Motor Neuron Disease, Bulbar and Pseudobulber Palsy Flashcards
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?
LOSS OF MOTOR NEURONS IN BOTH MOTOR CORTEX AND ANTERIOR HORN SC
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:
LM DEGENERATION
- Flaccid, wasted fasciculating tongue
- Jaw jerk normal/absent
- Quiet speech/hoarse/nasal
- Absent gag reflex
Dysarthria, dysphagia, tongue fasiculations
Can progress to ALS, worst prognosis
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
https://www.youtube.com/watch?v=zh0xmb_qqzo
Whats the difference between bulbar and pseudobulbar palsy
A bulbar palsy is a lower motor neuron lesion of cranial nerves IX, X and XII.
- Can be unilateral or bilateral
- Weak and wasted tone, tongue fasciulations
- If unilateral BP tounge deviates to SAME side of lesion
A pseudobulbar palsy is an upper motor neuron lesion of cranial nerves IX, X and XII.
- Always bilateral
- Small and psastic tongue. Jaw jerk exagerrated, gag reflex exagerrated.
- Tongue deviates to OPPOSITE side of lesion
Both have dysarthria, dysphagia, dysphonia, nasal regurg
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 - (STOKE) 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?
AFFECTS ANTERIOR HORN CELLS ONLY
LMN only: Affects distal muscle groups before proximal.
- Flaccid paralysis
- Muscle wasting
- Reduced/absent reflexes
- Babinski negative
- Fasciculations
- Clonus negative
Better prognosis than ALS
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?
MAINLY UMN DEGENERATION
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?
Think of MND in those >40 years with:
- Stumbling spastic gait
- Foot drop myopathy
- Weak grip
- Weak shoulder abduction (eg hair washing)
- Aspiration pnuemonia
- Frontotemporal dementia with MN signs
Look for UMN signs - spasticity, brisk reflexes, increased plantars
Look for LMN signs - wasting, fasciculations of tongue, abdomen back, thigh
Combo of UMN and LMN only affecting severeal regions asymetrically. SENSORY EXAMINATION NORMAL.
Speech/swallowing difficulty
How would you diagnose MND?
- Largely clinical diagnosis with EMG (confirms fasciculations and fibrillations), shows non specific muscle denervation
- 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) - slows progressive damage to motor neuron cells
- Baclofen - reduces spasticity
What class of drug is Riluzole?
Glutamate and NMDA receptor inhibitor
What supportive measures can be put in place for someone with MND?
MDT involvement:
- PT
- OT
- SALT
- Feeding Gastrostomy
- Non-invasive respiratory support
How would you manage problems with excess saliva in someone with MND?
- Advise positioning
- Oral care
- Suctioning
How would you manage problems with spasticity in someone with MND?
- Baclofen
- Exercise
- Orthotics
How would you address problems with communication in someone with MND?
Augmentative/alternative communication equipment
What type of dementia is ALS associated with?
Frontotemporal dementia
Why is it important to recognise early on that those with ALS can develop frontotemporal dementia?
Planning end-of-life decisions early on before cognitive decline
Aetiology motor neurone disease
Idiopathic
Genetic - AD (aothough ony 5% cases inhreited), mutations in SOD1 gene (found in 20% of familial cases)
Median onset of motor neuron disease
60 years
What are the fatal complications of MND?
Respiratory failure
Cardiac arrhythmias
