Review Note
Last Update: 04/01/2024 02:31 AM
Current Deck: Neurology::Spinal Cord
PublishedCurrently Published Content
Text
{{c1::Amyotrophic Lateral Sclerosis (ALS)::Condition}} is a condition that involves combined UMN and LMN deficits with no sensory, cognitive or oculomotor deficits.
Notes
Amyotrophic Lateral Sclerosis (ALS) is a progressive neurodegenerative disorder that affects motor neurons in the brain and the spinal cord. It leads to the degeneration and death of upper motor neurons (UMN) and lower motor neurons (LMN), resulting in a wide range of motor symptoms. Despite the motor system being the primary target of the disease, ALS does not typically involve sensory, cognitive, or oculomotor deficits, especially in the early stages. However, it's important to note that in later stages or certain subtypes of the disease, cognitive changes can occur in a subset of patients.
Pathophysiology Outline:
- Etiology: The cause of ALS is not fully understood, but it is thought to result from a combination of genetic and environmental factors. Mutations in several genes, such as the superoxide dismutase 1 (SOD1) gene, C9orf72, TDP-43, and FUS, are associated with familial forms of ALS.
- Mechanism: ALS is characterized by the progressive loss of motor neurons in the cortex, brainstem, and spinal cord. The degeneration of UMNs leads to symptoms such as spasticity, brisk reflexes, and pathological reflexes like the Babinski sign. LMN degeneration causes muscle weakness, atrophy, fasciculations, and eventually paralysis. The disease mechanism involves a complex interplay of factors, including glutamate excitotoxicity, mitochondrial dysfunction, oxidative stress, protein aggregation, and impaired axonal transport.
- Progression: ALS progresses at varying rates among individuals, but it typically leads to increasing motor disability. Patients may first notice muscle weakness in one part of the body (limb onset) or difficulty speaking or swallowing (bulbar onset). As the disease progresses, more regions become affected, leading to significant disability. Most individuals with ALS die from respiratory failure within 3 to 5 years from the onset of symptoms, although some patients may live longer.
ALS is unique among neurodegenerative diseases due to its specific focus on the motor system, sparing sensory neurons, and, initially, cognitive functions. However, up to 50% of patients may experience mild cognitive changes, and a subset can develop frontotemporal dementia (FTD), indicating that ALS can have broader neurological impacts beyond purely motor deficits. The lack of oculomotor involvement is a distinguishing feature of ALS, helping differentiate it from other conditions with similar presentations.
Mnemonic
Images
Related Videos
Missed Questions
UMN lateral corticospinal tracts
LMN anterior horn
One by one
No published tags.
Pending Suggestions
No pending suggestions for this note.