

• Patterns of Sensory loss
  • Sensory loss - over one side of body face/arm and leg is seen with contralateral intracranial pathology
  • Symmetrical cape-like loss of pain and temperature over shoulders and hands suggests syringomyelia
  • Loss of proprioception suggests B12 involvement with SACD or Tabes dorsalis
  • Glove and Stocking loss suggests peripheral neuropathy
  • Sensory loss below a certain area symmetrically suggests spinal cord disease
  • Reduced perineal sensation suggests cauda equina damage
• Perineal Examination
  • Becomes important when there is concern that lower sacral nerves have been affected usually by a suspected cauda equina lesion
  • Ask about urinary incontinence or overflow or retention and erectile dysfunction
  • Do a rectal exam and ask the patient to squeeze on your finger looking for signs of weakness

Dermatomes

• Thumb:C6
• Middle finger:C7
• Little finger: C8
• Breast nipple:T4
• Umbilicus:L4
• Big toe:L5
• Little toe:S1
• Inner back of legs: S2
• Saddle area: S1 to S5

Exam

1. Introduction and Consent

• Introduce Yourself: Clearly state your name and role.
• Explain the Procedure: Briefly explain what the sensory examination will involve.
• Obtain Consent: Ensure the patient agrees to proceed with the examination.

2. General Principles

• Positioning: The patient should be comfortably seated or lying down.
• Exposure: Expose the areas to be examined, ensuring privacy and dignity.
• Equipment: Gather necessary tools (cotton wisp, pin, tuning fork, monofilament).

3. Assessment of Light Touch

• Equipment: Use a piece of cotton wool.
• Procedure: Ask the patient to close their eyes. Gently touch the cotton wool to different parts of the body.
• Instructions to Patient: The patient says "yes" or "now" each time they feel the touch.
• Interpretation: Compare both sides of the body for symmetry.

4. Assessment of Pain (Sharp/Dull Discrimination)

• Equipment: Use a neurotip or the blunt and sharp ends of a safety pin.
• Procedure: Ask the patient to close their eyes. Alternately touch the skin with the sharp and dull ends.
• Instructions to Patient: The patient identifies "sharp" or "dull".
• Interpretation: Inability to distinguish sharp/dull or reduced sensitivity may indicate nerve damage.

5. Assessment of Temperature

• Equipment: Use two test tubes (warm and cold water) or specialized temperature probes.
• Procedure: Ask the patient to close their eyes. Touch the skin with the warm and cold objects.
• Instructions to Patient: The patient identifies "hot" or "cold".
• Interpretation: Abnormal findings may suggest damage to the spinothalamic tract.

6. Assessment of Vibration

• Equipment: A 128 Hz tuning fork.
• Procedure: Strike the tuning fork and place it on a bony prominence.
• Instructions to Patient: The patient reports when they first feel the vibration and when it stops.
• Interpretation: Diminished or absent sensation may indicate peripheral neuropathy.

7. Assessment of Proprioception (Joint Position Sense)

• Procedure: Hold the patient’s finger or toe by its sides, move it up or down, and ask the patient to identify the direction of movement with eyes closed.
• Instructions to Patient: The patient should respond with "up" or "down".
• Interpretation: Inability to correctly identify the direction may suggest a lesion in the dorsal columns.

8. Assessment of Discriminative Sensations

• Two-Point Discrimination: Use a caliper or paperclip to touch the patient’s skin simultaneously with two points and gradually decrease the distance.
• Graphesthesia: Draw a number or letter on the patient’s palm and ask them to identify it.
• Stereognosis: Ask the patient to identify a small object placed in their hand.
• Interpretation: Abnormalities may indicate cortical sensory processing issues.

9. Assessment of Gait (if applicable)

• Procedure: Ask the patient to walk across the room, turn, and walk back. Observe their gait for symmetry, balance, and coordination.
• Interpretation: An abnormal gait could indicate sensory ataxia or proprioceptive deficits.

10. Concluding the Examination

• Summarize Findings: Briefly summarize your findings to the patient.
• Thank the Patient: Thank the patient for their time and cooperation.
• Document: Record your findings accurately, noting any abnormalities.

11. Important Considerations

• Symmetry: Always compare sensations bilaterally.
• Systematic Approach: Ensure you cover all necessary sensory modalities.
• Patient Comfort: Maintain patient comfort and explain each step as you go.

Summary

The Neurological Sensory Examination in an OSCE setting tests your ability to assess various sensory modalities, including light touch, pain, temperature, vibration, proprioception, and discriminative sensations. Pay close attention to detail, communicate clearly with the patient, and accurately interpret the findings.