Neurosurgery

Question 1

What two intracranial areas/structures commonly calcify (can be seen on CT)?

Answer 1

pineal gland, choroid plexuses (in lateral ventricles)

Question 2

What pathology/variation is commonly found on the roof of the third ventricle? what can it cause?

Answer 2

colloid cyst; CSF obstruction –> hydrocephaly

Question 3

What is a Berg (BBS)?

Answer 3

Berg Balance Scale: functional scale; rates 14 items 0-4 (total /56) such as standing, sitting, transfers, sit-stand, and picking up items. 0-20: wheelchair, 41-56 independent.

Question 4

What is the link between aneurysms and hydrocephalus?

Answer 4

Ruptured aneurysms bleed; blood can interfere with CSF production and clearance – notably blood can ~clog arachnoid granulations

Question 5

What are major features of glioblastoma multiforme?

Answer 5

Very aggressive primary CNS tumour. Median survival w/o treatment a few months; with treatment under 2y. Rare cases have made it several years.

Question 6

Why is glioblastoma multiforme so difficult to treat, and what are recommended treatments?

Answer 6

Tumour cells progress along tracts in brain so it’s hard (impossible) to achieve totally clear margins. Treatment involves tumour resection but also adjuvant radiation and chemo; resection removes large masses of cells, but more general therapy aims to damage remaining cells that are less localized/concentrated.

Question 7

Why does resection of temporal lobe cause visual impairment, and what kind of impairment would it cause?

Answer 7

Optic tracts travel through either temporal lobe or parietal to occipital (primary visual); damage to temporal lobe can cause contralateral superior homonymous quandrantanopsia (? – “pie in the sky”, w/ same quadrant of each visual field affected; side missing is opp as side of damage)

Question 8

What are the outlets of CSF from the 4th ventricle?

Answer 8

there are 3:

• two lateral foramina (of Luschke), which go to the superior cistern (of the great cerebral vein)
• one medial foramen (of Magendie), which goes to the cisterna magna

Question 9

What is a mega cisterna magna (aside from a weird mix of dead languages)?

Answer 9

as it sounds: v large cisterna magna – space in posterior fossa, posterior to cerbellum. Filled with CSF normally. V large: often a normal variant, or an arachnoid cyst.

Question 10

How do you distinguish L5 from S1 radiculopathy?

Answer 10

Same: 45% of lumbar disc syndromes. Sciatic pattern of pain.
L5:
- Sensory (impairment?): dorsal foot to hallux.
- Motor: Extensor hallucis longus
- Reflex: medial hamstrings
S1:
- No sensory changes
- Motor: gastrocnemius, soleus (plantar flexion)
- reflex: achilles

Question 11

Pattern of L4 radiculopathy

Answer 11

<10% of lumbar disc syndromes. 
Pain: femoral
Sensory: medial leg
Motor: tibialis anterior (dorsiflexion)
Reflex: patellar

Question 12

Pattern of L5 radiculopathy

Answer 12

45% of lumbar disc syndromes.
Pain: sciatic.
Sensory: dorsal foot to hallux.
Motor: ext. hallucis longus (hallux extension ... dorsiflexion)
Reflex: Medial hamstrings

Question 13

Pattern of S1 radiculopathy

Answer 13

45% of lumbar disc syndromes.
Pain: sciatic.
Sensory: none.
Motor: gastrocnemius, soleus (plantar flexion)
Reflex: Achilles

Question 14

What is nerve claudication?

Answer 14

Discomfort/pain/numbness/weakness in one or both legs. precipitated by walking and prolonged standing. Classically relieved by a change in position or flexion of the waist (as well as rest). Common symptom of lumbar spinal stenosis.

Question 15

myelopathy

Answer 15

Any neurologic deficit related to the spinal cord.

• trauma: (acute) spinal cord injury
• inflammatory: myelitis.
• vascular: vascular myelopathy
• arthritic changes: spondylotic

Question 16

What is the most common myelopathy?

Answer 16

cervical spondylotic myelopathy (CSM): arthritic changes (spondylosis) of cervical spine –>spinal stenosis –> compression of the spinal cord.

Question 17

Presentations of cervical spondylotic myelopathy

Answer 17

• weakness (upper>lower extremity)
• decreased dexterity, loss of fine motor
• sensory changes
• UMN findings (hyperreflexia, clonus, babinski)
• funicular pain, characterized by burning and stinging +/- Lhermitte’s sign

Question 18

What is Lhermitte’s sign?

Answer 18

lightning-like sensation down the back with neck flexion. Seen in MS, cervical spondylotic myelopathy

Question 19

What is Spurling’s test?

Answer 19

Compression test of cervical nerve root. Rotation & lateral bending with vertical compressive force; radiation along affected dermatome is positive test.

Question 20

What are the approximate survival rates for acute epidural hematoma?

Answer 20

1/3 don’t make it to hospital, 1/3 don’t make it out, 1/3 survive

Question 21

Definitions of Chiari I & II malformations, & age of presentation

Answer 21

Chiari I: cerebellar tonsils lie below the level of the foramen magnum. Avg age at presentation: 15y.
Chiari II: part of cerebellar vermis, medulla, and 4th ventricle extent through foramen magnum, often to midcervical region. Present in infancy.

Question 22

How are Chiari malformations definitively diagnosed?

Answer 22

MRI

Question 23

What are clinical features of Chiari I malformations?

Answer 23

Many are asymptomatic. If symptomatic:
pain, weakness, numbness, central cord syndrome,
loss of temp sensation, foramen magnum compression syndrome, cerebellar syndrome, syringomyelia, hydrocephalus

Question 24

What are clinical features of Chiari II malformations?

Answer 24

Findings due to CN and brainstem compression.
Dysphagia, apnea, stridor, aspiration, arm weakness, downbeat nystagmus
Respiratory arrest is most common cause of mortality
Myelomeningocele and hydrocephalus v commonly associated.

Question 25

What is the treatment of Chiari I malformations?

Answer 25

If symptomatic, subocciputal craniectomy, duraplasty

Question 26

What is the treatment of Chiari II malformations?

Answer 26

If shunt, check it; consider surgical decompression via cervical laminectomy, duraplasty

Question 27

What is the cervicomedullary junction?

Answer 27

Point at which the brainstem meets the spine

Question 28

What is the obex?

Answer 28

The point at which the 4th ventricle narrows to become the central canal of the spinal cord. Caudal medulla; sensory fibres cross here.

Question 29

What are the three main treatment options for AVM, and pros/cons?

Answer 29

Surgical excision: quick, can be complete; invasive, sometimes hard to access, eg if deep
endovascular embolization: quick, less invasive; access can be hard
stereotactic radiation: noninvasive, good for asymptomatic <3cm but well localized; takes 2-3y to work! also v specific size range (too small: can’t target it), can cause inflammation etc with tissue dying slowly over time

Question 30

What is used as the embolus in endovascular embolization?

Answer 30

glue: dries v quick … have to take catheter out quick or can get stuck!
Onyx or Squid: newer, more flexibility with drying; can have issues with some catheters