20. Pathology of the Central Nervous System- 1

Question 1

Functions of the nervous system

Answer 1

Basic : Sensory → Motor
(mediated by central and peripheral nervous system, autonomic and somatic)

Higher : 
Consciousness
Complex and learned motor skills
Memory and planning
Communication/language etc…

Question 2

Brain

Answer 2

Cerebral hemispheres
Grey matter
White matter
Basal ganglia
Ventricular system
Brain stem
Cerebellum

Question 3

Meninges

Answer 3

Membranous coverings of the central nervous system

Protective function and important in production of cerebrospinal fluid

Question 4

Blood vessels - Arteries

Answer 4

The cerebral arteries supply a defined territory within the cerebral cortex

If blood supply to a particular part of the brain is interrupted, the patient will develop symptoms due to lack of function of the part of the brain supplied by that vessel

Question 5

The skull

Answer 5

The skull is a bony box which cannot expand
If the volume of tissue or fluid inside the skull increases the intracranial pressure rises
This results in herniation where a part of the brain moves from one compartment of the skull to another

Question 6

Herniation

Answer 6

Brain herniation frequently presents withabnormal posturing[2]a characteristic positioning of the limbs indicative of severe brain damage. These patients have a loweredlevel of consciousness, withGlasgow Coma Scoresof three to five.[2]One or both pupils may be dilated and fail to constrict in response to light.[2]Vomiting can also occur due to compression of thevomiting centerin themedulla oblongata.

Question 7

Spinal Cord

Answer 7

Communication of motor and sensory functions between brain and peripheral nervous system

Question 8

Basic Neuroanatomy

Answer 8

Spinal and cranial nerves
Branches of above linking CNS to peripheral sensory receptors and effector organs (muscles & glands)
Autonomic and somatic nervous systems

Question 9

Cells…

Answer 9

Neurons - the processors
Glial cells - supporting functions
- Schwann cells astrocytes & oligodendrocytes

Question 10

Localisation of motor and sensory territories

Answer 10

Post-central Gyrus = Sensory cortex

Pre-central gyrus = Motor cortex

Question 11

Speech and language

Answer 11

Broca’s area - Frontal lobe, anterior to pre-motor cortex
- Predominantly responsible for speech
production
Wernicke’s area - Temporal lobe, posterior to auditory
cortex
- Speech processing and comprehension
of written and spoken language

Question 12

Basic functional anatomy of the CNS

Answer 12

Frontal lobe
Parietal lobe
Temporal lobe
Occipital lobe
Brain stem
Cerebellum

Question 13

Frontal lobe

Answer 13

Complex executive functions involved in decision making; Emotional reactions: Formation of some types of memory; Motor cortex; Olfactory function; Generation of fluent speech

Question 14

Parietal lobe

Answer 14

Sensory cortex and processing of sensory information

Question 15

Temporal lobe

Answer 15

Language functions including auditory cortex and comprehension of written and spoken words; Memory

Question 16

Occipital lobe

Answer 16

Visual cortex

Question 17

Brain stem

Answer 17

Conduction of major motor and sensory pathways; Control of cardiorespiratory function and consciousness; Cranial nerve roots

Question 18

Cerebellum

Answer 18

Precise motor control; ?Others – language, attention (not yet well defined)

Question 19

Basic functional anatomy of the CNS

Answer 19

Spinal cord nerve roots:
Specific spinal nerves innervate defined motor functions and sensory territories
Damage to spinal cord at a specific level will cause loss of function of spinal nerves below that level
Sensory
Dermatomes:

Question 20

General and focal abnormal neurology

Answer 20

Focal neurological signs:
a set of symptoms or signs in which causation can be localized to an anatomic site in the central nervous system

Generalised neurological abnormality:
Essentially an alteration in level of consciousness

Question 21

Clinical application (1)

Answer 21

People who have regular contact with patients are often more likely to notice subtle changes in neurological parameters allowing prompt investigation and treatment
Basic neurological examination often allows localisation of lesion/injury in a patient with focal neurology

Question 22

Clinical application (2)

Answer 22

Imaging is usually required to confirm and better characterise the nature of the pathological process
Identification of the likely site by examination can assist in the precise radiological identification of a lesion
Assessment of consciousness allows identification of progression of a neurological insult

Question 23

Examples of focal neurological signs

Frontal lobe

Answer 23

Anosmia
Inappropriate emotions
Expressive dysphasia
Motor impairment

Question 24

Examples of focal neurological signs

Parietal lobe

Answer 24

Receptive dysphasia

Sensory impairment

Question 25

Examples of focal neurological signs

Temporal lobe

Answer 25

Cortical deafness

Receptive dysphasia

Question 26

Spinal cord lesions

Answer 26

Physical examination helps to identify the level of injury in spinal cord lesions
Signs limited to a single dermatome or nerve root suggest either a focal nerve root injury or injury to a peripheral nerve
Signs affecting several nerve roots below a certain level eg. Complete paralysis of body and legs with maintained head and neck movement is caused by injuries to the cervical spine (usually traumatic)

Question 27

Diffuse neurological injury

Answer 27

Usually manifest as impairment of consciousness
Most often due to  intracranial pressure (ICP)
May occur as a primary process or as a secondary to response to a focal injury

Question 28

Causes of reduced consciousness

Answer 28

May be obvious on external examination (eg. Trauma) or easily identified on basic observations (eg. Hypoxia, hypothermia)
May require additional bedside tests or more clinical history (eg. Hypo/ hyperglycaemia, post-ictal state in an epileptic patient)

Question 29

Assessing consciousness

Answer 29

Basic:
Assess responsiveness
A	: Alert
V	: Voice
P	: Pain
U	: Unresponsive

Question 30

Assessing consciousness

Answer 30

Things can change very quickly

You may be the first person to become aware of a reduction in conscious level

Prompt action is essential

Question 31

Summary

Answer 31

Neurological anatomy and function is very complex
Location of injury/pathology determines symptoms
Things can change quickly important to highlight changes to the team