9. Weakness

Question 1

What are general systemic causes of weakness?

Answer 1

Infectious
Neurologic
Toxic logic.
Metabolic
Physiologic

Question 2

Key points in weakness history

Answer 2

Nature, onset, progression of symptoms, exacerbation, or alleviating factors, fluctuations, and severity
Ask about review of symptoms, including cardiovascular, pulmonary, metabolic, infection, toxic, ingestion, medication, imbalance, or malignancy

Question 3

List five non-neurologic causes of weakness

Answer 3

Alterations and plasma volume, i.e. dehydration
Alterations, and plasma composition – glucose, electrolytes.
Derangement in circulating, red cell – anaemia or polycythemia
Decreasing cardiac function – MI.
Decrease in systemic vascular resistance – vasodilator shock.
Increased metabolic demand – local or systemic infection, endocrinopathy, toxin
Mitochondrial disfunction – severe sepsis or toxin mediated.
Global depression of the CNS – sedatives, stimulant withdrawal

Question 4

Physical exam key points for weakness

Answer 4

Vital signs
Physical exam, head to toe, including skin and mucous membranes

Question 5

Patient presents with generalized weakness with no focal loss of muscle power – where should you focus your assessment?

Answer 5

Non-neurologic weakness

Question 6

Patient presents with unilateral weakness: combination of arm, hand, or leg? What do you need to ask? Ask yourself? And what is your differential?

Answer 6

ipsi face involvement? Region of the cerebral cortex, corona radiata, internal capsule.

Contralateral, face, involvement or other CNS deficits – lesion of the brain stem

No involvement: lesion of the medial cerebral cortex, discrete, CT lesion or Brown sequard hemi syndrome

Question 7

You know lateral weakness: one limb only? If yes, what to consider next for assessment/differential.

Answer 7

Signs of radiculopathy, Plex apathy neuropathy? If yes, consider discreet motor lesion, brown sequard with contralateral pain, loss, neuromuscular junction, if no sensory deficit

No, consider diabetic with upper extremity weakness and no loss of power

Question 8

If a patient has bilateral weakness, what things do you need to consider and what is your differential diagnosis?

Answer 8

1. Lower extremities: Auntie record, equina, GBS
2. versus upper extremity: central cord syndrome
3. All four extremities: cervical anterior cord syndrome versus GBS
4. Proximal extremities only: consider myositis, rhabdomyolysis, neuromuscular junction disorder.
5. Distal extremities: consider lower extremities, GBS, chronic poly neuropathy versus.
   Upper extremity only: central cord syndrome

Question 9

If patients have facial muscle weakness, only, what do you you need to consider in your differential diagnosis and assessment?

Answer 9

Isolated cranial nerve seven: mastoiditis, parotitis, idiopathic

Vs

Not isolated to cranial nerve seven: consider a brain, stem lesion, a muscular junction disorder, or cranial polyneuropathy

Question 10

What general focal findings on exam indicate that weakness is more likely a potential neurologic cause

Answer 10

Lateralizing weakness
Numbness
Gait and stability.
Cranial nerve defects

Question 11

Moderate loss of power versus complete loss of motion, medical terms

Answer 11

Paresis
Plegia

Question 12

What neurologic signs might localize the unilateral weakness problem to the cortex?

Answer 12

Associated neglect
Visual field loss.
Expressive receptive aphasia

Question 13

A facial droop with forehead involvement is more likely what as a cause of issue?

Answer 13

Cranial nerve seven has forehead involvement

Stroke means that they will still have the ability to raise both eyebrows and show crinkling

Question 14

Brown sequard: what is this?

Answer 14

Internal capsule or brainstem lesion if the patient has unilateral weakness, contralateral, body pain, and temperature disturbances below the level of motor weakness

Question 15

What are signs of an upper motor neuron lesion is compared to a lower motor neuron

Answer 15

Upper typically later in disease has spasticity, Babinski reflex, hyperlexia

Question 16

Name six causes of critical diagnosis for neuromuscular causes of weakness

Answer 16

1. Ischemic or haemorrhagic stroke of the cerebral cortex or subcortical, or brain stem
2. Spinal cord, ischaemia or compression – disc, abscess, hematoma.
3. Peripheral nerve – GBS
4. Neuromuscular junction: myasthenic or colonic crisis, botulism, tick paralysis, organophosphate poisoning.
5. Muscle – rhabdo

Question 17

Name six causes of emergent diagnosis of neuromuscular weakness

Answer 17

1. Cerebral cortex or subcortical: tumor, abscess, demyleination
   2 brainstem: demyelination
2. Spinal cord: transverse, myelitis or compression: disc, spondylolysis.
3. Peripheral nerve: compressive apathy such as a haematoma or aneurysm, paraneoplastic vasculitis Uremia
4. Muscle – inflammatory myositis.

Question 18

Most peripheral lesions do/do not have some sensory component to their presentation?

Answer 18

They do, make sure you look at the dermatomes

Question 19

When are neuromuscular junction disorders considered?

Answer 19

Proximal arm leg muscles, wrist, extensors, finger, extensors, or ankle Dorsey flexors with mild fluctuating weakness that is often worse in the day

Question 20

What are the main causes of anterior cord syndrome?

Answer 20

External compression
Ischemia
Demyelination

Question 21

Non-emergent causes of peripheral neuropathy

Answer 21

Connective tissue disorder
External compression: entrapment syndrome, compressive Plexopathy
Endocrinopathy like diabetes
Paraneoplastic syndrome
Toxins, including alcohol
Trauma
Vitamin deficiency

Question 22

What is the classic concerning finding for GBS?

Answer 22

As symmetric weakness from lower extremities to upper, sensory findings, parallel the weakness and reflexes will likely be decreased at some point in the clinical course

Question 23

Differential diagnosis for common, acute proximal muscle weakness causes

Answer 23

Inflammatory, like polymyositis or dermatomyositis
Necrosis – including Rhabdo from HMG-CoA 3 reductase inhibitors

Muscles are often tendered to palpation

Question 24

Differential diagnosis for chronic or recurrent my fibre pathology

Answer 24

Muscular dystrophy
Channel apathies such as hyperkalaemic and hypokalaemic periodic paralysis.
Metabolic myopathy or mitochondrial myopathy

Question 25

Do you think you have an isolated cranial nerve 7 palsy but want to be sure it’s not brain stem. What other things do you need to check?

Answer 25

No extremity involvement.
No other cranial nerves involved.
Normal cerebellar testing.
Normal visual fields

Question 26

What findings might indicate a more likely posterior cerebral circulation or brain stem disorder?

Answer 26

Sarabel findings.
Visual field defect.
Sensory disturbance.
Extremity upper motor neuron signs

Question 27

What are the most common presentations for neuromuscular junction pathology?

Answer 27

Disfunction of one or more ocular, facial or frenal muscles

Question 28

Name three abnormalities of pre-synaptic release at the acetylcholine for neuromuscular junction disorders

Answer 28

Botulism
Eaton Lambert
Organic phosphate poisoning

Question 29

Name three medication’s that may worsen weakness inpatients with neuromuscular junction disease?

Answer 29

Aminoglycosides
Quinolones
Beta blockers

Question 30

What is the main difference between cauda equina syndrome and conus medullaris syndrome?

Answer 30

Very similar, except conus is typically more bilateral, sacral segment occasionally is preserved bulbocavernosus reflex