Motor Neuron Disease, Bulbar and Pseudobulber Palsy Flashcards
(30 cards)
What is motor neuron disease?
Cluster of neurodegeneraitve diseases characterised by selective loss of neurons in the motor cortex, cranial nerve nuclei and anterior horn cells
How would you distinguish MND from MS?
- There is no sensory disturbance or sphincter loss in MND
- MND never affects eye movements
What are the four clinical patterns/subtypes that can present in MND?
- Amyotropic lateral sclerosis
- Progressive Bulbar/Pseudobulbar palsy
- Progressive muscular atrophy
- Primary lateral sclerosis
What is the most common clinical pattern of MND?
Amyotopic lateral sclerosis
What are the features of ALS?
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
What is the pattern of an upper motor neuron lesion?
Pyramidal tracts
- Spaticity - clasp knife
- Weakness - loss of skilled movement
- Brisk reflexes
- Upgoing plantars
- Clonus
What is meant by a pyramidal pattern of weakness?
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
What are features of a LMN lesion?
Anywhere from anterior horn cell distally:
- Wasting
- Fasciculations
- Flacid paralysis
- Absent/Reduced reflexes
- Babinski negative
- Clonus negative
What are causes of mixed UMN/LMN signs?
- MND
- B12 defciency
- Taboparesis
What are features of the progressive bulbar palsy subtype of MND?
LMN lesion affecting cranial nerves IX-XII:
- Flaccid, wasted fasciculating tongue
- Jaw jerk normal/absent
- Quiet speech/hoarse/nasal
- Absent gag reflex
What are features of progressive pseudobulbar (corticobulbar) palsy?
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
What are causes of bulbar palsy?
- Motor neurone disease
- Syringobulbia
- Guillain-Barre syndrome
- Poliomyelitis
- Subacute menignitis (carcinoma, lymphoma)
- Neurosyphilis
- Brainstem CVA
What are causes of pseudobulbar palsy?
- Commonest - bilateral CVAs affecting the internal capsule.
- Multiple sclerosis
- Motor neurone disease
- High brainstem tumours
- Head injury
What are features of the progressive muscular atrophy subtype of MND?
LMN only:
- Flaccid paralysis
- Muscle wasting
- Reduced/absent reflexes
- Babinski negative
- Fasciculations
- Clonus negative
What part of the motor pathway does progressive muscular atrophy affect?
Anterior horn cell only - therefore LMN only
What are features of the primary lateral sclerosis subtype of MND?
Confined to UMN:
- Spasticity
- Muscle weakness
- Increased reflexes
- Babinski’s positive
- Clonus positive
- No muscle wasting
Marked spastic leg weakness and pseudobulbar palsy
What cells are affected in primary lateral sclerosis?
Betz cells in the motor cortex are lost
What is the mean age of onset of MND?
60 years, but think of in anyone over age 40 presenting with signs of MND
What common presentations may make you think of MND?
- Stumbling spastic gait
- Foot drop myopathy
- Weak grip
- Weak shoulder abduction
- Aspiration pnuemonia
- Frontotemporal dementia with MN signs
How would you diagnose MND?
- Largely clinical diagnosis with EMG
- CK - may be mildly elevated
- Other investigations exclude other diagnoses
What is the prognosis for someone with ALS?
Approximatley 4 years until death following diagnosis
What is the prognosis for someone with progressive bulbar palsy?
Approximately 2 years
What medications are used to manage MND?
- Riluzole - only medication shown to improve survival (about 3 months extra)
- Baclofen - reduces spasticity
What class of drug is Riluzole?
Glutamate and NMDA receptor inhibitor
