Pathology

Question 1

How can microorganisms spread to the CNS

Answer 1

Direct - from middle ear infection or a base of skull fracture
Blood borne - sepsis, infective endocarditis
Iastrogenic (ventriculoperitoneal shunt, surgery, lumbar puncture

Question 2

What is meningitis?

Answer 2

Inflammation of the leptomeninges (arachnoid and pia maters)

May present with sepsis

Question 3

What organisms cause meningitis in neonates?

Answer 3

E.coli

Listeria monocytogenes

Question 4

What organisms cause meningitis in 205 year olds

Answer 4

Haemophilus influenza

Question 5

What organisms causes meningitis in 5-30 year olds?

Answer 5

Neisseria meningitides

Question 6

How do you treat Neisseria meningitides meningitis? MOA?

Answer 6

Ceftriaxone
Cephalosporin (beta lacta)
Inhibits cell wall synthesis

Question 7

Causative organism of meningitis in people over 30

Answer 7

Stretococcus pneumoniae

Question 8

What causes chronic meningitis?

Answer 8

Mycobacterium tuberculosis

Question 9

What is encephalitis?

Answer 9

typically a viral infection, which affects the parenchyma of the brain. The virus causes neuronal cell death (and the neurons have inclusion bodies).

Question 10

What can cause encephalitis of the temporal lobe? spinal cord motor neurones, brainstem, in AIDS/HIV?

Answer 10

temporal lobe - herpes virus,
infection of the spinal cord motor neurons - polio,
infection of the brainstem - rabies.
Infection of the CNS prompts a lymphocytic inflammatory reaction.
Cytomegalovirus can also cause encephalitis – it is usually seen in HIV/AIDS – cells are large with inclusion bodies.

Question 11

What are causes of RICP?

Answer 11

Tumours - rare, don’t cross BBB
Haematomas
Abscesses
Infarction causing oedema of surrounding tissue
Inflammation - meningitis, encephalitis, trauma

Question 12

How does RICP present?

Answer 12

Headache, vomiting, papilloedema, then compression of tissues and herniation

Cushing’s response: hypertension, bradycardia and irregular respiration

Question 13

What is subfalcine herniation? What can it cause?

Answer 13

• Subfalcine herniation occurs on the same side as the mass – the cingulate gyrus is pushed under the free edge of the falx cerebri.

o This can lead to compression of the anterior cerebral artery, leading to ischaemia and infarction of the medial parts of the frontal and parietal lobes and corpus callosum.

Question 14

What is tectorial herniation? What can it cause?

Answer 14

Movement of the uncus & part of the parahippocampal gyrus through the tentorial notch. This can damage the ipsilateral occulomotor nerve and, and occlude blood flow in the posterior cerebral and superior cerebellar arteries.

o Often fatal – causes Duret haemorrhage (secondary haemorrhage into the brainstem)

o Common mode of death in people with large tumours or in intracranial haemorrhage

Question 15

What is tonsillar herniation? wHat does it cause?

Answer 15

Cerebellar tonsils are pushed into the foramen magnum compressing the brainstem. There becomes compression on the brainstem resulting in a coma. Further compression of the cerebral peduncles can cause a hemiparesis (weakness of one side of body), before producing apnoea and cardiac arrest from further compression on brainstem structures.

Question 16

What is focal damage?

Answer 16

• Focal damage, where there is bruising and laceration of the brain (cerebral contusion) as it hits the internal surface of the skull, with addition of causing subdural haematoma too. The damage to the brain can then be divided into coup (focal damage at site of impact) or contrecoup (damage on the opposite side of the brain) injury.

Question 17

What is diffuse damage?

Answer 17

• Diffuse damage is the direct tearing of axons as a result of the injury, known as Diffuse Axonal Injury (DAI), and the axons are torn from cell bodies due to the force of impact. The micro-tears that develop will heal by gliotic scarring. This commonly leads to a vegetative state developing, dementia, and gliotic scarring resulting in epilepsy.

Question 18

What are tension headaches? Management?

Answer 18

Most common
Neurovascular irritation from excessive tension in the scalp muscles
Tight band sensations, pressure behind the eyes, throbbing and bursting sensations
Depression can accompany

Management: firm reassurance, avoiding precipitating causes, analgesic withdrawal (often exacerbates pain), pharmacological interventions

Question 19

What is migraine? Differentials?

Answer 19

A migraine is a recurrent headache associated with visual and gastrointestinal disturbances (aura).
There is vasodilatation or oedema in blood vessels, stimulating nearby nerve endings, with some precipitating factors also being noticed.

Prodromal symptoms - altered visual function(/aphasia/sensory changes) that last for minutes to hours
Main attach (hemicranial (head-splitting) pain beginning locally and then becoming generalised)
Sleep and feeling drained afterwards

Ddx: menignitis, sub-arachnoid haemorrhage, TIA

Question 20

What is a cluster headache?

Answer 20

Recurrent bouts of excruciating unilateral pain, keeping patient awake, commonly clustering around one eye.
Common in males from 30-40 years old
No serious sequealae

Question 21

What is temporal arteritis?

Answer 21

Giant cell arteritis
Inflammatory granulomatous arteritis
Severe headache, especially over inflamed artery regions
Artery becomes hard, tortuous, thickened, with the scalp over inflamed region becoming red.
Associated facial pain and visual problems

Severe malaise and tiredness

Question 22

CT vs MRI?

Answer 22

CT better for bone, MRI for soft tissues
CT 5 mins, MRI 30 mins
CT ionising radiation
CT - differentiate areas of hard and soft tissue, MRI differentiates between different soft tissue

Question 23

What is EEG?

Answer 23

• Electroencephalogram (EEG) – useful in identifying abnormal brain activity, often abnormal in epilepsy (even interictal), encephalitis, dementia and some metabolic states

Question 24

What are evoked potentials?

Answer 24

monitoring the electrical potentials in the spinal cord or cortex following stimulation of afferent pathways – delays in the response to the evoked potentials can indicate pathologies

o	Visual evoked response (VER) – monocular stimulation and measuring potentials in the scalp above the occipital cortex. Delay indicates optic neuropathy.
o	Auditory – monoaural stimulation and recording potentials at the vertex of the scalp. Useful in assessing auditory function in those who cannot co-operate with an audiologist.
o	Somatosensory (SEP – somatic evoked potentials) – electrical stimulation of a peripheral nerve is detected in the somatosensory area of the cortex. Good at detecting conditions such as MS or B12 deficiency. They can also be used following trauma