Patterns of sensory deficit

Question 1

Classes of sensory symptoms

Answer 1

Positive symptoms: Parasthesia Negative symptoms: numbness

Question 2

What are the five patterns of sensory loss in spinal cord lesions?

Answer 2

1. Complete transverse lesion:
2. Hemisection (Brown-sequard syndrome):
3. Central cord lesion:
4. Posterior column loss:
5. Anterior spinal syndrome:

Question 3

Pattern of loss in complete transverse lesion

Answer 3

: loss of all sensory modalities below the level of the lesion.

Caused by trauma, cord compression and transverse myelitis

Question 4

What is Brown-sequard syndrome>

Answer 4

Caused by hemisection of the spinal cord.

Loss of ipsilateral conscious proprioception, vibration and fine touch below the level of the lesion (dorsal column neurons do not dessucate til the medulla)

loss of contralateral pain and temperature sensation below the lesion. (Sensory loss of pain and temperature will be two levels below the loss of proprioception and touch because the spinothalamic neurons ascend two levels in the spinal cord before synapsing)

Caused by compression, trauma and transverse myelitis

Question 5

Pattern of loss in a central cord lesion

Answer 5

Syringomyelia - loss of pain and temperature sensation at the level of the lesion, because the spinothalamic tract has not been damaged.

Can cause pain, paralysis and weakness.

Question 6

Pattern of sensory loss in posterior column loss

Answer 6

Loss of conscious proprioception. Pain and temperature sensation intact because spinothalamic tracts lie anterior to the the dorsal columns (and spinal cord) and so are unaffected.

Caused by tabes dorsalis (syphillis) or subacute degeration of the spinal cord (B12 deficiency)

Question 7

Sensory loss in anterior spinal syndrome

Answer 7

Loss of pain and temperature sensation wth preserved conscious proprioception, vibration sense and touch.

Can be caused by infarcts in the anterior spinal artery

Question 8

How would a patient with thalamic syndrome present?

Answer 8

Hemisensory loss of all modalities of the contralateral side to the lesion/ damage

Question 9

Factors associated with risk developing chronic pain

Answer 9

Badly managed acute pain

Emotionally sensitive patient

Poor coping skills

Previous bad pain experiences

Surgical complications

Genetic predisposition

Question 10

Acoustic neuroma

Answer 10

Benign tumour that develops from the schwann cells of the vestibulocochlear nerve.

Slow growing, symptoms develop over years.

Presents as:
Ipsilateral sensorineural hearing loss
Tinntus
Numbness or parathesia in the face
Weakness of facial muscles
Vertigo
Ataxia

Question 11

Myotactic reflex

Answer 11

Muscle fibres contain contractile spindle fibres that help it adjust to changing muscle length.

Intrafusal fibres are innervated b gamma motor neurons and keep the muscle spindle under load during muscle contraction

The myotactic reflex is a muscle contraction in response to stretch. (prevents excess muscle stretch)

When the muscle lenghtens, the spindle is stretched and 1a afferent neurons carry sensation from the spindle to dorsal and spinocerebellar pathways (proprioception). Muscle spindles in the antagonist muscle are inhibited.

Question 12

Inverse myotactic reflex

Answer 12

Golgi tenson organs detect stretch in the tendons and initiate a protective reflex.

Stretch in the tendon is sensed by the golgi tendon organ. 1b afferent neurons carry sensation from the tendon organ to the spinal cord.

Reflex arc inhibits agonist muscle and stimulates contraction of the antagonist muscle.

Question 13

Withdrawal in response to pain

Answer 13

Flexor withdrawal:
Withdrawal of a limb from a painful or noxious stimulus mediated by free nerve endings. Stimulates flexor of ipsilateral limb and inhibits extensors.

Cross-extenson reflex:
Ipsilateral flexion and contralateral extension.