Neuromuscular Flashcards
The definitive diagnostic test for inclusion body myositis is
(a) muscle enzyme serum levels.
(b) cerebrospinal fluid.
(c) muscle biopsy.
(d) electromyography
Answer: (c)
Commentary: Inclusion body myositis (IBM) is a slowly progressive myopathy that tends to
affect middle-aged and older individuals. Clinical manifestations can include distal as well as proximal weakness, which can be asymmetrical. Muscle enzyme levels may be slightly elevated or normal. Myopathic motor units can be seen, although this finding is nonspecific, since it exists in other inflammatory myopathies, as well. Acquisition of cerebrospinal fluid is not part of the work-up for myopathy. Muscle biopsy is diagnostic with rimmed cytoplasmic vacuoles and cytoplasmic and nuclear inclusions.
Reference: Kegan L. Inclusion body myositis. In: Kagen L, editor. The inflammatory myopathies. New York: Humana Press;2009. p 279-294
2013
Following a crush injury with axonotmesis, the approximate growth regeneration rate at the wrist is 1 centimeter per
(a) day.
(b) week.
(c) month.
(d) year.
Answer: (b)
Commentary: Regenerating axons grow approximately 1 millimeter a day, 1 centimeter a week, 1 inch a month, or 1 foot a year. The rate of axon regeneration depends chiefly on type of injury (crush or laceration) and whether the lesion is proximal or distal. Growth rate following a crush injury with axonotmesis in the upper arm is about 8 millimeters a day; in the upper forearm it is about 6 millimeters a day, at the wrist about 1-2 millimeters a day, and in the hand about 1.0-1.5 \millimeters a day. Easier figures to remember, however, are 1mm/day, 1cm/week, or 1 inch/month.
Reference: (a) Stewart, JD. Focal peripheral neuropathies. 3rd ed. Montreal (Quebec):McGill Univ; 2000. p 25. (b) Ref: Dumitru D, Zwarts MJ, Amato A, Peripheral nervous system’s reaction to injury: electrodiagnostic medicine. 2nd ed. Philadelphia: Hanley & Belfus; 2002. p
120-1
2013
Which finding is associated with a more favorable prognosis in amyotrophic lateral sclerosis
(ALS)?
(a) Bulbar involvement presentation
(b) Predominance of lower motor neuron findings on electrodiagnostic studies
(c) Young age and male sex
(d) Short time period from symptoms to diagnosis
Answer: (c)
Commentary: Several prognostic predictors exist for determining the severity of a person’s ALS
course. Presentation with bulbar or pulmonary dysfunction (or both), short time period from
symptom onset to diagnosis, electrodiagnostic findings indicating primarily lower motor neuron
involvement and advanced age all potentially indicate a poor prognosis. Women present with
bulbar symptoms more frequently than men do. Bulbar palsy, which indicates a poor prognosis,
appears to progress more rapidly in women. Young males with ALS have the best prognosis and
may have a longer life expectancy. Overall, the median 50% survival rate is 2.5 years after
diagnosis. In patients who present with bulbar symptoms, the 50% survival rate drops to 1 year.
Survival rates vary depending on the patient’s decision to use a feeding tube and assisted
ventilation. Nonetheless, by 5 years postdiagnosis, the overall survival rate is only 28%.
2013
When applying cryotherapy in the treatment of musculoskeletal disorders, which of the following
events is NOT a contraindication to its use?
(a) Paroxysmal cold hemoglobinuria
(b) Impaired sensation
(c) Arterial insufficiency
(d) Spasticity
Answer : (d)
Commentary: Contraindications for the use of cryotherapy include paroxysmal cold
hemoglobinuria, impaired sensation and arterial insufficiency.Other contraindications are cold
hypersensitivity, cryopathies, cold intolerance, cryotherapy-induced neurapraxia, and Raynaud disease. Spasticity is one of the general uses of cryotherapy in addition to musculoskeletal injuries and pain syndromes, postoperative conditions and emergency treatment of minor burns.
2012
Which barrier is perceived by older individuals to be the LEAST significant obstacle to physical
activity?
(a) Time, money, family commitments
(b) Illness and injury
(c) Fear of injury
(d) Availability of an exercise partner
Answer: (a)
Commentary: Perceived barriers are a powerful negative predictor of physical activity in the elderly. Although individual variation is the rule, overall obstacles to physical activity tend to change with age, and seem to increase for many aging individuals. Elderly patients report that time, money and family commitments are less significant barriers as they age. Availability of an
exercise partner, illness, injury and fear of injury become more prominent concerns as they grow older.
2012
Which disorder does NOT have pes cavus as a feature?
(a) Poliomyelitis
(b) Cerebral palsy
(c) Friedreich ataxia
(d) Peroneal spastic foot
Answer: (d)
Commentary: The etiology of pes cavus includes malunion of calcaneal or talar fractures, burns,
sequelae resulting from compartment syndrome, residual clubfoot, and neuromuscular disease.
The remaining cases are idiopathic and nonprogressive. Neuromuscular diseases, such as muscular dystrophy, Charcot-Marie-Tooth (CMT) disease, spinal dysraphism, polyneuritis,
intraspinal tumors, poliomyelitis, syringomyelia, Friedreich ataxia, cerebral palsy and spinal cord tumors can cause muscle imbalances that lead to elevated arches. Multiple theories have been proposed for the pathogenesis of pes cavus. Duchenne described intrinsic muscle imbalances causing an elevated arch. Whereas, peroneal spastic foot is characterized by pain in the foot, limited subtalar motion, pes planus deformity, and shortening with spasm of the peroneal muscles
often initiated by minor trauma or unusual activity.
2011
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
Answer: (b)
Commentary: 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
2011
Which muscle fiber types are recruited first in isometric contractions?
(a) Type 1
(b) Type 1b
(c) Type 2
(d) Type 2b
Answer: (a)
Commentary: Fatigue-resistant type 1 fibers are recruited initially followed by type 2b fibers.
There are no type 1b fibers
2011
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
deep tendon reflexes and normal findings on manual muscle testing. Standard sensory and motor
nerve 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
electromyography results are normal.
Upon further investigation, you would most likely find what additional clinical finding?
(a) Asthma
(b) Dry mouth
(c) Ptosis
(d) Skin rash
Answer (c)
Commentary: 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.
2011
Which symptom is the most predictive of cardiac disease in Duchenne muscular dystrophy?
(a) Palpitations
(b) Syncope
(c) Dyspnea
(d) Cachexia
Answer: (c)
Commentary: 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.
2011
What is the benefit of using ankle-foot orthoses (AFOs) for a patient with Duchenne muscular dystrophy?
(a) Improves the patient’s ambulation
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(b) Assists the patient with rising from the floor
(c) Prevents contractures when used at rest
(d) Improves wheelchair positioning
Answer: (c)
Commentary: Resting AFOs can help prevent ankle plantar flexion contractures, but are not required for proper wheelchair positioning. Duchenne muscular dystrophy is an x-linked disease with progressive muscle weakness/degeneration that is usually diagnosed in early childhood. Loss of independent ambulation generally occurs in early adolescence, necessitating the transition to a wheelchair. The progressive weakness leads to compensatory strategies for ambulation such that AFOs may further impede ambulation or transferring.
2013
Which finding is associated with a more favorable prognosis in amyotrophic lateral sclerosis (ALS)?
(a) Bulbar involvement presentation
(b) Predominance of lower motor neuron findings on electrodiagnostic studies
(c) Young age and male sex
(d) Short time period from symptoms to diagnosis
Answer: (c)
Commentary: Several prognostic predictors exist for determining the severity of a person’s ALS course. Presentation with bulbar or pulmonary dysfunction (or both), short time period from symptom onset to diagnosis, electrodiagnostic findings indicating primarily lower motor neuron involvement and advanced age all potentially indicate a poor prognosis. Women present with bulbar symptoms more frequently than men do. Bulbar palsy, which indicates a poor prognosis, appears to progress more rapidly in women. Young males with ALS have the best prognosis and may have a longer life expectancy. Overall, the median 50% survival rate is 2.5 years after diagnosis. In patients who present with bulbar symptoms, the 50% survival rate drops to 1 year. Survival rates vary depending on the patient’s decision to use a feeding tube and assisted ventilation. Nonetheless, by 5 years postdiagnosis, the overall survival rate is only 28%.
2013
In patients with neuromuscular disease, which measurement is shown to be the most influential in
determining the intensity of their aerobic exercise?
(a) 70%-85% maximum heart rate
(b) 60%-80% of heart rate reserve
(c) Borg scale of perceived exertion
(d) Delayed-onset muscle soreness
Answer: (d)
Commentary: Thirty-three studies, to date, report absent or negligible adverse effects of exercise
in neuromuscular disease patients. Maximum heart rate and cardiac reserve are the same goals
for able bodied and neuromuscular patients. Delayed onset muscle soreness is shown to be the
most influential factor for patients to modify their own exercise program.
2010
Which modification can be used to increase the sensitivity of repetitive testing in neuromuscular
junction disorders?
(a) Decrease the muscle temperature below 30°C.
(b) Allow the muscle to be rested for 6 minutes.
(c) Test the most distal muscles in the feet.
(d) Test the muscles after inducing ischemia.
Answer: (d)
Commentary: In postjunctional disorders, such as myasthenia gravis, the proximal muscles seem
to be more affected and it is thought that this difference is due to the increased temperature as one
gets closer to the core of the body. The higher temperatures potentiate a reduced safety factor.
Hence, the sensitivity of detecting a decrement response is higher with proximal muscle testing.
Maximal exercise can help in demonstrating postactivation exhaustion. When repetitive
stimulation is normal in both proximal and distal muscles, testing under ischemic conditions can
demonstrate a decrement in the responses.
2010
Which electrodiagnostic feature is more common in type 2 Charcot-Marie-Tooth (CMT) disease
than in CMT type1?
(a) It is primarly demyelinating.
(b) Lower limbs are more affected than upper.
(c) Conduction velocity slows.
(d) Secondary axonal changes occur over time.
Answer: (b)
Commentary: The type-2 form of Charcot-Marie-Tooth disease (CMT2) tends to affect the lower
extremities more than the upper extremities. In CMT type 1 (CMT1), which is primarily a
demyelinating neuropathy, anatomic changes directly affect the myelin sheath, with secondary
axonal changes. In areas of focal demyelination, impulse conduction from 1 node of Ranvier to
the next is slowed, because current leakage occurs and the time for impulses to reach threshold at
successive nodes of Ranvier is prolonged. The prolongation slows conduction velocity along the
nerve segment. CMT2 is often a clinically less severe disease than CMT1.
2010
In a patient with neuromuscular disease, which pulmonary function parameter best represents
abdominal and chest wall strength?
(a) Tidal volume
(b) Maximal inspiratory pressure
(c) Peak cough
(d) Maximal expiratory pressure
Answer: (d)
Commentary: The maximal inspiratory pressure reflects diaphragm strength and ventilatory
ability. Maximum expiratory pressure is indicative of abdominal and chest wall muscle strength
and the ability to cough and clear secretions. The tidal volume represents the normal volume of
air displaced between normal inhalation and exhalation when extra effort is not applied. Peak
cough flow is a measure of the amount of air flow that a patient can generate during a volitional
cough
2010
A patient with neuromuscular disease complains of morning headache and excessive daytime
fatigue. What is your initial diagnostic evaluation?
(a) Order chest radiographs.
(b) Order pulmonary function tests.
(c) Monitor end-tidal carbon dioxide levels.
(d) Measure assisted-cough peak flows.
Answer: (c)
Commentary: Patients with neuromuscular disease (NMD) are often sent for pulmonary function
tests designed for patients with lung disease. Patients with NMD often do not have a history of
asthma or cigarette smoking and most of these tests are unnecessary, except for spirometry.
Because underventilation often begins during sleep, spirometry or simple determination of vital
capacity is best done in the supine position. The patient’s carbon dioxide level will provide
insight into hypoventilation and should be monitored, especially when the patient complains of
excess fatigue and headaches.
2010
Which muscle fiber is characterized by slow-twitch oxidative metabolic properties?
(a) Type 2a
(b) Type 1
(c) Type 2b
(d) Type 3
Which muscle fiber is characterized by slow-twitch oxidative metabolic properties?
(a) Type 2a
(b) Type 1
(c) Type 2b
(d) Type 3
2010
What is the effect of treadmill training in Parkinson patients?
(a) It has no effect on fall risk.
(b) It improves quality of life.
(c) It produces no change in gait impairments.
(d) It reduces tremor.
Answer: B
Commentary:A 6-week treadmill training program in patients with Parkinson disease showed
that the program decreased fall risk, improved quality of life, and improved gait impairments.
There was no indication of a reduction of tremors
2009
Which finding is frequently associated with sensory neuronopathies?
a. Symmetric onset
b. Rheumatoid arthritis
c. Paraneoplastic syndrome
d. Impaired mobility secondary to weakness
Option c is correct.
Sensory neuronopathies are uncommon and affect large sensory fibers. The onset is typically asymmetric and gait abnormalities are secondary to impaired proprioception as opposed to weakness. The differential diagnoses include paraneoplastic syndrome, toxins and Sjögren’s syndrome but not rheumatoid arthritis.
2014
