L9 Motor Neuron Flashcards
What is the Spinal Cord
A long fragile structure that begins at brainstem and continues down the spine.
Consists of nerves responsible for incoming and outgoing messages between the brain and body
Spinal Nerves
Emerge in two branches known as anterior and posterior root
Anterior Root
Carries motor signals from brain to peripheries
Posterior Root
Carries sensory signals from the peripheries to the brain
Cauda Equine
Spinal Cord tapers towards the end and carries impulses to and from the legs
What does the CNS control and what neurons does it consist of
Controls skeletal muscle and consists of UMN and LMN
Upper Motor Neuron
Originate in primary motor cortex and pass through the internal capsule .
In spinal cord they form the lateral corticospinal tract and synapse with LMN .
Axons of upper motor neurons make up the pyramidal tracts and decussate forming the pyramids
Lower Motor Neurons
cell body located in spinal cord
Axons emerge from anterior root and joins with sensory fibres and form mixed nerves.
What is a motor unit
The motor end plates of each nerve and uscle fibres they support form a motorunit
What is Motor Neuron Disease
A group of neurodegeneratice disorders that selectively affect motor neurons, the cells which control the voluntary movement of the body
How is MND classified
Inherited or Sporadic
Locus of degeneration
Amytrophic Lateral Sclerosis
Both upper and lower motor neurons
Most common form of MND
3-5 years
Primary Lateral Sclerosis (PLS )
Upper motor neurons only
Up to 20 years for patients who dont develop ALS
Progressive Muscular Atrophy
Lower Motor Neurons only
Variable evolution to ALS
5 years
Progressive Bulbar Palsy
Form of ALS, eventually develops ALS
Impacts speech and swallowing first
2-3 years
Clinical presentation of ALS
Also known as Lou Gehrigs disease
-onset is asymetrical and distal
-muscle wasting and dasiculaitons
-weight loss and emotional lability
-5 years
long time to diagnose
cognitive and behavioural impairments
Bulbar onset (Clinical Representation)
25-30% of patients
speech and swallowing
weight loss
difficulty breathing when lying flat
emotional lability
75% ALS will display bulbar
Progressive Muslucar Atrophy (clinical representation)
Lower motor neuron
males
weakness and arm wasting, power is preserved
Respiration impaired, speech preserved
5 years
Primary Lateral Sclerosis (Clinical Presentation)
Affects legs first, power is preserved
Urge incontinence
Emotional lability
Neuropathology
Abnormal protein agregates or inclusions
Familial MND
10% of cases
Autosomal Dominant
20% of these cases relate to SOD 1
Pathogenic Mechanisms of ALS
Oxidative Stress
Excitotoxicity
Abnormal Protein precipitation and/or Aggregration
Cytoskeletal Defects
Axonal Transport
Neuroinflammation
Apoptosis
Lack of Growth Factors
Pharmacotherapies
Riluzole (approved)
¨ Edaravone (approved since 2017)
¨ Ceftriaxone
¨ Tamoxifen
¨ Arimoclomol
¨ Stem cell therapies
¨ Antisense therapies
¨ Antioxidants
Non pharacotherapy
OT
SLT
Nutritionalist
Auto cough
Suction Machine
