Motor System Lesions Flashcards
major sources of motor disruption
- peripheral motor connections
- cortical connections
- basal ganglia
- cerebellum
Motor disorders involving the peripheral nervous system can involve disruptions of
- The neuromuscular junction
- peripheral nerves
- spinal nerve roots
produce motor disruption by altering the connections between motor axons and muscle (neurotransmission)
Neuromuscular Junction Disease (NMJ)
Neuromuscular Junction Disease (NMJ) involves
- motor axon
- the neurotransmitter (acetylcholine)
- neurotransmitter receptors on the muscle or the metabolism of the neurotransmitter
autoantibodies are formed to acetylcholine receptors where the antibodies can block neuromuscular transmission
Myasthenia Gravis
Can have weakness mainly in skeletal muscles innervated by cranial nerves with ocular weakness and bilateral ptosis
Myasthenia Gravis
treatment for Myasthenia Gravis
cholinesterase inhibitors, which prevent the breakdown of acetylcholine after it is released by the nerve
one of a group of toxins from a bacterium (clostridium botulinum, one type of food poisoning) that irreversibly blocks the release of acetylcholine by binding to the presynaptic membrane in neuromuscular junctions and at preganglionic autonomic terminals
Botulinum Toxin
Nerve terminals fully disrupted by botulinum toxin must regrow or “sprout” locally for function to be restored
Botulinum Toxin
with Botulinum Toxin what type of muscles are affected?
Both smooth and skeletal muscle
with Botulinum Toxin you typically have weakness in
cranial nerve muscles and then in the limbs
dry mouth, abdominal cramping, vomiting and diarrhea because of an absence of peristalsis are symptoms of what
autonomic symptoms of Botulinum Toxin
Peripheral Nerve [Lesions- axons] can include damage to
- Dorsal roots
- Ventral roots
- And /or a spinal nerve
deficits usually associated with a particular spinal segment or restricted to particular muscles/groups that can be attributed to the functions of a single nerve
Mononeuropathy
in Mononeuropathy sensory loss is often used to identify what?
the nerve or root involved
Flaccid paralysis followed relatively rapidly (weeks to months) by atrophy of the muscle is what?
Peripheral Motor System Lesions
Hypotonia is what?
decreased muscle tone
Hyporeflexia, areflexia is what?
weakening or absence of tendon reflexes
Fibrillations or fasciculations of motor units as a result of denervation due to what?
Peripheral Motor System Lesions
Disseminated
result from metabolic diseases
Onset of what may be very slow and almost unnoticed (e.g. diabetes) or very rapid in some autoimmune neuropathies
Disseminated
typical pattern is the “stocking” or “glove” like deficits in limbs that usually involve both motor and sensory problems in what
Disseminated
isolated sensory or motor deficits is the compression of nerve roots as they leave the spinal cord
Nerve Compression at Spinal Roots - Radiculopathies
- Compressions of sensory roots are usually painful, or produce paresthesias
- Motor roots can also be selectively disrupted resulting in weakness of muscles innervated by the spinal root
Nerve Compression at Spinal Roots - Radiculopathies
symptoms of what type of lesion can be more complex and dependent upon the structure(s) damaged
Central Nervous System Motor Lesions
- paralysis or paresis with muscles that are initially weak and flaccid followed by (Spasticity, Hypertonia, Hyperreflexia, altered cutaneous reflexes including the Babinski sign (or Hoffmann sign) , and Clonus and a clasp knife response may also be present)
- Basal ganglia disturbances
- Cerebellar disturbances
Central Nervous System Motor Lesions
what lesion can produce upper motor neuron signs to varying degrees
Primary Motor Cortex Lesions
what lesion causes effects on movement
Primary Motor Cortex Lesions
lesions restricted to what produce disruptions of fine motor control such as finger movements
Primary Motor Cortex Lesions
typical upper motor neuron signs from more severe injuries result in
part from the loss of cortical influences (often inhibitory) on tracks originating in the brainstem
posturing or decorticate rigidity in humans results from brainstem sections above the superior colliculus that leaves the red nucleus and the influence of the rubrospinal tracts in place
Decortication
the upper limb is flexed, while the lower limbs remain extended
Decortication
produce a higher flexor tone in the upper limb (flexor activation is generally stronger than extensor)
Decortication
what results in unopposed extensor muscle activity in all four limbs or decerebrate rigidity
Brainstem Spinal Influences Lesions
when there is a Brainstem Spinal Influences Lesions what does it interrupt?
the lower midbrain interrupts the corticospinal and rubrospinal tracts
what produces motor processing problems
motor cortical areas outside of primary motor cortex
what is expressed as the inability to use the affected body part to perform voluntary or learned movements in spite of the lack of spasticity, paralysis or altered tone in the muscles
Apraxias
Lesions of premotor cortex usually result in
apraxias
Lesions of premotor cortex can affect
the ability to coordinate action on the two sides of the body, particularly in relation to learned movements
integration and processing of important feedback information from muscle spindles and other sensory receptors that can be used to guide motor activities
feedback control in the cerebellum
information to motor areas of cortex, not only to monitor and correct motions in progress but what
provide appropriate cues for subsequent actions
precise coordination of movement rather than the initiation or control of movement is what
Cerebellar Dysfunction- Motor Disruption
when there is a motor disruption what aspect of movements can be affected?
posture, gait, speech, and eye movements
when posture, gait, speech, and eye movements are affected what region is the damage in?
cerebellar region
tests show a lack of coordination of motor tasks, but not a problem with initiating and actually performing the movement
Resembles a sobriety test
poor walking, unsteady
Ataxia (cerebellar)
past point sign-unable to gage distance in motor tasks
Dysmetria
unable to perform rapid alternating movements
dysdiadochokinesia
oscillations during directed movement
Intention tremor
a slow / thick speech
scanning speech
Lesions of the cerebellum will disrupt the feedback to the what
motor cortex on the opposite side of the midline
when there is a lesion in the cerebellum the symptoms are?
on the same side of the midline (ipsilateral) to the lesion site
what lesion result in a variety of movement disorders that include involuntary movements (dyskinesias) to rigidly contracted muscles (dystonias)
Basal Ganglia Lesions
what diseas is a major hallmarks of the basal ganglia disease are involuntary movements and alteration of muscle tone
Parkinson disease
arise from lesions to a balanced system of excitatory and inhibitory influences on movement
extrapyramidal symptoms
what disorder is characterized by a paucity of movement and rigidity- increased muscle tone throughout the range of motion that does not vary with passive acceleration
Hyperkinetic disorders
what is the most common hypokinetic disorder?
Parkinson’s Disease
Parkinson disease will begins what?
unilaterally and slowly progress to the opposite side
Parkinson can effect what?
postural instability may result in total disability
hereditary disorder with an trinucleotide expansion on chromosome 4
Huntington Chorea
onset of Huntington Chorea is?
around age 40
movements on one side of the body and hypotonus associated with a unilateral (contralateral ) destruction of the subthalamic nucleus is what?
Hemiballismus
what creates and imbalance in basal ganglia circuitry that results in loss of inhibition
Hemiballismus
slow loss (possibly decades) of neurons in the substantia nigra pars compacta (pigmented, dopaminergic)
Parkinsonism (paralysis agitans)
what is a Hypokinetic Movement disorder?
- lack of movement
- reduced amplitude of movements
- slow movement
- rigidity
sustained muscle contractions that may be focal or broadly distributed
Dystonia
if dystonia is drug induced dystonias it is usually from?
dopaminergic agents
what percent is responsive to L-Dopa
5-10%
slow writhing movements-generally associated with broad pathological changes in cortex and neostriatum
Athetoid Movements
an immaturity of the organization of movement
Developmental Coordination Disorder (Developmental Dyspraxia)
Developmental Coordination Disorder (Developmental Dyspraxia) affects ___ of people an ___ severely
10%; 2%
- not exclusively motor
- poor short term memory
- cognitive problems
- difficulty with language skills
Developmental Coordination Disorder (Developmental Dyspraxia)
