Muscle Weakness Flashcards
If a patient presents with hyper acute symptoms that occurred over seconds to minutes, which of the following is this MOST likely to be?
1 - Vascular
2 - Vascular / inflammatory
3 - Inflammatory / Metabolic
4 - Neoplastic*
5 - Degenerative
6 - Metabolic
1 - Vascular
If a patient presents with acute symptoms that occurred over hours, which of the following is this MOST likely to be?
1 - Vascular
2 - Vascular / inflammatory
3 - Inflammatory / Metabolic
4 - Neoplastic*
5 - Degenerative
6 - Metabolic
2 - Vascular / inflammatory
If a patient presents with sub-acute symptoms that occurred over days to weeks, which of the following is this MOST likely to be?
1 - Vascular
2 - Vascular / inflammatory
3 - Inflammatory / Metabolic
4 - Neoplastic*
5 - Degenerative
6 - Metabolic
3 - Inflammatory / Metabolic
If a patient presents with chronic symptoms that occurred over months to years, which 2 of the following is this MOST likely to be?
1 - Vascular
2 - Vascular / inflammatory
3 - Inflammatory / Metabolic
4 - Neoplastic*
5 - Degenerative
6 - Metabolic
4 - Neoplastic*
5 - Degenerative
If a patient presents with acute on chronic symptoms that worsened an existing condition, which of the following is this MOST likely to be?
1 - Vascular
2 - Vascular / inflammatory
3 - Inflammatory / Metabolic
4 - Neoplastic*
5 - Degenerative
6 - Metabolic
6 - Metabolic
The descending tracts are important pathways, what are they though?
1 - transmit information about pain
2 - transmit information relating to proprioception and fine touch
3 - transmit information relating initiate movements from upper to lower motor neurons
4 - all of the above
3 - transmit information relating initiate movements from upper to lower motor neurons
The descending tracts are important pathways for motor function. Which 2 of the following are the 2 groups they can be separated into?
1 - Voluntary control of movement = pyramidal/corticospinal tract
2 - Involuntary control of movement = Extrapyramidal tracts (4 in total)
3 - Cerebrospinal track - unconscious movements
4 - Spinothalamic tract = pain and sensation
1 - Voluntary control of movement = pyramidal/corticospinal tract
2 - Involuntary control of movement = Extrapyramidal tracts (4 in total)
The descending corticospinal tract is a 2 neuron circuit. Where does the 1st order neuron begin?
1 - cell body in the cerebellum
2 - cell body in the cerebral cortex
3 - cell body in the posterior parietal lobe
4 - cell body in the pyramids
2 - cell body in the cerebral cortex
- passes through corona radiata, internal capsule (both white matter pathways, located between the thalamus and the basal ganglia)
The descending corticospinal tract is a 2 neuron circuit. Where does the 1st order neuron end?
- enter brain stem
- 80% decussate in the medulla
- 20% do not decussate in the medulla and remain
Once the upper neuron (1st order) in descending corticospinal tract (CST) reaches the order in the spine where to which the nerves innervate the body, where does the 80% of fibres that decussated at the pyramids enter the spinal cord?
1 - lateral fasciculus and into the lateral ventral horn
2 - anterior fasciculus and then into the ventral horn
3 - substantia gelatinosa
4 - lateral gentate and anterior spinal nerve
1 - lateral fasciculus and into the lateral ventral horn = 80% that decisated at medulla
2 - anterior fasciculus and then into the ventral horn = 20% that did not decusate at medulla
- here they BOTH innervate alpha and gamma motor neurons
Once the upper neuron (1st order) in descending corticospinal tract (CST) reaches the order in the spine where to which the nerves innervate the body, they will enter the lateral (80% of CST) or anterior (20% of CST) fasciculus and then into the ventral horn of the spinal cord. What do they synapse with here?
- lower motor (2nd order) neuron
- alpha and gamma motor neurons
- this neuron will then innervate target tissues
Match where the alpha and gamma motor neurons innervate?
- extrafusal = muscle shortening (contract)
- intrafusal = muscle spindles (proprioceptive)
1 - alpha = extrafusal muscle
2 -gamma =intrafusal muscle
Where can alpha (voluntary movement) and gamma (muscle spindles) neurons be located in the spinal cord as part of the descending corticospinal tract?
- located in the grey matter
- trunk, limbs, flexor and extensor muscles are all located in different regions
If there is a lesion in the descending corticospinal tract that originates above or below the medualla oblongata will the symptoms present on the same or opposite side of the body?
- above medulla = contralateral (opposite) side of the body
- below medulla = ipsilateral side (same side) of the body
The pyramidal/corticospinal tracts is the descending tract that controls conscious fine conscious motor movement. Why is it called the pyramidal/corticospinal tract?
- decussates at the pyramids in the medulla oblongata
- originates in the pyramidal cells of the primary motor cortex
The corticospinal tract is the pyramidal tract which leaves the cortex, decussates at the pyramids (80% do and 20% do not decussate) and travels in the lateral and anterior fasciculus, before synapsing in the ventral horn. Of the 80 and 20% that do and do not decussate, what parts of the the body do they innervate?
- 80% that decussates travel in lateral fasciculus and innervate the distal muscles for fine motor movements
- 20% that do not decussates travel in anterior fasciculus and innervate the axial muscles for fine large movements
The corticospinal tract is the main descending motor control tract in the nervous system. This system connects the motor cortex with where?
1 - posterior (dorsal) horn
2 - lateral horn
3 - anterior (ventral) horn
4 - target tissue
3 - anterior (ventral) horn
The corticospinal tract is the main descending motor control tract in the nervous system. Which motor neurons does the corticospinal tract communicate with?
1 - gamma motor neurons
2 - alpha motor neurons
3 - delta motor neurons
4 - y motor neurons
2 - alpha motor neurons
- innervate the contractile fibres that shorten called extrafusal fibres
If a patient has an upper motor neuron lesion, it could be in all of the following locations, EXCEPT where?
1 - primary motor cortex in frontal lobe
2 - cerebellum
3 - brainstem (midbrain, pons, medulla)
4 - spinal cord
5 - anterior horn of spinal cord
2 - cerebellum
- everything else is classed as an upper motor neuron
Which 2 of the following are commonly observed in patients who have a lesion in the corticospinal tract?
1 - excessive elbow extension
2 - excessive elbow flexion
3 - excessive knee flexion
4 - excessive knee extension
2 - excessive elbow flexion
4 - excessive knee extension
- suspected to be evolution allowing us to still eat whilst stabilising ourselves in upper motor neuron pathologies
In upper motor neuron lesions, which can occur anywhere in the image we can get a reduction in muscle mass. Why does this occur?
1 - cortex to muscle is lost so no innervation and atrophy occurs
2 - loss of inhibition from the medullary reticulospinal nuclei
3 - increased afferent (Away from muscle) pathway activity
4 - reduced innervation of the alpha motor neurons
1 - cortex to muscle is lost so no innervation and atrophy occurs
- aprox 15-20% loss
- in lower motor neuron lesions there is a greater loss in muscle mass
- often called denervation atrophy
- aprox 65-70% loss
The medullary reticulospinal tract that begins in the medulla is a descending tract. What is the function of this tract?
1 - extensor muscle control
2 - flexor muscle control
3 - flexor and extensor muscle control
4 - inhibition of all ascending tract
2 - flexor muscle control
In upper motor neuron lesions, which can occur anywhere in the image we can get a increase in muscle tone called hypertonia. Why does this occur?
1 - cortex to muscle is lost so no innervation and atrophy occurs
2 - loss of inhibition from the medullary reticulospinal nuclei (MRN)
3 - increased afferent (Away from muscle) pathway activity
4 - reduced innervation of the alpha motor neurons
2 - loss of inhibition from the medullary reticulospinal nuclei (MRN)
- some fibres from the corticospinal tract branch off and innervate the MRN
- the MRN then travels to the anterior horn and inhibits/fine tunes muscle contractions of alpha motor neurons
- loss of this means alpha motor neurons fire too much, hence the increased tone
In upper motor neuron lesions, which can occur anywhere in the image we can get a increase in reflexes tone called hypertonia. Why does this occur?
1 - cortex to muscle is lost so no innervation and atrophy occurs
2 - loss of inhibition from the medullary reticulospinal nuclei (MRN)
3 - increased afferent (Away from muscle) pathway activity
4 - reduced innervation of the alpha motor neurons
3 - increased afferent (Away from muscle) pathway activity
- increased alpha motor activity in a muscle that already has increased tone causes hyper-reflexia
- causes spasticity
- normal physiology =
1 - increased firing of action potential along 1a nerve fibre
2 - 1a nerve fibre synapses with alpha motor neuron in anterior horn of spinal cord
3 - activation of alpha motor neurons in extensor muscles causes knee to extend
4 - this extension is a way of shortening the muscle spindles to protect the quadriceps
Patients with an upper motor neuron lesion can experience spasticity. Which of the following is NOT true about spasticity?
1 - imbalance between resistance in flexion vs extension
2 - spasticity is velocity dependent (faster movement causes more spasticity)
3 - caused by hypertonia and reflexia
4 - not velocity dependent
4 - not velocity dependent
Patients with an upper motor neuron lesion can experience spasticity. Which of the following is NOT true about rigidity?
1 - no imbalance between resistance in flexion vs extension
2 - spasticity is velocity dependent (faster movement causes more spasticity)
3 - caused by hypertonia and reflexia
4 - not velocity dependent
2 - spasticity is velocity dependent (faster movement causes more spasticity)
Muscle tone can cause rigidity and spasticity. Match spasticity and rigidity to pyramidal and extrapyramidal.
- spasticity = pyramidal
- linked with clasped knife spasticity
- rigidity = extrapyramidal
- think the fine movements are not as well controlled as we have lost the ability to fine tune the movements, so it becomes rigid and jumpy
- typically called parkinsonia rigidity due to basal ganglia issues
Patients with an upper motor neuron lesion can experience spasticity, which can also be associated with an imbalance between resistance in flexion vs extension. Are flexors and extensors typically stronger in the upper of lower limbs in a motor neuron lesion?
- upper = stronger flexors
- lower = stronger extensors
- this can only be assessed if the patient has some power to begin with
- this comes back to evolution where we can eat and still stand if we have any neurological issues
A Babinski sign is when the patient flexes the big toe and the other toes flair out and upwards. This is due to a loss in the corticospinal tracts inhibition of dorsiflexors, meaning increased stimulation of the dorsiflexors over the plantar flexors. Does this happen in both upper and lower motor neuron lesions?
- no
- only an upper motor neuron lesion
no inhibition of dorsiflexors mean over activation and toes curl up - this is extension of the toes and confirms a stronger extensor over flexor response in the lower limbs in upper motor neuron lesions
If there is a lesion in the cervical aspect of the spine, would we expect to see legs and arms affected?
- yes
- cervical and above would typically cause Hemiplegia (weakness on one side of the body)
If there is a lesion below the cervical aspect of the spine, would we expect to see legs and arms affected?
- no
- just the legs affected
- bowel and bladder are often also affected
The corticobulbar bulbar tract, which begins in the medulla is important as it supplies innervation to some cranial nerves. Which cranial nerve does it NOT innervate?
1 - VII = facial nerve
2 - X = vagus nerve
3 - IX = glossopharyngeal nerve
4 - XI = accessory nerve
5 - XII = hypoglossal nerve
1 - VII
- essentially 9-12 that originate in the medulla
If a patient presents with peripheral weakness, eye problems, respiratory, swallowing, autonomic, cardiac and speech difficulty, where is the lesion likely to be?
1 - cerebral cortex
2 - cerebellum
3 - brain stem
4 - spinal cord
3 - brain stem
Which of the following is NOT an aspect of a lower motor neuron?
1 - ventral (anterior) horn
2 - exit as dorsal roots into plexus
3 - peripheral Nerves
4 - neuromuscular junction
5 - muscle
2 - exit as dorsal roots into plexus
- exit at the ventral roots
In lower motor neurons fasciculations can occur, which are visible, involuntary twitching of an individual muscle. What is the typically the cause of this?
1 - cortex to muscle is lost so no innervation and atrophy occurs
2 - loss of inhibition from the medullary reticulospinal nuclei
3 - increased afferent (Away from muscle) pathway activity
4 - acetylcholine is released at lower levels
4 - acetylcholine (ACh) is released at lower levels
- low ACh forces post synapse on muscle to up regulate ACh receptors
- post-synapse becomes hypersensitive and mechanically open allowing Na+ to enter the cell causing depolarisation
Do fasciculations occur in both upper and lower motor neuron disorders?
- only lower motor neuron disorders
- wasting is common in lower motor neuron disorders
In lower motor neuron disorders is tone increased or decreased?
- typically flaccid, but can be normal
In lower motor neuron disorders are reflexes increased or decreased?
- typically absent or reduced
It is possible to have a pathology that is a mixture of both upper and lower motor neuron disorder. Where would this most likely affect to cause a mixed upper and lower motor neuron disorder?
1 - ventral (anterior horn)
2 - nerve root
3 - cerebral cortex
4 - neuromuscular junction
1 - ventral (anterior horn)
Which of the following is a disease affecting both the lower and upper motor neurons?
1 - Stroke
2 - Amyotrophic Lateral Sclerosis (ALS)
3 - Multiple Sclerosis
4 - Friedreich’s Ataxia
2 - Amyotrophic Lateral Sclerosis (ALS)
- progressive neuromuscular disease with no known cure
- life expectancy is 3 years
If we suspect a patient has motor neuron disease, there are 3 typical tests to do. Which of the following is NOT one of these tests?
1 - MRI Brain and spinal cord to rule out compressive or alternative pathology
2 - ECG
3 - Electromyography can demonstrated “denervation”
4 - Rule out a peripheral neuropathy
2 - ECG
Myotomes are specific nerve roots that innervate muscles. Which 2 of the following are innervated by the nerve roots C5 and C6?
1 - Shoulder abduction
2 - Elbow flexion
3 - Finger extensors
4 - Thumb extension
1 - Shoulder abduction
2 - Elbow flexion
Myotomes are specific nerve roots that innervate muscles. Which of the following is NOT innervated by the nerve roots C7 and C8?
1 - Shoulder abduction
2 - Elbow extension
3 - Finger extensors
4 - Thumb extension
1 - Shoulder abduction
Myotomes are specific nerve roots that innervate muscles. Which 2 of the following are innervated by the nerve roots C8 and T1?
1 - Elbow extension
2 - Thumb extension
3 - Thumb abduction
4 - Finger flexors
3 - Thumb abduction
4 - Finger flexors
Myotomes are specific nerve roots that innervate muscles. Which 2 of the following are innervated by S1?
1 - Hip flexion
2 - Hip extension
3 - Knee flexion
4 - Ankle plantarflexion
3 - Knee flexion
4 - Ankle plantarflexion
Myotomes are specific nerve roots that innervate muscles. Which of the following are innervated by L2?
1 - Hip flexion
2 - Hip extension
3 - Knee flexion
4 - Ankle plantarflexion
1 - Hip flexion
Myotomes are specific nerve roots that innervate muscles. Which of the following are innervated by L5-S1?
1 - Hip flexion
2 - Hip extension
3 - Knee flexion
4 - Ankle plantarflexion
2 - Hip extension
Myotomes are specific nerve roots that innervate muscles. Which of the following are innervated by L3-L4?
1 - Hip flexion
2 - Hip extension
3 - Knee extension
4 - Ankle dorsiflexion
3 - Knee extension
Myotomes are specific nerve roots that innervate muscles. Which of the following are innervated by L4?
1 - Hip flexion
2 - Hip extension
3 - Knee extension
4 - Ankle dorsiflexion
4 - Ankle dorsiflexion
Any motor neuron disorder of the nerve routes is typically caused by all of the following, EXCEPT which one?
1- compression
2 - metabolic
3 - inflammatory
4- infiltrative (neoplastic)
2 - metabolic
- when nerve roots are affected, the reflex associated with that nerve root are typically also lost
- image is an example of compression
Any motor neuron disorder causing multiple peripheral nerves to be affected is typically caused by all of the following, EXCEPT which one?
1- trauma
2 - compression
3 - inflammatory
4- infiltrative (neoplastic)
2 - compression
The following are examples of what?
- Median nerve (carpal tunnel)
- Ulnar nerve
- Radial nerve
1 - Amyotrophic Lateral Sclerosis (ALS)
2 - Mononeuropathy
3 - Multiple Sclerosis
4 - Friedreich’s Ataxia
2 - Mononeuropathy
Carpal tunnel syndrome that affects the median nerve is an example of a mononeuropathy. Which of the following is NOT true about carpal tunnel syndrome?
1 - Pain and paraesthesia thumb, index finger, middle finger, median half of ring
2 - increased sensation
3 - Thumb abduction weakness
4 - wasting may occur in the thenar eminence
5 - median nerve is compressed as it enters the hand
2 - increased sensation
- typically causes reduced sensation
Ulnar nerve entrapment is an example of a mononeuropathy. Which of the following is NOT true about ulnar nerve entrapment?
1 - compression of the lateral elbow
2 - leaning, prolonged flexion, direct injury
3 - sensory disturbance ring and little finger
4 - weakness of finger abductors/ adductors, thumb abduction, little finger opposition
1 - compression of the lateral elbow
- ulnar nerve runs medially
Radial nerve entrapment is an example of a mononeuropathy. Which of the following is NOT true about radial nerve entrapment?
1 - wrist drop
2 - weakness of brachoradialis, extensors, supinator, triceps
3 - compression typically occurs in the axilla or upper arm
4 - no loss of sensation
4 - no loss of sensation
- can get loss of sensation on back of hand closest to thumb
The term used to describe nerves affects in generalised polyneuropathy is the glove and stocking distribution. Which of the following is NOT a typical cause of this?
1 - alcohol
2 - vitamin deficiency (B12)
3 - connective tissue disease/cancer
4 - inactivity
5 - diabetes
4 - inactivity
The term used to describe nerves affects in generalised polyneuropathy is the glove and stocking distribution. Of the following which is the most common category causing this phenotype?
1 - Metabolic (B12, HbA1c, EtoH)
2 - Drug induced (Chemotherapy, Idiopathic)
3 - Elderly, usually sensory
4 - Immune mediated (Guillan Barre, Syndrome, Chronic Inflammatory
5 - Neoplastic (Lymphoma, Lung cancer)
1 - Metabolic (B12, HbA1c, EtoH)
- remember ABCDE for most common causes:
- A = alcohol
- B = B12
- C = connective tissue disorder
- D = Diabetes
- E = everything else (rare causes)
Multiple individual nerves can be affected in motor neuron diseases. What are the most common causes where multiple individual nerves are affected?
1 - diabetes
2 - vasculitis
3 - connective tissue disease
4 - all of the above
4 - all of the above
- order of nerves affected typically is sequential, e.g. Left median then Right ulnar then left radial
The neuromuscular junction can be affected and cause a lower motor neuron disorder. What is the most common neuromuscular condition?
1 - Lambert-Eaton syndrome (LES)
2 - Botulism
3 - Myasthenia Gravis
4 - Motor neuron disease
3 - Myasthenia Gravis
- key characterisation is fatigueable weakness
Can also cause:
- Ptosis, Extra ocular muscle weakness (diplopia)
- Facial weakness (asymmetry)
- Dysarthria & Dysphagia
- Limb weakness
- Shortness of breath (especially orthopnoea)
- No sensory involvement
