Clinical signs and Patterns of Motor Control Impairment Flashcards
Where are motor movements controlled in the cortex
Frontal lobe executes movement.
What areas are involved in frontal love execution of movement and what is each area responsible for
1- Primary motor cortex ( M1 ) : large pyramidal neurons that travel down spinal cord and synapse with motor neurons
2- premotor cortes : organizes and sequences movements
3- Prefrontal and orbitofrontal : abstract planning and selecting a goal to tell premotor cortex the steps required to reach that goal
What are the lower motor neurons
Cell bodies within the anterior horn of spinal cord / brainstem.
Alpha motor neurons : voluntary muscle contraction, myosatic stretch reflex
OR
Gamma motor neurons: regulate muscle tone , maintain proprioception
The descending motor pathway can be divided into which two groups
1- Pyramidal tracts ( Direct )
2- Extrapyramidal tracts ( Indirect )
Explain the descending Pyramidal Corticospinal motor pathway ( 6 steps )
1- Corticospinal tract begins at cortex and receives input from primary , premotor and supplementary areas
2- Neurones descend through internal capsule ( between he thalamus and basal ganglia )
3- Neurone then passes through the crus cerebra of midbrain, the pons and into the medulla
4- in the inferior part ( caudal ) of the medulla and then divides into 2 tracts
5- Lateral corticospinal tract crosses over at the medulla and then descends into spinal cord.
Anterior corticospinal tract stays ipsilateral and descends in the spinal cord.
6- Lateral tracts terminates at ventral horn and then synapses with lower motor neurons. Anterior tract terminates at ventral horn of Cervical and upper thoracic levels.
7- signals carried to musculature of the body except face and neck
What is the clinical importance of the internal capsule of the pyramidal motor pathway
Internal capsule susceptible to compression from haemorrhage bleeds ( capsular strokes ) which could result in lesion of descending tracts
Explain he Corticobulbar tract motor pathway
1- Arises from lateral aspect of primary motor cortex
2- receive same input as the corticospinal tract
3- pass through internal capsule to the brainstem
4- neurons terminate on motor nuclei of cranial nerves
5- synapse with lower motor neurones that carry signals to face and neck
Where do the extrapyramidal tracts originate
Brainstem
What are extrapyramidal tracts responsible for
involuntary and automatic control of musculature ex: muscle tone, balance, posture , locomotion
What are pyramidal tracts responsible for
Voluntary control of the musculature of the body and face
What are the 4 extrapyramidal tracts
1- Vestibulospinal
2- Reticulospinal
3- Rubrospinal
4- Tectospinal
Explain the Vestibulospinal tract motor pathway
- 2 pathways : medial and lateral.
- arise from vestibular nuclei that receive input from organs of balance
- remains ipsilateral and tract conveys balance info to spinal cord
Control balance and posture by innervating anti-gravity muscles via lower motor neurons ( arm flexors/leg extensors )
Explain the Reticulospinal tract motor pathway
2 tracts
Medial : arises from pons & facilitates voluntary movement and increase muscle tone
lateral: arises form medulla & inhibits voluntary movements and reduces muscle tone
Explain the Rubrospinal tract motor pathway
- Originates from red nucleus ( midbrain )
- Fibres cross over when they emerge and descend spinal cord ( contralateral innervation )
Role in fine control of hand movements
Explain the tectospinal tract motor pathway
- begins at colliculus of the midbrain , receives input form optic nerves
- neurons cross over and enter spinal cord , terminating at cervical levels
- function: coordinate head movements in relation to vision stimuli
Where do the Motor pathway tracts receive inhibitory signals form
Cortex
A movement to ensure stability is usually done before or after anticipated movement
Usually the Brain will ensue postural stability BEFORE anticipated movement ex: gastrocnemius contracting before biceps do when pulling on handle
Define paraparesis
weakness of legs
Define paraplegia
complete weakness of legs
Define paraesthesia
abnormal sensation
Define Quadra/tetraparesis
Weakness of arms and legs
Define Hemiparesis
weakness of half of body
Define prefix Mylo
something of the spinal cord
Define prefix Radiculo
something of the nerve roots
Define ataxia
lack of coordination of limb movements and or gait
Damage above the medulla will result in what
- Contralateral hemiplegia
- pattern of flexed ULs & extended LLs
Damage below the medulla will result in what
Spinal cord syndrome
- Cervical sc = quadriplegia
- thoracic or lumbar sc = paraplegia
- hemisection of cord - Brown-sequard syndrome
What is Brown-sequard syndrome
neurological condition due to a hemisection lesion of spinal cord. Results in hemiparaplegia of one side of body and hemianesthesia on the opposite side
Define hemianestehesia
loss of sensation on side of body
What will and UMN lesion result in terms of stretch reflex
Hyperexcitability of the stretch reflex due to loss of inhibitory control.
Since stretch is applied quickly contraction is stronger ( increased tone ) = clasp knife
List the signs of UMN lesions
1- Hypertonia 2- Hyperreflexia 3- Clonus ( involuntary, rhythmic contractions ) 4- Babinski sign ( extensor plantar ) 5- muscle weakness
How would hemiparesis look
1- Adducted + flexed UL
2- Extended LL
3- plantar flexed + inverted
If there is spastic paraperesis of all 4 limbs the lesion must be above …
C5
Define spastic paraparesis
Weakness in limbs ( with muscle spasms )
How would a lesion in the cervical spinal cord usually present as
1- Spastic paraperesis of 4 limbs if lesion above C5
If lesion complete
1- complete paralysis below lesion
2- loss of all sensory modalities below lesion
3- loss of bowel,bladder, sexual function
How would a lesion in the thoracic or lumbar spinal cord usually present as
1- Spastic paraparesis in legs but normal arms
2- lesion will be below T1
Lesions often incomplete
3- bilateral leg weakness , not complete paralysis
4- impaired sensory function
5- defective bowel, bladder, sexual function
If there’s posterior column spinal cord lesion will there be UMN signs in the legs and why
No because the pyramidal tracts would be sparred since they are lateral
Will the bladder be affected in a posterior column spinal cord lesion ? if not what type of lesion would affect it ?
Bladder will probably be intact , usually affected by anterolateral lesions
Which conditions can cause UMN signs
1- Brain tumour 2- ischaemic stroke 3- ICH 4- Post head injury 5- multiple sclerosis 6- spinal cord stenosis 7- prolapsed disc
What does a LMN lesion mean ( damage where ? )
Damage to the peripheral nervous system :
- motor neuron in anterior horn
- nerve roots / plexus
- peripheral nerve
- muscle
- neuromuscular junction
What are the signs of LMN signs
1- Muscle wasting and flaccid tone
2- Waddling gait
3- Fasciculations
4- hyporeflexia
What are patterns of LMN
1- Flaccid areflexic paraplegia
2- primal weakness ( difficulty rising ,stairs, hair washing )
3- distal weakness : focal or widespread ( phone , writing )
4- fatiguable weakness ( worse with repeated effort )
what is Flaccid areflexic paraplegia
weakness or paralysis and reduced muscle tone due to trauma affecting nerves associated with muscle
Define plexopathy
Disorder of brachial or lumbosacral plexus of nerves
Define radiculopathy
symptoms due to pinching of nerve in spinal column
What drops are seen with LMN lesions
1- Foot drop - can't dorsiflex foot - floppy ankle 2- wrist drop - can't extend wrist - hand hangs flaccidly
What could cause a wrist drop
radial nerve lesion due to penetrating trauma , extrinsic compression , humeral fracture or Motor neuron disease
What could cause a foot drop
Lesion to - deep/common perineal nerve - sciatic nerve - lumbosacral plexus = L5 nerve root
What are common LMN diseases in out-patients
1- foot drop ( perineal ) 2- bells palsy ( facial ) 3- peripheral neuropathy ( diabetic? ) 4- ocular myasthenia gravis 5- muscular dystrophy 6- radiculopathy due to prolapsed disc
What is ocular myasthenia gravis
muscles moving eyes and eyelids are fatigued and weakened.
Presenting with Dropping eyelids or double vision
What are common LMN diseases in ward patients
1- Motor neurone disease 2- cauda equina syndrome 3- Traumatic plexopathy 4- Guillain-barre syndrome 5- CIDP 6- Cristial illness neuropathy 7- Mysasthenia gravis 8- Inflammatory Myopathies
What is Guillain-barre syndrome
Rare neurological condition affecting feet, hands and limbs causing weakness, numbness and pain
What is CIDP
Chronic inflammatory demyyelinating polyradiculoneuropathy
rare autoimmune disorder causing body to attack myelin sheaths
What if patient presents with both UMN & LMN signs
Suspect damage to anterior horn in spinal cord. Could cause tract and segmental signs due to spinal cord lesion and still cause LMN signs due to lower motor neurons being affected .
Could be MND
Fasiculations and atrophy are lesion in ?
LMN
Brisk reflexes and extensor plantar are lesion in ?
UMN
What is the pathology of a basal ganglia problem
1- movements are fragmentary , incomplete and staccato
2- Hypokinesis
2- Hyperkinesis
What is Hypokinesis
Too little movement
- rigidity
- resisting tremor
- bradykinesia : deceased speed and amplitude of movement
What is hyperkinesis
too much movement
- essential tremor
- chorea
- ballism
- myoclonus
- dystonia
What is the purpose of basal ganglia in extrapyramidal tracts
Sequencing and smooth control of movement. gives fluidity to movement
Parkinson’s disease is an example of problem in ?
Basal ganglia
What is the purpose of the cerebellum
Coordinates muscle activity during learner movement and receives input from proprioceptors, inner ear and cortex
Signs of cerebellar dysfunction
1- Nystagmus 2- dysarthria 3- intention tremor / dysmetria 4- dysdiadochokinesia 5- wide based unsteady gait 6- truncal sway
Left cerebellar hemisphere lesion will cause what
Left sided ataxia
What are examples of extrapyramidal and cerebellar diseases in out patients
1- Parkinson's disease 2- essential tremor 3- thyrotoxic tremor 4- Huntington's chorea 5- tics 6- wry neck ( torticollis )
What are examples of extrapyramidal and cerebellar diseases in ward patients
1- asterixis ( liver flap )
2- anaesthesia induced myoclonus
3- alcohol related ataxia
4- viral cerebellitis ( in kids )
