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A 52-year-old female (a proud Gulf War veteran) presents in the doctor’s…
A 52-year-old female (a proud Gulf War veteran) presents in the doctor’s office complaining of recent challenges with completing normal tasks. Her muscle weakness has impacted other areas. Genetic testing confirms that this patient also has ALS.
Upstream Causes
Possible Direct Upstream Causes
Familial ALS
Familial ALS is inherited. Around 5 to 10 percent of cases are familial. The child of a person with ALS will have a 50 percent chance of developing the condition. Rarely, it can affect a person in their teens. Researchers are investigating which genes are involved.
Disorganized immune response
The immune system may attack some of the body's cells, possibly killing nerve cells.
Chemical imbalance
People with ALS often have higher levels of glutamate, a chemical messenger in the brain, near the motor neurons. Glutamate in high quantities is known to be toxic to nerve cells.
Mishandling of proteins
If proteins are not processed correctly by nerve cells, abnormal proteins could potentially accumulate and cause the nerve cells to die.
Possible Indirect Upstream Causes
Possible environmental factors
One study has reported that military personnel deployed in the Gulf region during the 1991 war were more likely to develop ALS than military personnel deployed elsewhere.
Some possible links have been found between ALS and exposure to
Mechanical or electrical trauma
Military service
High levels of exercis
High levels of agricultural chemicals
High levels of a variety of heavy metals
Downstream Effects
Direct Problem
Progression varies between individuals. In the early stages, signs and symptoms may be barely noticeable, but the weakness becomes more visible over time.
Dementis
Some people may have problems with decision-making and memory, eventually leading to a form of dementia called frontotemporal dementia.
difficulty carrying out daily activities, including walking
increased clumsiness
weakness in the feet, hands, legs, and ankles
cramping and twitching in the arms, shoulders, or tongue
difficulty maintaining good posture and holding the head up
uncontrolled outbursts of laughing or crying, known as emotional lability
cognitive changes
slurring of speech and difficulty with voice projection
pain
fatigue
problems with saliva, and mucus
difficulty breathing and swallowing, in the later stages
Early Symptoms
Early symptoms often include clumsiness, abnormal limb fatigue, muscle cramps and twitches, and slurred speech. Symptoms will spread to all parts of the body as ALS progresses.
Late effects
affects both upper and lower motor neurons
usually affects limbs first
can sometimes affect facial and throat muscles first
generally symptoms of both upper and lower motor neuron damage can present simultaneously (it's complicated)
Background Information
Physiology
Function of upper motor neurons
The upper motor neuron (UMN) is the motor system that is confined to the central nervous system (CNS) and is responsible for the initiation of voluntary movement, the maintenance of muscle tone for support of the body against gravity,
Function of Cerebral cortex
Frontal Lobe
Forward part of cerebral cortex responsible for motor function, language, memory, and planning
Prefrontal Cortex
Part of frontal lobe responsible for thinking, planning, and language
Broca's Area
Formation of speech
Motor Cortex
Body movement/Voluntary movements
Parietal Lobe
Upper middle part of cerebral cortex behind the frontal lobe that is for touch and perception; damage means neglect of opposite side of body from where damage happened
Primary sensory cortex
Receives data about sensations in skin, muscles, and joints; regions of the cerebral cortex that initially process information from the senses
Occipital Lobe
Back part of cerebral cortex specialized for vision
Visual Association cortex
Analyzes visual data to form images
Primary visual cortex
Receive nerve impulses from the visual thalamus
Temporal Lobe
Hearing, understanding language and memory
Auditory Association cortex
Analyzes data about sound, so we can recognize words and melodies
Primary Auditory cortex
Detects qualities of sound, such as pitch and volume
Wernicke's Area
Interprets spoken and written language; damage can cause difficulties understanding speech
Association cortex
Regions of the cerebral cortex that integrate simpler functions to perform more complex functions
Basal Ganglia
Structures buried deep inside the cortex that help to control movement
Function of lower motor neuron
The lower motor neuron (LMN) is the efferent neuron of the peripheral nervous system (PNS) that connects the central nervous system (CNS) with the muscle to be innervated. The entire function of the CNS is manifested through the lower motor neuron.
Treatment and prevention
There is no cure for ALS, so treatment aims to alleviate symptoms, prevent unnecessary complications, and slow the rate of disease progression.
Physical therapy
can help people with ALS manage pain and address mobility issues
Occupational therapy
can help a patient maintain their independence for longer by:
helping patients choose adaptive equipment and assistive technologies to help them keep up their daily routines
train them in ways to compensate for hand and arm weaknesses
Breathing therapy
may be needed in time, as the respiratory muscles get weaker.
Speech therapy
is useful when ALS begins to make it harder to talk. Speech therapists can help by teaching adaptive techniques. Other methods of communication include writing and computer-based communications equipment.
Nutritional support
Nutritional support is important, as difficulty with swallowing can make it hard to get enough nutrients. Nutritionists can advise on preparing nutritious meals that are easier to swallow. Suction devices and feeding tubes may help.
Anatomy
Upper motor neurons
Originate in the cerebral cortex
Frontal Lobe
Motor Cortex
Parietal Lobe
Primary sensory cortex
Occipital Lobe
Visual Association Cortex
Primary visual cortex
Temporal lobe
Auditory Association cortex
Primary Auditory cortex
Wernicke's Area
Association cortex
Basal Ganglia
Lower motor neuron
long axon which will synapse on skeletal muscles; soma is in the ventral horn; some start in the precentral gyrus, premotor cortex, or brainstem, but all synapse in the ventral horn; organized based on innervation (medial muscles will be in medial part of ventral, etc.); part of peripheral nervous system; can be somatic motor neuron or alpha motor neuron
lower motor neurons and interneurons are located
ventral horn motor neurons, or branchial/somatic neurons of the brainstem (CN 3, 4, 5, 6, 7, 9, 10, 11, 12) innervate skeletal musclesl
lower motor neurons divisions
alpha and gamma
Lower motor neuron
The lower motor neuron is a motor neuron that transmits nerve impulses from the upper motor neurons to the effector muscles. It may originate from anterior gray column, anterior nerve roots or cranial nerve nuclei of the cranial nerves or the brainstem. The main function of lower motor neurons is to connect spinal cord or the brainstem to the muscles. Therefore, the lower motor neurons are the cranial and the spinal nerves. The formation of spinal nerves at the spinal