Gulseren_EMG

8/7/2019 Gulseren_EMG

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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

Gulseren_EMG

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