gulseren_emg
TRANSCRIPT
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Professor, Chief of Department
of Physical Medicine &
Rehabilitation, Marmara
University, Istanbul TURKEY
Secretary General of
Mediterranean Forum of Physical
Medicine and Rehabilitation
Interest: Algology/Pain rehabilitation Clinical Neurophysiology
Osteoporosis
Cancer rehabilitation
Enjoys : Travel, sudoku
Contact: [email protected]
Gulseren AKYUZ
MD
mailto:[email protected]:[email protected] -
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Low Back Pain (LBP)
The prevelance of lifetime : 60-80 %
Risk of recurrent in lifetime : 85 %
Low back pain >2 weeks : 14 %
There is only 10 % sciatica
Sciatica > 2 weeks : 1.6 %
Highest prevalence : Between the age of 45-64
Symptomatic lumbar disc herniation : 1-2 %
70% will recover within one month and 95% within 3 months
Lawrence RC: Arth Rheum 1998; Deyo RA et al: Spine 1987; Boden SD et al: J Bone Joint Surg Am 1990
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Advanced Age (> 50)
Gender (F:M; 2:1)
Overweight
Cigarette smoking
Occupation
Vibrational exposure
Repetitive heavy lifting
Prolonged sitting
Psychological factors
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Mechanical conditions Nonmechanical
conditions
Visceral causes
Lumbar strain, sprain
Lumbar disc herniation
Degenerative processes of disks and
facets
Chronic degenerative discdisease
Spinal stenosis
Osteoporotic fracture
Spondylolisthesis
Traumatic fracture
Congenital disease
Severe kyphosisSevere scoliosis
Transitional vertebrae
Internal disk disruption or diskogenic
low back pain
Presumed instability
Neoplasia
Multiple myeloma
Metastatic carcinoma
Lymphoma and leukemia
Spinal cord tumorsRetroperitoneal tumors
Primary vertebral tumors
Infection
Osteomyelitis
Septic diskitis
Paraspinous abscess
Epidural abscessInflammatory arthritis (often
associated with HLA-B27)
Ankylosing spondylitis
Psoriatic spondylitis
Reiters syndrome
Inflammatory bowel disease
Scheuermanns disease
(osteochondrosis)Pagets disease
Disease of pelvic organs
Prostatitis
Endometriosis
Chronic pelvic inflammatory disease
Renal diseaseNephrolithiasis
Pyelonephritis
Perinephric abscess
Aortic aneurysm
Gastrointestinal disease
Pancreatitis
CholecystitisPenetrating ulcer
McDonough, KA, Wipf, JE,
Deyo, RA. Low back pain.
In: Office Practice of
Medicine, 4th ed, Branch,WT (Ed), Saunders 2003
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Disc herniation (lifting heavy items e.g.)
Spondylosis
Spondylolisthesis
Spinal stenosis
Trauma (fractures, dislocations)
Tumors Primary (neural-bone)
Metastasis
Infections
Diabetes mellitus
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Cervical and lumbosacral radiculopathies are
among the most common orders referring to
the electrophysiology laboratory
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Plain X-rays
MRI
CT Bone scan
Myelography
Need after the first 4 to 6 weeks when the presence
of risk factors
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Imaging studies
Plain Films: In most situations should be initial
imaging study ordered
Computerized Tomography: Frequently
ordered in trauma cases to detect fractures
Magnetic Resonance Imaging: Excellent soft
tissue contrast
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Radionuclide Scan, Thermography, Discography,
CT Discography
These imaging modalities may be too nonspecific (thermography)
carry additional risk (discography)
Radyonuclide scan can be useful to detectstress fractures or metastasis
American College of Radiology. ACR Appropriateness Criteria www.acr.org
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Why we should not order imaging studies?
Have high false positive ratios
Do not always provide a diagnosis for back pain
Focused on confirming a lesion Anotomical reason can not be found, but pain is
still real and needs to be managed
Do not give a precise information about timing ofthe lesion (new or former?)
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Electrodiagnosis (EDX) : a definition
An extension of neurological examination developed
to diagnose the diseases of the lower motor neuron
system
In peripheral nervous system, problems can be
caused by the motor neuron, peripheral nerve,
neuromuscular junction or muscle
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To find out
Etiology
Level of pathology
Localization of the involved structure (myelin
or axon)
Severity of injury (mild, moderate, severe)
Phase of injury (acute, chronic)
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If the root compression causes the axonal
loss, the findings of abnormal spontaneous
activity may be observed 1 week later in the paraspinal muscles
2-3 weeks later in the extremity muscles
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Radiculopathy
Spinal stenosis
Piriformis syndrome
Pelvic tumors (causing plexopathy)
Postoperative failed back
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Degenerative joint
disease
Ankylosing spondylitis
Osteoporosis
Fractures
Sprains
Sensory onlyradiculopathy
Spondylolisthesis
Scoliosis
Fibromyalgia syndrome
Myofascial Pain syndrome
Pregnancy
Vascular disorders
Psychogenic disorders
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Evaluation of the radiculopathies requires
strong functional anatomy knowledge
The myotomal charts about the innervations
of muscles are prepared and some muscles
are accepted as the key muscles for specific
root levels due to multisegmental innervation
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A detailed physical examination is the most
important guide for the electrodiagnostic
testing It should be done prior to the investigation
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Motor and sensory nerve conduction studies
Late responses (F waves, H reflex)
Needle EMG Spinal root stimulation (SRS)
Somatosensory evoked potentials (SEPs)
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Latency
Amplitude
Nerve conduction velocity
Abnormal findings should be highligted
Abnormalities can be recorded as increased or
decreased
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The evaluation of radiculopathy begins with
the sensory and motor nerve conduction
studies
Generally no pathology has been seen
because the muscles take branches from
more than one root
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Since the lenght of root is very short, the nerve
conduction studies are found normal
Motor and sensory nerve conduction studies in the
diagnosis of radiculopathy are very limited
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F wave is especially used to examine
the proximal nerve segments
Because of the F responses are veryvariable (different motor neurons are
stimulated in each stimulation) at
least 10 stimulations should be given
and the average of responses should
be taken
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Late Responses : F Wave - II
When F wave parameters have found
normal, and the needle EMG findings have
been abnormal
It is suggested that F wave could not define
radiculopathy in sufficient sensitivity
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The Hoffmann (H) reflex is recorded
most easily from the soleus muscle with
the use of the posterior tibial nerve
stimulation
H-reflex is a monosynaptic reflex
Pathognomonic for S1 root pathology
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Late Responses : H Reflex - II
The latency asymmetry of the H reflex is very
sensitive in the diagnosis of S1 radiculopathy
It can not be found unilaterally
The upper limit reported for the lower
extremity side-to-side difference is between
1-1.8 ms
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Very important part of electrophysiological
assessment for radiculopathies
Evaluation of electrical activity with a needleelectrode inserted in muscle
Painful for the patient
Dynamic process
Used in many neuromuscular problems
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Findings in Needle EMG
Insertional activity (increased/decreased/normal)
Spontaneous activity (fibrillation potentials/PSWs/
myotonic discharges/fasciculations)
MUAP morphology (duration/polyphasicity/amplitude)
Recruitment (decreased/early/normal)
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Insertional activity
When the needle electrode is inserted into the
muscle there is a silence period normally
May be decreased due to the fibrosis of themuscles in the chronic stage of radiculopathies
accompanied with atrophy
May be increased due to nerve excitation Clinical importance in the diagnosis of radiculopathy
is very low
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In some pathological situations;
Positive sharp waves (PSW),
Fibrillation potentials
Complex repetitive discharges
Fasciculation potentials have been observed inmuscles at rest
Complex repetitive discharges and fasciculation potentials maybe observed rarely but these potentials are only complementaryand can not lead to diagnosis alone
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First abnormality of EMG in relation to the
interruption of the muscle fibers-nerve continuity is
acute denervation findings, e.g. PSWs and
fibrillation potentials due to the negative courseof the resting membrane potential
Positive sharp waves
Fibrillation potentials
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When the force of contraction is increased, a lot of
MUAPs are recruited
The reduced recruitment is the first detectable sign
of nerve root dysfunction
But it is difficult to determine motor unit loss less
than 30%
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Single ossilation
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In the subacute or chronic stage of radiculopathies, the giant
polyphasic potentials can be seen
Reinnervation may occur as early as 5 to 6 weeks after root
injury In normal individuals, the number of polyphasic MUPs are
not more than 20%
When reinnervation occurs, properties of MUAPs change :
Polyphasic
Low amplitude
Prolonged MUAP
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Paraspinal EMG can increase sensitivity and
decrease the number of investigating muscles
Spontaneous activities begin within 7-10 days in PS
muscles and 3-6 weeks in extremity muscles
There is no another muscle in human bodyinnervated by a single root except spinal muscles
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Lying in the prone position
Identification of L2-L5 spinal processes by palpation
corresponding to the iliac crest L2,3,4= 2.5 cm lateral and 1 cm superior to the
inferior aspect of the L24 spinous process.
L5=between the posterior superioriliac spine, 2.5 cm lateral to the S1
spinous process.
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Paraspinal Mapping
Paraspinal mapping is the best predictor of increased
systematization and quantification of paraspinal
needle electromyography
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Four muscles investigation including the
paraspinal muscles define radiculopathy as
88-97% six muscles investigation define it as 98-
100%
Youare here!
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PSM had higher sensitivity than either
peripheral EMG or imaging studies for lumbar
radiculopathy
PSM had a higher sensitivity than MRI in
asymptomatic lumbar spinal stenosis
Yagci I, Gunduz OH, Ekinci G, Diracolu D, Us O, Akyuz G: The Utility of LumbarParaspinal Mapping in the Diagnosis of Lumbar Spinal Stenosis. Am J Phys Med
Rehabil. 2009 Aug
Chiodo A, et al.Clin Neurophysiol. 2007 Apr;118(4):751-6.
Haig AJ.Muscle Nerve. 1993 May;16(5):477-84.
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Spinal root stimulation (SRS)
Needle electrode stimulation performs to the
L5 and S1 levels with recordings from the
tibialis anterior or the flexor hallucis brevismuscles for evaluating the L5 and S1 roots
It may be diagnostic method especially in
such cases with no needle EMG abnormality
Bahadr C, Gndz OH, Us O, Akyz G: Is it useful to stimulate roots in the diagnosis of
cervical root compression Neurosurg Q 2008;18(3):182-7
Tsai, 1994; Pease, 1190; Berger, 1987
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SEPs are based on recording of spinal and cortical
potentials formed by stimulation of peripheral
nerves
They provide information about central conduction
time, primary somatosensory cortex and thalamus
functions
Amplitudes and latencies of the peripheral, spinal
and cortical potentials are evaluated
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The absence of the potentials is accepted the
most important abnormality
May be obtained very small potentials from thescalp which is another abnormal finding
It is not a routine investigation of radiculopathy
because of nature
It gives more reliable results in diseases affecting
many roots as lumbar stenosis
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Electrophysiologic investigation ofradiculopathies is a dynamic process and can notbe standardized
It is complementary to neuroimaging studiesbecuase EMG/NCV studies
help making diagnosis give information about severity of the root nerve
involvement establishing prognosis of radiculopathy
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Thank you