Special Studies in Neurology

8/12/2019 Special Studies in Neurology

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SPECIAL STUDIES IN NEUROLOGY

dr. ASHARI BAHAR, M.Kes, Sp.S, FINS

DEPARTMENT OF NEUROLOGY

FACULTY OF MEDICINE

UNIVERSITY OF HASANUDDIN2011


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Whenever an ancillary diagnostic test isproposed, the specific indication for the test

should be considered carefully and critically: Only after thorough and meticulous clinical history taking and neurological examination.

Only after the formulation of a clinical differential diagnosis, in which all of the competing

diagnoses are ranked by probability.

The study that should be performed is the one whose result is most likely to be important

for further diagnostic and therapeutic management, but only if this will be of clear benefit tothe patient, and only if the risks of performing the study do not outweigh any potential

benefit that its findings might bring.

Multiple studies providing the same diagnostic information should not be performed merely

for repeated confirmation of the findings.

A study should not be performed if, regardless of its result, another study will have to be

performed that is likely to yield at least as much information. Only very rarely should studies be performed to confirm a diagnosis that is already

practically certain.

If a genetic study is contemplated, the potential consequences should be discussed

thoroughly with the patient and his or her family before the study is performed.

The costs must not be forgotten.


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CSF StudiesMyelography and

Radiculography

Basic studies


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Cerebrospinal Fluid Studies

Indications

Lumbar puncture is useful in the diagnosis of

diseases affecting the meninges, the brain and

spinal cord, and the nerve roots, which can

manifest themselves with changes in the

biochemical or cellular properties of the

cerebrospinal fluid.


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Indications

Diagnostic

Therapeutic

Follow up

Anesthetic


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foramen of

Magendie

Cerebral

aqueduct

(Sylvius)

foramen of

Luschka

Choroid

plexus of

lateral

ventricle

foramen

Monro

Choroid

plexus of3rd ventricleChoroid

plexus of 4th

ventricle

Subarachnoid

space

Subarachnoid

space


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Patient position for lumbar puncture


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Clinically relevant CSF Studies


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Myelography and Radiculography

Technique

Radiculomyelography (the visualization of intraspinal structures with

contrast medium) is generally performed after the injection of 1015 ml of

watersoluble contrast medium into the subarachnoid space via lumbarpunctureor, rarely, via suboccipital puncture.

The passage of contrast medium through the subarachnoid space,

including the nerve root sleeves, can then be followed on the radiologic

image and any obstructions to the flow of contrast medium can be identified

(e. g., spinal tumors).

The nerve roots appear as filling voids within the nerve root sleeves.The bony spine is seen on the myelographic images as well and can be

evaluated at the same time.


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IndicationsClinically evident lumbar radiculopathy with unclear CT findings

Suspected radiculopathy, but no clear segmental localization

Suspected spinal cord compressionSuspected spinal stenosis

Clinically evident spinal stenosis

Suspected myelopathy due to cervical spondylosis

Suspected myelitis or demyelination


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Typical findings in contrast myelography


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Imaging Studies

Skull radiographs Plain radiographs of the spine

Conventional SkeletalRadiographs

Myelography and

Radiculography

CT AngiographyComputed Tomography (CT)

MR AngiographyMagnetic Resonance

Imaging (MRI)

Angiography withRadiological Contrast Media

Diagnostic Techniques of

Nuclear Medicine


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Conventional Skeletal Radiographs

Skull radiographs

Skull radiographs are performed for very few purposes

nowadays and are hardly ever indicated.

(They cannot be used as a substitute for CT in head

trauma; if a CT is indicated, but unavailable for some

reason, then the patient should probably be transportedto a center where a CT can be performed.)

Plain films of the skull enable visualization of:

fractures (though much less well than on CT)

congenital malformations of the bony skull, and

various developmental disorders

Skull radiographs are useless in the diagnostic

evaluation of headache or intracranial processes.


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Plain radiographs of the spine

Plain radiographs of the spine are sometimes useful for

the demonstration of:

fractures,

bony tumors (which, however, are more easily seen by CT or MRI),

degenerative diseases and slippage (olisthesis) of

the spine,

infections involving bone,

axial skeletal deformities,

dynamic abnormalities (abnormal mobility or

instability of individual spinal segments; their

demonstration requires special radiological

techniques, socalled functional studies).


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Skull fracture seen in a plain skull radiograph.

The (a) and (b) images both reveal a fracture line medial to the

lambdoid suture on the right (arrow).


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Computed Tomography (CT)

Normal CT scan of the head. a Note the symmetrical,

normal-sized frontal and occipital horns of the lateral ventricles.

The cerebral cortex and deep white matter can be distinguished from each other, and the falx cerebri

can be seen in both the frontal and occipital regions. A number of blood vessels can be seen.

Also note the bilateral calcifications of the choroid plexus of the lateral ventricles.

b. Some of the blood vessels around the base of the brain (arrows) are well seen after the

administration of contrast medium.


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Magnetic Resonance Imaging (MRI)

ah Normal MRI of the brain in 5 mm sections from the base of

the brain to the vertex


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Comparative indications of CT and MRI of the head


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Angiography with Radiological Contrast

Media

Diagnostic imaging of the

cerebral blood vessels is

indicated when a vascularstenosis, occlusion, or

malformation is suspected as

the cause of a neurological

illness.


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Angiography with Radiological Contrast

Media

Indications for angiography of the intracranial vessels Visualization of saccular aneurysms

Visualization of arteriovenous malformations and fistulae

Detailed representation of saccular aneurysms (after diagnosis by

MRI, as an aid to treatment by neurosurgical or interventional

neuroradiological methods) Detailed representation of arteriovenous malformations (after

diagnosis by MRI, as an aid to treatment by neurosurgical or

interventional neuroradiological methods)

Visualization of other vascular anomalies:

moyamoya

agenesis of vessels and other developmental anomalies

vascular stenosis or occlusion

arterial dissection


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Electrophysiological Studies

Electroencephalography(EEG)

Polysomnography (PSG)

Visual evoked potentials (VEP)Auditory evoked potentials (AEP)

Somatosensory evoked potentials (SSEP)

Motor evoked potentials (MEP)

Evoked potentials

Electromyography (EMG)

Electroneurography (ENG)

Oculography

Electronystagmography

Retinography

Other Electrophysiological

Studies


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Electroencephalography (EEG)

Principle

The surface EEG registers fluctuations in electrical

potential that are generated by the cerebral

cortex.

These represent the sum of the excitatory and

inhibitory synaptic potentials.


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The main indications for electroencephalography

Confirmation of the diagnosis of epilepsy

Determination of the type of epilepsy that is present

Brief, episodic impairment of consciousness of

unknown etiology

Longer-lasting disturbances of consciousness, delirium

Metabolic disturbances CreutzfeldtJakob disease

Sleep studies (e. g., in suspected narcolepsy)


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Placement of EEG electrodes according to the 1020 system


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Normal EEG. a Monopolar recording, b bipolar recording.


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Technique

Polysomnography is a special application of EEG in which the EEG is

recorded simultaneously with a number of other electrophysiological

parameters.

It is used to assess sleep and sleep disturbances. The EEG changes that normally occur during sleep are related to the

progression of the individual through various sleep stages, including

deep or REM sleep (REM = rapid eye movement).

The recorded parameters include eye movements (by electro-

oculography), respiratory excursion, airflow in the nostrils, muscleactivity (by surface EMG), cardiac activity (by ECG), and the partial

pressure of oxygen (by transcutaneous pulse oximetry)


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Indications

The most important indication for a sleep study is

a clinical suspicion of sleep apnea syndromeon

the basis of a characteristic history obtained fromthe patient or bed partner, together with related

physical findings and a low partial pressure of

oxygen measured during sleep by pulse oximetry.

Polysomnography is also indicated for the

diagnosis of narcolepsy, as well as for the

assessment of excessive fatigue and daytime

somnolence.


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Indications

In disorders affecting muscle, EMG

can be used to determine whether

the underlying pathological process

is located in the muscle itself

(myopathic process), in the nerveinnervating it (neuropathic

process), or at the neuromuscular

junction.

It can also be used to grade the

severity of muscle denervation and

the extent of reinnervation.

In combination with

electroneurography (see below),

EMG is a very important type of

ancillary study for the diagnosis of

neuromuscular diseases.

Electromyography (EMG


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Electromyography (EMG


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Electroneurography (ENG)


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Indications for EMG and ENG


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Ultrasonography

There are two main types of

ultrasound study:

Doppler sonography

duplex sonography


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Ultrasonography

Indications

The velocity and flow profile (laminar or turbulent) of the

blood flowing within a particular vessel depend, among

other things, on the vessels caliber and on the nature of

its wall.

Ultrasound studies aid in the detection of vascular stenosis

and occlusion, vessel wall irregularities, abnormalities of

the speed and direction of blood flow, and turbulent flow.

Insonation of the extra- and intracranial vessels (e. g., of

the middle cerebral a. through the thin bone of the

temporal window, or of the basilar a. through the

foramen magnum) yields an informative picture of the

current state of blood flow in the brain.


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Ultrasonography


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Ultrasonography


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Ultrasonography


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Other Ancillary Studies

Tissue Biopsies

Muscle biopsy

Nerve biopsy

Brain biopsy

Perimetry

Static computed perimetry


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Automatic (Octopus) perimetry in right

homonymous hemianopsia

Perimetry is used to detect visual field defects


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Special Studies in Neurology