Neurosurgery Flashcards Preview

► Med Misc 36 > Neurosurgery > Flashcards

Flashcards in Neurosurgery Deck (19):
1

An unconscious patient is brought into the Emergency department as an emergency. He has been assaulted with a hammer by an unknown individual.
An emergency CT scan reveals an extradural haematoma. The CT reveals a fracture through the right pterion.
Which blood vessel has bled?
(Please select 1 option)

Anterior branch of the middle meningeal artery
Maxillary artery
Middle cerebral artery
Posterior auricular artery
Posterior branch of the middle meningeal artery

Anterior branch of the middle meningeal artery


The pterion is an area of the cranium where the frontal, parietal, temporal and sphenoidal bones meet. It is the weakest part of the skull.

It is significant clinically as it overlies the anterior branch of the middle meningeal artery, which is a branch of the maxillary artery.

2

A 78-year-old gentleman is admitted on the acute medical intake having lost the use of his left arm. Within 24 hours he has made a full recovery.
ECG and echocardiography were normal. Subsequent carotid duplex USS shows a 100% stenosis of the right internal carotid artery and 72% stenosis of the left internal carotid artery.
Which of the following treatment options could be considered?
(Please select 1 option)
Left carotid bypass
Left carotid endarterectomy
Right and left endarterectomy
Right carotid angioplasty
Right carotid endarterectomy

Left carotid endarterectomy

This gentleman has had a transient ischaemic attack affecting the right side of the brain.

The right internal carotid is completely occluded and therefore any intervention should not be considered on this side.

The role of endarterectomy for asymptomatic carotid disease (as in the case on the left side) is topical with emerging evidence that it reduces the risk of future stroke.

3

A 44-year-old male, who is heavily intoxicated, is brought to the emergency department after he fell off a first floor window onto the concrete pavement. His blood pressure is 110/82 mmHg and pulse rate is 86/min. His GCS is 3.
He is noted to have bilateral periorbital haematomas and bruising over the left mastoid process. There is discharge of blood, mixed with a thin fluid, from his left nostril and left ear. Otoscopic examination of the left ear reveals blood behind the tympanic membrane.
From the options below choose the one which you think is the most likely diagnosis in this patient.
(Please select 1 option)
Basal skull fracture
Extradural haemorrhage
Le Fort II fracture
Subdural haemorrhage
Subarachnoid bleed

Basal skull fracture

This patient is most likely to have a basal skull fracture. Trauma, such as due to fall from heights and road traffic accidents, are common causes of this fracture. These fractures commonly involve the roof of the orbits, the sphenoid bone, or portions of the temporal bone.

The classical signs and symptoms of basal skull fracture include

Periorbital haematoma (raccoon eyes)
Subconjunctival haemorrhage where the posterior margins cannot be seen
Battle's sign (post auricular bruising and blood behind the eardrum, although this sign may take 24-48 hours to develop in some patients)
Rhinorrhoea/otorrhoea (blood mixed with CSF which does not clot; this is caused due to the damage to the cribriform plates).
The investigations for the diagnosis of suspected basal skull fracture (and of other serious head injuries) include CT and MRI scans.

Indications for CT scan include

A GCS less than 13
Unreliable history or examination due to alcohol and/or drug ingestion
Loss of consciousness for more than 5 minutes
Persisting/progressive headache and/or persistent vomiting
Ante- and/or retrograde amnesia
Clinical suspicion of basal skull fracture
Skull fracture with neurological signs and/or convulsions.
Patients with GCS less than 8 have a risk of respiratory compromise and hence need to be intubated.

Prophylactic antibiotics should be administered in patients with basal skull fractures to minimise the risk of developing meningitis.

Some recognised complications of basal skull fracture include

Meningitis (especially following CSF rhinorrhoea)
Facial palsy
Isolated VI nerve palsy.

4

A 45-year-old female is admitted with a subarachnoid haemorrhage.
She initially makes satisfactory progress but five days later her level of consciousness begins to deteriorate.
Which of the following is the most likely cause of the deterioration?
(Please select 1 option)
Acute hydrocephalus
Bacterial meningitis complicating lumbar puncture
Cerebral abscess
Coning of the medulla
Dural sinus thrombosis

Acute hydrocephalus

Organised blood in the subarachnoid space may cause obstruction to the flow of cerebrospinal fluid and result in hydrocephalus.

5

A 14-year-old boy bangs heads with an opponent during an unofficial football game. He is knocked out for 30 seconds and is amnesic for the event. He recovers quickly and continues playing.
Two hours later he complains of headache, begins vomiting then loses consciousness. He had a full term normal delivery with no neonatal complications. His immunisations are up to date. There is no FH/SH of note.
On examination he responds only to deep pain. He is apyrexial with respiratory rate of 10/min (irregular), pulse of 40/min. He has a large bruise in the right temporal area.
What is the most likely diagnosis?
(Please select 1 option)
Cerebral contusion
Contrecoup injury
Extradural haematoma
Subdural haematoma
Tonsillar herniation

Extradural haematoma

The history is of a closed head injury, followed by a lucid period followed by decreasing level of consciousness.

The time course suggests an extradural haematoma, where there is arterial bleeding which accumulates rapidly outside the dura causing raised intracranial pressure. Subdural haematoma in infants may accompany massive axon injury in 'Shaken baby syndrome', and presents acutely. Retinal haemorrages are often present. (Chronic subdurals due to birth trauma can present much later due to the open fontanelle.)

Epidural haematoma, typically from a torn middle meningeal artery and associated with skull fracture, accumulates much more rapidly.

There may be apparent recovery from the initial concussion, but deterioration is usually within 15-30 minutes.

6

Which of the following is true of berry aneurysms?
(Please select 1 option)
Associated with diabetes mellitus
Associated with polycystic renal disease
Most often found on the basilar artery
The result of abnormalities in the intimal layer of the artery
The result of atheroma

Associated with polycystic renal disease

Berry aneurysms are not more common in those with diabetes but are strongly associated with polycystic renal disease.

Berry aneurysms are not related to atheroma, and are dependent on genetic predisposition with physiological influences (for example, blood pressure).

Berry aneurysms most frequently arise from the circle of Willis and arise from an abnormality of the medial wall of the artery.

7

Regarding the base of the skull, which of the following is untrue?
(Please select 1 option)
Foramen ovale transmits the mandibular nerve
Foramen spinosum transmits the middle meningeal artery
Jugular foramen transmits the vagus nerve
Pterygotympanic fissure transmits the chorda tympani
Stylomastoid foramen transmits the trigeminal nerve

Stylomastoid foramen transmits the trigeminal nerve

The foramen ovale is part of the greater wing of the sphenoid and transmits the mandibular and lesser petrosal nerve.

This nerve enters the infratemporal fossa through the petrotympanic fissure and runs downward and forward to join the lingual nerve.

The foramen spinosum transmits the middle meningeal artery from the infratemporal fossa into the cranial cavity.

The jugular foramen transmits the following structures from before backward: inferior petrosal sinus, CN IX, X, XI, and the large sigmoid sinus.

The facial nerve exits the cranium via the stylomastoid foramen.

8

Which of the following is true in cervical spine trauma with an associated injury to the spinal cord?
(Please select 1 option)
Autonomic hyper-reflexia occurs in 25% of quadriplegics
Autoregulation of spinal cord blood flow will protect against moderate hypotension
Hypotension should be treated with a rapid infusion of 1 litre of colloid
Steroids have no proven benefit
Suxamethonium can be used during the first 72 hours following injury

Suxamethonium can be used during the first 72 hours following injury

Autonomic hyperreflexia is seen in 85% of quadriplegics and can develop days to weeks after an injury. It is characterised by hypertension and arrhythmias with cutaneous vasodilatation above the injury and vasoconstriction below the level of the cord lesion.

Autoregulation of blood flow to the spinal cord is the same as for the rest of the central nervous system, and is similarly abolished by trauma. The spinal cord perfusion pressure is the difference between the mean arterial pressure and the cerebrospinal fluid pressure.

The use of high-dose methylprednisolone (30 mg/kg) followed by an infusion, given within eight hours of the injury has a beneficial effect. The protective mechanism is believed to be free-radical scavenging and inhibition of lipid peroxidation. Spinal shock may last for weeks and aggressive fluid resuscitation can precipitate pulmonary oedema. Therefore, fluid administration should be titrated against the central venous pressure (CVP) or pulmonary artery occlusion pressure (PAOP).

Suxamethonium can be used safely up to 72 hours following spinal cord injury. Hyperkalaemia and cardiac arrest can occur beyond 72 hours due to the increased potassium efflux and this effect lasts for up to 12 months, or until full recovery has occurred.

9

Which of the following is true regarding the blood supply to the brain?
(Please select 1 option)
The internal carotid arteries divide into the anterior and middle cerebral arteries
The internal carotid arteries provide one third of the blood supply
The ophthalmic artery is a branch of the anterior cerebral artery
The posterior cerebral arteries are branches of the vertebral arteries
The posterior communicating artery links the two posterior cerebral arteries

The internal carotid arteries divide into the anterior and middle cerebral arteries

The arterial blood supply to the brain is provided by the two internal carotid arteries (two thirds) and the two vertebral arteries (one third).

The internal carotid artery divides into the anterior and middle cerebral arteries that supply the anterior two thirds of the cerebral hemispheres. The ophthalmic artery is a branch of the internal carotid artery (not anterior cerebral artery).

The vertebral arteries unite to form the basilar artery, which supplies the brain stem and cerebellum. The basilar artery then divides into the two posterior cerebral arteries that supply the posterior one third of the cerebral hemispheres.

The circle of Willis is formed by anastomoses linking the carotid arterial system to the vertebrobasilar system.

The anterior communicating artery links the anterior cerebral arteries and the posterior communicating arteries link the vertebrobasilar system to the carotid system. This provides a collateral blood supply should one or more of the four extracranial arteries supplying the brain become diseased.

10

Which of the following is true concerning the spinal cord?
(Please select 1 option)
Arachnoid membrane terminates at the level of second lumbar vertebra
Is continuous above with the pons
Is intimately related to the dura mater throughout its course
Receives its blood supply from the carotid arteries
Segment consists of both anterior and posterior nerve roots

Segment consists of both anterior and posterior nerve roots This is the correct answerThis is the correct answer
At the upper border of the atlas, the spinal cord is directly continuous with the medulla oblongata. Inferiorly, the cord usually extends as far as the first lumbar intervertebral disc where it terminates as the conus medullaris.

The pia mater is a highly vascular layer which closely invests the spinal cord and nerves, and surrounds the termination of the spinal cord (conus medullaris) and continues as the filum terminale as far as the posterior surface of the coccyx.

The arachnoid membrane is continuous with the cranial arachnoid through the foramen magnum and below, it ends at the level of the second sacral vertebra.

The spinal nerves are attached to the spinal cord by anterior and posterior nerve roots. The region of the spinal cord to which one pair of anterior and posterior nerve root attaches is called a spinal segment.

The spinal cord receives its arterial supply from the anterior and posterior spinal arteries which arise from the vertebral arteries and are reinforced by branches of deep cervical, intercostal and lumbar arteries.

11

Which of the following is correct regarding raised intracranial pressure after head injury?
(Please select 1 option)
Can lead to irregular respiration
Causes constriction of the ipsilateral pupil
Causes hemiparesis of the ipsilateral side
Results in rise in pulse rate and fall in blood pressure
The pressure usually rises immediately after severe head injury

Can lead to irregular respiration

In the early stages of head injury there is a non-linear relationship between an expanding haematoma and the elevation of the intracranial pressure (ICP) - that is a haematoma may expand without any significant rise in pressure.

Once this early compliance is lost, the pressure will rapidly rise. This severely jeopardises cerebral perfusion (cerebral perfusion pressure is equal to mean arterial blood pressure minus intracranial pressure).

As ICP rises, cerebrospinal fluid is driven out of the intracranial compartment - the first stage in compensation. As the ICP continues to rise, brain shifts occur within the cranial cavity.

The most important of these brain shifts is uncal transtentorial herniation or 'coning'. This causes

Impairment of conscious level
Development of an ipsilateral fixed dilated pupil (due to third nerve compression)
Hemiparesis of the contralateral side (due to compression of the cerebral peduncle), and later
Cardiovascular and respiratory abnormalities due to brain stem compression.
The agonal event is often accompanied by a rise in blood pressure and a fall in the pulse rate - Cushing's reflex.

12

Which of the following statements regarding the jugular foramen is incorrect?
(Please select 1 option)
Contains the superior ganglia of the glossopharyngeal and vagus nerve
Is medial to the carotid foramen
Is medial to the orifice of emergence of the hypoglossal nerve
Lies between the occipital and temporal bones
Transmits the inferior petrosal sinus

Is medial to the orifice of emergence of the hypoglossal nerve

The jugular foramen is a large irregular opening from the posterior cranial fossa that is bounded anteriorly by the petrous part of the temporal bone and posteriorly by the jugular notch of the occipital bone.

The jugular foramen transmits the inferior petrosal sinus, the glossopharyngeal, vagus, and accessory nerves, and the internal jugular vein.

The carotid foramen or the foramen lacerum is lateral to the jugular foramen.

The foramen lacerum is located between the basisphenoid and the apex of the petrous part of the temporal bone.

13

The intracranial pressure is decreased by which of the following?
(Please select 1 option)
A rise in the arterial pCO2
Hypoventilation
Intravenous furosemide
Placing the patient in a head-up position
The administration of sodium nitroprusside

Placing the patient in a head-up position

Mannitol is an osmotic diuretic which is used in cerebral oedema - a typical dose is 1g/kg as a 20% solution given by rapid intravenous infusion.

If the body is accelerated upward (positive g) then blood moves toward the feet and arterial pressure at the level of the head decreases.

Hyperventilation causes hypocapnia and this causes a reduction in cerebral blood flow because of the direct constrictor effect of hypocapnia on the cerebral vessels.

Sodium nitroprusside is used in hypertensive encephalopathy to reduce blood pressure. It can increase the intracranial pressure through vasodilatation.

14

Which of the following is correct regarding the lateral spinothalamic tract?
(Please select 1 option)
Carries fibres that carry information on temperature and pain
Carries fibres which terminate in the hypothalamus
Contains nerve fibres from receptors on the ipsilateral side of the body
Fibres decussate at the level of the brainstem
Half of the fibres terminate in the cerebellum

Carries fibres that carry information on temperature and pain

The lateral spinothalamic tract contains fibres that project to non-specific thalamic nuclei.

Axons carrying sensory information synapse in the dorsal horn of the spinal cord, decussate and then pass as second-order neurones to the thalamus and reticular formation. The posterior columns decussate at the brainstem.

Pain and temperature are associated with the lateral spinothalamic tract whilst the remainder of the touch fibres (not carried by the dorsal columns) is associated with the anterior (ventral) tract. They contain nerve fibres from receptors on the contralateral side of the body.

Fibres from the lateral spinothalamic tracts pass to the thalamus and reticular formation, and they have no direct path to the cerebellum.

15

Which of the following is true of the cavernous sinus?
(Please select 1 option)
Is posterior to the inferior orbital fissure
Is situated above the pituitary gland
Lies behind the body of the sphenoid bone
Transmits the maxillary branch of the trigeminal nerve
Transmits the optic nerve

Transmits the maxillary branch of the trigeminal nerve

The cavernous sinus is situated bilaterally on each side of the sella turcica on the upper body of the sphenoid bone. It lies both beneath and lateral to the pituitary gland.

Each sinus extends from the superior orbital fissure in front to the apex of the petrous part of the temporal bone behind.

Both the ophthalmic and maxillary divisions of the trigeminal nerve run forward in the lateral wall of the sinus.

Both the third and fourth cranial nerves run through the lateral wall of the sinus.

16

Which of the following is true regarding cerebrospinal fluid (CSF)?
(Please select 1 option)
Blockage of the arachnoid granulation causes non-communicating hydrocephalus
Is absorbed mainly through the arachnoid granulations in the inferior sagittal sinus
Is produced by the modified ependymal cells of the choroid plexus
The arachnoid granulation is in contact with the media of the venous sinuses
The ventricular system communicates with the subarachnoid space through the roof of the third ventricle

Is produced by the modified ependymal cells of the choroid plexus

Cerebrospinal fluid (CSF) is produced by the choroid plexuses within the lateral, third, and fourth ventricles of the brain.

Aggregates of arachnoid villi (arachnoid granulations) serve as sites where the CSF diffuses into the bloodstream.

CSF leaves the ventricular system of the brain and enters the subarachnoid space between the arachnoid and pia mater, where it cushions and nourishes the brain.

In certain areas the arachnoid projects into the venous sinuses to form arachnoid villi and is in contact with the venous endothelium.

Hydrocephalus occurs when there is obstruction (communicating hydrocephalus) to the outflow of CSF, which can occur if there is blockage of the arachnoid granulations.

17

The middle meningeal artery:
(Please select 1 option)
Ascends the anterior cranial fossa
Is a direct branch of the external carotid artery
Is a branch of the maxillary artery
Passes through the foramen lacerum
Surface markings are 3.5cm behind and 1.5cm above the mastoid process

Is a branch of the maxillary artery

The maxillary artery is a terminal branch of the external carotid. The maxillary artery further subdivides into five branches one of which is the middle meningeal artery. The meningeal artery ascends through the foramen spinosum into the middle cranial fossa. The surface markings are 3.5cm behind and 1.5cm above the zygomaticfrontal suture.

18

Which of the following is true of the pituitary gland?
(Please select 1 option)
Develops from the hindbrain vesicle
Enlargement results on pressure on the optic chiasma
Is bounded laterally by the diaphragma sellae
Is bounded medially by the body of the sphenoid bone
Is bounded superiorly by the cavernous sinus

Enlargement results on pressure on the optic chiasma

The pituitary gland is composed of an anterior lobe (adenohypophysis) and posterior lobe (neurohypophysis).

The adenohypophysis develops from the ectoderm while the neurohypophysis develops from a neuroectodermal down growth from the floor of the third ventricle.

The pituitary gland lies in its fossa (sella turcica) which is formed by the body of the sphenoid bone.

The diaphragma sellae bounds the gland superiorly and the cavernous sinuses laterally. The optic chiasma lies above and towards the back of the diaphragma sellae.

A pituitary tumour, rising upwards, presses on the lower anterior part of the chiasma and the medial sides of the optic nerves resulting in hemianopia.

19

When considering the pathophysiological response to head injury (HI) which of the following is true?
(Please select 1 option)
A linear vault fracture increases the chance of intracranial haematoma by a factor of 10
Autoregulation of cerebral blood flow in compensation for an expanding mass is described by the Monro-Kellie doctrine
Cerebral perfusion pressure is the mean arterial blood pressure (MAP) minus intracranial pressure
In a severe head injury cerebral blood flow autoregulation often remains normal
Normal cerebral blood flow is approximately 80 ml/100 g of brain/minute

Cerebral perfusion pressure is the mean arterial blood pressure (MAP) minus intracranial pressure

The calculation of cerebral perfusion pressure is based on mean arterial BP (MAP) minus intracranial pressure. A perfusion pressure of less than 70 mmHg is associated with a poor outcome.

Normal cerebral blood flow (CBF) is less than 50 ml/100 g of brain per min. Less than 25 ml/100 g/min sees a reduction in EEG activity, and at approximately 5 ml/100 g/min leads to cell death and irreversible damage. CBF auto regulation is normally markedly disturbed in a patient with a severe head injury. This makes management of a rising ICP harder. These patients are very susceptible to secondary brain injury from hypotension and hypoxia.

The Monro-Kellie doctrine states that the skull is a rigid, non-expansile box and therefore the total volume of the intracranial content must remain constant. The addition of an intracranial mass (haematoma) means that one of the other components must be reduced to keep the volume constant. Cerebrospinal fluid (CSF) and venous blood are squeezed out. Eventually this reaches a critical point when no further compensation is possible, hence a rise in intracranial pressure (ICP).

A linear vault fracture of the skull increases the risk of intracranial haematoma by approximately 400 times.