EMG, NCV and SSEP for evaluating and diagnosing upper extremity neuromuscular disorders Dr. David...

EMG, NCV and SSEP for evaluating and diagnosing

upper extremity neuromuscular disorders

Dr. David Stannard

• Dr. David Stannard D.C., FCCO(C), FACO, FABES.• Doctor of Chiropractic (Research Honors)• Chiropractic Orthopedic Specialist• Fellow of the College of Chiropractic Orthopedists

(Canada)• DABCO• Fellow of the North American Academy of

Impairment Rating Physicians• Fellow of the American Board of Electrodiagnostic

Specialties

Additional post graduate training• Completed advanced training in acupuncture• Completed advanced training in vestibular

disorders, diagnosis, treatment and rehabilitation

• Completed the electrodiagnosis program and performed EDX studies for 1 ½ years

• Recently completed the Diplomate Neurology program and is currently board eligible.

• Hospital privileges at the Medicine Hat Regional Hospital for 5 years.

• WCB authorized provider• Appointed Independent Medical Consultant

(IMC) as registered by the Alberta Insurance Bureau.

• Operates a full orthopedic rehabilitative clinic including casting and bracing of fractures.

Appointments

Appointments include Canadian Director for the North American Academy of Impairment Rating Physicians. (10 years to current)

Currently serves as Director for The Pain Society of Alberta– a multi-disciplinary medical society.

Qualified as an expert witness in the Alberta judicial courts system.

Publications and presentations

• Adverse Effects of Diagnostic Ultrasound, A Review. Journal of Chiropractic Research and Clinical Investigation 1990. (Peer reviewed journal).

• Rigid Lumbar Orthosis (Masters Thesis) poster presentations to the International Society for the Study of the Lumbar Spine (2003).

• The Tempromandibular apparatus: a commonly overlooked source of head pain. (manuscript in progress)

Electrodiagnosis

• Electrodiagnostic (EDX) studies play a key role in the evaluation of patients with neuromuscular disorders.

• Among these studies are nerve conduction studies (NCV), repetitive stimulation, late responses (F-wave and H reflex), SSEP, blink reflexes and needle electromyography (EMG), in addition to a variety of other specialized examinations.

NCV’s and EMG

• NCV’s and needle EMG form the core of the EDX study. These studies are performed first and usually yield the greatest diagnostic value.

• Performed and interpreted correctly, EDX studies yield critical information about underlying neuromuscular disorders and allow use of other diagnostic imaging or laboratory tests in an appropriate and efficient manner.

EDX looks at function of the nervous system

• The specialized nerve tests like EMG, NCV and SSEP are designed to investigate and diagnose the functioning of the nervous system; while imaging studies like the CT scans or MRI scans look at the structure or anatomy of a particular body part or organ.

What is an NCV

• NCV, or Nerve Conduction Velocity, is an electrical diagnostic test that provides information about abnormal conditions in the nerves. Nerves are stimulated with small electrical impulses by one electrode while other electrodes detect the electrical impulse "down-stream" from the first electrode.

NCV wave form may look like this

Interpreting NCV

• When interpreting NCV, the distance between electrodes and the time it takes for electrical impulses to travel between electrodes are used to calculate the speed of impulse transmission. Slower than normal speed could indicate nerve damage from direct trauma, demyelination, diabetic or peripheral neuropathy, viral nerve infection or nerve entrapment diseases like the Carpal Tunnel Syndrome among other conditions.

What is EMG?

• EMG, or Electromyography is a technique for evaluating and recording the electrical activity produced by muscles. An electromyogram detects the tiny amount of electricity generated by muscle cells when they are activated by the nerves connected to them.

Types of EMG

• There are two types of EMG: intramuscular EMG and surface EMG. The intramuscular EMG is the most common. It involves inserting a needle electrode through the skin into the muscle that is being studied. Surface EMG (SEMG) involves placing electrodes on the skin over the muscle to detect the electrical activity of the muscle. It is not used as often because it provides less useful information than the intramuscular EMG.

EMG

• EMGs can detect abnormal muscle electrical activity in many diseases and conditions, including inflammation of muscles, pinched nerves, damage to nerves in the arms and legs, disc herniation, and degenerative diseases such as muscular dystrophy, Lou Gehrig's disease and Myesthenia gravis, among others. The EMG helps doctors distinguish between muscle conditions that begin in the muscle and nerve disorders that cause muscle weakness.

EDX supports dx and appropriate care

• The information gained from EDX studies often lead to specific chiropractic treatment strategies, medical treatment or surgery.

•

EDX support your clinical examination

• In practice, EDX studies serve as an extension of the clinical examination and should always be considered as such.

EDX Quantitates Nerve and/or Muscle Injury

• Provides Useful Data Regarding Nerve Injury

• Site• Type• Severity• Duration• Prognosis

Nerve Conduction Studies

• Studies of the waveforms generated in the• peripheral nervous system.• – Motor nerve conduction (CMAP)• Stimulation of a peripheral nerve while

recording from a muscle innervated by that nerve.

• Sensory nerve conduction (SNAP)• Stimulation a mixed nerve while recording from

a mixed or cutaneous nerve

Terminology• LATENCY (DL) Interval between the onset of a stimulus and the onset of a response.• AMPLITUDE (AMP) The maximum voltage difference between two point. It is proportional to the

number and size of nerve fibers that are depolarized. Provides an estimate of the amount of nerve tissue that is electrically active• DURATION The time from onset to termination. Total duration measures the dispersion of all components. Measures the differences in conduction of the nerve fibers• CONDUCTION VELOCITY (CV) The “speed” at which the nerve fibers are carrying the electrical stimulus between

two sites. Comparison of conduction between two segments of the same nerve can localize

a lesion.

Types of nerve conductionstudies

• Sensory: typically antidromic - Commonly examined nerves: Sural, ulnar,

median, occasionally radial, superficial peroneal or lateral femoral cutaneous nerve.

Sensory NCS Parameters

• Onset and peak latencies Conduction velocity determined by velocity

of a very few fast fibers• Amplitude determined by the number of large sensory

fibers activated

Motor Nerve Conductions

• Vital part of EDX as this important for identifying demyelination and compression

• Need to do proximal and distal studies to evaluate for conduction velocity, conduction block, temporal dispersion

• Typical nerves: ulnar, median, peroneal, and tibial.

• Less common: radial, femoral, phrenic, spinal accessory, facial.

F-waves and H-reflex

• Useful for identifying proximal segmental Demyelination

• Can only be done when motor amplitude is > 1 mV

• Dependent on patient’s height.

F wave and H reflex

F waves

• Motor F wave studies proximal roots: Antidromic motor to the anterior horn of the spinal cord; orthodromically to the muscle.

• Pure motor test.• A prolonged asymmetric F waves suggest a proximal root

lesion.• Clinical application best for plexopathy. – Quite prolonged in demyelination, AIDP, mild prolongation

in axonal injury.• Less sensitive than EMG for radiculopathy since only short

segment of nerve is demyelinated in radiculopathy.

F - wave

Abnormal demyelinating PN F-wave

H REFLEX

• Reflex loop: Orthodromic sensory and motor - Utilized to assess for radiculopathy of S1, *C6/7• S1; Popliteal fossa, record in Medial Gastrocnemeus• C6/7; Median nerve at wrist, record at Flexor Carpi

Radialis• Unilateral delay, absent suggests tibial, sciatic, sacral

plexus, cord, S1 motor or sensory roots. – Once abnormal, may not normalize; – Often absent in polyneuropathy or > 60 years of age.

Example of a H – Reflex

Needle Electromyography: Techniques

• Needle electrode is inserted into the muscle• Needle is disposable, single use• Multiple muscles are accessible for

examination• Combination of muscles tested - Dependent upon clinical question - Level of discomfort is mild

Needle Electromyography: Data

• Insertional Activity• Spontaneous Activity• Motor Unit Configuration• Motor Unit Recruitment• Interference Pattern

EMG data

Needle EMG

• Insertion activity increases within a few days of muscle denervation, whereas abnormal spontaneous activity takes 2 4(3) weeks to ‐develop, depending on the distance between the nerve lesion and the muscle

• Abnormal spontaneous activity and increased insertion activity are not pathognomonic of denervation, may occur in certain disorders of muscle or the neuromuscular junction

EMG: Recruitment

• When a muscle is voluntarily contracted a single motor unit may fire.

• As the muscle is further contracted more motor units are added or recruited.

• Normally, recruitment of additional motor units occurs at relatively low levels of effort

• If there is a loss of MUAPs with any disease process then recruitment is reduced.

• Loss of nerve axons• Conduction block at the neuromuscular junction• Sufficient loss of muscle fibers

EMG

• The electromyographic findings may provide a guide to the time of onset of the lesion and to its chronicity.

• If a patient reports that a wrist drop has developed immediately after an operative procedure and needle electromyography performed shortly thereafter reveals abnormal spontaneous activity (fibrillation potentials and positive sharp waves) in the extensor muscle of the wrist, it is likely that the lesion is at least 2 3 weeks old and therefore it preceded the ‐surgery.

EMG motor unit configuration

• Similarly, the presence of long duration, ‐large amplitude, polyphasic motor unit ‐potentials indicates that the denervation occurred several weeks or more before surgery because some reinnervation has occurred.

When to order EDX

• Mononeuropathy• Mononeuropathy Multiplex• Polyneuropathies• Cranial neuropathies (Trigeminal

Mononeuropathy (blink reflex)• Radiculopathy• Plexopathy (Brachial or Lumbosacral)• Myopathy

EDX Findings; Polyneuropathy

• Axonal Sensory +/ Motor‐ Normal CV Normal DL Reduced to absent Amp. Normal F Wave (if amp. > 1MV)‐ Needle EMG in motor or sensorimotor;

Denervation and reinnervation changes (slowly progressive can show only reinnervation changes)

EDX Findings; Polyneuropathy

• Demyelinating Motor + Sensory change Slow NCV Conduction Block Distal Latency: Long Slow F waves‐ Amplitude: Normal to reduced (late) Needle EMG: Normal (late with axonal loss

Denervation and/or reinnervation).

Most common causes of polyneuropathy

• 1) diabetic (fasting blood sugar, Hb A1C)• 2) thyroid (TSH, total, free, TPO, T antibodies)• 3) Anemia (aplastic)• 4) Vit deficiencies (B12, Folate, B1, B6)• 5) Infections (CBC white cell count,viral panel,

Lyme; HSV1,2; cytomegalovirus; EBV; HIV)• 6) Neoplastic (Athena labs has a neoplastic study.)• 7) Autoimmune (Mag/Sulfatide, GM, Gallop)• 8) Inherited (HMSN )

PAINFUL NEUROPATHIES:Differential Diagnosis

• Toxic Alcohol Metals: Thallium; Arsenic Medications: cis platinum; Disulfiram; ‐

Ifosfamide; Nitrofurantoin; Dilantin; Perhexiline; Taxol; Thalidomide; Vinca alkaloids


• Immune - Acute onset 1) Guillain Barré - Diffuse pain during acute course; Distal

pain with incomplete recovery; Immobility. 2) Acute panautonomic - Anti Sulfatide Antibody associated polyneuropathies‐ - Connective tissue diseases - HIV (DILS) - M protein‐ - Ganglionopathies: Sjögren's; Paraneoplastic (Hu)


• Hereditary - α‐galactosidase (Fabry's) - GM2 gangliosidosis: Late onset‐ - Sensory Neuropathy I Lancinating pains - Motor Sensory Neuropathy I & II Foot deformity‐ - Burning feet syndrome - Amyloidosis - Polyneuropathy: Pain & Paraesthesias in legs

Carpal tunnel syndrome: Pain in hands - Porphyria - Restless legs syndromes: Some with PNS involvement - Hereditary (Acromelalgia) : 12q - HSN 1 - HMSN 5 - CMT 2 - Huntington disease like 1‐ - Also: Renal failure


• Metabolic - Diabetic: Acute: Lumbar or Thoracic radiculopathy; Distal sensory. Chronic:

"Small fiber"neuropathy. - Alcoholic: Acute - Pellagra ( niacin) - Beriberi (thiamine) - Strachan syndrome (Cuban neuropathy) - Post gastroplasty - Hypertriglyceridemia - Chronic mountain sickness Idiopathic - Distal sensory polyneuropathy syndromes - Erythromelalgia Mononeuritis multiplex


• Motor disorders with pain - Diabetic amyotrophy - PolioInfections: - Polio; HIV• Localized disorders - Nerve lesions: Trigeminal Brachial plexus Lumbosacral plexopathy Thoracic outlet syndrome Median Posterior tibial (Tarsal tunnel syndrome) Radiculopathies: Upper & Lower Extremities

Painful neuropathies differential dx.

- Burning mouth syndrome - Diabetic Amyotrophy - Reflex Sympathetic Dystrophy (Complex

regional pain syndrome) - Infections: Herpes zoster - Neoplastic infiltration: Burning pain with

dysesthesia in area of sensory loss - Post surgical localized pain syndromes


• Acute onset of pain & paresthesias - Acute porphyria - Toxic: Thallium; Arsenic; Perhexiline; Vinca

alkaloids - Guillain Barré‐

Diabetes and PNS Diseases

• Symmetric PolyneuropathiesChronic - Distal sensory +/- Autonomic - Autonomic - Sensory-motorAcute - Painful - Reversible

PNS diseases

Asymmetric neuropathies - Lumbosacral plexopathy - Mononeuropathies i.e., CTS - Mononeuritis multiplexPredisposition to immune PN - CIDP - Diabetic amyotrophy - Perineuritis - Muscle infarction

Common Mononeuropathies

• Median at the Wrist (CTS)• Ulnar at the Elbow (Tardy Ulnar Palsy)• Peroneal Palsy at the Fibular Head

Plexopathy: Selected Etiologies

• Compression - (CABG)• Inflammatory - (Parsonage Turner Syndrome)‐• Radiation Injury - (Radiotherapy)• Traumatic Injury - (Traction, laceration,

missile)• Ischemia - (Diabetic amyotrophy)

Carpal Tunnel Syndrome

- prolongation of the median nerve motor/sensory latency upon stimulation at the wrist ("terminal" or "distal" latency),

- normal median motor conduction velocity in the forearm, - slow median sensory conduction velocity across the wrist, - normal motor and sensory NCS of the ulnar nerve (not

involved in CTS). NCS are positive in 91 98% of patients ‐with clinical CTS

- Diagnosed by comparing Median to Ulnar sensory and motor DL’s.

Case study of right hand dominant pt.

• A 78 year old female presented with cervical pain, bilateral forearm pain, and bilateral hand pain ongoing for 3 months and slowly worsening. No associated inciting trauma or specific causative event. The forearm and hand pain occurred all day and night, and possibly worse at night but “not really different day or night”. The extremity pain pattern was poorly defined by the patient and she felt it may involve the entire hand however the lateral hand and general forearm was most noticeable. There were no defined exacerbating factors as the pain was “pretty well constant day and night”. She could not recall finding remission with any position and over the counter NSAIDs were “not very helpful”. Significant orthopedic tests to the cervical spine showed Spurling’s test at the L and R ; and cervical extension to be provocative. DTR”s at the biceps triceps and brachioradialis were 2+ during L and R challenges. Allen’s test at the L and R demonstrated a normal response.

Case Study (cont)

• Phalen’s, reverse Phalen’s and Tinal tap was not provocative at the L and R. Two point touch was diminished at the thumb and index finger at the L and R. Tenderness with slight increased symptoms was noted during palpation at the pronator teres L and R. No abnormalities were palpated over the medial epicondyle. Jamar dynamometer grip strength testing demonstrated 6 kg right and 8 kg left. Radiographs of the C-sp showed moderate to severe disc degeneration with IVF encroachment at mid and lower levels of the cervical spine. The patient was using a night splint at both wrists/hands for the last 3 weeks with no effect.

Trial of treatment

• Pt had a trial of treatment involving cervical mobilization, myofascial release techniques, manual traction, active release techniques at the pronator teres, volar forearm and carpal tunnel areas. Mobilizations at the carpals and transverse retinaculum stretches were done. Electrotherapy and ultrasound was also used. The pt was given home based exercises at the cervical spine and CTS exercises.

Treatment had no effect

• The patient was unresponsive to a variety of physiologic, chiropractic, bracing, ergonomic and therapeutic endeavors.

Referral for a trial of cortisone

• Pt was referred to a pain management specialist for cortisone injections at the carpal tunnel left and right for therapeutic and diagnostic purposes.

• This had no effect.

Where do we go from here?

• Possible diagnostic work up needed: MRI of the C-sp? Blood tests to R/O possible causes of peripheral polyneuropathy? Electrodiagnostic studies?

EDX

• Electro diagnostic studies would be the most prudent test to order and would provide the most diagnostically accurate information as it can differentiate and Dx spinal nerve root lesion, brachial plexus lesion, peripheral neuropathy such as demyelination, and conduction block such as carpal tunnel syndrome. Plus if a carpal tunnel syndrome is confirmed, then an Edx study is needed and is the gold standard for a surgeon to perform a carpal tunnel release.

Results

• Results of the EDX: Demonstrated increased latency at the median nerve at the wrist, with decreased conduction velocity and decreased NCV amplitude. SNAPS showed increased latency and decreased amplitude. EMG was significant for denervation at the APB showing spontaneous activity and increased insertional activity. Cervical paraspinal EMG was normal. All other cord level muscles emg was done C5-T1 were normal. Diagnostic impression: moderate /severe median neuropathy at the wrist at the left and right.

Case study #2

• A 35 year old male smoker presented with severe cervical pain, right shoulder girdle pain, and radiations into the right upper extremity. The pain intensity was high with a burning and sharp throbbing nature. Symptoms had been ongoing for a few months and pt was unsure of inciting trauma or causation. He did have a bad chest cold for a few weeks prior to his symptoms with a lot of coughing, and sneezing which his doctor told him was viral and “would not give him antibiotics” for that. He thought the coughing bothered his neck and lying in bed a lot watching tv with his head propped up. He had sought the treatment of a general chiropractor for one month with poor effect for a diagnosis of “a rib out of place”.

Examination

• Upon examination, the right upper extremity was held in the dependant position. There was weakness in right shoulder abduction and external rotation, elbow flexion and there was winging of the scapula. Active and passive shoulder girdle movements were acutely painful. Spurling’s test was provocative during R challenges as was cervical extension.

Case study #2

Case Study #2

• Note atrophy of the supraspinatus, infraspinatus and deltoid. There was numbness described at the lateral shoulder and lateral forearm/hand including the thumb and index finger. DTR’s were decreased at the biceps and brachioradialis 1+ at the right. Cervical radiographs were taken and revealed mild disc degeneration at C5-T1 spinal levels.

Where do we go from here?

• MRI of the C-sp? Chest films R/O pancoast tumor? Shoulder films? EDX? Ultrasound of the shoulder to R/O rotator cuff disease? MRI of the shoulder?

What is your diagnostic impression?

• Electrodiagnosis should also be considered initially to confirm neuropathic diagnosis and to rule out various other conditions (eg, cervical spine disease, radiculopathy, neuropathy, amyotrophic lateral sclerosis, etc).

Diagnosis

• EDX confirmed Parsonage Turner syndrome (Brachial Plexus Amyotrophy) at the right.

• The paraspinal emg was normal ruling out cervical nerve

root disease, as well as the levator scapula (C5 nerve root). EMG showed muscles innervated by the upper plexus but involving different peripheral nerves were involved including suprascapular nerve, axillary nerve, long thoracic nerve, musculocutaneous and radial. These muscles showed denervation such as sharp’s and fibs. CMAP’s and SNAP’s were normal at the distal nerves.

Parsonage Turner Syndrome

• Pts often present with symptoms following a viral infection although many other inciting factors have been associated. Some studies show 20-50% have a history of viral illness or vaccination that occurred days or weeks to the onset of symptoms. Some studies also note trauma, severe exercise, and surgery as a probable cause.

Thank-you

• Thank – you for allowing me to present this information to you!!

EMG, NCV and SSEP for evaluating and diagnosing upper extremity neuromuscular disorders Dr. David...

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