Neurophysiology

ELECTRO ENCEPHALO GRAPHY

:- To check the records of brain waves, and to detect the level of electrical activity in the brain is called EEG

The "10-20 System" of Electrode Placement The 10-20 System of Electrode Placement is a method used to describe the location of scalp electrodes. These scalp electrodes are used to record the electroencephalogram (EEG) using a machine called an electroencephalograph. The EEG is a record of brain activity. This record is the result of the activity of thousands of neurons in the brain. The pattern of activity changes with the level of a person's arousal - if a person is relaxed, then the EEG has many slow waves; if a person is excited, then the EEG has many fast waves. The EEG is used to record brain activity for many purposes including sleep research and to help in the diagnosis of brain disorders, such as epilepsy.

One second of EEG signal

Historically four major types of continuous rhythmic sinusoidal EEG waves are recognized (alpha, beta, delta and theta).

•Alpha (Berger's wave):The frequency range from (8 Hz to 13 Hz). It is characteristic of a relaxed, alert state of consciousness . Alpha rhythms are best detected with the eyes closed. Alpha attenuates with drowsiness and open eyes, and is best seen over the occipital (visual) cortex.

•Beta :The frequency range 13-30 Hz. Low amplitude beta with multiple and varying frequencies is often associated with active, busy or anxious thinking and active concentration. Rhythmic beta with a dominant set of frequencies is associated with various pathologies and drug effects.

Delta:The frequency range up to 4 Hz and is often associated with the very young and certain encephalopathies and underlying lesions. It is seen in stage 3 and 4 sleep.

•Theta:The frequency range from 4 Hz to 8 Hz and is associated with drowsiness, childhood, adolescence and young adulthood. This EEG frequency can sometimes be produced by hyperventilation. Theta waves can be seen during hypnagogic states such as trances, hypnosis, deep day dreams, lucid dreaming and light sleep and the preconscious state just upon waking, and just before falling asleep. asleep

Some examples of EEG waves.

THE BASIC PRINCIPLES OF EEG DIAGNOSIS

What abnormal results mean  Seizure disorders (such as epilepsy or convulsions)  Structural brain abnormality (such as a brain tumor or brain abscess)  Head injury, encephalitis (inflammation of the brain)  Hemorrhage (abnormal bleeding caused by a ruptured blood vessel)  Cerebral infarct (tissue that is dead because of a blockage of the blood supply)  Sleep disorders (such as narcolepsy) Note:EEG may confirm brain death in someone who is in a coma.

ATYPICAL BUT NORMAL WAVE FORMS

K Complexes

K Complexes occur in sleep when arroused - thus K complexes are seen with noises or other stimuli especially in stage 2 sleep. The K complex is often followed by an arrousal response - namely a run of theta waves of high amplitude. Following this the EEG shows sleep again or the awake state.

Lambda and POSTS are similar morphologically, and have a triangular shape.They occur posteriorly and symmetrically. POSTS stands for 'positive occipital transients of sleep' and occurs in stage 2 sleep. Lambda occurs in the awake Lambda and POSTS patient when the eyes stare at blank surfaces. Both are normal wave forms and can occur singly or inlong or short runs.

V Waves

V waves occur in the parasaggital areas of the two sides and take the form of sharp waves or even spikes which show in the biparietal regions(vertex) withphase reversal at the midline in tranverse montages or at the vertex in frontto-back ones. They are seen in stage 2 sleep along with spindles, K complexes, POSTS, etc..

MU activity

Mu activity is a rhythm in which the waves have a shape suggestive of a wicket fence with sharp tips and rounded bases. It may show phase reversal between two channels. The frequency is generally half of the fast activity present.

Psychomotor Variant

Psychomotor variant is a rare rhythm which appears to be an harmonic of two or more basic rhythms causing a complex form. As can be seen it is higher in amplitude than the surround and the waves have a notched appearance. It is quite assymetrical and is often mistaken for paroxysmal activity. It is benign. It is also known as

Fourteen and Six Rhythm

Fourteen and six activity is most often seen in children and adolescents. As seen it takes the form of 6 Hz and 14 Hz waves sometimes going in the same direction(up or down) and in others in opposite directions. It is typically seen in sleep or drowsiness and is usually seen in monopolar recordings.

ELECTRO MIO GRAPHY

Amplifier parameters

Chann e l s

Sensitivity

Scaling for analysis

fo

fu

50 Hz notch

Spontanous

1

0,1 mV/div

0,1 mV/div

10 kHz

5 Hz

x

x

MAP-Analyse

1

0,1 – 0,2 mV/div

0,1 mV/div

10 kHz

5 Hz

x

x

Maximal-innervation

1

1 mV/div

1 mV/div

10 kHz

5 Hz

x

x

Aquisitionparameters

Rctf.

Ext. Input

Auto-matic offset

Monitor time

Analysis time

Trigger-mode

Averager mode

Sweeps (no. of passes)

Artefact Detection

Spontan-aktivität

10 ms/div

10 ms/div

Internal

Standard

---

---

MAP-Analyse

10 ms/div

10 ms/div

Internal

Standard

---

---

100 ms/div

100 ms/div

Internal

Standard

---

---

Maximalinnervation

An electromyogram (EMG) is a test that is used to record the electrical activity of muscles. When muscles are active, they produce an electrical current. This current is usually proportional to the level of the muscle activity. EMGs can be used to detect abnormal muscle electrical activity that can occur in many diseases and conditions, including muscular dystrophy, inflammation of muscles, pinched nerves, peripheral nerve damage. The EMG helps to distinguish between muscle conditions in which the problem begins in the muscle and muscle weakness due to nerve disorders. The EMG can also be used to detect true weakness, as opposed to weakness from reduced use because of pain or lack of motivation.

NEEDLE EMG CRANIAL MUSCLES

Frontalis

Masseter

Orbicularis Oculi

Trapezius

Orbicularis Oris

Sternocleidomast oid

Tongue Genioglossus

NEEDLE EMG | FOOT MUSCLES

Abductor Digiti Quinti - Foot

Abductor Hallucis

First Dorsal Interosseous Foot

Extensor Digitorum Brevis

NEEDLE EMG | FOREARM MUSCLES Ancone us ANCONEUS

BRACHIORADIALIS

EXTENSOR CARPI RADIALIS (Lt.)

EXTENSOR INDICIS

EXTENSOR DIGITORUM COMUNIS

FLEXOR CARPI RADIALIS (Rt.)

FLEXOR CARPI ULNARIS

FLEXOR POLLICIS LINGUS

FLEXOR DIGITORUM PROFUNDUS

SUPINATOR

PRONATOR TERES

NEEDLE EMG | HAND MUSCLES

ABDUCTOR DIGITI MINIMI (HAND)

ABDUCTOR POLLICIS BRAVIS

FIRST DORSAL INTEROSSEOUS

NEEDLE EMG | LEG MUSCLES

ANTERIOR TIBIAL

SOLEUS

EXTENSOR DIGITORUM LONGUS

GASTROCNEMIUS (MEDIAL HEAD)

GASTROCNEMIUS

EXTENSOR HALLUCIS LONGUS

PERONEAL LONGUS

NEEDLE EMG | PARASPINAL MUSCLES

Multifidus - Caudal Insertion

Multifidus Perpendicular Insertion

Multifidus - Rostral Insertion

NEEDLE EMG | ARM AND SHOULDER MUSCLES

BICEPS BRACHLI

INFRASPINATUS

LEVATOR SCAPULA

DELTOID (ANTERIOR)

Pectoralis Major Clavicular

DELTOID (MIDDLE)

Pectoralis Major Sternocostal

RHOMBOID (MAJOR)

SERRATUS ANTERIOR

RHOMBOID (MINOR)

TRICEPS BRACHII (LONG HEAD)

SUPRASPINATUS

TRICEPS BRACHII (Lateral head)

NEEDLE EMG | THIGH AND PELVIS MUSCLES

ABDUCTOR LONGUS

Semimembranosus

BICEPS FEMERIS

GLUTEUS MEXIMUS

Semitendinosus

GULUTEUS MEDIUS

VASTUS LATERALIS

LLIACUS

VASTUS MEDIALIS

NERVE CONDUCTION VELOCITY

:- To check the electrical activity of nerves

Amplifier parameters

Channels

Sensitivity

Scaling for analysis

fo

fu

Motoric NCV

1

2 mV/div

2 mV/div

3 kHz

5 Hz

Sensory NCV

1

10 µV/div

5 µV/div

3 kHz

20 Hz

Mot. Sens. NCV

2

2 mV/div

2 mV/div

3 kHz

20 Hz

10 µV/div

5 µV/div

3 kHz

20 Hz

Myastheni a

1

2 mV/div

2 mV/div

3 kHz

20 Hz

50 Hz notch

Rctf.

Ext. Input

Input

x x

x

X

Aquisitionparameters

Monitor time

Analysis time

Trigger-mode

Averager

Motoric NCV

20 ms/div

2 ms/div

internal

standard

20

----

Sensory NCV

10 ms/div

2 ms/div

internal

standard

20

----

Mot. Sens. NCV

20 ms/div

2 ms/div

internal

standard

20

1,0 ms

Myastenia

20 ms/div

2 ms/div

internal

standard

----

mode

Sweeps (no. of passes)

Artefact Detection

2,0 ms

Stimulationparameters

Stim. Ferquency

Stim. Mode

Duration

Stimulation current step

Traces

Motorische NLG

1,0 Hz

Single puls

200 µs

automatic

3

Sensible NLG

3,0 Hz

Single puls

200 µs

automatic

2

Mot. Sens. NLG

2,0 Hz

Single puls

200 µs

automatic

2

Myasthenia

3,0 Hz

Single puls

200 µs

automatic

10 automatic trace advance

Reflex Amplifier param eters

Channels

Sensitivity

Scaling for analysis

fo

fu

50 Hz notch

Rctf.

Ext. Inpu t

Automatic offset

Blink reflex

2

100 µV/div

100 µV/div

3 kHz

20 Hz

x

H-Reflex

1

1 mV/div

1 mV/div

3 kHz

20 Hz

x

F-Wave

1

200 µV/div

200 µV/div

10 kHz

5 Hz

x

Aquisitionparameters

Monitor time

Analysis time

Triggermode

Averager mode

Sweeps (no. of passes)

Artefact Detection

Blink reflex

20 ms/div

10 ms/div

internal

Standard

---

---

H-Reflex

20 ms/div

10 ms/div

internal

Standard

---

---

F-Wave

5 ms/div

5 ms/div

internal

Standard

10

---

Stimulationparameters

Stim. Ferquency

Stim. Mode

Duration

Stimulation current step

Traces

Blink reflex

0,5 Hz

Single puls

200 µs

0,5 mA

2

H-Reflex

0,5 Hz

Single puls

500 µs

Automatic

10 automatic trace advance

F-Wave

1,0 Hz

Single puls

100 µs

Automatic

10 automatic trace advance

Nerve conduction studies have been found to be medically necessary for the following indications ?  Carpal tunnel syndrome  Diabetic neuropathy  Disorders of peripheral nervous system  Disturbance of skin sensation  Fasciculation  Joint pain  Muscle weakness  Myopathy

 Nerve root compression  Neuritis  Neuromuscular conditions  Pain in limb  Plexopathy  Spinal cord injury  Swelling and cramps  Trauma to nerves.  Myositis

Major nerves of ULs (Upper Limbs) are:-

MEDIAN MOTOR / APB Distance = 5cm

Stim Points: Elbow / Wrist

MEDIAN SENSORY / Index Distance = 8cm

Stim Points: Elbow / Wrist

ULNAR MOTOR / ADM Distance = 5cm

Stim Points: Above Elbow / Below Elbow / Wrist

ULNAR SENSORY / Vth Distance = 8cm

Stim Points: Elbow / Wrist

RADIAL SENSORY / Dors Hnd Distance = 10cm

Stim Points: Forearm

Major nerves of LLs (Lower Limbs) are:-

PERONEAL MOTOR / EDB Distance = 7cm

Stim Points: Above/Below-Fibular Head/Ankle

PERONEAL SENSORY Distance = 14cm

Stim Points: Dist / Prox

POSTERIOR TIBIAL MOTOR Distance = 14cm

Stim Points: Pop Fossa / Ankle

SURAL SENSORY / Beh Mall Distance = 14cm

Leg

H-Reflex (Soleus) H-Reflex Potentials

NERVE ENTRAPMENT GUIDE PERONEAL NEUROPATHY WHAT IS INVOLVED Peroneal Nerve

LOCATION  Most frequently at the Head of the Fibula  Could be just above or below it involving the Common Peroneal Nerve or the Deep or Superficial branches selectively

COMMON SYMPTOMS  Foot drop  Patient unable to pull foot or toes up  Usually unilateral, could be bilateral  No associated pain  Main complaint is tripping, falling  Occasional leg/top of foot numbness  Symptoms always present, no night/day preference

RADIAL NEUROPATHY (WRIST DROP) WHAT IS INVOLVED Radial Nerve

LOCATION  Most frequently at the Spiral Groove of the humerus  Could be at the Axilla (Saturday Night palsy)  Or in the Forearm (Posterior Interosseous Syndrome)

COMMON SYMPTOMS  Wrist drop, Patient unable to extend wrist or fingers up  Almost always unilateral  No associated pain  Occasional forearm/hand/thumb numbness  Symptoms always present no night/day preference

NERVE SHOULDER / ARM / HAND PROBLEMS /TARSAL TUNNEL SYNDROME WHAT IS INVOLVED Posterior Tibial Nerve LOCATION Posterior Tibial nerve entrapment at the Tarsal Tunnel in the foot at the level of the medial malleolous

COMMON SYMPTOMS  Foot, Ankle, Sole pain/burning and aching  Worse at night  Occasional numbness/tingling sole of foot  No muscle weakness  Usually unilateral  Difficulty walking because of pain and discomfort with shoes  Positive Tinel (tingling upon tapping nerve) sign behind the medial malleolous

SHOULDER / ARM /HAND PROBLEMS /ULNAR NEUROPATHY WHAT IS INVOLVED Ulnar Nerve LOCATION Most frequently at the Elbow from leaning on it or trauma

COMMON SYMPTOMS  Weak hand, dropping objects, difficulty turning keys, ignition, doorknobs  Numbness/tingling fourth, fifth fingers  Wasting of the interosseii muscles  Occasional elbow soreness  Symptoms not related to night/daytime  Frequently on both sides

SHOULDER / ARM / HAND PROBLEMS /CARPALTUNNEL SYNDROME WHAT IS INVOLVED Median Nerve at the wrist LOCATION The Carpal Tunnel, at the wrist

COMMON SYMPTOMS  Worse in the dominant hand  Dropping objects  Numbness tingling, hand/wrist ----> Thumb, Index and/or Middle finger  May radiate up the arm, occasionally to the shoulder  Symptoms primarily at night. Patient wakes up and shake their hands to obtain relief  Frequently bilateral, although may only be symptomatic on one side

• VEP

• BAEP • SSEP

VISUAL EVOKED POTANTIAL

:- To check the electrical activity of optic (eyes) nerve.

Amplifier parameters

Aquisitionparameters

Stimulationparameters

Channels

Sensitivity

Scaling for analysis

fo

fu

50 Hz notch

1

20 µV/div

2 µV/div

100 Hz

0,5 Hz

x

Rctf.

Ext. Input

Automatic offset x

Monitor time

Analysis time

Triggermode

Averager mode

Sweeps (no. of passes)

Artefact treshold

Artefact Detection

20 ms/div

50 ms/div

Internal

Standard

50

95

---

Stim. Ferquency

Stim. Type

Stim. Field

Size

Patter n

Stim. Mode

Contrast

Trace s

1 Hz

Pattern

Full

Standard

Check

Invert

light

3

BRAIN AUDITORY EVOKED POTENTIAL

:- To check the electrical activity of hearing nerves.

Amplifier parameters

Aquisitionparameters

Stimulationparameters

Channels

Sensitivity

Scaling for analysis

fo

fu

1

10 µV/div

200 nV/div

3 kHz

100 Hz

50 Hz notch

Rctf.

Ext. Input

Auto-matic offset x

Monitor time

Analysis time

Triggermode

Averager mode

Sweeps (no. of passes)

Artefact treshold

Artefact Detection

20 ms/div

1 ms/div

Internal

Standard

2000

15

500 µs

Stim. Ferquency

Stim. Type

Stim. Field

Polarity

Volume stimulus

Volume noise

Contrast

15 Hz

Click

200 µs

alternated

70 dB relativ

40 dB, relativ

4

SOMATO SENSORY EVOKED POTENTIAL

Somatosensory Evoked Potential (SSEP) is a test showing the electrical signals of sensation going from the body to the brain. The signals show whether the nerves that connect to the spinal cord are able to send and receive sensory information like pain, temperature, and touch. When ordering electrical tests to diagnose spine problems, SSEP is combined with an electromyogram (EMG), a test of how well the nerve roots leaving the spine are working. An SSEP indicates whether the spinal cord or nerves are being pinched. It is helpful in determining how much the nerve is being damaged. SSEP is used to double check whether the sensory part of the nerve is working correctly.

Amplifier parameters

Channels

Sensitivity

Scaling for analysis

fo

fu

50 Hz notch

SEP N. tibialis

2

10 µV/div

2 µV/div

1 kHz

2 Hz

x

SEP N. medianus

1

10 µV/div

2 µV/div

1 kHz

2 Hz

Rctf.

Ext. Input

Automatic offset x

Aquisitionparameters

Monitor time

Analysis time

Triggermode

Averager mode

Sweeps (no. of passes)

Artefact Detection

Aquisitionparame ters

SEP N. tibialis

20 ms/div

10 ms/div

Internal

Standard

400

---

---

SEP N. medianus

20 ms/div

10 ms/div

Internal

Standard

200

Stimulationparameters

Stim. Ferquency

Stim. Mode

Duration

Stimulation current step

Traces

SEP N. tibialis

3 Hz

Single puls

200 µs

Automatic

4

SEP N. medianus

3 Hz

Single puls

200 µs

Automatic

2

REPETITIVE NERVE STIMULATION

RNS TEST IS USED FOR MYASTHENIA GRAVIS: DIAGNOSTIC TESTS

Decremental response to RNS in Myasthenia Gravis

MYASTHENIA GRAVIS

Cogan

Tensilon test: Before (left); After (right)

Repetitive Nerve Stimulation

NERVE CONDUCTION QUICK SET-UPS | BLINK / FACIAL

H-Reflex (Soleus)

H-Reflex Potentials

Transcranial Doppler (TCD) ultrasound is a non-invasive method to estimate the blood flow velocities in the large intracranial vessels of the circle of Willis. Using established TCD techniques, sections of the internal carotid artery (ICA), middle cerebral artery (MCA), anterior carotid artery (ACA), posterior cerebellar artery (PCA) and the basilar and periorbital arteries can be examined. TCD typically uses a 2 MHz pulse ultrasound which produces a velocity spectrum throughout the cardiac cycle.

• MCA:- Middle Cerebral Artery • ACA:- Anterior Cerebral Artery • PCA:- Posterior Cerebral Artery • Vertebral Artery • Basilar Artery

• Vertebral Artery • Basilar Artery