Motor Neuron Disease Flashcards
What is motor neuron disease?
Untreatable and rapidly progressive neurodegenerative disease = mainly clinical diagnosis, variable clinical phenotypes
What are the main features of motor neuron disease?
Muscle weakness
Cognitive impairment
Issues with speech, swallow or breathing
UMN and/or LMN signs without sensory problems
What is the progression of motor neuron disease?
Focal onset and continuous spread = results in generalised paraesthesiae
Median survival is 3 years
What is the most common subtype of motor neuron disease?
Amyotrophic lateral sclerosis = worst prognosis and has mixed UMN and LMN signs, less common in non-Caucasians
What is the epidemiology of motor neuron disease?
Slightly more common in men
90% sporadic and 10% familial
Sporadic peaks at age 50-75 (declines after age 80)
What is the genetic occurrence of motor neuron disease?
Genetic aetiology has been identified in up to 20% of sporadic and 60% of familial cases
What are the different kinds of motor neuron disease?
Primary lateral sclerosis
Progressive muscular atrophy
Progressive bulbar palsy
What are some features of primary lateral sclerosis?
Rarest subtype
Presents with mostly UMN signs
What are some features of progressive muscular atrophy?
LMN variant of primary lateral sclerosis
Has variable prognosis
What is progressive bulbar palsy?
Bulbar variant = mixed upper and lower motor neuron signs but only confined to mouth
What are the UMN signs of motor neuron disease?
Pseudobulbar affect
Moderate weakness
Spasticity and hyperreflexia
Extensor plantar reflexes
What are the LMN signs of motor neuron disease?
Severe weakness and muscle cramps
Fasciculations
Hypotonicity and hyporeflexia
Muscle atrophy
What part of the body do most patients present with symptoms in?
The limbs = extremities (70%, upper>lower), bulbar (25%) and thoracic (2%)
What signs are most prominent?
LMN signs
What is motor neuron disease katabolism?
Increased metabolic rate = occurs in 40-50%
What are some features of progressive bulbar palsy?
More common in women aged 60-80
Always generalises into ALS
Affects tongue, facial and pharyngeal muscles
May need early communicator and nutritional support
What is split hand syndrome?
Preferential wasting of thenar group = seen occasionally in ALS
What mutation has been implicated in motor neuron disease?
C9orf72 expansion = present in 41% of familial ALS and 5-10% of sporadic ALS
What are some variants of ALS?
Flail arm/leg syndrome = one limb affected
Focal distal spinal muscular dystrophy
All have more benign prognosis
What is used to diagnose ALS?
Diagnosis of exclusion
Use neuroimaging and El Escorial criteria
How is suspected motor neuron disease investigated?
Electrophysiology
What is the underlying disease process of motor neuron disease?
Motor neuron degeneration and death
What are some conditions motor neuron disease is misdiagnosed as?
Carpal tunnel syndrome, stroke and neuropathy
How common are false positive diagnoses of motor neuron disease?
7-10% of cases
What are some conditions which are mistaken for motor neuron disease?
Multifocal motor neuropathy, Kennedy’s disease, myopathy, cervical spondylotic radiculomyelopathy
What is an example of a drug used to treat motor neuron disease?
Riluzole = gives patient extra three moths at end of disease, needs blood monitoring as affects kidneys and liver
Where are patients with motor neuron disease referred?
Specialist MND services = allocated to one consultant and two nurse specialists at time of diagnosis, seen 4-6 weekly if needed
What is a poor survival indicator in motor neuron disease?
Weight loss > 10% at diagnosis
How are communication difficulties managed?
Using AACs
What are some features of a gastrostomy?
Either PEG, RIG, PIGG or NG used
Carers may need to be involved in maintenance
Narrow window for effectiveness
What are some treatments for sialorrhoea?
Hyoscine or buscopan orally
Glycopyrronium if cognitive impairment
Botox and suction also options
How are muscle cramps treated?
Quinine or baclofen
How are muscle spasms treated?
Baclofen, tizanidine, dantrolene or gabapentin
What is one of the main causes of death in motor neuron disease?
Weakness of respiratory muscles = treated with non-invasive ventilation, BiPAP commenced at night initially and gradually increased
What is cognitive impairment associated with?
Frontotemporal dementia
How does cognitive impairment present in motor neuron disease?
Apathy, disinhibition, poor planning/decision making, inappropriate laughing or crying
What are some respiratory red flags?
SOB, orthopnoea, recurrent chest infections, disturbed or non-refreshed sleep, nightmares, daytime sleepiness, poor concentration
