Neurophysiology of DOOM

What rhythm attenuates with eye opening?

Alpha rhythm

The mu rhythm:

Can be attenuated by movement of the extremities or the thought of movement

Lambda waves occur over the?

Occipital region

EEG features of drowsiness include all the following except? (Which option is false?)

Decrease in beta activity

What are features of slow wave sleep?

Spindles, V-waves, POSTs

Where does the spinal cord end?

L1 vertebral body

Cell bodies of motor neurons are found in the

Gray matter of the central spinal cord

Is the dorsal root ganglion for motor or sensory?

Sensory

Which of the following nerves controls extension of the fingers, wrist, elbow and sensation to the dorsal- lateral aspect of the hand?

Radial nerve

What is the I cranial nerve (1st)?

Olfactory

What is the II cranial nerve? (2nd)

Optic

What is the III cranial nerve?

Oculomotor

What is the IV cranial nerve?

Trochlear

What is the V cranial nerve?

Trigeminal

What is the VII cranial nerve?

Facial

What is the VIII cranial nerve?

Vestibulocochlear

What is the IX cranial nerve?

Glossopharyngeal

What is the X cranial nerve?

Vagus

What is the XI cranial nerve?

Accessory

What is the XII cranial nerve?

Hypoglossal

Regarding eye movement artifact, what is the polarity of the cornea & retina?

Cornea (front) is relatively positive compared to the retina (back)

How is sweat artifact characterized?

Generalized, undulating, slow wave activity

What do tremor, bad electrode to patient contact and/or eye flutter cause?

EEG artifact

EKG artifact

May be irregular if the heart rate is irregular

Eye movement artifact can:

Mimic frontal slowing of cerebral origin, be asymmetric, be suppressed by technician holding the eyes

At rest the inside of the cell is negative relative to the outside of the cell membrane, the major cation inside the cell membrane is

Potassium

The all or none law of action protentials applies to

An action potential recorded from a single nerve fiber (single nerve fiber= axon)

Potential inside of a cell is negative compared to the potential outside of the cell, this is called the resting membrane potential which is approximately

-70 mV

Depolarization is the result of:

Opening of sodium channels

Excitation-contraction coupling involves the release from the sarcoplasmic reticulum of:

Calcium

Which is true?

Action potential propagation depends on electron flow outward from the initial site of depolarization

When the nerve impulse reaches the axon terminals of a motor nerve fiber, it stimulates the release of:

Acetylcholine

After returning to a resting membrane potential, Na+ channels aren’t able to open for a period of time and it is not possible to elicit a second action potential with further stimulus or a stimulus of greater intensity that usual, what is this called?

Refractory period

Lennox-Gastaut Syndrome is usually characterized by all of the following except? (Which characterization is false?)

Normal intellect

What characterizes Lennox-Gastaut Syndrome?

Frequent seizures, onset between 2-6 years of age, slow spike & wave

Is the 6 Hz Spike & Wave benign or epileptiform?

Benign

When are 14 & 6 Hz positive spikes are usually seen during?

Drowsiness

What EEG pattern is associated with infantile spasms?

Hypsarrhythmia/electrodecremental

The most common region giving rise to focal epileptiform abnormalities in the brain is?

Temporal

LPDs can be seen with?

Acute strokes, hemorrhages, herpes encephalitis

You are performing a motor nerve conduction study. No change in the compound muscle action potential amplitude occurs when you increase the stimulus intensity from 80 to 100 milliamps. 100 milliamps is referred to as:

Supramaximal current

A-Alpha nerve fibers have all the following characteristics except? (Which option is false)

Supply pain sensation

What are characteristics of A-alpha nerve fibers?

Innervate muscle fibres, fast conduction velocity, large fiber diameter, myelinated

What could happen if your G1 (active) and G2 (reference) electrodes are less that 3.0-4.0 cm apart during sensory nerve conduction studies?

Amplitude will be reduced

The SNAP (sensory nerve action potential) of proximal stimulation is never higher than that of distal stimulation because:

Action potentials of slower conducting fibers arrive later when traveling over longer distances

If the lesion was proximal to the dorsal root ganglion, you would expect to find which of the following results on an ulnar antidromic study

Normal SNAP amplitude proximally and distally

All of the following seizure types can be seen in generalized epilepsies except for? (Which option is false?)

Focal Impaired Awareness

The EEG pattern observed in patients with childhood absence epilepsy is?

Generalized 3Hz spike & wave

What can trigger generalized absence seizures?

Hyperventilation

Following a generalized tonic-clonic seizure, post-ictal EEG typically shows diffuse suppression then delta, is this true or false?

True

What does postictal EEG show following a tonic-clonic seizure?

Diffuse suppression and then delta

Generalized tonic/atonic seizures are most commonly associated with which EEG pattern?

Generalized paroxysmal fast activity

Conduction failure with no structural change is called:

Neuropraxia (neurapraxia)

Wallerian degeneration is:

Degeneration of the distal axon when it is separated from its anterior horn cell or sensory neuron cell body in the dorsal root ganglion

A patient presents with 6 months weakness and tingling of the right hand and you suspect right ulnar neuropathy. A right ulnar motor nerve conduction study shows an amplitude of 2.0 mV on above elbow stimulation and an amplitude of 6.5 mV on wrist stimulation. Assuming that there are no technical errors, this is most compatible with:

Conduction block

You perform a median motor nerve conduction study. The amplitude on elbow stimulation is 7.2 mV and on wrist stimulation is 6.9 mV. All the following are possible explanations except:

Conduction block is present

You perform a median motor nerve conduction study. The amplitude on elbow stimulation is 7.2 mV and on wrist stimulation is 6.9 mV. What could possible explanations be?

Intensity of stimulation applied at wrist is too low (submaximal), cathode of stimulating electrode at the wrist is not directly over the median nerve, intensity of proximal stimulation is too high

Which of the following is a false statement regarding sensory nerve conduction studies?

Sensory axon loss is compensated by collateral sprouting

What is true of sensory nerve conduction studies?

Much lower in amplitude when compared to motor studies, useful in distinguishing between pre and post ganglionic lesions, sensory axons have a greater range of diameter than motor axons, useful in detecting focal lesions (ex CTS)

The medial antebrachial supplies sensation to the ______

Medial forearm

Which nerve is not supplied by the median nerve?

Abductor digiti minimi

What muscles are innervated by the median nerve?

Abductor policies brevis, flexor pollicis brevis, opponens pollicis, pronator teres

Which is true regarding carpal tunnel syndrome?

Treatment options include splinting the wrist in a neutral or hyperextended position

A median motor study reveals CMAP amplitude on proximal stimulation (elbow) of 4.7 mV with an initial downward deflection (positivity). The CMAP amplitude on distal stimulation was 4.6 mV without an initial downward deflection (positivity). The most appropriate step to perform next is:

Stimulate the ulnar nerve proximally and distally (recording APB) to check our crossover

A median motor study reveals CMAP amplitude on proximal stimulation of 7.9 mV and amplitude on distal stimulation of 8.5 mV. Conduction velocity was 50 m/sec and distal latency was 4.3 ms. An explanation for these results is?

A normal study

A student undergoes a median motor nerve temperature study; she has no symptoms in the hand. The study shows a distal latency of 4.6 ms; CMAP amplitude of 7.9 mV on proximal stimulation and 8.5 mV on distal stimulation; conduction velocity of 47 m/sec. The most likely cause for these findings is?

Low hand temperature

What muscles does the ulnar nerve innervate?

Abductor digiti minimi, flexor digitorum profundus, first dorsal interosseous, flexor carpi ulnaris

The ulnar nerve does not innervate the?

Abductor pollicis brevis

An ulnar motor study demonstrates CMAP amplitude at the elbow of 6.5 mV and CMAP amplitude at the wrist of 6.1 mV, what is the most likely explanation?

Understimulation at the wrist

An ulnar motor study shows CMAP amplitudes as follows: elbow= 6.7 mV; below elbow= 6.8 mV; wrist= 11 mV. Conduction velocity from elbow to wrist is 53 m/sec, and below elbow to wrist is 56 m/sec. What is the appropriate next step?

Stimulate the median nerve at the elbow and wrist (recording ADM) to check for crossover

A patient complains of weakness of his hand. The dorsal ulnar cutaneous and ulnar antidromic sensory studies are normal. Ulnar motor to the ADM and FDI are abnormal. Assuming the abnormal findings are caused by an ulnar neuropathy, the most likely site would be?

Midway through Guyon’s canal

An ulnar motor study shows CMAP amplitude of 6.2 mV at the elbow, 6.3 mV below the elbow, and 6.5 mV at the wrist. Conduction velocity was 50 m/sec from above the elbow to the wrist. These results suggest:

Conduction slowing at the elbow

Clinical manifestations of temporal lobe seizures include:

Amnesia of seizure (common), may affect language (if onset involves language dominant hemisphere), oral & manual automatisms, possibly experiential/gustatory/olfactory auras

Do most focal seizures last less than 15 seconds?

No

True or false: ictal tachycardia may serve as a marker of seizure onset

True

True or false: postictal delta slowing is often present over side of seizure onset

True

True or false: Focal series typically start with rhythmic theta discharge over temporal lobe of origin

True

True or false: Ictal EEG is very reliable in diagnosing occipital seizures

False

True or false: complex visual images may occur at the onset of occipital lobe seizure

True

True or false: frontal lobe seizures often occur during arousal from sleep

True

True or false: localized low voltage beta is of high localizing significance in frontal lobe seizures

True

The most common site of focal seizure onset is the?

Temporal lobe

Tonic-clonic, absence and atonic are all types of:

Generalized epilepsies

Complex partial epilepsy is a type of:

Focal seizure

What EEG pattern is observed with childhood absence epilepsy?

3 Hz Spike & Wave

Can generalized absence seizures be triggered by hyperventilation?

Yes

Follow a generalized tonic-clonic seizure, postictal EEG typically shows:

Diffuse suppression then delta

What is not a characteristic of generalized atonic seizure?

Normal development

What are characteristics of generalized atonic seizures?

Typically brief, generalized electrodecremental pattern, paroxysmal fast activity

What EEG pattern is associated with infantile spasms?

Hypsarrhythmia pattern interictally, and electrodecremental pattern ictally during spasm

Focal seizures most commonly originated in the:

Temporal lobe

Typical pattern of absence seizure is?

3 Hz spike & wave

What is not a characteristic of generalized tonic-clonic seizures?

Usually lasts less than 30 seconds

What are characteristics of generalized tonic-clonic seizures?

Can evolve from a focal seizure or as a generalized/bihemispheric seizure from the beginning, postictal phase, strained (ictal) cry, generalized hypertonus then clonic activity

You are crushing this!

Party time!

You rock

Treat yo self

The deep fibular nerve supplies sensation to the:

Cleft between the first and second toes (webspace)

What conditions can lead to fibular entrapment neuropathy?

Diabetes, habitual leg crossing, prolonged squatting or kneeling, prolonged surgery and immobilization

A fibular motor study showed proximal amplitude of 2.5mV and distal amplitude of 2.3 mV. This is definitely NOT ________

conduction block at the fibular head

In a 25yo patient with foot drop has weakness to dorsiflex the foot as well as invert and evert the foot, no response could be obtained with stimulation of the fibular nerve at the knee or ankle recording over EDB. The tibial study was normal. The superficial fibular study was normal. What is the likely explanation?

L5 radiculopathy