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Stage 3 > Neurology: Hydrocephalus, SOL > Flashcards

Neurology: Hydrocephalus, SOL Flashcards

1
Q

What causes hydrocephalus (water in the brain)?

A

Abnormal increase in the volume of CSF and size of the cerebral ventricles (ventriculomegaly)

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2
Q

What are the two types of hydrocephalus?

A

1) Obstructive hydrocephalus
2) Communicating hydrocephalus

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3
Q

How causes obstructive hydrocephalus?

A

1) CSF cannot exit the ventricular system
2) This causes dilation of the ventricles up-stream

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4
Q

Where are the places obstruction can occur in obstructive hydrocephalus and what is an example of a cause at each of these places?

A

1) Foramen of Monro e.g. colloid cysts
2) Cerebral aqueduct e.g. aqueduct stenosis - common cause
3) Fourth ventricle e.g. posterior fossa tumour

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5
Q

What causes communicating hydrocephalus?

A

CSF can exit the ventricular system but there is an obstruction to CSF absorption at the subarachnoid space

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6
Q

What are two common causes of communicating hydrocephalus?

A

1) Subarachnoid haemorrhage
2) Infective meningitis

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7
Q

How does hydrocephalus typically present?

A

Features of raised ICP e.g. early morning headache, N&V (+ ventriculomegaly on CT if obstructive)

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8
Q

How can you treat hydrocephalus?

A

Use shunts to drain the extra CSF into the heart or peritoneal cavity

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9
Q

What condition would show dilated lateral ventricles and third ventricle but relatively normal fourth ventricles (obstructive hydrocephalus) on CT scan?

A

Cerebral aqueduct stenosis (obstruction between third and fourth ventricles) - the aqueduct connects the third and fourth ventricles so the fourth ventricles will be of a relatively normal size

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10
Q

Which two ventricles does the cerebral aqueduct connect?

A

Third and fourth ventricles

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11
Q

What commonly causes cerebral aqueduct stenosis?

A

Congenital - presents in younger patients e.g. 30

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12
Q

Which type of hydrocephalus is associated with ventriculomegaly?

A

Obstructive

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13
Q

What investigation do you do for hydrocephalus?

A

CT scan

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14
Q

What treatment can be used to decrease ICP as a result of cerebral oedema?

A

Mannitol - increases cerebral blood flow

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15
Q

How can a cranial space occupying lesion present?

A

1) Prominent worsening headache - worse on waking, lying down, coughing/straining, associated with vomiting
2) Non-specific early signs of raised ICP - headache + morning N&V
3) Cranial nerve palsies - unsteadiness, double vision, abducens palsy
4) Cushing’s reflex
5) Progressive focal neurological signs e.g. subacute onset left leg weakness, increased tone, brisk reflexes
5) Advanced cases - drowsiness, seizure activity, pupillary abnormalities, bilateral papilloedema, hypertension
6) Night sweats

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16
Q

Which cranial nerve is particularly affected by space occupying lesions and why?

A

Abducens nerve (CN VI)
1) Exits the ventral pons and travels upwards before protruding forward through the cavernous sinus
2) Therefore it is compressed against the sphenoid bone as pressure from above increases

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17
Q

What are symptoms of the Cushing’s reflex?

A

1) Raised BP
2) Bradycardia
3) Abnormal breathing incl. Cheyne-Stokes respiration (cyclical episodes of apnea and hyperventilation)

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18
Q

What are the four differential diagnoses/major groups of causes of space occupying lesions?

A

1) Tumours (space occupying neoplasia) - metastatic disease and primary CNS tumours
2) Vascular lesions
3) Infective processes
4) Granulomata

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19
Q

Which primary cancers typically metastasise to the brain causing SOL?

A

Breast, lung, melanoma

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20
Q

What are the two types of primary CNS tumours?

A

1) Benign e.g. meningiomas
2) Malignant e.g. glioblastoma multiforme

21
Q

Why can all CNS tumours be life threatening (even if they are benign)?

A

Bc of the tight physical constraints of the cranial vault

22
Q

What are examples of infective processes leading to SOL?

A

1) Cerebral abscesses
2) Rarer diseases e.g. cysticercosis, amoebiasis, TB

23
Q

Which patients are more prone to intra-cerebral infections?

A

Patients who are immunosuppressed - so look for risk factors e.g. HIV

24
Q

Which investigation might be indicated in ambiguous SOL cases?

A

Biopsy of the lesion

25
Q

How do you diagnose SOL/cause of SOL?

A

Cranial imaging - MRI (brain and orbits) more useful than CT for detecting and characterising lesions

26
Q

What are neurological features of hyponatraemia alone?

A

1) Altered mental status
2) Seizures
3) Coma

27
Q

Which patients typically get idiopathic intracranial hypertension (IIH)?

A

Young and obese women (9:1) - not associated with focal neurological signs

28
Q

When should TB be considered in SOL?

A

Space occupying CNS lesions (tuberculomas) + pulmonary disease + new TB in young patient (TB more often disease of the young) + systemic features of disseminated mycobacterial disease e.g. fevers, night sweats

29
Q

What are two common findings in small cell lung cancer?

A

1) Hyponatraemia
2) Peripheral coin-shaped lesion on CXR

30
Q

Can migraine be associated with focal neurological deficits?

A

Yes - hemiplegic migraine

31
Q

What symptoms would a tumour pressing on the oculomotor nerve elicit?

A

1) Double vision
2) Abduction downwards in one eye
3) One pupil larger/dilated than other eye (due to unopposed sympathetic activity)

32
Q

What does the oculomotor nerve do?

A

1) Exits the brain at the level of the midbrain and supplies all the extraocular muscles apart from the lateral rectus and superior oblique
2) Also has efferent fibres that module pupillary size

33
Q

What is the occipital cortex?

A

The primary area of visual processing

34
Q

How would lesions/tumours pressing on the occipital cortex present?

A

1) Visual field defects
2) Seizures
3) If big enough can cause mass effect leading to dysfunction of other brain areas or hydrocephalus
- Would not cause eye movement or pupillary abnormalities

35
Q

What does the abducens nerve do?

A

Exits the brainstem at the level of the medullary-pontine border and innervates the lateral rectus muscle

36
Q

What will damage/tumour pressing on the abducens nerve cause?

A

Ipsilateral loss of gaze abduction from the midline

37
Q

Where does the optic chiasm sit?

A

Above the sella turcica

38
Q

Why do pituitary lesions grow towards the optic chiasm?

A

Pituitary lesions are often constrained in every other direction so rise out of the sella turcica, grow caudally towards the chiasm and compress it

39
Q

What do optic chiasm (pituitary) lesions result in?

A

Bitemporal hemianopia

40
Q

What would lesions/tumour pressing on the optic nerve cause?

A

Monocular visual loss (would not affect eye movements - sensory only cranial nerve)

41
Q

How might a pituitary tumour present?

A

1) Tiredness and lethargy
2) Bitemporal hemianopia
Acromegaly:
1) New onset diabetes
2) Change in voice
3) Worsening acne
4) Increasing shoe size

42
Q

What is a ring enhancing lesion on CT?

A

Area of decreased density surrounded by a bright rim from concentration of the enhancing contrast dye

43
Q

What are examples of conditions associated with ring enhancing lesions?

A

Cerebral toxoplasmosis, CNS lymphoma, cerebral abscess, glioblastoma

44
Q

What are dilated ventricles on CT caused by?

A

Obstructive hydrocephalus - blockage of CSF

45
Q

What are examples of causes of obstructive haemorrhage and dilated ventricles on CT?

A

Haemorrhage, infective processes and SOLs

46
Q

What is tonsillar herniation syndrome also known as?

A

Coning

47
Q

What are concerning features suggestive of coning e.g. due to cerebral neoplasia?

A

1) Abducens palsy
2) Hypertension

48
Q

Secondary to what type of cerebral lesion does coning usually occur?

A

Posterior fossa lesion

49
Q

What should be done if coning is suspected?

A

Urgent CT head, request neurosurgical input, acute measures to reduce ICP

Stage 3 (61 decks)

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