ALS Flashcards
1
Q
What does ALS stand for
A
- Amyotrophic Lateral Sclerosis
2
Q
Generally describe ALS
A
- aka Lou Gehrig’s disease
- Severely progressive neurodegenerative disease that affects nerve cells in the brain & spinal cord
- Adult onset type of progressive motor neuron disease
- Both UMN (cortical neurons) and LMN (anterior horn cells) and axons can be affected
- Damage/loss of motor neurons lead to profound muscle weakness
- Cortical neuron impairments: cognitive function issues like attention deficits, language comprehension, & abstract reasoning
3
Q
Define ALS
A
- Amyotrophy: no muscle nourishment/muscle wasting
- Lateral sclerosis: gliotic scarring of lateral corticospinal tracts
4
Q
Incidence/etiology of ALS
A
- Rare condition
- Onset around 40-60 yrs
- 90% of cases are sporadic (cause unknown) and 5-10% being familial (FALS)
5
Q
Risk factors of ALS
A
- Clusters have been reported in groups of people living/working in close proximity or participating in same sport
- Chronic exposure to heavy metal: lead, mercury
6
Q
Hallmarks of ALS disease
A
- Degeneration and loss of motor neurons, astrocytic gliosis, and microglial proliferation
7
Q
UMN, LMN, and axon loss with ALS
A
- UMN: in motor cortex/primary motor cortex, frontotemporal cortex, hippocampus, thalamus, & substantia nigra
- LMN: in brainstem & spinal cord, loss of anterior horn cells through out spinal cord, specially in cervical, lumbar regions & bulbar pyramids
- Axon loss with astrocytic gliosis in corticospinal & corticobulbar tracts (to non-oculomotor CNs 5, 7, 9, 10, 12)
8
Q
What part is mostly spared in ALS
A
- Posterior horn cells & columns are mostly spared
- So sensation iis preserved
9
Q
Describe pathogenesis of ALS
A
- Genetic abnormalities in neurons: RNA content is reduced in damaged cells
- Excessive production of reactive O2 species is also responsible for cell death
- Disruption in axonal transport: spheroids found in axon & dendrites
- Excitotoxic damage to cells from increased presence of glutamate
- Selectivity in types of motor neurons affected: oculomotor neurons are spared
10
Q
Describe limb onset and bulbar onset
A
- Limb: cortical & spinal motor neurons are affected 1st; limb muscles are affected (70% cases)
- Bulbar: motor neurons of brainstem are affected 1st; muscles of throat, mouth, face are affected (25% cases)
11
Q
How can initial clinical presentation vary
A
- Trouble grasping a pen/lifting a coffee cup (loss of pincer grip due to split hand sign)
- Tripping/falls
- Muscle cramps/twitches
- Change in vocal pitch when speaking
- Uncontrollable periods of laughing or crying (pseudo-bulbar sign)
12
Q
How do patterns of muscle involvement/progression vary
A
- Asymmetric progressing to symmetric weakness progressing from distal to proximal
- Progressive muscle wasting (atrophy)
- Extensors become weaker than flexors
13
Q
Clinical manifestations of ALS
A
- Cervical extensor weakness causes drooping of the head (forward) with compensatory increase in lumbar lordosis to extend the neck
- Weakness is followed by deformities in extensor muscles
- Sensory functions, eye movements, bladder & bowel functions are mostly preserved
- Cognitive impairment in 50% of cases: memory, attention, problem solving
- Respiratory muscles affected in later stages: accessory breathing and respiratory distress can occur at night
- Bulbar onset is more predictive of cognitive deficits than limb onset
14
Q
Describe UMN signs and LMN signs of ALS
A
- LMN: cramping, muscle fasciculations, weakness, muscle wasting (atrophy)
- UNM in limbs: spasticity, postive Babinski, exaggerated reflexes, clonus
15
Q
Bulbar signs and Pseudobulbar signs of ALS
A
- Bulbar (LMN): dysarthria, hoarse & whispering voice, nasal tone, difficult swallowing, drooling, choking, facial & tongue muscle weakness/low tone (difficulty manipulating food in mouth)
- Pseudobulbar (UMN): aka pseudobulbar palsy; corticobulbar tracts to brainstem are affected = slurred speech, difficulty chewing/swallowing, spastic tongue, uncontrolled emotional outbursts
