Clinical implications of reflex excitability

Question 1

What are the disorders of reflex excitability?

Answer 1

Hyporeflexia
Hyper-reflexia
Spinal shock

Question 2

What is hyporeflexia?

Answer 2

Depressed or absent reflexes
Lower motor neuron lesions (spinal cord)
Loss of motor neurons
Denervation of muscles (injury or disease)
Thyroid deficiency (chronic alcoholism)

Question 3

What is hyper-reflexia?

Answer 3

Exaggerated reflexes, spasticity and rigidness
Upper motor neuron lesions (higher part of the brain)
Spinal trauma or trans- section (hyper-reflexia below the lesion)
Brain haemorrhage (interruption of M1-spinal cord pathways)
Drug misuse (cocaine, amphetamine, stimulants)

Question 4

What is spinal shock?

Answer 4

Loss of sensation and motor paralysis

Follows partial or complete transection of spinal cord

Question 5

What is initial areflexia?

Answer 5

Complete absence of reflexes (3 days post lesion)

Question 6

What is return of “normal” reflexes?

Answer 6

Some reflex responses (3 days post lesion)

Question 7

What is sustained hyper-reflexia?

Answer 7

Spasticity (high resting tone in muscles)

Question 8

What does spinal shock reflect?

Answer 8

Abrupt loss of motor commands from brain

Lack of inhibitory control from the brain (hyper-reflexia)

Question 9

What does the trans-section location affect?

Answer 9

High cervical/thoracic- autonomic dysfunction
Loss of bladder control
Hyperactivity of sympathetic nervous system
Lack of parasympathetic and sympathetic control of the heart