Neuromuscular disease

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Neuromuscular disease

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Title: 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

(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.

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

C XP 21 X-linked recessive

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.

(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.

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.

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

ALS typically affects males or females more
predominantly?
Males
Females

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

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.

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.

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.

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.

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

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.

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

(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.

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

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.

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

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.

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

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.

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.

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.

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.

C FSH muscular dystrophy

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

Peripheral neuropathy
Werdnig Hoffman
CMT-1
Inflammatory myopathy

C) CMT-1 ONION BULB FORMATION

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.

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.

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.

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

A) Vincristine

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.

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.

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

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.

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

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.

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.

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 .

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.

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

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

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.

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

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

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

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.

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

A) Hip and knee extensor weakness

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.

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

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

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

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

B. Uhthoffs phenomenon

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

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)

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

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.

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.

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)

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.

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)

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.

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)

C. Electromyography with low voltage, polyphasic
potentials

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

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.

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

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.

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

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.

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

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)

B. Sensory impairment

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)

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.

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)

(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.