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Neurology Y2 > L12 - Disorders of the motor unit and spinal cord pathways > Flashcards

L12 - Disorders of the motor unit and spinal cord pathways Flashcards

1
Q

State the two categories of muscle disease? (2)

A
  1. Genetic

2. Inflammatory

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2
Q

Describe Myasthenia Gravis?

A
  • Acquired autoimmune disease.
  • Antibodies to postsynaptic acetylcholine receptor
  • will impair neuromuscular transmission.
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3
Q

Myasthenia Gravis preferentially affects…

A

Young women (20s and 30s)

Second peak in older men (60s and 70s)

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4
Q

What are some clinical features of Myasthenia Gravis?

A
  • Fatigable muscle weakness.
  • Typically worse in day and following exertion.
  • Affects eyes, causing fatigable ptosis and diplopia.
  • Affects bulbar muscles (dysphagia and dysarthria) and upper limb muscles.
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5
Q

What is Lambert-Eaton myasthenic syndrome?

A
  • Rare, autoimmune syndrome.

- Antibodies against calcium channels of presynaptic motor nerve terminal.

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6
Q

Where does Lambert-Eaton myasthenic syndrome commonly affect?

A

Lower limbs.

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7
Q

Define muscular dystrophies and give an example?

A

Inherited disorders characterized by progressive muscle weakness and wasting.
e.g. Duchenne muscular dystrophy

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8
Q

What causes Duchenne muscular dystrophy?

A

Caused by mutation in the gene coding for the protein dystrophin.
X-linked recessive, affecting males alone.

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9
Q

What is another disease also caused by mutation of dystrophin?

A

Becker muscular dystrophy.

Less severe.

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10
Q

Describe myotonic dystrophy?

A

Autosomal dominant.

  • demonstrates genetic anticipation
  • subsequent generations are increasingly severely affected.
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11
Q

Patients with myotonic dystrophy will usually present in early adulthood with…

A
  • Distal limb weakness
  • stiffness
  • myotonia (delayed muscle relaxation contraction)
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12
Q

Myotonia

A

Delayed muscle relaxation following contraction.

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13
Q

What are some other features of myotonic dystrophy?

loadz

A 
Mild cognitive impairment 
Early prefrontal balding 
Cataract formation 
Bilateral ptosis 
Testicular atrophy 
Diabetes mellitus 
Cardiomyopathy with conduction defects 
Pituitary dysfunction
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14
Q

Briefly describe carpal tunnel syndrome?

A

Compression of median nerve at wrist.

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15
Q

Give examples of processes that may affect bones or ligaments, thus leading to narrowing of the carpal tunnel…

A 
Pregnancy 
Obesity 
Hypothyroidism 
Acromegaly 
Rheumatoid arthritis 
Diabetes Mellitus
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16
Q

What are some symptoms of carpal tunnel syndrome?

A
  • Weakness of thumb abduction.

- Wasting of thenar eminence.

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17
Q

What is Phalen’s sign?

A

Patient flexes wrist maximally.

Positive test = tingling in thumb, index finger and middle / lateral 1/2 of ring finger.

Used in diagnosis of Carpal Tunnel Syndrome

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18
Q

What is Tinel’s sign?

A

Performed by light tapping over nerve to elicit sensation of pins and needles.

Positive test = tingling, parasthesia into thumb

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19
Q

Whats the difference between mononeuropathy and mononeuritis multiplex?

A

Mononeuropathy: disorder of a single peripheral nerve
- usually results from trauma or compression of the nerve

Mononeuritis multiplex: damage to two or more peripheral nerves, painful
- usually results from nerve infarction

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20
Q

Compression of the ulnar nerve at elbow may result in?

A

Weakness and wasting of intrinsic hand muscles and hypothenar muscles.
- splitting of ring finger sensation

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21
Q

Compression of radial nerve at axilla or mid humerus may reuslt in?

A

Weakness of wrist and finger extension

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22
Q

Compression of sciatic nerve may result in?

A

Weakness of knee flexion

Weakness of ankle dorsiflexion, inversion, eversion and plantar flexion.

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23
Q

Compression of common peroneal at the knee may result in?

A

Weakness of ankle dorsiflexion and ankle eversion.

24
Q

Compression of the lateral cutaneous nerve of thigh, at the pelvis, may result in?

A

No weakness!

Purely a sensory nerve.

25
Q

What is peripheral neuropathy?

A

‘length dependent nerve damage’

- begins distally and spreads symmetrically. Legs affected before arms.

26
Q

In peripheral neuropathy why are the legs affected before the arms?

A

Peripheral nerves are longer in the lower limbs.

27
Q

What are the common culprits for peripheral neuropathy?

A

Diabetes Mellitus
Chronic alcohol abuse.

also: vitamin B12 deficiency, renal failure and thyroid disease.

28
Q

Describe Guillain-Barre syndrome?

A

Cell mediated autoimmune response is triggered against myelin or other components of the peripheral nerve, causing nerve damage.

29
Q

What are some key clinical features of Guillain-Barre syndorme?

A

Usually appears 2-4 weeks after a diarrhoeal or upper resp tract infection.

  • weakness in proximal limb muscles.
  • facial weakness
30
Q

Describe cauda equina syndrome?

A

Compressive lesion located below the end of spinal cord.

  • multiple lumbosacral nerve roots are compressed.
  • severe lower back pain., leg weakness, numbness over buttocks and perineum and urinary retention.
31
Q

What is cervical spondylosis?

A

Degenerative changes of the cervical vertebrae, intervertebral joints and ligaments.
- changes may narrow vertebral canal, causing nerve compression.

32
Q

What symptoms are often present in cervical spondylosis?

A

Neck pain, arm pain, tingling and weakness.

33
Q

How may subacute degeneration of the cord occur?

A

Vitamin B12 deficiency.

34
Q

What is syringomyelia?

A

Presence of fluid-filled cystic cavity within the central canal of the spinal cord.

35
Q

What is Syringobulbia?

A

Presence of fluid-filled cyctic cavity within the brainstem.

36
Q

Recap: Arnold-Chiari malformation

A

Developmental abnormality in which cerebellar tonsils extend through foramen magnum.

37
Q

Patients with the Arnold-Chiari formation will often present with?

A

20-40 y/o
Upper limb pain.
Tingling worsened by coughing.
Loss of pain and temperature sensation (from selective impairment of spinothalamic tracts) in upper limbs may lead to painless burns.

38
Q

Transverse myelitis

A

Acute inflammation of the spinal cord.

39
Q

Paraplegia

A

Impairment in motor or sensory function of lower extremities.
- does not affect arms

40
Q

Tetraplegia

A

Paralysis caused by illness or injury resulting in partial or total loss of use of all four limbs and torso.

41
Q

Patients with Transverse myelitis may develop?

A

Paraplegia or Tetraplegia.
Bowel and bladder dysfunction.
Sensory loss below level of lesion.

42
Q

Which artery provides blood supply to most of the spinal cord?

A

Anterior spinal artery.

43
Q

Occlusion in the anterior spinal artery may result in?

A

‘spinal stroke;

- sudden paraplegia, urinary retention and loss of spinothalamic sensation.

44
Q

What is foot drop?

A

Weakness of the dorsiflexion muscles in foot.

45
Q

Where might you expect a lesion to be that causes spontaneous unilateral foot drop?

A 
Usually has a peripheral cause. 
Lesion in L5 nerve root 
Sciatic nerve 
Common peroneal nerve 
Deep peroneal nerve 
Superficial peroneal nerve.
46
Q

What is the most common cause of spontaneous foot drop?

A

Peroneal neuropathy, often as a result of compression at neck of fibula at knee level.
- here common peroneal nerve only covered by skin and subcutaneous tissue.

47
Q

What is Amyotrophic Lateral Sclerosis?

ALS

A

Rare, neurological diseases that mainly involve nerve cells responsible for controlling voluntary movement.

48
Q

What occurs in ALS?

A

UMM & LMM degenerate.
Stop sending messages to muscles.
Muscles unable to function, gradually weaken, start to twitch (fasciculations) and waste away (atrophy).

49
Q

What is Brown-Sequard syndrome?

A

Results in weakness, paralysis on one side of body (hemiparaplegia) and loss of sensation on other (hemianesthesia).

50
Q

What may be a cause of BSS?

A
  • traumatic injury to spine of neck.

- can occur as result of spinal disorders such as cervical spondylosis, arachnoid cyst or epidural hematomas.

51
Q

What is an epidural hematoma?

A

When bleeding occurs dura mater and skull.

52
Q

Describe motor neurons:

A
  • control essential voluntary muscle activity.
    UMM - nerve cells in brain
    LMM - nerve cells in brainstem and spinal cord.

UMM direct LMM to produce movements such as walking/chewing.
LMM control movement in arms, legs etc.

53
Q

Spinal motor neurons are also known as…

A

Anterior horn cells.

54
Q

Upper motor neurons are also known as…

A

Corticospinal neurons

55
Q

Compare and contrast Upper motor neuron lesions to Lower motor neuron lesions:

A

UMN

  • spasticity (increased muscle tone)
  • muscle bulk normal
  • no fasciculations
  • loss of some superficial reflexes such as abdominal or cremasteric.

LMN

  • Hypotonia (decreased muscle tone)
  • wasting may occur
  • fasciculations possibly
  • superficial reflexes preserved

Neurology Y2 (24 decks)

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