Neurosurgery

Question 1

Ventricular system

Answer 1

Paired lateral ventricles
Communicate by foramin of Munro with third ventricle

Third ventircle communicates via the aqueduct to the foruth ventricle

Outflow foramina: Luschka, and Magendie connect with basal and subarachnoid spaces

Large CSF cisterns around the base of the brain (e.g. cisterna magna, cerebellopontine cistern).

Question 2

Anterior cerebral artery supplies

Answer 2

Frontal lobe and medial parts of parietal lobes

Question 3

Middle cerebral artery supplies

Answer 3

Posterior frontal region and most of temporal and parietal regions

Question 4

Posterior circulation supplies

Answer 4

Brain stem
Cerebellum
Occipital lobes
Inferior part of temporal lobes

End-arteries –> well defined stroke syndromes

Paired vertebral arteries –> basilar artery –> paired posterior cerebral arteries

Posterior cerebral arteries communicate with the anterior circulation through the posterior communicating arteries

Question 5

In a normal supine adult, ICP is the same as the CSF pressure

Answer 5

Opening pressure of LP = ICP

Question 6

Cerebral perfusion pressure (CPP)

Answer 6

= MAP - ICP

Question 7

Why do you get a brady with raised ICP?

Answer 7

Rising ICP

Cerebral perfusion pressure = MAP - ICP

To achieve CPP, MAP increases as ICP increases

Increased MAP –> reflex bradycardia

Question 8

Cerebral perfusion pressure (CPP)

Answer 8

= MAP - ICP

CPP of > 60 mmHg is generally required to sustain adequate cerebral perfusion

Question 9

Sub-falcine herniation (cingulate gyral)

Answer 9

Caused by para-sagittal mass

Ipsilateral cingulate gyrus may herniate beneath the free edge of the falx

Anterior cerebral artery may be compressed leading to hemispheric infarction
Otherwise, reduced GCS is only clinical sign

Question 10

Tentorial herniation

Answer 10

Large ipsilateral lesion

Medial part of temporal lobe is pushed down through tentorial notch –> becomes wedged between tentorial cerebelli edge and midbrain

Cerebral peduncle is pushed against sharp tenrotial edge

Midbrain and uncus become wedges at tentorium

Aqueduct is compressed , obstructing CSF flow

Obstruced venous flow –> midbrain haemorrhage

Uncul herniation:
-Falling GCS
-Motor component of GCS becomes asymmetrical
-Ipsilateral 3rd nerve palsy, dilated an ddixed pupil
-Hypertension and bradycardia
-Respiratory arrest

Question 11

Tonsillar herniation

Answer 11

Caused by a lesion in the posterior fossa. lowest part of the cerebellum pushed down into the foramen magnum and compresses the medulla.

Question 12

Uncal hernation

Answer 12

Uncul herniation:
-Falling GCS
-Motor component of GCS becomes asymmetrical
-Ipsilateral 3rd nerve palsy, dilated an ddixed pupil
-Hypertension and bradycardia
-Respiratory arrest

Question 13

Berri aneurysms

Answer 13

85% in anterior circulation

Question 14

Nimodipine

Answer 14

Medical management of SAH for vasospasm

Alonside maintaining CCP and haemodilution

Avoid hypotension and fever - associated with poorer outcome.

Question 15

Amyloid angiopathy

Answer 15

Common cause of intracerebral bleed

Question 16

Coma

Answer 16

Defined as GCS of 8 or less

Question 17

Indications for haematoma evacuation

Answer 17

> 5mm midline shift

Significant impairment of GCS

Protracted headache or vomiting

Question 18

Intracranial haematoma risk pattern

Answer 18

No skull fracrure, GCS 15 –> 1 in 6,000

Skull fracture, GCS 15 –> 1 in 30

GCS 14 or less –> 1 in 4

Question 19

Cervical spinal trauma

Answer 19

Commonly subluxation C5 on C6

Question 20

Glioblastoma

Answer 20

Grade IV

Question 21

Gliosarcomas

Answer 21

Grade IV

Question 22

Anaplastic astrocytoma

Answer 22

Grade III

Question 23

Anaplastic oligodendroglioma

Answer 23

Grade III

Question 24

Astrocytoma

Answer 24

Grade II

Question 25

Oligodendroglioma

Answer 25

Grade II

Question 26

Ependymoma

Answer 26

Grade II

Question 27

Pilocystic astrocytoma

Answer 27

Grade I

Question 28

Dysembroplastic neuroepithelial tumour

Answer 28

Grade I

Question 29

Ganglioma

Answer 29

Grade I

Question 30

Shwannomas

Answer 30

Cranial nerve tumour Nearly all affect the vestibulocochlear nerve Grows and expands within internal auditory meatus Cranial nerve VII and VIII become compressed as it grows into cerebellopontine angle Early VIII th nerve symptoms: -Progress deafness -Tinnitus -Vertigo Larger tumours may involve the trigeminal nerve, eading to diminished facial sensation, as well as the pons and cerebellum, leading to ataxia and nystagmus. Compression of fourth ventricle --> hydrocephalus

Question 31

Prostate cancer metastasis

Answer 31

Commonly mets to cranium itself NOT brain parenchyma

Question 32

Galidium contrast doesn't cross BBB so...

Answer 32

In areas of pathology there is breakdown of the BBB --> uptake by tumours Meningiomas are mesodermal in origin hence don't have BBB ---> they will take up contrast depist being only Grade I

Question 33

Brain Primary

Answer 33

Primary cerebral tumours arise from: supporting cells of the brain (gliomas) from the walls of ventricles (ependymomas) from the roof of the fourth ventricle (medulloblastomas).

Question 34

Paediatric primary brain tumours

Answer 34

Age <2: Teratomas, Astrocytomas, PTENs Occur anywhere Age 2 - 15: Usually PTENs (primitive neuroectodermal tumours) (also known as medulloblastomas when in posterior fossa), astrocytomas and ependymomas Most common site is posterior fossa

Question 35

Management of paediatric brain tumours

Answer 35

Surgery alone is not curative in High Grade tumours Combination of surgery, chemotherapy and radiotherapy used Radiotherapy not suitable for children under 3 --> damages developing brain Age 3- 8: Radiotherapy may cause loss of IQ and other neurodevelopmental delays

Question 36

Open spinal dysraphism

Answer 36

Spina bifida aperta Myelomenigocoele Open spinal defect with LMN signs, weakness and numbness below lesion and a neuropathic badder Often develop hydrocephalus post closure and require a ventriculoperitoneal shunt 90% have malformation of hindbrain: Chiari II --> respiratory and feeding difficulties Also develop scoliosis

Question 37

Closed spinal dysraphism

Answer 37

Spina bifida occulta Encompasses lesions: Lipomyelomeningoceole, meningoceole, tight filum terminale syndrome, sinus tract and intradural dermoids, split cord malformations and cuadal agenesis Often asymptomatic Later neurological deterioration or bladder dysfunction are due to tethering of the developing cord at the lesion site Mx: surgical untethering Individuals do not develop hydrocephalus and there is no association with the Chiari malformation

Question 38

Causes of hydrocephalus

Answer 38

Osbtruction - non-communication -Congenital: aqueduct stenosis -Tumour -Arachnoid adhesions or fibrosis secondary to intraventricular haemorrhage or SAH Communicationg / external -Ventricular system is patent -There is reduced flow through basal cisterns or absrobtion of CSF by arachnoid granulations --> commonly due to fibrosis post meningitis, SAH, or sagittal sinus thrombosis Over-production -Choroid plexus papilloma

Question 39

Gait ataxia, Incontinence and Cognitive decline

Answer 39

Normal pressure hydrocephalus

Question 40

Craniosynostosis

Answer 40

Premature closure of / absence of cranial suture Premature fusion of sagittal suture: Scaphocephaly Premature fusion of coronal suture: Plagiocephaly

Question 41

Dermal sinuses

Answer 41

Squamous epithelium communicate with intracranial cavity Mostly occipital region Associated with inclusion dermoids

Question 42

Complications of chronic disc herniation

Answer 42

Nerve root compression: lateral recess stenosis Cord compression: Spondylitic myelopathy Cauda equina: Lumbar canal stenosis Pain along root of compression and diminished sensation in roots below

Question 43

Mx of disc prolapse

Answer 43

If mild causing radiculopathy: conservative +/- delayed micropdiscectomy at 6 weeks If posterior rupture into canal: urgent removal and plating