Clinical Lecture: Somatosensory Disturbance

Question 1

Ms A, a 20 year old Medical Student
Gradual onset tingly numbness starting in both feet and gradually ascending to level around upper chest “like a tight band”.
When sitting in a hot bath, noticed the water felt hotter on the left side of her body.

On examination, had disordered temperature sensation in the left leg and loss of vibration and proprioception on the right.
Brisk reflexes on right side.

Where is the lesion?

Answer 1

Temperature is carried by the spinothalamic pathway and proprioception via the dorsal column medial lemniscus pathway.

The lesion is in the neck. The sensory level of C5 is the chest. Lesions in the neck we get tightness in the chest.

This is a hemi-chord lesion often called: “Brown-Sequard” syndrome - only the right half side could have affected both pathways. It can be caused by anything can injure half of the spinal cord.

Here caused by inflammation of the spinal chord (“myelitis”) but can be viral (such as zoster virus) or first presenting feature of multiple sclerosis (MS).

Question 2

35 year old rugby player presented with pain in neck after a rugby match
Rapidly developed vertigo, unsteadiness, hoarse voice and difficulty swallowing
On examination, there was a Left Horners syndrome, and loss of pain and temperature in the left side of the face, but the right side of the body
Where is the lesion?

Answer 2

• There must be an issue with spinothalamic pathway on the right side (for the body) - right in the area of the stoke
  - The DCML fibres are spared
  Issue with the trigeminal sensory pathway - pain and temperature travel through the caudal spinal nucleus.
  - Horner’s is damage of the sympathetic fibres as it comes up to the eye
  The lesion is in the brainstem

There must be a lesion in the right lateral medulla. Stroke often caused by the occlusion of PICA
In this due to a dissection of the vertebral artery.

Question 3

56 year old smoker underwent repair of an abdominal aortic aneuysm
Afterwards, he realised he had lost all strength in both legs (paraplegia).
On examination, he had lost pain and temperature sensation below the umbilicus, but vibration and proprioception was preserved.
Where is the lesion?

Answer 3

• All strength was loss means an issue with the corticospinal pathway
  - Preserved proprioception means that the DCML pathway is conserved
  The lesion therefore is not at the level of the dorsal column but instead the lateral corticospinal tract

Blood supply to the anterior is via the anterior spinal and reinforced by medullary segmental branches
Diagnosis:
Anterior spinal artery syndrome

Question 4

What is a loss of sensation to all modalities indicative of?

Answer 4

Thalamic lesion

Question 5

What would a lesion to the parietal cortex look like?

Answer 5

People with a parietal stroke do not feel numb. It is very profound issues. Example include:

	- Dysgraphaesthesia - inability to recognise symbols traced on the skin (if minor)
	- Hemisensory neglect they do not perceive that side of the body of their own
	- Right/left confusion

Question 6

How does peripheral neuropathy present?

Answer 6

Glove and stocking distribution. Reflexes tend to disappear.

Question 7

Give example causes of peripheral neuropathy.

Answer 7

• Diabetes mellitus - most common in the world
  - Autoimmune (Guillain-Barre, CIDP, vasculitis)
  - Toxic (including drugs) - most common is alcohol and after this drug
  - Vitamin deficiency
  - Paraneoplastic
  - Chronic kidney, liver disease
  - Inherited (Charcot-Marie-Tooth disease)