5. Sensory syndromes in damage to the peripheral nerves, posterior roots and posterior horns of the spinal cord. Thalamic and cortical sensory syndromes. Pain.

Sensation - study of common sensation, sensory symptoms, sensory syndromes.

Study (Examination) of Common Sensation

The patient should have closed eyes and be compared bilaterally.

1.Superficial Sensibility

• Touch: cotton wool or tissue
• Pain: pin or neurotip (sharp/blunt discrimination)
• Temperature: warm and cold objects

2.Deep Sensibility "PVP"

• Position sense: movement of fingers or toes up/down
• Vibration sense: 128-Hz tuning fork over bony prominences
• Pressure sense: pressure applied to muscles/tendons

Cortical Sensory Functions

(Tested only if superficial and deep sensation are intact)

1.Stereognosis: identification of an object by touch

2.Graphesthesia: recognition of numbers/letters drawn on skin

3.Two-point discrimination

4.Barognosis: recognition of object weight

Sensory Symptoms

1.Positive Symptoms (Irritative)

Abnormal sensations experienced by the patient.

• Paresthesia: Abnormal sensation without stimulus. Tingling. Pins and needles. Prickling
• Dysesthesia: Unpleasant abnormal sensation, spontaneous or evoked.
• Hyperesthesia: Increased sensitivity to stimulation.
• Hyperalgesia: Exaggerated pain response to a painful stimulus.
• Allodynia: Pain caused by a normally non-painful stimulus.
• Neuralgia: Pain along the course of a nerve.

2.Negative Symptoms (Loss of Sensation)

• Anesthesia: Complete loss of sensation.
• Hypesthesia: Partial reduction of sensation.
• Analgesia: Loss of pain sensation.
• Thermoanesthesia: Loss of temperature sensation.
• Loss of Proprioception: Impaired position and vibration sense causing sensory ataxia.

Sensory Syndromes

1. Peripheral Nerve Syndrome::Sensory loss follows the distribution of a specific nerve.

• Features: Pain. Paresthesias. Hypesthesia/anesthesia. Weakness may coexist
• Example: Median nerve neuropathy.

2. Polyneuropathy Syndrome: Symmetrical distal sensory impairment.

• Features: "Glove and stocking" distribution. Paresthesias. Reduced reflexes. Distal weakness
• Common causes: Diabetes mellitus. Alcoholism. Vitamin B12 deficiency

3. Radicular Syndrome: Damage to spinal nerve roots.

• Features: Sharp shooting pain. Dermatomal sensory loss. Reduced corresponding reflexes
• Example: Lumbar disc herniation.

4. Spinal Cord Sensory Syndromes: Posterior Column Syndrome

• Loss of: Vibration sense. Position sense. Discriminative touch
• Results in: Sensory ataxia. Positive Romberg sign. Spinothalamic Syndrome
• Loss of: Pain. Temperature. Usually contralateral below the lesion.

5. Thalamic Syndrome: Lesion of the thalamus.

• Features: Contralateral sensory loss
• Severe spontaneous pain (thalamic pain). Hyperesthesia

6. Cortical Sensory Syndrome: Parietal lobe lesion.

• Features:. Astereognosis (cannot identify objects by touch). Agraphesthesia. Impaired two-point discrimination

Primary sensations remain relatively preserved.