Motor Neuron Disease, Bulbar and Pseudobulber Palsy

Question 1

What is motor neuron disease?

Answer 1

Cluster of neurodegeneraitve diseases characterised by selective loss of neurons in the motor cortex, cranial nerve nuclei and anterior horn cells

Question 2

How would you distinguish MND from MS?

Answer 2

• There is no sensory disturbance or sphincter loss in MND
• MND never affects eye movements

Question 3

What are the four clinical patterns/subtypes that can present in MND?

Answer 3

• Amyotropic lateral sclerosis
• Progressive Bulbar/Pseudobulbar palsy
• Progressive muscular atrophy
• Primary lateral sclerosis

Question 4

What is the most common clinical pattern of MND?

Answer 4

Amyotopic lateral sclerosis

Question 5

What are the features of ALS?

Answer 5

Simulataneous UMN and LMN involvement - present with signs of both

• Starts in one limb, then gradually to other limbs and trunk
• Progressive focal muscle weakness and wasting
• Muscle fasciculations
• Signs of UMN - spasticity, brisk reflexes, up going plantars, asymmetric spastic paraparesis
• Signs of LMN - flaccid paralysis, wasting, fasciculations

Question 6

What is the pattern of an upper motor neuron lesion?

Answer 6

Pyramidal tracts

• Spaticity - clasp knife
• Weakness - loss of skilled movement
• Brisk reflexes
• Upgoing plantars
• Clonus

Question 7

What is meant by a pyramidal pattern of weakness?

Answer 7

UMN weakness affects groups of muscles:

• Arms - extensors predominantly affected - flexors left stronger
• Legs - Flexors predominantly affected - extensors left stronger

Anti-gravity muscles are left stronger

Question 8

What are features of a LMN lesion?

Answer 8

Anywhere from anterior horn cell distally:

• Wasting
• Fasciculations
• Flacid paralysis
• Absent/Reduced reflexes
• Babinski negative
• Clonus negative

Question 9

What are causes of mixed UMN/LMN signs?

Answer 9

• MND
• B12 defciency
• Taboparesis

Question 10

What are features of the progressive bulbar palsy subtype of MND?

Answer 10

LMN lesion affecting cranial nerves IX-XII:

• Flaccid, wasted fasciculating tongue
• Jaw jerk normal/absent
• Quiet speech/hoarse/nasal
• Absent gag reflex

Question 11

What are features of progressive pseudobulbar (corticobulbar) palsy?

Answer 11

UMN lesion of cranial nerves IX-XII:

• Increased/normal gag reflex
• Spastic tongue
• Increased jaw jerk
• Slow, deliberate, spastic speech
• Labile emotions - unprovoked weeping, mood-incongruent giggling

https://www.youtube.com/watch?v=zh0xmb_qqzo

Question 12

What are causes of bulbar palsy?

Answer 12

• Motor neurone disease
• Syringobulbia
• Guillain-Barre syndrome
• Poliomyelitis
• Subacute menignitis (carcinoma, lymphoma)
• Neurosyphilis
• Brainstem CVA

Question 13

What are causes of pseudobulbar palsy?

Answer 13

• Commonest - bilateral CVAs affecting the internal capsule.
• Multiple sclerosis
• Motor neurone disease
• High brainstem tumours
• Head injury

Question 14

What are features of the progressive muscular atrophy subtype of MND?

Answer 14

LMN only:

• Flaccid paralysis
• Muscle wasting
• Reduced/absent reflexes
• Babinski negative
• Fasciculations
• Clonus negative

Question 15

What part of the motor pathway does progressive muscular atrophy affect?

Answer 15

Anterior horn cell only - therefore LMN only

Question 16

What are features of the primary lateral sclerosis subtype of MND?

Answer 16

Confined to UMN:

• Spasticity
• Muscle weakness
• Increased reflexes
• Babinski’s positive
• Clonus positive
• No muscle wasting

Marked spastic leg weakness and pseudobulbar palsy

Question 17

What cells are affected in primary lateral sclerosis?

Answer 17

Betz cells in the motor cortex are lost

Question 18

What is the mean age of onset of MND?

Answer 18

60 years, but think of in anyone over age 40 presenting with signs of MND

Question 19

What common presentations may make you think of MND?

Answer 19

• Stumbling spastic gait
• Foot drop myopathy
• Weak grip
• Weak shoulder abduction
• Aspiration pnuemonia
• Frontotemporal dementia with MN signs

Question 20

How would you diagnose MND?

Answer 20

• Largely clinical diagnosis with EMG
• CK - may be mildly elevated
• Other investigations exclude other diagnoses

Question 21

What is the prognosis for someone with ALS?

Answer 21

Approximatley 4 years until death following diagnosis

Question 22

What is the prognosis for someone with progressive bulbar palsy?

Answer 22

Approximately 2 years

Question 23

What medications are used to manage MND?

Answer 23

• Riluzole - only medication shown to improve survival (about 3 months extra)
• Baclofen - reduces spasticity

Question 24

What class of drug is Riluzole?

Answer 24

Glutamate and NMDA receptor inhibitor

Question 25

What supportive measures can be put in place for someone with MND?

Answer 25

MDT involvement:

• PT
• OT
• SALT
• Feeding Gastrostomy
• Non-invasive respiratory support

Question 26

How would you manage problems with excess saliva in someone with MND?

Answer 26

• Advise positioning
• Oral care
• Suctioning

Question 27

How would you manage problems with spasticity in someone with MND?

Answer 27

• Baclofen
• Exercise
• Orthotics

Question 28

How would you address problems with communication in someone with MND?

Answer 28

Augmentative/alternative communication equipment

Question 29

What type of dementia is ALS associated with?

Answer 29

Frontotemporal dementia

Question 30

Why is it important to recognise early on that those with ALS can develop frontotemporal dementia?

Answer 30

Planning end-of-life decisions early on before cognitive decline