Makindo Medical Notes

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 travels from the receptor → spinal cord → thalamus → contralateral parietal lobe.
• Entry: via the dorsal root of the spinal cord.
• Two key ascending pathways:
  • 🌟 Dorsal Columns: Proprioception, vibration, fine touch. Fibres ascend ipsilaterally → decussate in medulla → contralateral cortex.
  • 🔥 Spinothalamic Tracts: Pain, temperature, crude touch. Fibres decussate almost immediately → ascend contralaterally → thalamus → cortex.
• Basic exam: Compare both sides with pinprick & cotton wool, test proprioception & temperature.

🔎 Sensory Modalities

• Proprioception (Dorsal Column): Move distal joints (finger/toe up/down) with eyes closed. 🌐 Romberg Test: Feet together, eyes closed. Instability = dorsal column dysfunction.
• Vibration (Dorsal Column): 128 Hz tuning fork on bony prominences (e.g. hallux, malleolus).
• Temperature (Spinothalamic): Use warm/cold tubes or tuning fork. Loss = spinothalamic lesion (e.g. Brown-Séquard, lateral medullary syndrome).
• Fine Touch (Dorsal Column): Cotton wool over dermatomes, moving from abnormal → normal.
• Pinprick (Spinothalamic): Disposable neurotip/pin for pain perception.

🩺 Interpretation

• 🧩 Patterns of sensory loss:
  • Hemibody (face/arm/leg) → contralateral brain lesion.
  • Cape-like loss over shoulders/arms → syringomyelia.
  • Loss of vibration/proprioception → B12 deficiency (SACD, tabes dorsalis).
  • Glove & stocking → peripheral neuropathy (e.g. diabetes).
  • Sensory level → spinal cord lesion.
  • Reduced perineal sensation → cauda equina syndrome.
• 🩺 Perineal exam: Essential if cauda equina suspected → check saddle sensation, anal tone, continence history.

📍 Dermatomes

• 👍 Thumb: C6
• ☝️ Middle finger: C7
• 🤏 Little finger: C8
• 👕 Nipple line: T4
• 🪙 Umbilicus: T10
• 🦶 Big toe: L5
• 🦵 Little toe: S1
• 👖 Inner thigh: S2
• 🪑 Saddle area: S3–S5

🧾 Examination Steps (OSCE Style)

1. Introduction & Consent

• Introduce yourself, confirm patient identity & role.
• Explain procedure: “I’ll be testing different types of sensation.”
• Gain verbal consent, check comfort.

2. General Principles

• Position: patient seated or supine, relaxed.
• Exposure: only necessary areas, maintain dignity.
• Equipment: cotton wool, pin/neurotip, tuning fork (128 Hz), warm/cold tubes.

3. Light Touch

• Use cotton wool. Patient closes eyes, responds “yes” when touched.
• Compare both sides; map abnormalities.

4. Pain (Sharp/Dull)

• Use pin/neurotip alternating sharp vs blunt.
• Patient identifies “sharp” vs “dull.”
• Loss → spinothalamic dysfunction.

5. Temperature

• Use warm vs cold test tubes.
• Patient distinguishes warm vs cold → spinothalamic tract.

6. Vibration

• Strike tuning fork, place on bony prominence (toe, ankle, sternum).
• Ask patient when vibration starts/stops.
• Loss → peripheral neuropathy or dorsal column lesion.

7. Proprioception

• Hold digit by sides, move up/down with eyes closed.
• Patient identifies movement direction.
• Loss → dorsal column dysfunction.

8. Higher Discriminative Sensation

• Two-point discrimination: Paperclip/calipers.
• Graphesthesia: Draw number on palm.
• Stereognosis: Identify familiar object (coin, key) in hand.