Neuromuscular disease

1
Board Review- Neuromuscular Disorders
2

• Which muscle fiber is characterized by
  fast-twitch oxidative metabolic properties?
• (a) Type 1
• (b) Type 2a
• (c) Type 2b
• (d) Type 3

3

• (B) Humans have 2 primary types of muscle fiber.
  They are divided according to many different
  characteristics, including speed of contraction
  and sources of fuel. Type 1 muscle fibers are
  slow-twitch with oxidative metabolic pathways.
  Type 2 muscle fibers are fast-twitch fibers. The
  type 2 fibers can then be further divided into
  fast-twitch oxidative (type 2a) and fast-twitch
  glyclolytic (type 2b). There are no muscle fibers
  designated as type 3.

4

• Duchenne/Becker muscular dystrophy is a defect
  within codes 4 dystrophy molecule located
• XP 11
• XP 16
• XP 21
• XP 18

5

• C XP 21 X-linked recessive

6

• Which one of the following characteristics is
  typically associated with Charcot Marie Tooth
  (CMT) disease type 2?
• (a) minimal level of disability.
• (b) minimal decrease in nerve conduction
  velocity.
• (c) autosomal recessive inheritance.
• (d) absence of sensory deficits.

7

• (B) minimal decrease in nerve conduction
  velocity.
• Charcot Marie Tooth (CMT) disease type 2 has
  greater variability and produces more disability
  than type 1. The disability can range from very
  mild to severe in CMT type 2. In addition to the
  weakness typical of the hereditary sensory motor
  neuropathy diseases, paresis of diaphragm, vocal
  cord, and intercostal muscle has been reported.
  CMT type 2 disease is characterized by less
  hypertrophic change in myelin, with more neuronal
  or axonal involvement. Sensory deficits are
  common to both forms. Both have autosomal
  dominant inheritance.

8

• All of the following is true about ALS except
• Characterized by progressive degeneration and
  loss of motor neurons and cortex, brain stem and
  spinal cord.
• Spares bulbar function
• Affects respiratory and limb musculature.
• Results in both upper motor neuron and lower
  motor neuron signs.

9

• B. Spares bulbar function
• ALS does affect cranial nerves (bulbar function)

10

• ALS typically affects males or females more
  predominantly?
• Males
• Females

11

• A Males 1.5-2.01 ratio approaching 11 with
  increasing age over 70.
• Remember Lou Gehrig !

12

• All of the following suggest a poor prognosis of
  the ALS patient except
• Upper motor neuron signs at the time of
  diagnosis.
• Short duration of time from onset of symptoms.
• Older age of onset
• Bulbar dysfunction early in disease course.
• Pulmonary dysfunction early in disease course.

13

• A Upper motor neuron signs at the time of
  diagnosis.
• Typically it is lower motor neuron signs at the
  time of diagnosis not upper motor neuron signs to
  suggest a poor prognosis.
• REVIEW POOR PROGNOSIS
• Older age at time of onset
• Bulbar dysfunction early in disease course
• Pulmonary dysfunction early in disease course
• Short period of time from onset of symptoms to
  diagnosis.
• Lower motor neuron signs at the time of diagnosis.

14

• All of the following needle EMG findings in LMN
  dysfunction in ALS patients would be suspected
  except
• Increased MUAP amplitude, increased duration and
  polyphasic potentials.
• Decreased MUAP amplitude, short duration,
  polyphasic potentials.
• myotonic discharges
• Increased jitter single fiber needle EMG.

15

• A Youd expect a neuropathic pattern on needle
  EMG
• Increased MUAP amplitude, increased duration,
  decreased recruitment, polyphasic potentials.
• Denervation potentials (fibrillations and
  positive sharp waves) would also be expected.
• Jitter on single fiber EMG is more suggestive of
  myasthenia gravis.
• Decreased MUAP amplitude, decreased duration is
  more suggestive of myopathies.

16

• 72-year-old Caucasian male with PMH of
  hypertension, atrial fibrillation, BPH,
  aggressive weakness and functional disability
  from advancing ALS. Now progressive swallowing
  dysfunction and sialorrhea. He decided to manage
  his sialorrhea and the best choice would be?
• Amitriptyline
• Scopolamine
• Bethenachol
• Botox parotid gland injection

17

• D Botox parotid gland injection
• Anticholinergic medications have a relative
  contraindication in patients with glaucoma, BPH,
  and cardiac conduction disorders. Botox would
  probably be an excellent choice in this case.

18

• A 70-year-old man presents with a 3-month history
  of numbness in patchy areas over the limbs and
  torso. His numbness began in the left foot, then
  the right hand, followed by numbness over the
  back and all the limbs. He has no complaints of
  bowel or bladder problems. He has a long history
  of smoking. His examination reveals normal
  strength, normal cranial nerve function, but
  sensation is decreased to pin prick, vibration,
  and position in the limbs. Deep tendon reflexes
  are absent. Electrophysiologic studies show
  normal motor nerve conduction and needle
  examination of the upper and lower limb muscles.
  The sensory nerve conduction studies show small
  or absent responses. Based on this information
  what test would you order next?
• (a) Nerve and muscle biopsies
• (b) Radiologic studies to assess for a tumor
• (c) Skin biopsy to assess small nerve fibers
• (d) Repetitive nerve conduction studies

19

• (B) The clinical and electrophysiologic
  presentation is consistent with a sensory
  neuropathy. With no evidence to suggest motor
  involvement, the numbness is likely a disorder of
  the dorsal root ganglion. There are only a few
  distinct disorders associated with acute or
  subacute cases described by the history and
  physical in this clinical vignette. They may be
  part of a paraneoplastic syndrome, connective
  tissue disorder such as Sjogrens, a post
  infectious condition, pyridoxine intoxication, or
  as an isolated autoimmune process. In this
  patient with a history of smoking, a cancer work
  up would include obtaining anatomic studies of
  the chest. Biopsies of the nerve, muscle, or skin
  would not add much to the case. Repetitive nerve
  conduction studies would be considered if a
  neuromuscular junction disorder was suspected.

20

• Which are the typical histologic characteristics
  of patients with post polio syndrome.
• Motor units are 7-8 times larger.
• High PMNs count found surrounding sarcolemma.
• Muscle biopsy shows frequent, isolated, atrophic
  fibers rather than groups of atrophic fibers.
• Fiber type grouping
• A C
• B D
• All of the above

21

• E A C
• Histologic evidence indicates motor units are 7-8
  times larger than normal due to ongoing
  denervation reinnervation. Over time,
  denervation becomes permanent. Muscle biopsy
  shows frequent isolated atrophic fibers rather
  than groups of atrophic fibers.

22

• Post polio muscle pain is thought to be secondary
  to
• Persistent muscle spasticity
• Likely due to mechanical joint fatigue and
  overuse.
• Neuropathic pain from spinal cord neuron damage.
• Inflammatory myopathy

23

• B. Likely due to mechanical joint fatigue and
  overuse.
• Post polio muscle pain characterized often by
  superficial burning, cramping and tired feeling
  or a deep muscle ache commonly occurs with muscle
  overuse. Is likely due to muscle strain, fatigue
  and overuse of the joint and muscle. Usually it
  occurs at night or after activity. Neuropathic
  pain in PPS can occur but typically from
  entrapment neuropathies such as CTS or
  radiculopathy rather than spinal cord neuron
  damage.

24

• The polio foot is characterized by the
  following
• Atrophy, foot drop
• Lymphedema
• Erythema and burning foot pain.
• Ankle contracture/soft tissue contracture

25

• B. typical changes of post polio foot include
  skin changes, lymphedema. Secondary to polio
  vascular beds in the limb have not developed
  normally and lymphedema ensues.

26

• All of the following are true about the use of
  steroids in the treatment of Duchenne muscular
  dystrophy except
• Steroids are the only pharmaceutical palliative
  treatment available for Duchenne
• Prolongs motor function
• Reducing risk of scoliosis progression
• Does not cause the problems of weight gain
  typically seen in the adult patient.

27

• D steroids do in fact cause weight gain.
• The steroids used in Duchenne muscular dystrophy
  is in fact the only pharmaceutical palliative
  treatment for Duchenne. It is not universally
  used. He does prolong motor function however
  there is a high incidence of side effects
  specifically weight gain and osteoporosis.

28

• The patient in the picture above is seen in the
  outpatient clinic. Based on inspection respected
  physical diagnosis would be?
• Disuse atrophy and weakness of the rhomboids and
  trapezius.
• Polyneuropathy especially affecting long thoracic
  nerve and dorsal scapular nerves.
• FSH muscular dystrophy
• bilateral frozen shoulder with scapulohumeral
  disassociation.

29

• C FSH muscular dystrophy

30
Q A patient with weakness in lower extremities
has a sural nerve biopsy. Diagnosis based on
biopsy?

1. Peripheral neuropathy
2. Werdnig Hoffman
3. CMT-1
4. Inflammatory myopathy

31

• C) CMT-1 ONION BULB FORMATION

32

• Spinal muscular atrophy is characterized by
  selective destruction of the anterior horn cells.
  SMA-1 and SMA-2 had similar effects and
  presentation. The primary difference between the
  two is
• Findings on biopsy consisting of both
  hypertrophic and atrophic fibers.
• Findings on EMG/MCV
• SMA-1 patients never could sit
• SMA-1 in the pediatric onset, SMA-2 is adult
  onset.

33

• C SMA-1 patients never gained the ability to
  sit. Fairborn A. floppy infant whereas SMA 2
  patients onset is 2-12 and therefore may be
  sitting and walking prior to onset.

34

• What is the correct chronologic order that the
  following SMA syndromes occur based on onset of
  disease?
• Kugelberg Welander, SMA-2, Werdnig Hoffman
• SMA-2, Werdnig Hoffman, Kugelberg Welander
• Werdnig Hoffman, SMA-2, Kugelberg Welander
• None are correct since two of these syndromes are
  not SMA syndromes.

35
C Werdnig-Hoffman, SMA 2, Kugelberg-Welander

• type I (Also called Werdnig-Hoffman.) This is
  the most severe type of SMA and may be present at
  birth. Infants have problems holding their head,
  sucking, feeding, swallowing, and typically move
  very little. The muscles of the chest are also
  affected. The motion of the tongue is described
  as having "worm-like" movements. Death results
  usually by the age of two to six years from
  breathing problems.
• type II (intermediate form) This form of SMA is
  seen in children from seven months to 18 months
  of age. They typically have generalized muscle
  weakness and may require braces, walkers, or a
  wheelchair for assistance. Life-expectancy may
  extend to the 20s and 30s.
• type III (Also called Kugelberg-Welander.) This
  form of SMA affects children older than 18 months
  of age. These children show signs of clumsiness,
  difficulty walking, mild muscle weakness, and may
  be developmentally delayed. These children live
  long into their adult years.
• type IV This form of SMA affects adults in their
  30s and 40s, resulting in a walking disability.

36

• Which medication causes axonal neuropathy most
  frequently?
• A) Vincristine
• B) Vinblastine
• C) Cisplatin
• D) cyclophosphamide

37

• A) Vincristine

38

• A Duchennes muscular dystrophy patient has been
  describing morning headaches to his parents. On
  routine follow-up appointment you recommend for
  this complaint
• a) MRI of brain
• b) Nonsteroidal anti-inflammatory medications
• c) Tylenol
• d) Sleep study
• e) Pulmonary function tests to rule out
  hypoventilation.

39

• D) Sleep study
• Morning headaches may be a sign of sleep apnea.
  A sleep study may be more appropriate. Although
  pulmonary function tests are important for
  monitoring of Duchenne patients in this case you
  need to rule out sleep apnea.

40

• All of the following myopathic conditions would
  typically demonstrate negative EMG except
• Myophosphorylase deficiency
• Steroid myopathy
• Hyperthyroid myopathy
• Inclusion body myositis

41

• D inclusion body myositis are a group of
  inflammatory myopathies with MUAP and denervation
  potentials. Remember, endocrine myopathies and
  storage disease myopathies typically have
  abnormal EMG.

42

• Which of the following potential neurotoxic
  agents cause axonal neuropathy?
• Amiodarone
• Arsenic
• Gold
• Tacrolimus
• EtOH

43

• E EtOH causes a typical axonal loss pattern with
  reduced SNAP and CMAP amplitudes. Neuropathies
  typically affect the legs gtarms.
• Women her more susceptible to neuropathy
  secondary to EtOH
• Substances the cause demyelinating disease
  include N- hexane, Suramin, amiodarone,
  chloroquine, cytosine arabinoside, tacrolimus,
  procainamide, goals, arsenic. The rest cause
  typically more axonal disease.

44

• You are called to the ICU for a electrodiagnostic
  consultation to rule out critical illness
  polyneuropathy. The patient has failed weaning
  from the ventilator. She is on external pacing,
  she is on heparin for anticoagulation. The
  pulmonologist asks you to clarify whether or not
  the NCV can be done with the patient on
  pacemaker. The following is the most appropriate
  response
• EMG/NCV can be done on patients with pacemaker
  so long as is not done vicinity of the pacemaker.
• EMG/NCV is contraindicated in this case.
• EMG/NCV can be safely done without complications
  or precautions on patients with pacemakers.
• Call the neurologist, maybe there crazy enough to
  do it.

45

• B EMG/NCV is contraindicated. Why?
• Because this patient has an external pacemaker
  and not an internal pacemaker. Patient with an
  external pacemaker should not have NCV testing.
• AANEM recommends with implanted pacemakers there
  is little risk of harm to the patient with a
  pacemaker when performing NCVS testing unless you
  stimulate near the brachial plexus ipsilateral to
  the pacemaker .

46

• Which of the following statements is true
  regarding needle EMG studies?
• There is no contraindication to needle EMG in
  patients with prosthetic joints when sterile
  single use EMG needles are used
• Prophylactic antibiotics are required with
  significant heart valve disease prior to the EMG
  / NCVS procedure
• There is no significant concerns performing
  needle EMG and patients with lymphedema.
• EMG NCV studies are contraindicated in pregnancy.

47

• A There is no contraindication to needle EMG in
  patients with prosthetic joints when sterile
  single use EMG needles are used

48

• What effect is having the active and reference
  electrodes closer than 3-4 cm apart?
• Increased SNAP amplitude
• Increased SNAP dispersion
• Decreased SNAP amplitudes
• This measurement will not matter as he will
  obtain the same values

49

• C If the active and reference electrodes are
  placed less than 3 4 cm apart when performing a
  sensory conduction, then both electrodes will
  record similar information which is then canceled
  out leading to a decrease in the value for the
  SNAP amplitude

50
The potentials above are (a) complex repetitive
discharges. (b) myotonic discharges. (c)
neuromyotonia. (d) myokymia.
51

• B) Myotonic discharges are single fiber
  discharges that wax and wane in frequency and
  amplitude.

52

• Which potentials have manifestations that CANNOT
  be observed on physical examination?
• (a) Fasciculation potentials
• (b) Myokymic discharges
• (c) Complex repetitive discharges
• (d) Cramp potentials

53

• C CRDs can only be detected with EMG. The
  remainder of the discharges have manifestations
  that can be observed on physical exam

54

• Which neuromuscular disorder is NOT usually
  associated with thyroid disease?
• A. peripheral neuropathy
• B. neuromuscular junction disorder
• C. Myopathy
• D. Radiculopathy

55

• D. Thyroid disease is associated with several
  different aspects of the neuromuscular system.
  In both hypothyroidism and hyperthyroidism, there
  can be neuromuscular junction disorders
  (myasthenia), and myopathy. Hypothyroidism is
  associated with sensorimotor peripheral
  neuropathy and entrapment neuropathy, especially
  carpal tunnel syndrome. Thyroid disease is not
  associated with radiculopathy.

56

• What condition casues the typical myopathic
  gait seen in a young boy with Duchenne muscular
  dystrophy with accentuated lumbar lordosis and
  toe walking?
• (a) Hip and knee extensor weakness
• (b) Hip flexion and ankle plantar flexion
  contractures
• (c) Hip extensor weakness and plantar flexion
  contracture
• (d) Hip flexion contracture and knee extensor
  weakness

57

• A) Hip and knee extensor weakness

58

• Factors associated with poor prognosis in
  multiple sclerosis include
• (a) female gender.
• (b) age at onset less than 20 years.
• (c) cerebellar involvement at onset.
• (d) relapsing remitting course at onset.

59

• C Patients have a poor prognosis if they are
  male, gt35 y/o, polysymptomatic, rapidly
  progressive, motor symptoms, ataxia, tremor, high
  rate of relapse

60

• Which of the following neuropathies has the
  slowest conduction velocity?
• A. dejerine sottas
• B. friedreichs ataxia
• C. fabrys disease
• D. CMT type 1
• E. CMT type 2

61

• A. Dejerine Sottas CV is usually less than 10 m/s

62

• MS patients experience a marked sensitivity to
  heat. This is called
• A. Lhermittes sign
• B. Uhthoffs phenomenon
• C. Hoffmans sign
• D. Kennedy phenomenon

63

• B. Uhthoffs phenomenon

64

• All of the following diseases may present with
  ptosis except
• A. Myasthenia Gravis
• B. Botulism
• C. Myotonic Dystrophy
• D. Fascioscapulohumeral dystrophy

65

• D. Fascioscapulohumeral dystrophy
• In FSH, the extraocular muscles are spared

66
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67

• A patient having difficulty late in the day
  getting up from a chair, going up or down stairs,
  and reaching with his arms presents for
  electrodiagnostic studies.
• Physical exam demonstrates normal DTRs and normal
  findings on manual muscle testing.
• Standard sensory and motornerve conduction
  studies are normal. Repetitive axillary nerve
  stimulation (RNS) performed at 2Hz demonstrates
  20 decremental response.
• Immediately after exercise, the RNS decrement is
  no longer observed. Three minutes following
  exercise, however, the decrement is greater.
  Needle EMG results are normal.
• 
  (SAE)

68

• Upon further investigation, you would most likely
  find what additional clinical finding?
• (a) Asthma
• (b) Dry mouth
• (c) Ptosis
• (d) Skin rash

69

• C. Ptosis
• The patient presents with myasthenia gravis
• (MG), a postsynaptic neuromuscular junction
• disorder. Ptosis and extraocular weakness often
• occur in MG.
• Lambert-Eaton myasthenic syndrome (LEMS), a
• presynaptic neuromuscular junction disorder,
• would demonstrate postexercise facilitation (at
• least 100 increase in first response CMAP
• immediately following exercise) and likely have
• low-amplitude baseline CMAP results. Autonomic
• symptoms such as dry mouth often accompany
• LEMS.

70

• Long-term steroid treatment for asthma may
• cause myopathy without significant needle EMG
• results, but RNS would be normal.
• Although dermatomyositis typically presents with
  proximal weakness, no abnormalities
  characteristic of an inflammatory myopathy were
  seen on needle electromyography.

71

• Which muscle group displays the earliest pattern
  of weakness in Duchenne muscular dystrophy?
• A. Ankle dorsiflexors
• B. Neck flexors
• C. Shoulder flexors
• D. Knee extensors
• (SAE)

72

• B. Neck flexors
• In Duchenne muscular dystrophy, weakness is first
  seen in the neck flexors during preschool years.
  Pelvic girdle weakness precedes shoulder girdle
  weakness by several years.
• Ankle dorsiflexors are weaker than
  plantarflexors ankle everters are weaker than
  inverters knee extensors are weaker than
  flexors hip extensors are weaker than flexors.

73

• In performing motor nerve conduction studies,
  what is the effect on the compound muscle action
  potential (CMAP) of placing the recording
  electrodes (active and reference) closer
  together, over the same muscle?
• A. No effect on the onset latency of the CMAP
• B. An increase on the CMAP amplitude
• C. A prolongation of the peak latency
• D. A decrease in the calculated conduction
  velocity
• 
  (SAE)

74

• A. No effect on the onset latency of the CMAP
• If the active and reference electrodes are placed
  too close together, similar waveforms will be
  recorded on both sites and these waveforms will
  be rejected. This will result in an CMAP
  amplitude drop. There is no effect on the onset
  latency.

75

• What feature is suggestive of polymyositis?
• A. Distal symmetric weakness without pain
• B. Reduced motor nerve conduction velocities and
  conduction block
• C. Electromyography with low voltage, polyphasic
  potentials
• D. Brisk tendon reflexes
• (SAE)

76

• C. Electromyography with low voltage, polyphasic
  potentials

77

• Cognitive deficits are common in
• A. Duchenne muscular dystrophy
• B. Inclusion body myositis
• C. Fascioscapulohumeral dystrophy
• D. Becker muscular dystrophy
• 
  (SAE)

78

• A. Duchenne muscular dystrophy
• Brain isoform of dystrophin exists and there are
  documented mildly decreased Intelligence Quotient
  scores in people with Duchenne muscular
  dystrophy. These lower scores may be specific to
  deficits with tasks requiring attention to
  complex verbal information.

79

• All hereditary sensory motor neuropathies are
  characterized by
• A. Decreased intelligent quotient scores
• B. Spinal deformities
• C. Muscle weakness
• D. Joint contractures
• 
  (SAE)

80

• C. Muscle weakness
• The residual muscle force in the later stages of
  the disease is 20-30 of normal. Intelligence
  quotient reduction, significant joint
  contractures, pulmonary/cardiac abnormalities and
  spinal deformities are not typical of HSMN.

81

• Which symptom is most predictive of cardiac
  disease in Duchenne muscular dystrophy?
• A. Palpitations
• B. Syncope
• C. Dyspnea
• D. Cachexia
• 
  (SAE)

82

• C. Dyspnea
• The most frequent predictive symptom is dyspnea.
• Absence of exertion dyspnea from lack of physical
• activity allows myocardial impairments to remain
• clinically silent and difficult to detect. A high
  index
• of suspicion is required.
• Electrocdardiogram abnormalities in both
• Duchenne and Becker muscular dystrophy patients
• are attributed to progressive fibrosis of the
  cardiac
• conduction system and impairment in the cardiac
• autonomous nervous system.
• Palpitations and syncope will be related to the
• conduction abnormalities and occurs late in the
  disease process.

83

• Cachexia is a late finding that occurs when
  feeding
• becomes difficult as a result of heart failure
  and
• dyspnea

84

• A prominent feature of the most common form of
  CharcotMarie-Tooth disease is
• A. Truncal ataxia
• B. Sensory impairment
• C. Severe proximal weakness
• D. Mild mental retardation
• 
  (SAE)

85

• B. Sensory impairment

86

• A 36 year-old man has a known history of HIV.
  His family has observed worsening confusion and
  memory loss. He later develops progressive
  paraparesis, ataxia, posterior column sensory
  loss, and neurogenic bowel and bladder. The most
  likely diagnosis is
• A. Viral myelitis
• B. Multiple sclerosis
• C. Cytomegalovirus (CMV) polyradiculopathy
• D. Vacuolar myelopathy
• (SAE)

87

• D. Vacuolar myelopathy
• Vacuolar myelopathy is the most common cause of
  spinal cord dysfunction in (HIV) patients, being
  found in 11 to 22 of acquired immunodeficiency
  disease (AIDS) cases, and demonstrable in as many
  as 40 of cases at autopsy. It is strongly
  associated with HIV dementia, and shares a
  virtually identical histopathology. The other
  diagnoses are less common, and can be ruled out
  or in with imaging, laboratory and
  electrodiagnostic studies.

88

• A 40-year-old woman is currently
• hospitalized for a severe flare of her
  polymyositis.
• On consultation, you recommend that while in the
• hospital she begin
• (a) passive range-of-motion exercises to prevent
  contractures.
• (b) isometric strengthening exercises at the
  bedside to maintain her strength.
• (c) ambulation with a walker in the hallways
  supervised by her therapist.
• (d) strengthening exercises with light hand and
  ankle weights.
• (SAE)

89

• (a) passive range-of-motion exercises to prevent
  contractures.
• Passive range of motion to maintain joint
  movement is recommended during periods of acute
  flares. With resolution of the flare,
  active-assisted exercises may be started,
  progressing to strengthening exercises and
  ambulation.

90

• Which statement regarding glossopharyngeal
  breathing is TRUE?
• A. It is typically useful in patients with weak
  oropharyngeal muscles
• B. It is recommended therapy in a patient with
  laryngeal cancer
• C. It is generally used when a patient has a
  tracheostomy
• D. It is a useful backup for any mechanical
  failure of ventilatory assistance
• 
  (SAE)

91

• D. It is a useful backup for any mechanical
  failure of ventilatory assistance