Impairment of motor control - clinical signs and patterns Flashcards
Within the frontal lobe how does the signal to move start?
- Prefrontal cortex will initiate idea to move (tells premotor cortex steps required to move)
- Premotor cortex will then organise and sequence movements
- Primary motor cortex send signals down spinal cord
- these synapse with motor neurones
How does the signal to move progress after leaving the cortex (descending motor pathways)?
- From cortex signal descends through the internal capsule
- form upper motor neurones (corticospinal tracts)
- these neurones pass through the pons
- at the level of the medulla the neurones cross to form lateral corticospinal tract
- the lateral corticospinal tracts then synapse with the lower motor neurones or cranial nerves of the brainstem
What makes up a lower motor neurone?
peripheral nerve connecting anterior horn of spinal cord /brainstem to muscle
What is the function of Alpha motor neurones?
voluntary muscle contraction and myostatic stretch reflex
What is the function of gamma motor neurones?
regulate muscle tone and maintain proprioception
What are the possible descending motor pathways?
Corticospinal tracts
Rubrospinal
Vestibulospinal
Reticulospinal
What sets the baseline muscle tone?
- Spinal Neurones
- Brainstem motor areas
(these are then overridden by cortex exerting inhibitory signals)
What does Arevflexic mean
lack of a reflex response
What does Paraparesis and paraplegia mean?
Paraparesis - weakness of legs
Paraplegia - Complete weakness of the legs
What does parasthesia mean?
Abnormal sensation
What does Hemiparesis mean?
weakness in half body
What does Quadra/tetraparesis mean?
Weakness of arms and legs
What does Myelo- mean?
of the spinal cord
What does radiculo- mean
of the nerve roots
What does ataxia mean?
lack of co-ordination of limb movements and/or gait
What will result from a lesion above the medulla?
contralateral hemiplegia
- pattern of flexed upper limbs and extended lower limbs
- arms adduct, foot plantar flexes and leg extends
What will result from a lesion below the medulla?
Cervical - quadriplegia
Thoracic/lumbar - paraplesgia
Hemisection of cord - Brown-Sequard syndrome
What are the common signs of UMN?
- Increased tone/spasticity
- Clonus
- Hyperreflexia
- Babinski sign/extensor plantar
Where is the most likely lesion location if there is spastic paraparesis in 4 limbs?
above C5 usually complete as very traumatic causes e.g. car crash
Where is the most likely lesion location if there is spastic paralysis in only legs not arms?
- Below T1
- lesion usually incomplete (usually not traumatic)
How will a complete lesion differ from incomplete?
complete - complete paralysis, loss of all sensory modalities and loss of bowel and bladder
incomplete - weakness, impaired sensory functions, defective bowel/bladder
What are the tract signs of spinal cord lesion?
- UMN signs
- sensory level
- bladder/bowel/sexual dysfunction
What are the segmental signs of spinal cord lesion?
- pain
- dermatomal sensory disturbance
- LMN signs
What are the conditions with UMN signs?
- Brain tumour
- Ischaemic stroke
- IC haemorrhage
- head injury/trauma
- MS
- Spinal cord stenosis
- prolapsed disc
Where are the possible LMN lesion locations?
(Between motor neurone and anterior horn of spinal cord)
- nerve roots
- nerve plexus
- peripheral nerve
- neuromuscular junction
- muscle
What are the LMN signs?
- wasting and flaccid tone
- waddling gait
- fasciculation’s
- muscle wasting
- hyporeflexia
What is a typical presenting symptom in Guillain-Barré syndrome?
distal weakness and paresthesia which is ascending and increasing in severity
What problems will patients with distal vs proximal weakness experience?
distal - difficulty with fine tasks, writing and using phone
proximal - difficulty with rising, stairs and washing hair
How will fatiguable weakness present?
- worse at end of day or if more effort
What type of weakness is seen in MG (Myasthenia Gravis)?
Fatiguable weakness
What conditions will present with proximal weakness?
- plexopathy
- Radiculopathy
- Muscular dystrophies
What conditions will present with distal weakness?
- Focal (radial/ulnar neuropathy)
- widespread (peripheral neuropathy)
Where are the common lesions which would have foot drop as symptom?
- peroneal nerve
- possibly sciatic nerve
What is the common lesion location for general lower leg weakness (possibly with foot drop)?
- L5 nerve root
What lesion will result in Wrist drop?
radial nerve - can be caused by penetrating trauma or humeral fracture
How will patient with both UMN and LMN lesions present?
- fasiculations
- atrophy
- brisk reflexes and extensor and plantar responses
What is the most common location of pathology if UMN and LMN signs?
- anterior horn of spinal cord
- usually due to motor neurone disease or lesion
What are the parts of the basal ganglia?
- striatum (caudate & putamen)
- Globus Palidus
- Sub-Thalamic Nucleus
- Substantia Nigra
What is the function of the basal ganglia?
- sequencing and control of fluid movements
What will be the symptoms of basal ganglia damage?
- jerky or tremulous movements
- fragmentory or incomplete movements
What are the two types of basal ganglia pathology?
- Hypokinesis (too little move)
- Hyperkinesis (too much move)
What are the key features of parkinsons?
- bradykinesia
- rigidity
- resting tremor
What are the common symptoms of hyperkinesis?
- essential tremor
- chorea
- ballism
- myoclonus
- dystonia
What is the function of the cerebellum?
- co-ordination of muscle activity during learned movements
- uses input from proprioceptors, inner ear and cortex to know where body is in space
How can you differentiate ataxia due to alcohol intoxication or lesion in cerebellum?
- if the problem is in dark or when eyes closed more likely due to cerebellum
What are the signs of cerebellar dysfunction?
- Nystagmus
- Dysarthria
- Intention tremor (tremor induced when going to do something)
- dysdiadochokinesia (breakdown of rapid alternating movement)
- wide based unsteady gait due to balance
Is cerebellar pathology ipsilateral?
YEs
What condition is associated with droopy eyelids with fatigue weakness?
Myasthenia Gravis
