LECTURE STUFF Flashcards
1
Q
LP indications (5)
A
To diagnose:
- brain or spinal cord neoplasm
- cerebral haemorrhage
- meningitis
- encephalitis
- degenerative brain disease.
2
Q
LP CONTRAINDICATIONS (5)
A
- uncooperative patient.
- patient with increased intracranial pressure
- severe degenerative spinal joint disease
- psychosomatic illness because may associate a lumbar puncture with the potential of paraplegia.
- patient with infections near the lumbar puncture site
3
Q
LP COMPLICATIONS (5)
A
- Persistent cerebrospinal fluid leak
- bacteria into the cerebrospinal fluid, causing suppurative meningitis.
- Herniation of the brain through the tentorium cerebelli or herniation of the cerebellum through the foramen magnum
- puncture of the spinal cord.
- Puncture of the aorta or the vena cava, causing serious retroperitoneal haemorrhage.
4
Q
CP DEFINITION
A
During this procedure CSF is drawn from the cerebellomedullary cistern (cisterna magna) via the insertion of a needle between the atlas and the occipital bone.
5
Q
CP INDICATIONS
A
- To obtain CSF for examination when it cannot be obtained at the lumbar level
- To demonstrate a subarachnoid blockage by performing a cisternal puncture simultaneously with a lumbar puncture
- To provide drainage of cerebrospinal fluid when a lumbar puncture is contraindicated
- To introduce contrast material or air for myelography
- To perform encephalography
6
Q
ELECTROENCEPHALOGRAPHY DEFINITION. WHAT IS IT USED FOR.
A
Records electrical activity of the brain with sensitive electronic equipment from recording electrodes that are placed at measured intervals on the patients scalp. Electrical activity is mainly due to graded potentials (summed postsynaptic potentials). Used clinically to monitor the electrical activity of the brain. They provide important information on:
- background electrical activity
- epileptiform discharges (in idiopathic epilepsy, the clinical exam and imaging are usually normal)
7
Q
EEG DEVIATIONS (2)
A
Seisure activity
Cerebral lesions
8
Q
EEG INDICATIONS (5)
A
- Investigate epileptic states
- Investigate headaches
- Diagnose cerebral lesions eg abscess
- Determine cerebral death in coma patient
- Monitor cerebral blood flow during surgery
9
Q
EVOKED POTENTIALS DEFINITION AND APPARATUS
A
Evoked potentials are electrical signals of nerves, spinal cord, brain in response to
- light stimulation from the eyes
- sound stimulation from the ears
- mild electrical stimulation of the nerves in the arms and legs
Electrodes are placed along several points in the sensory pathway and computers analyse electrical impulses. The results of each test are represented graphically, which gives us info about amplitude (strength) and latency (time the signal took to reach each electrode) of the nerve signal.
10
Q
EVOKED POTENTIALS APPLICATIONS (4)
A
- Can be used to explore neuro pathways connecting sensory organs and corresponding cortical centres.
- Can be used to investigate intermediate neurological relay stations.
- Used to diagnose nervous system disorders such as
- ms
- hearing loss
- various spinal disorders
- Used to monitor nervous system function during surgery.
11
Q
VISUAL EVOKED POTENTIALS DEVIATIONS (5)
A
Optic neuritis
Optic neuropathy
Diabetes
MS
Tumours compressing the optic nerve (eg pituitary tumours)
12
Q
BRAINSTEM AUDITORY EVOKED POTENTIALS INDICATIONS (2)
A
Assessments of patients who might have:
- CNVIII tumour (acoustic neuroma)
- Lesion of the brainstem auditory pathway (eg MS
) Clinical screening and assessment of hearing loss in infants and young children.
13
Q
SOMATOSENSORY EVOKED POTENTIALS DEFINTION
A
Records the somatosensory electrical potentials travelling through the peripheral nerves towards the brain.
14
Q
MOTOR EVOKED POTENTIALS DESCRIPTION
A
Transcranial electrical/magnetic stimulation of the motor cortex produces a descending response that traverses the corticospinal tracts, eventually generating a measureable response in the form of:
- muscle activity
- spinal cord synaptic response in the ventral horn cells.
MEPs can be used to assess the integrity of the motor pathways in unconscious patients
15
Q
MOTOR EVOKED POTENTIALS PROCEDURE
A
MEPs are recorded from muscles following:
- direct stimulation of exposed motor cortex
- transcranial stimulation of motor cortex (magnetic or electrical)
16
Q
MOTOR EVOKED POTENTIALS TRANSCRANIAL PROCEDURE
A
- A cortical magnetic stimulator is passed over the scalp
- The stimulating coil is passed over the motor cortex, causing motor stimulation
- A contraction of contralateral muscles is induced, and detected by surface electrodes
- The muscle contraction is recorded for analysis
17
Q
MOTOR EVOKED POTENTIALS DEVIATIONS (5)
A
- Demyelinating diseases (e.g. Multiple sclerosis)
- Spinal cord injury
- Other neurological disorders (e.g. Parkinson’s disease)
- Lesions of the optic nerve, optic tract, visual centre, and the eye
- Abnormal latency in adults may indicate brain dysfunction or early tumour especially posterior fossa tumours
18
Q
MOTOR EVOKED POTENTIALS INDICATIONS (6)
A
Diagnose, evaluate and monitor:
- ms
- stroke
- cervical myelopathy
- spinal cord injury
- MND
Surgical monitoring:
- avoidance of CNS damage during tumour removal, corrective surgery for scoliosis, spinal cord function during thoracoabdominal aneurysm repair
Tx for focal hand dystonia (writers cramp)
To evaluate patients with spinal cord injuries
To evaluate the location and extent of areas of brain dysfunction after head injury
To pinpoint tumours at an early stage
19
Q
ELECTROMYOGRAPHY DEFINITION
A
Electromyography is based on the fact that muscular contraction is associated with electrical activity on the muscle-cell’s surface. This electrical activity (potentials) can be viewed on an oscilloscope screen or recorded as an electromyogram. The electromyogram is examined for abnormalities in amplitude, duration and shape. The electromyogram may also reveal spontaneous electrical discharges (e.g. fibrillations indicative of denervation or intrinsic muscle disease). It is an audio or visual record of the electrical activity of a skeletal muscle.
EMG’s are produced via a stimulating electrode that is either inserted into the muscle or placed on the skin over the muscle.
EMG aids in the diagnosis of neuromuscular disorders.
20
Q
ELECTROMYOGRAPHY INDICATIONS
A
Used to diagnose:
- muscle spasticity
- muscular disorders
- nerve impingement in the back, neck, etc.
- other neuromuscular disorders
21
Q
ELECTROMYOGRAPHY DEVIATIONS
A
- fibrillation and fasciculation
- primary muscle disorder (e.g. polymyositis, muscular dystrophies, and various myopathies)
- myasthenia gravis
- peripheral nerve damage
22
Q
ELECTROMYOGRAPHY CONTRAINDICATIONS
A
- uncooperative patients
- patients on anticoagulant therapy
- extensive skin infections
23
Q
NERVE CONDUCTION STUDIES DEFINITION
A
Peripheral nerve fibres may be stimulated from the surface of the skin by an electrode. By placing recording electrodes (on the skin) along the path of the nerve being tested, the resulting evoked action potential can be detected. The recording electrode may also be placed over the corresponding muscle in the case of motor nerve testing. The information from the electrodes may be displayed on an oscilloscope screen or recorded on a paper strip. Measures the speed at which nerves transmit signals
24
Q
MNCV DEFINITION
A
MNCV is evaluated by recording the compound muscle action potential (CMAP) that is created when a muscle contracts following the electrical stimulation of the motor nerve fibres supplying that muscle.
The CMAP is the sum of all the action potentials occurring individually in the contracting muscle fibres
25
SNCV DEFINITION
SNCV is determined by examining the sensory nerve action potential (SNAP) that is obtained from the nerve itself, by recording electrodes on the skin, following electrical stimulation of the nerve being investigated
The SNAP is the sum of all the action potentials generated in the sensory nerve fibres by the stimulatory electrical shock.
26
NCV INDICATIONS
Suspected nerve disorders:
* MND
* entrapment neuropathies
* carpal tunnel syndrome
* peroneal neuropathies
* polyneuropathies
* plexopathies (brachial;lumbar)
Neuromuscular disorders:
* Myasthenia gravis
* Lambert Eaton syndrome
* Botulism
Some myopathies
RADICULOPATHIES
27
Mental status examination:
General behaviour:
- Is the patient normal, hyperactive, agitated, quiet, immobile?
General appearance:
- Is the patient neat or slovenly? Does the patient dress in accordance with age, peers, sex, and background?
Stream of talk:
- Does the patient converse normally? Is the speech rapid, incessant, under great pressure, or is it slow and lacking in spontaneity? Is the patient discursive and unable to reach the conversational goal?
Mood and affective responses:
- Is the patient euphoric, agitated, inappropriately gay, giggling, or is she silent, weeping, angry? Does their mood swing in a direction appropriate to the subject matter of the conversation? Are they emotionally labile?
Content of thought: - Does the patient have illusions, hallucinations or delusions, and misinterpretations? Are they preoccupied with bodily complaints, fears of cancer or heart disease, or other phobias? Does the patient suffer delusions of persecution and surveillance by malicious persons or forces?
Intellectual capacity: - Is the patient bright, average, dull, or obviously demented or mentally retarded?
Sensorium:
1. Consciousness
2. Attention span
3. Orientation for time, place, and person
4. Memory, recent and remote, as disclosed during history taking
5. Fund of information
6. Insight, judgement, and planning
7. Calculation
28
Diagnostic Catechism
**Is there a lesion?**
1. The patient with a neurological condition Many patients will have no identifiable lesion.
2. Does the patient have an emotional disorder, an organic disorder, or both?
3. To answer "Yes" to the question, "Is there a lesion?" you hope to find at least one sign.
4. One firm sign is more important than a multitude of symptoms.
**Where is the lesion?**
1. Is the lesion structural, genetic, biochemical etc. in nature?
2. Can a decision be made as to the organ or organs, system or systems involved by the lesion?
If the lesion appears to involve the nervous system:
a. Is it intra-axial or extra-axial? Distal or proximal? Motor or sensory (or sensorimotor, headache or organic mental syndrome)?
3. When the patient has a non-motor complaint which is likely to be of neurological origin, attempt to classify the complaint as motor, sensory, sensorimotor, headache, or organic mental syndrome.
**What is the lesion?**
- Try to select the simplest diagnosis that will explain the signs and symptoms.
**What tests, clinical or laboratory, will confirm or reject the provisional diagnosis and establish the final diagnosis?**
- 1. Can you do any other clinical tests? If not, select laboratory procedures, according to these principles:
a. Can the test provide critical evidence to support or reject the provisional diagnosis?
b. Is the test the simplest, safest, and cheapest one?
c. When faced with a hopeless or untreatable disorder, have you taken all reasonable steps to exclude a treatable disorder?
**What is the optimum management?**
1. State realistic therapeutic goals
2. What agencies or institutions might help the patient?
3. Other persons are known to be at risk? Consider for patients with environmentally induced, contagious-infectious, or hereditary diseases.
4. Follow up on the patient
29
AchR- Ab Test for?
The anti-acetylcholine receptor antibody tests is a blood test. The antibody damages the receptor site causing malfunction of the neural synapse.
Myasthenia Gravis
30
AchR- Ab test pathology
Approximately 85-90% of patients with myasthenia gravis (MG) express three types of auto-antibodies to the acetylcholine receptor (AChR):
Binding antibody:
Activates complement causing AChR destruction
Blocking antibody:
Impairs binding of Ach to the receptor, leading to poor muscle contraction
Modulating antibody:
Causes receptor endocytosis resulting in loss of AChR expression, which correlates most closely with clinical severity of disease
31
AchR- Ab Test Deviations
Serum auto-Ab’s are found in 80-90% of patients with generalised MG
Serum auto-Ab’s are found in 55-70% of patients with ocular MG
32
AchR- Ab test indications
evaluation of muscle weakness
diagnosis of MG in patients with:
* Drooping eyelid;
* Double vision;
* Decreased eye movement control
* Dysphagia with choking, drooling and gagging
* Slurred speech
* Weak neck muscles; trouble holding up head
* Difficulty breathing
* Difficulty walking; altered gait
* Specific muscle weakness but normal feelings/sensations
* Muscle weakness that worsens with sustained effort & improves with rest
evaluation of MG disease activity
evaluation of response to therapy
33
Plain skull xray deviations
* Focal changes in bone & soft tissue density (skull/brain tumours [primary/secondary], cysts etc.)
* Opacification of the nasal sinuses ( Ddx: sinusitis, haemorrhage, or tumour)
* Shift of midline structures (unilateral haematoma or tumour)
* Sella turcica erosion, enlargement etc (pituitary tumours)
* Linear defects (bone fracture lines) etc
34
Plain skull xray Indications
Suspected spine fractures following back trauma
Suspected skull fractures following head trauma
35
Xray Contraindications
* Patients who cant sit still
* Uncooperative patients
36
Spinal Xray Indications
* Investigate persistent pain, numbness, or weakness
* Check for spondylosis (arthritis, osteophytes etc.)
* Check for intervertebral disc degeneration
* Check for spinal injuries (e.g. fractures or dislocations)
* Find evidence of infections, tumours
* Identify abnormal curvatures of the spine (e.g. scoliosis)
* Screen for suspected congenital problems (e.g. spina bifida)
* Check the spine post spinal surgery
37
Cervical Xray Deviations
* Fracture (trauma patients)
* Spondylolisthesis
* Spondylosis
38
Thoracic Xray Deviations
* Crush Fracture (osteoporosis)
* Kyphosis, scoliosis
* Metastases (esp. breast, kidney, lung & thyroid cancers)
39
Lumbosacral Xray Deviations
* Spondylosis
* Scoliosis
* Metastases (esp. breast, kidney, lung & thyroid cancers)
* Spondylolisthesis
40
Myelography Definition
An imaging procedure in which a needle is inserted into the spinal canal, & contrast material injected into the space around the spinal cord & nerve roots (subarachnoid space)
41
Myelography Deviations (5)
* Cord tumours
* meningeal tumours
* metastatic spinal tumours
* herniated intervertebral discs and arthritic bone spurs present as canal narrowing or as varying degrees of obstruction to the flow of the dye column within the canal
* nerve root impingements
42
Myelography Indications
* Myelography is most commonly used to detect suspected abnormalities affecting the:
* spinal cord
* spinal canal
* spinal nerve roots
* blood vessels that supply the spinal cord
* To visualise the extent of a known lesion
* To investigate persistent, unexplained pain, numbness, or weakness
* To determine if an IVD herniation is compressing nerve roots, spinal cord or cauda equina
* To detect suspected spinal stenosis caused by osteophytes or thickening of adjacent ligaments
43
Myelography Complications
* Seizures
* Contrast allergy (infrequent & mild)
* Bleeding
* Cancer (excessive exposure to radiation)
* HA (uncommon)
* CSF leakage from the puncture site
* Infection
44
Cerebral Angiography Definition
An imaging procedure in which a catheter is used to inject iodine-containing contrast material into a cerebral vessel
45
Cerebral Angiography Deviations (5)
* Vascular tumours (appear as masses containing multiple small AV fistulas)
* Non-vascular tumours: (avascular masses which distort the normal vascular pattern)
* abscesses
* haematomas
* AV malformations
* narrowing of the vascular lumen
* obstruction of the vascular lumen
46
Cerebral Angiography Indications (2 with parts)
To detect abnormalities of the cerebral circulation e.g.:
* aneurism
* stenosis (e.g. due to atherosclerotic plaques)
* occlusion (e.g. due to thrombi or emboli;)
* arterio-venous malformation
* CNS tumours
* extent of stroke
To investigate unexplained neurological ssx e.g.:
* severe headaches
* memory loss
* slurred speech
* dizziness
* blurred or double vision
* weakness or numbness
* loss of coordination or balance
47
Cerebral Angiography Contradindications
Pregnancy
Breastfeeding should be delayed for 24 hours after contrast material injection
Severe renal disease
48
Cerebral Angiography Complications (8)
* allergic reaction from contrast material
* renal failure (contrast)
* arterial rupture & hemorrhage
* thrombus & embolus formation
* stroke (catheter dislodges plaque)
* Infection
* bleeding at the puncture site
* cancer (radiation exposure)
49
CT Scan Explanation
Xrays are passed through the brain. As it comes out the other side the beam is attenuated slightly because it has hit dense living tisues on the way through.
- very dense tissue blocks some
- less dense blocks less
Xray detectors positioned around the circumference of the scanner collect attentuated reading from multiple angles.
Computer turns 2D images into 3D image
50
CT deviations
TUMOUR (e.g. NEOPLASIA, HEMATOMA etc)
INFARCTION
CORTICAL ATROPHY
VENTRICULAR DISPLACEMENT/ENLARGEMENT
CEREBRAL ANEURISM
CEREBRAL HAEMORRHAGE
AV-MALFORMATION
51
CT indications
Rapid visualisation of brain injuries (CT’s provide good images in a matter of minutes)
Evaluation of brain edema
Assessment of ventricle size
To monitor disease progress
To monitor treatment outcomes
52
CT contraindications
Uncooperative patients
Patients with iodine dye allergy
53
CT vs MRI
Both CT and MRI are extremely useful in visualizing CNS anatomy and pathology
CT is more easily available and excellent for imaging bony structures. It is adequate for most CNS investigations
However, MRI is superior in imaging neurological tissue
54
CT vs MRI advantages
CT scan advantages:
* are better at detecting fresh blood
* may be done frequently after the injury to monitor the amount of brain injury
MRI is better at detecting:
* remnants of old haemorrhaged blood
* damaged but intact nerve tissue
* Magnetic Resonance Angiogram is a specialised form of MRI which detects blood vessels instead of brain tissue and can be used to check for bleeding or for the health of blood vessels
55
Radionuclide Scan Phases:
* 1st phase: is the perfusion phase or vascular phase i.e. demonstrates and characterises the blood flow (perfusion) to a particular tissue or lesion
* 2nd phase: blood pooling phase or soft tissue phase or diffusion phase. Areas with moderate to severe inflammation have dilated capillaries, resulting in “stagnant” blood flow which causes the radioisotope to "pool". Hence, excessive pooling indicates the presence of intense or acute inflammation
56
PET definition
PET is a computer-based imaging technique which provides a picture of the brain's activity rather than its structure.
Substances (e.g. glucose) that have been labelled with a radioactive tracer are tracked. Patient is injected or asked to ingest glucose. As the glucose is metabolised, the radioactive tracker creates a positron (a positive electron). The positron combines with an electron and 2 gamma rays are given off, which travel in opposite directions. The gamma rays are detected by a circular array of detectors. The computer maps the area of radioactivity on a cathode ray screen.
PET provides quantitative information about brain function. Measurements of glucose metabolism correlate with blood flow, which in turn reflects brain activity.
57
SPECT
A radiation emission source (radionuclide) is injected into the bloodstream. Its movement is then monitored.
SPECT acquires information about the concentration of radionuclides introduced into the patient’s body. The radionuclide does not enter the brain itself but stays in the bloodstream. It allows examination of the brain’s blood supply which is normally reduced in damaged areas.
SPECT imaging involves the rotation of a photon detector array around the body to acquire data from multiple angles.
SPECT uses a γ camera to acquire multiple 2-D images from multiple angles. A computer is used to create a 3D reconstruction based on the multiple 2D projections.
Using this technique, the position and concentration of radionuclide distribution is sought.
Thus SPECT measures blood flow in different areas of the brain.
58
SPECT vs PET
SPECT imaging is inferior to PET because of attainable resolution and sensitivity. Different radionuclides are used for SPECT imaging that emit a single photon. Positron emission which results in two photons as occurs in PET.
Because only a single photon is emitted from the radionuclides used for SPECT, this results in a tremendous decrease in detection efficiency as compared to PET.
Despite SPECT’s poorer resolution, the availability of new SPECT radiopharmaceuticals, particularly for the brain, and the practical and economic aspects of SPECT instrumentation make this mode of emission tomography attractive for clinical studies of the brain.
