Motor Neurone Disease Flashcards
Define
a progressive neurodegenerative disorder of cortical, brainstem and spinal motor neurons (lower and upper motor neurons)
Subtypes:
Amyotrophic Lateral Sclerosis (ALS)
- AKA Lou Gehrig’s disease
- Combined generation of upper AND lower motor neurones resulting a mix of LMN and UMN signs
Progressive Muscular Atrophy Variant
- Only LMN signs
- Better prognosis
Progressive Bulbar Palsy Variant
- Dysarthria
- Dysphagia
- Wasted fasciculating tongue
- Brisk jaw jerk reflex
Primary Lateral Sclerosis Variant
- UMN pattern of weakness
- Brisk reflexes
- Extensor plantar responses
- NO LMN signs
Causes
UNKNOWN
Free radical damage and glutamate excitotoxicity have been implicated
Pathology
- Progressive motor neurone degeneration and death
- Gliosis replacing lost neurones
Associations
- Frontotemporal lobar dementia
Epidemiology
RARE
Incidence: 2/100,000
Mean age of onset: 55 yrs
5-10% have a family history with autosomal dominant inheritance
Symptoms
Weakness of limbs
Speech disturbance (slurring or reduction in volume)
Swallowing disturbance (e.g. choking on food)
Behavioural changes (e.g. disinhibition, emotional lability)
Signs
Combination of UMN and LMN signs
LMN Features
- Muscle wasting
- Fasciculations
- Flaccid weakness
- Hyporeflexia
UMN Features
- Spastic weakness
- Extensor plantar response
- Hyperreflexia
Sensory examination - should be NORMAL
Investigations
Bloods
- Mild elevation in CK
- ESR
- Anti-GM1 ganglioside antibodies
Electromyography (EMG)
Nerve conduction studies - often normal
MRI - exclude cord compression and brainstem lesions
Spirometry - assess respiratory muscle weakness
