Motor Cortical Control Flashcards
What are the negative affects of an upper motor neurone lesions?
Loss of voluntary motor function
Paresis: graded weakness of movements
Paralysis (plegia): complete loss of voluntary muscle activity
What is meant by negative?
Loss of function
What is meant by positive?
Unwanted gain of function
What are the positive affects of an upper motor neurone lesions?
Increased abnormal motor function due to loss of inhibitory descending inputs
Spasticity: increased muscle tone
Hyper-reflexia: exaggerated reflexes
Clonus: abnormal oscillatory muscle contraction
Babinski’s sign
What is apraxia?
Consequence of UMN lesion
disorder of skilled movement
Patients are not paretic but have lost information about how to perform skilled movements
What can cause apraxia?
Lesion of inferior parietal lobe, the frontal lobe
e.g. stroke and dementia
What are the symptoms of a lower motor neurone lesions?
Weakness
Hypotonia (reduced muscle tone)
Hyporeflexia (reduced reflexes)
Muscle atrophy
Fasciculations
Fibrillations
What are fasciculations?
damaged motor units produce spontaneous action potentials, resulting in a visible twitch
What are fibrillations?
spontaneous twitching of individual muscle fibres; recorded during needle electromyography examination
What is MND?
Motor Neuron Disease
What is motor neurone disease?
Progressive neurodegenerative disorder of the motor system
Affects UMN and LMN’s
Also known as Amyotrophic Lateral Sclerosis (ALS)
Which muscles are particularly affected by MND?
Tongue
Upperlimb
Intercostal muscles
Lower limb
What are the signs of upper motor neurone disease? in MND
Spasticity (increased tone of limbs and tongue) Brisk limbs and jaw reflexes Babinski’s sign Loss of dexterity Dysarthria (difficulty speaking) Dysphagia
What are the signs of lower motor neurone disease? in MND
Weakness Muscle wasting Tongue fasciculations and wasting Nasal speech Dysphagia
What disorders are associated with basal ganglia dysfunction?
Parkinson’s
Huntington’s
Ballism
What causes Parkinson’s?
Degeneration of the dopaminergic neurons that originate in the substantia nigra and project to the striatum
What are the symptoms of Parkinson’s?
Bradykinesia Hypomimic face Akinesia Rigidity Tremor at rest
What is bradykinesia?
slowness of (small) movements (doing up buttons, handling a knife)
What is hypomimic face?
expressionless, mask-like (absence of movements that normally animate the face)
What is akinesia?
difficulty in the initiation of movements because cannot initiate movements internally
What is rigidity?
muscle tone increase, causing resistance to externally imposed joint movements
What are the main feature of the Parkinson’s tremor?
4-7 Hz, starts in one hand (“pill-rolling tremor”); with time spreads to other parts of the body
What causes Huntington’s disease?
Degeneration of GABAergic neurons in the striatum, caudate and then putamen
Genetic neurodegenerative disorder
Chromosome 4, autosomal dominant
CAG repeat
What are the symptoms of Huntington’s?
Choreic movements Speech impairment Difficulty swallowing Unsteady gait Later stages, cognitive decline and dementia
What are choreic movements?
(chorea - dance)
rapid jerky involuntary movements of the body; hands and face affected first; then legs and rest of body
What are the main signs of cerebellar dysfunction?
Ataxia Dysmetira Intention tremor Dysdiadochokinesia Scanning speech
What is ataxia?
General impairments in movement coordination and accuracy. Disturbances of posture or gait: wide-based, staggering (“drunken”) gait
What is dysmetria?
Inappropriate force and distance for target-directed movements (knocking over a cup rather than grabbing it)
What is intention tremor?
Increasingly oscillatory trajectory of a limb in a target-directed movement (nose-finger tracking)
What is dysdiadochokinesia?
Inability to perform rapidly alternating movements (rapidly pronating and supinating hands and forearms)
What is scanning speech?
Staccato, due to impaired coordination of speech muscles
How is Parkinson’s diagnosed?
Clinical diagnosis
If unclear dopaminergic agent trial can be used
If symptoms improve the diagnosis can be confirmed
e.g. Levodopa
What is the primary option of mild parkinson’s?
Levodopa
What dopamine receptor agonists are used to treat parkinson’s?
Ropinirole
Procyclidine
What is important re Levodopa?
Reduced effectiveness with time
Cannot stop abruptly
