EMG SAEs Flashcards
Which clinical tool BEST measures and predicts the safety of ambulation in older adults?
(a) Berg Balance Scale (BBS)
(b) Braden Scale
(c) Timed Up and Go (TUG) test
(d) Katz Index
Answer: (c)
Commentary: The Berg Balance Scale (BBS) is a 56-point scale to evaluate performance during
14 common activities, such as standing, turning and reaching for an object on the floor. It does
not rate walking. The Braden Scale is for predicting pressure sore risk, and is used to help
determine the risk of skin breakdown or decubitus ulcer. In the Timed Up and Go (TUG) test, a
patient is asked to rise from an armchair, walk 3 meters (10 feet), turn around, walk back to the
chair, and sit down again (the score is the time in seconds it takes to complete these tasks). This
test has high interrater and content reliability, and predicts whether a patient can safely walk
outside alone. The Katz Index is widely used to measure independence in activities of daily living
(ADLs), but does not include measures of mobility, such as walking or stair climbing.
One advantage of a concentric needle compared to a monopolar needle is its
(a) higher amplitude of motor unit action potentials(MUAPS).
(b) decreased likelihood of electrical interference.
(c) ability to vary the recording surface size.
(d) longer duration of the MUAPs.
Answer: (b)
Commentary: The shaft of a concentric needle serves as the reference electrode, whereas an
additional electrode (typically a surface electrode) is needed as a reference when using a
monopolar needle. MUAPs recorded from monopolar needles are slightly longer in duration and
have higher amplitude, since they record from the entire area around the needle tip rather than
only from the fibers facing the bevel. Because the concentric needle shaft serves as the reference
electrode, the recording surface size is fixed and interference from surrounding muscles is
minimized.
A 42-year-old woman with multiple sclerosis comes to you describing profound afternoon
fatigue. You recommend
(a) tizanidine (Zanaflex).
(b) amantadine (Symmetrel).
(c) azathioprine (Imuran).
(d) glatiramer acetate (Copaxone).
Answer: (b)
Commentary: Many medications are indicated for multiple issues relating to multiple sclerosis
(MS). Medications for fatigue include amantadine (Symmetrel) and modafinil (Provigil).
Medications for use in exacerbations include prednisone, ACTH and Solu-Medrol. These drugs
are supposed to decrease the length and severity of exacerbation. Disease altering medications
including the interferons beta 1A and beta 1B as well as glatiramer acetate (Copaxone) can
decrease the number of exacerbations. Medications for chronic MS include cyclophosphamide
(Cytoxan), azathioprine (Imuran), and cyclosporine (Sandimmune), which are supposed to slow
progression in chronic MS. Medications for spasticity include baclofen (Lioresal), dantrolene
(Dantrium), tizanidine (Zanaflex), and diazepam (Valium). Medications for ataxia can include
clonazepam (Klonopin) as well as isoniazid (Nydrazid).
In patients with steroid myopathy, the needle electromyographic study usually reveals
(a) small motor unit action potentials (MUAPs) with early recruitment.
(b) small MUAPs with reduced recruitment.
(c) positive waves and fibrillation potentials in proximal muscles.
(d) normal MUAPs and normal recruitment.
Answer: (d)
Commentary: Needle examination in patients with steroid myopathy usually reveals normal
insertional activity and no abnormal spontaneous activity. Motor unit potential morphology and
recruitment do not reveal any abnormalities. This combination occurs because in steroid
myopathy the type 2 muscle fibers are preferentially affected, in contrast to the first-recruited
type 1 fibers.
Your patient is having difficulty writing or performing tasks in certain positions. He has an
asymmetric tremor that is present only with movement. You suspect which type of tremor?
(a) Essential
(b) Primary orthostatic
(c) Cerebellar
(d) Dystonic
Answer: (d)
Commentary: Suspect a dystonic tremor if it is very asymmetrical and shows postural
dependence. There may be associated dystonia elsewhere in the body. The tremor may have task
specificity, such as writing or postural dependence. A cerebellar tremor will often have other
cerebellar signs present and often improves if the patient performs movement with eyes closed.
Essential tremor is symmetrical and best seen with an outstretch hand. Primary orthostatic tremor
presents as unsteadiness or tremor in the legs that increases with prolonged standing, and the
symptoms are relieved by sitting or walking.
A neurologist refers a patient to you with Parkinson disease and poor gait. What treatment
strategy is recommended to prevent frequent falls?
(a) Methylphenidate medication trial to increase attention and concentration
(b) Physical therapy with balance training and cueing strategies
(c) Referral to a neurosurgeon for implantation of a deep brain stimulator
(d) Maximized levodopa medication to improve balance control
Answer: (b)
Commentary: Physical therapy with cueing strategies, such as rhythmic auditory stimulation with
a metronome and balance and strength training are shown to be useful in improving gait and
decreasing falls. Treadmill training is still in its infancy and its role in improving gait is unclear,
although early studies are positive. The use of methylphenidate in initial trials was positive but a
recent randomized, double blinded study using methylphenidate showed no improvement in gait.
The use of deep brain stimulation is very inconsistent in its effect on balance and gait and further
study is needed to optimize type of stimulation and to define new targets for stimulation.
Levodopa can improve gait, but can also cause a worsening of gait and balance, possibly due to
drug-induced dyskinesias.
Which finding would you expect in a 35-year-old man with type 1 hereditary motor sensory
neuropathy?
(a) Absence of ankle reflexes
(b) Pes planus
(c) Motor nerve conduction velocity slowing, with evidence of temporal dispersion
(d) Absence of electromyographic spontaneous activity
Answer: (a)
Commentary: Hereditary motor sensory polyneuropathy type 1 (HMSN-1, the demyelinating
form of Charcot-Marie-Tooth disease) presents in young adult life with insidious onset of distal
weakness and sensory loss. Clinically, it typically presents with pes cavus, hammertoes and foot
drop. Ankle reflexes are absent. Temporal dispersion would indicate an acquired, not hereditary,
process. Secondary axonal loss is expected, which would result in positive waves and
Fibrillations.
Personality changes and/or aphasia are typical of which dementia?
(a) Alzheimer
(b) Frontotemporal
(c) Parkinson’s disease with dementia
(d) Vascular
Answer: (b)
Commentary: Frontotemporal dementia is a neurodegenerative disease of unknown etiology with
atrophy and neuronal loss in the frontal and temporal lobes of the brain resulting in a gradual and
progressive decline in behavior and/or language. Overuse of stock phrases, lack of
conversational initiation and echolalia are more common in frontotemporal dementia. Alzheimer
disease is primarily associated with memory and visuospatial loss of function, and speech is more
fluent than in persons with frontotemporal dementia. Parkinson disease with dementia is
associated with symptoms of memory loss, fluctuating cognition, and visual hallucinations with
spontaneous parkinsonism motor features. Persons with vascular dementia usually have a history
of stroke or have focal neurologic deficits, early gait disturbance, changes in personality and
mood and a history of frequent falls or unsteadiness.
Cooling can produce physiological changes in the body. One of these changes is an increase in
(a) nerve conduction rate.
(b) stretch receptor sensitivity.
(c) elasticity of connective tissue.
(d) general sympathetic activity.
Answer: (d)
Commentary: Nerve conduction rate is slowed by cooling. The stretch receptor sensitivity in
muscles and tendons is reduced, and the elasticity of connective tissue diminishes with cooling.
The general sympathetic activity is increased with cooling of the body, and this may affect the
responses of the stretch receptors in a beneficial way.
A significant improvement in quality of life for advanced ALS patients is attributed to
(a) having advanced directives.
(b) invasive ventilation to prolong life.
(c) earlier hospice transition.
(d) placement in long-term care.
Answer:(c)
Commentary: Improved quality-of-life for advanced ALS patients is attributed to optimizing inhome
care and early hospice transition. Hospice can ease the burden of care by the family
members. Hospice organizations have guidelines for early entry into hospice during advanced
stages. Most patients who undergo invasive mechanical ventilation do so emergently and often
against their wishes. Invasive ventilation is not preferred in over 92% of ALS patients surveyed.
Often, there is a lack of advanced directives to guide the treating team. Lack of physician
communication with the patient about advanced directives is the major barrier to patients
developing their advanced directives.
A 33-year-old woman who had a prolonged labor 6 weeks ago, reports pain in the groin radiating
along the medial aspect of the thigh. Needle electromyographic exam shows evidence of
denervation in the gracilis and adductor muscles. Most likely she has a lesion in the
(a) femoral nerve.
(b) obturator nerve.
(c) sciatic nerve.
(d) genitofemoral nerve.
Answer: (b)
Commentary: The nerve common to the affected muscles is the obturator nerve. There is some
innervation of the adductor magnus by a branch off the sciatic nerve, but the gracilis, adductor
brevis, and adductor longus are supplied by the obturator nerve. Injuries of the obturator nerve are
uncommon, but one cause in such cases is compression of the nerve between the fetal head and
the pelvic wall during prolonged labor.
A patient presents to your clinic with a 1-month history of mild hand numbness and clumsiness
without weakness. Electrodiagnosis confirms a primarily sensory median neuropathy at the wrist
without axon loss. Symptoms are not interfering with work. What is the most appropriate
treatment recommendation to provide short-term relief for this patient?
(a) Immediate referral to surgery for carpal tunnel release
(b) Neutral wrist splints to be worn at night
(c) Thumb spica splint
(d) Injection of platelet rich plasma into carpal tunnel
Answer (b)
Commentary: Wrist splints are shown to effectively decrease symptoms of carpal tunnel
syndrome in the short-term. Splints should be worn at night and during the day if possible. Brace
should place wrist in neutral (up to 5o of extension): note that many off-the-shelf carpal tunnel
braces place the wrist in excessive extensions. A thumb spica splint is not effective in treating
carpal tunnel syndrome. Conservative treatment is essential in mild to moderate cases of carpal
tunnel syndrome. Surgical referral should be considered for patients with weakness or worsening
symptoms not improved with conservative treatment. Platelet rich plasma injections are not an
effective treatment for carpal tunnel syndrome.
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.
