2. Special Techniques For Neurologic Diagnosis

Question 0

T/F: LP should generally be preceded by CT or MRI whenever elevation of ICP is suspected.

Answer 0

True

Question 1

Indications for lumbar puncture:

Answer 1

1. To obtain pressure measurements & procure a sample of CSF for cellular, cytologic, chemical, & bacteriological examination
2. To aid in therapy by the administration of spinal anesthetics & occasionally, antibiotics or antitumor agents, or by reduction of CSF pressure
3. To inject radiopaque substance, as in myelography, or a radioactive agent, as in radionuclide cisternography

Question 2

Corticosteroids are particularly useful in situations in which increased ICP is caused by __________

Answer 2

Vasogenic cerebral edema

Question 3

LP is easiest to perform at _____ interspace.

Answer 3

L3-L4

Question 4

L3-L4 interspace corresponds to __________

Answer 4

The axial plane of the iliac crests

Question 5

The most common complication of LP

Answer 5

Headache

Question 6

Normal opening pressure in an adult:

Answer 6

100-180 mm H2O or 8-14 mm Hg

Question 7

LP opening pressure reflecting increased ICP:

Answer 7

> 200 mm H2O

Question 8

LP opening pressure indicating intracranial hypotension:

Answer 8

</= 50 mm H2O

Question 9

Test which confirms the presence of a spinal subarachnoid block confirmed by jugular venous compression (tests for rapid rise in pressure within a few seconds after release of pressure on the vein):

Answer 9

Queckenstedt test

Question 10

How much RBCs imparts a hazy or ground glass appearance to CSF?

Answer 10

200/mm^3

Question 11

How much RBCs imparts a hazy pink to red color of the CSF?

Answer 11

1000-6000/mm^3

Question 12

Distinguish a traumatic lumbar tap from subarachnoid hemorrhage:

Answer 12

Traumatic tap:

1) decreasing number of RBCs on 2nd & 3rd tubes
2) CSF pressure is usually normal
3) it will clot

Question 13

In SAH, RBCs begin to hemolyze within a few hours giving a pink-red discoloration to the supernatant fluid. This is called __________

Answer 13

Erythrochromia

Question 14

In SAH, if the supernatant fluid from a lumbar tap is left to stand for a day or more, the fluid becomes yellow brown. This is called __________

Answer 14

Xanthochromia

Question 15

The pigments that discolor the CSF following SAH are:

Answer 15

Oxyhemoglobin
Bilirubin
Methemoglobin

Question 16

This pigment appears within several hours of hemorrhage, becomes maximal in approximately 36 h, & diminishes over a 7- to 9-day period:

Answer 16

Oxyhemoglobin

Question 17

This pigment begins to appear in 2-3 days & increases in amount as oxyhemoglobin decreases:

Answer 17

Bilirubin

Question 18

This pigment appears when blood is loculated or encysted & isolated from the flow of CSF:

Answer 18

Methemoglobin

Question 19

Protein content of lumbar spinal fluid:

Answer 19

</= 45-50 mg/dL

Question 20

A combination of:

1) CSF protein content of >/= 1000 mg/dL, indicating a block to CSF flow
2) fluid is deeply yellow
3) clots readily due to presence of fibrinogen

Answer 20

Froin syndrome

Question 21

What is the major immunoglobulin in normal CSF?

Answer 21

IgG

Question 22

What is the normal CSF glucose concentration?

Answer 22

45-80 mg/dL (about 2/3 of that in the blood)

Question 23

T/F: As a rule, viral infections of the meninges and brain lower the CSF glucose

Answer 23

False

Question 24

What is the average osmolality of the CSF?

Answer 24

295 mOsm/L (identical to that of plasma)

Question 25

What is the normal pH of the CSF?

Answer 25

7.31 (slightly lower than arterial blood: pH 7.41)

Question 26

T/F: In T1-weighted images, CSF appears dark while in T2-weighted images, CSF appears white

Answer 26

True

Question 27

This is a type of susceptibility technique in MRI which is especially sensitive to blood & its breakdown products

Answer 27

Gradient-echo (GRE) sequences

Question 28

An MRI technique which gives a high signal for parenchymal lesions & a low signal for CSF

Answer 28

FLAIR (fluid-attenuated inversion recovery)

Question 29

A paramagnetic agent that enhances the process of proton relaxation during the T1 sequence of MRI, which permits even sharper definition & highlights regions surrounding many types of lesions where the BBB has been disrupted

Answer 29

Gadolinium

Question 30

A procedure that has been invaluable in detecting the earliest stages of ischemic stroke (generally within 2 hrs or less of onset) & also useful in distinguishing between cerebral metastases & abscesses

Answer 30

Diffusion-weighted imaging (DWI)

Question 31

This is the main technique used in functional MRI (fMRI), which measures the difference between oxy- & deoxyhemoglobin, which reflects blood delivery to the region

Answer 31

Blood-oxygen level dependent (BOLD) signal

Question 32

8- to 12-per-second sinusoidal waves in both occipital & parietal regions that wax & wane spontaneously & are attenuated or suppressed completely with eye opening or mental activity

Answer 32

Alpha waves

Question 33

Faster than 12 Hz & of lower amplitude (10-20 mV) that are normally recorded from the frontal regions

Answer 33

Beta waves

Question 34

Waves below 4Hz with amplitudes from 50-350 mV

Answer 34

Delta waves

Question 35

Waves with frequency of 4-7 Hz

Answer 35

Theta waves

Question 36

Transient high-voltage waveforms that have a pointed peak at recording speeds & duration of 20-70 ms & 70-200 ms

Answer 36

Spikes or sharp waves

Question 37

Spikes or sharp waves that occur interictally in people with epilepsy or in individuals with a genetic disposition to seizures

Answer 37

Epileptiform discharges

Question 38

3-per-second spike-and-wave complexes that characteristically appear in all leads of the EEG simultaneously & disappear almost as suddenly at the end of the seizure are associated with what type of seizure?

Answer 38

Absence seizures

Question 39

The most pathologic EEG finding

Answer 39

Electrocerebral silence