Topic 26 Motor neuron diease

Question 1

Definition of MND

Answer 1

MND is an adult onset neurodegenerative disorder characterised by loss of UMNs (including Betz cells of the motor cortex) and LMNs (anterior horn cells of the spinal cord and brainstem nuclei).

Question 2

Pathology of MND

Answer 2

Demyelination and gliosis of the corticospinal and corticobulbar tracts caused
by degeneration of the Betz cells in the motor cortex result in upper motor neuron symptoms. UMN

Loss of anterior horn cells of the spinal cord and motor cranial nerve nuclei in brainstem result in denervation muscle atrophy and weakness - Lower motor neuron.

Question 3

• Describe the UMN and LMN changes that occur in amyotrophic lateral sclerosis(ALS)

Answer 3

MND is an adult onset neurodegenerative disorder characterised by loss of:
UMNs (including Betz cells of the motor cortex)
LMNs (anterior horn cells of the spinal cord and brainstem nuclei).
ALS affects both upper and lower motor neurons

Question 4

• Describe the pathologies, symptoms and signs and clinical features of motor neuron disease (ALS)

Answer 4

Signs
LMN signs : muscular weakness and atrophy
UMN signs : spasticity

Symptoms
Muscle cramps and fasciculations
Dysarthria
Dysphagia
Dyspnoea
Cognitive/executive dysfunction (on formal testing)}

Question 5

Syringiomelia Definition

Answer 5

Chronic progressive disorder in which cavitation develops within the central grey matter of the spinal cord

Question 6

Aetiology/Cause of Syringiomelia

Answer 6

• Sometimes associated with a congenital anomaly at the craniocervical junction
• may follow localised injuries to the spinal cord
• rare (prevalence 8/100,000)
• chronic, progressive degenerative condition in which a tubular cavitation, called a -syrinx, develops within the central parenchyma of the spinal cord.
• Although the syrinx usually develops in the lower cervical region, it may extend downwards in the thoracic or lumbar regions, or upwards into the medulla oblongata and pons (syringobulbia).

Question 7

Signs & Symptoms of Syringiomelia

Answer 7

loss of pain & temperature sense in upper limbs and upper chest
wasting of small muscles of the hand
progressive weakness & wasting of upper limbs
spastic paresis of lower limbs

*Diagram of pathology
Affected lateral corticospinal tract( Pain & temp interrupted) on ipsilat and contralat side affected
Discriminative touch and proprioception still intact