DISORDERS OF THE MOTOR UNIT
motor unit - basic functional unit of the peripheral nervous system
elements:
> cell body of the motor neuron - located in the anterior horn of the spinal cord
> axon of the motor neuron - travels via spinal nerves and peripheral nerves to muscle
> neuromuscular junction
> muscle fibers - innervated by the neuron
Disorder can be:
> neurogenic
- lower motor neuron disorders
- affecting the cell bodies and peripheral nerves of the motor unit
> neuromuscular - affect the neuromuscular junction or the muscle itself
> myopathic - origin and generally cause muscle weakness and atrophy of skeletal muscle
NEUROGENIC DISORDERS
Peripheral Neuropathies
- motor neurons in the anterior horn of the spinal cord - mediate voluntary movement and reflexes that produce motor behavior
- characteristics of movement - determined by the pattern and firing frequency of specific motor units
- Muscle contraction - output of the motor system
- lower motor neuron system
> cell bodies in the anterior horn of the spinal cord and their axons
> nuclei of cranial nerves III through X (located in the brain stem) and their axons.
> motor fibers of the lower motor neurons contain:
= somatic motor components:
~ alpha motor neurons - innervate skeletal muscles (extrafusal fibers)
~ gamma motor neurons ~ innervate muscle spindles (intrafusal fibers)
> location of lesions:
= anterior horn cells of the spinal cord
= spinal nerves
= peripheral nerves
= cranial nerves or their nuclei in the brain stem
> causes of lesion:
= nerve root compression
= trauma (e.g., bone fractures and dislocations, lacerations, traction, or penetrating wounds and friction)
= toxins (e.g., lead, phosphorus, alcohol, benzene, or sulfonamides)
= infections (e.g., poliomyelitis or Guillain-Barré syndrome)
= neoplasms (e.g., neuromas and multiple neurofibromatosis)
= vascular disorders (e.g., arteriosclerosis, diabetes mellitus, peripheral vascular anomalies, polyarteritis nodosa)
= degenerative diseases of the central nervous systems (e.g., amyotrophic lateral sclerosis)
= congenital malformation (Charcot-Marie-Tooth Disease
Guillain-Barré Syndrome
- other names:
> acute idiopathic neuropathy
> infectious polyneuritis
> Landry’s syndrome
- acute, inflammatory disorder in which the body’s own immune system attacks part of the peripheral nervous system
- immune system destroys the myelin sheath that surrounds the axons of many peripheral nerves or even the axons
themselves, damaging the nerves’ ability to transmit signals to the muscles
- no known cause or cure
- not understood why this disorder strikes some people and not others
- often is after an upper respiratory or gastrointestinal viral infection, usually within 1 to 2 weeks
- occasionally triggered by surgery or vaccinations
> acute and complex disorder came to public attention when it struck a number of people who received the 1976
swine flu vaccine
- Affecting males and females equally
- symptoms:
> varying degrees of weakness and sensory changes in the legs (initial symptom)
> rapidly progressive ascending weakness of bilateral extremities, usually proceeding from distal to proximal (feet
to trunk)
> initial sensations such as tingling, “crawling-skin,” or painful sensations
> demyelination – problems with breathing, speaking, swallowing, blood pressure, or heart rate
- third week of the illness, 90% of all clients are at their weakest
- PHASES:
, > (1) initial, or acute, phase
- begins with the client’s first conclusive symptoms and lasts until there is no further decline in physical
status
- 1 to 3 weeks
> (2) plateau phase
- begins when the client’s physical state is stable, with no further deterioration of physical status and no
evidence of physical recovery
> (3) recovery phase
- period when the client slowly begins to recover physical abilities and symptoms gradually decrease.
- This phase can last up to 2 years, depending on the extent of paralysis.
- no known cure for GBS
- Role of the Occupational Therapist
> referred to OT when medically stable
> assessments:
= ROM
= MMT
= sensation testing
= swallowing assessment
= Functional assessments: quality of movement, coordination, and self-care
> intervention
= initial phase
- daily passive ROM
- positioning
- splinting - to prevent contracture and deformity and to protect weak muscles
- electronic aids for daily living (EADLs) - increase the level of independence
= recovery phase
- intensive interdisciplinary rehabilitation program
> Instruction to the client and family in key concepts:
>> energy conservation
>> work simplification
>> avoidance of overstretching
>> overuse of muscles
- Adaptive equipment
> Mobile arm supports may be used to alleviate muscle fatigue, promote active
assistive use of upper extremities, and encourage independence with occupations.
- frequent rest breaks
- Pshych
> acute progressive phase
= severe anxiety
= fear
= panic
> plateau phase
= anger
= depression
> recovery phase
= severe depression - occurred as clients contemplated the long, slow convalescence and the possibility
of permanent neurologic deficits
>>OT
= facilitates:
- feelings of self-worth
- positive attitude
- encouragement through the engagement in valued occupations.
= lifestyle redesign process – initiated in inpatient rehabilitation phase
= outpatient or home setting
- resumption of their previous life roles
- assist clients in returning to productive community involvement
- leisure occupations
- teach engagement and participation in meaningful occupations
Poliomyelitis and Postpolio Syndrome
Poliomyelitis - highly contagious viral disease that enters through the mouth via the fecal-oral route
(i.e., it is spread in unsanitary conditions with poor hand-washing techniques).
> Pathphysio:
- The virus moves from the throat into the digestive tract and is shed through fecal material for several weeks.
motor unit - basic functional unit of the peripheral nervous system
elements:
> cell body of the motor neuron - located in the anterior horn of the spinal cord
> axon of the motor neuron - travels via spinal nerves and peripheral nerves to muscle
> neuromuscular junction
> muscle fibers - innervated by the neuron
Disorder can be:
> neurogenic
- lower motor neuron disorders
- affecting the cell bodies and peripheral nerves of the motor unit
> neuromuscular - affect the neuromuscular junction or the muscle itself
> myopathic - origin and generally cause muscle weakness and atrophy of skeletal muscle
NEUROGENIC DISORDERS
Peripheral Neuropathies
- motor neurons in the anterior horn of the spinal cord - mediate voluntary movement and reflexes that produce motor behavior
- characteristics of movement - determined by the pattern and firing frequency of specific motor units
- Muscle contraction - output of the motor system
- lower motor neuron system
> cell bodies in the anterior horn of the spinal cord and their axons
> nuclei of cranial nerves III through X (located in the brain stem) and their axons.
> motor fibers of the lower motor neurons contain:
= somatic motor components:
~ alpha motor neurons - innervate skeletal muscles (extrafusal fibers)
~ gamma motor neurons ~ innervate muscle spindles (intrafusal fibers)
> location of lesions:
= anterior horn cells of the spinal cord
= spinal nerves
= peripheral nerves
= cranial nerves or their nuclei in the brain stem
> causes of lesion:
= nerve root compression
= trauma (e.g., bone fractures and dislocations, lacerations, traction, or penetrating wounds and friction)
= toxins (e.g., lead, phosphorus, alcohol, benzene, or sulfonamides)
= infections (e.g., poliomyelitis or Guillain-Barré syndrome)
= neoplasms (e.g., neuromas and multiple neurofibromatosis)
= vascular disorders (e.g., arteriosclerosis, diabetes mellitus, peripheral vascular anomalies, polyarteritis nodosa)
= degenerative diseases of the central nervous systems (e.g., amyotrophic lateral sclerosis)
= congenital malformation (Charcot-Marie-Tooth Disease
Guillain-Barré Syndrome
- other names:
> acute idiopathic neuropathy
> infectious polyneuritis
> Landry’s syndrome
- acute, inflammatory disorder in which the body’s own immune system attacks part of the peripheral nervous system
- immune system destroys the myelin sheath that surrounds the axons of many peripheral nerves or even the axons
themselves, damaging the nerves’ ability to transmit signals to the muscles
- no known cause or cure
- not understood why this disorder strikes some people and not others
- often is after an upper respiratory or gastrointestinal viral infection, usually within 1 to 2 weeks
- occasionally triggered by surgery or vaccinations
> acute and complex disorder came to public attention when it struck a number of people who received the 1976
swine flu vaccine
- Affecting males and females equally
- symptoms:
> varying degrees of weakness and sensory changes in the legs (initial symptom)
> rapidly progressive ascending weakness of bilateral extremities, usually proceeding from distal to proximal (feet
to trunk)
> initial sensations such as tingling, “crawling-skin,” or painful sensations
> demyelination – problems with breathing, speaking, swallowing, blood pressure, or heart rate
- third week of the illness, 90% of all clients are at their weakest
- PHASES:
, > (1) initial, or acute, phase
- begins with the client’s first conclusive symptoms and lasts until there is no further decline in physical
status
- 1 to 3 weeks
> (2) plateau phase
- begins when the client’s physical state is stable, with no further deterioration of physical status and no
evidence of physical recovery
> (3) recovery phase
- period when the client slowly begins to recover physical abilities and symptoms gradually decrease.
- This phase can last up to 2 years, depending on the extent of paralysis.
- no known cure for GBS
- Role of the Occupational Therapist
> referred to OT when medically stable
> assessments:
= ROM
= MMT
= sensation testing
= swallowing assessment
= Functional assessments: quality of movement, coordination, and self-care
> intervention
= initial phase
- daily passive ROM
- positioning
- splinting - to prevent contracture and deformity and to protect weak muscles
- electronic aids for daily living (EADLs) - increase the level of independence
= recovery phase
- intensive interdisciplinary rehabilitation program
> Instruction to the client and family in key concepts:
>> energy conservation
>> work simplification
>> avoidance of overstretching
>> overuse of muscles
- Adaptive equipment
> Mobile arm supports may be used to alleviate muscle fatigue, promote active
assistive use of upper extremities, and encourage independence with occupations.
- frequent rest breaks
- Pshych
> acute progressive phase
= severe anxiety
= fear
= panic
> plateau phase
= anger
= depression
> recovery phase
= severe depression - occurred as clients contemplated the long, slow convalescence and the possibility
of permanent neurologic deficits
>>OT
= facilitates:
- feelings of self-worth
- positive attitude
- encouragement through the engagement in valued occupations.
= lifestyle redesign process – initiated in inpatient rehabilitation phase
= outpatient or home setting
- resumption of their previous life roles
- assist clients in returning to productive community involvement
- leisure occupations
- teach engagement and participation in meaningful occupations
Poliomyelitis and Postpolio Syndrome
Poliomyelitis - highly contagious viral disease that enters through the mouth via the fecal-oral route
(i.e., it is spread in unsanitary conditions with poor hand-washing techniques).
> Pathphysio:
- The virus moves from the throat into the digestive tract and is shed through fecal material for several weeks.
