Motor Neurone Disease Flashcards
What is MND?
a progressive neurodegenerative disorder of cortical, brainstem + spinal motor neurons (LMN + UMNs)
List 4 subtypes of MND
Amyotrophic Lateral Sclerosis (ALS):
Combined degeneration of upper + lower motor neurones resulting a mix of LMN + UMN signs
Progressive Muscular Atrophy: Only LMN signs e.g. flail arm/ foot. Better prognosis
Progressive Bulbar Palsy: Dysarthria + Dysphagia. Wasted, fasciculating tongue (LMN). Brisk jaw jerk reflex (UMN)
Primary Lateral Sclerosis: UMN pattern of weakness, Brisk reflexes, Extensor plantar responses. NO LMN signs
What causes MND?
UNKNOWN
Free radical damage + glutamate excitotoxicity have been implicated as mutations in SOD1 gene
What is the pathology behind MND?
Progressive motor neurone degeneration + death with gliosis replacing lost neurones
What condition is MND associated with?
Frontotemporal lobar dementia
What is the epidemiology of MND?
RARE
Mean age of onset: 55y
5-10% have FH with AD inheritance
List 4 symptoms of MND
Weakness of limbs (focal or asymmetrical) Speech disturbance (slurring/ reduction in volume) Swallowing disturbance (e.g. choking) Behavioural changes (e.g. disinhibition, emotional lability)
What LMN signs are seen in MND?
Muscle wasting
Fasciculations
Flaccid weakness
Hyporeflexia
What UMN signs are seen in MND?
Spastic weakness
Extensor plantar response
Hyperreflexia
What general signs are seen in MND?
UMN + LMN signs, often affecting several regions asymmetrically
Sensory examination: should be NORMAL
What bloods are tested for/ seen in MND?
Mild elevation in CK
ESR (high in certain neuropathies (inflammation))
Anti-GM1 ganglioside antibodies: to exclude multifocal motor neuropathy (treatable)
What other tests are performed in MND?
EMG: acute/ chronic denervation with giant motor unit APs in >1 limb +/- paraspinals
Nerve conduction studies; often normal
MRI: exclude cord compression + brainstem lesions
Spirometry: assess respiratory muscle weakness (FVC)
