FRCS Flashcards
Foster Kennedy Syndrome?
Ipsilateral optic atrophy and contralateral pappilloedema.
Secondary to tumour compression and raised ICP.
Gerstmann Syndrome?
Dominant parietal lobe dysfunction, involving the angular gyrus.
Agraphia without alexia
Finger agnosia
Right to left disorientation
Acalcula
Radiological indication for decompressive hemicraniectomy in MCA stroke?
CT Head infarct involving >50% of MCA territory
+/- PCA or ACA infarct
+/- MRI restricted diffusion > 145cm3
What nerve do acoustic neuromas arise from?
Superior vestibular nerve of VIII
ATRT?
Atypical Teratoid Rhaboid tumours.
WHO grade IV.
10-20% of paediatric CNS tumours under 3 years old.
Poor prognosis with CNS metastasis.
Associated with mutated INI1 tumour suppressor gene on chromosome 22.
Grading of atlantoaxial rotatory subluxation?
Fielding and Hawkins:
I: rotation without anterior displacement of C1
- transverse ligament intact
II: rotation with 3-5mm of C1 anterior displacement
- transverse ligament damaged
III: rotation with >5mm of C1 anterior displacement
IV: posterior displacement of C2
- rare, in rheumatoid
NF1
Incidence 1/3,000 births.
Chromosome 17.
Gene product = neurofibromin.
Occasional pheochromocytoma and common scoliosis.
Malignant peripheral nerve sheath tumour = 2%
Intra medullary cord tumour = astrocytoma
NF2
Incidence 1/40,000
Autosomal dominant.
Chromosome 22.
Gene product Schwannomin/ Merlin.
Cutaneous schwannomas
Cataracts common.
Most common spinal cord tumour = ependymoma
Most common extradural tumour of clivus?
Chordoma
Two most common sites of origin for chordoma?
1) sacrum
2) clivus
CSF tumour marker positive in Germinomas?
Placental alkaline phosphotase
What tumours are associated with raised alpha fetal protein?
Embryonal carcinoma and yolk sac tumours.
Test to distinguish Primary CNS Lymphoma from other HIV mass lesions?
Fluorine-18 flurodeoxyglucose PET. Higher uptake in Primary CNS lymphoma.
Most common posterior fossa primary brain tumour in adults and children?
Adults: haemangioblastoma
Children: polycytic astrocytoma
What is the test dose for intrathecal baclofen?
50micrograms
How is spasticity graded?
Modified Ashworth scale:
0 = normal tone
1 = ‘catch and release’
1+ = catch followed by slight increase in tone
2 = increased tone throughout range of movement but passive movement easy
3 = difficulty with passive movement
4 = Rigid limb fixed in flexion or extension
Mechanism of Baclofen?
GABA-B agonist
Dermatomes of the trigeminal nerve?
Opthalmic V1: Anterior scalp, forehead, upper eyelid, cornea, nose, frontal sinus.
Maxillary V2: Lower eye lid, cheek, upper lip and gums, maxillary and ethmoid sinus
Mandibular V3: Jaw, chin, lower lip, gums and teeth
What are Hartel’s landmarks?
Percutaneous trigeminal rhizotomy.
2.5cm lateral to the mouth
Coronal plane aiming 3cm anterior to the external auditory meatus
Sagittal plane towards the ipsilateral pupil
Anatomical relations of the subthalamic nucleus
STN:
lateral to the red nucleus
medial to the internal capsule
ventral to the thalamus
dorsal to the substantia nigra
The STN is caudal in the diencephalon, close to the junction with the midbrain
What cognard grade has the highest risk of haemorrhage?
Type 2a + b
Describe the cognard grading for dural AV fistulas
Type 1: Antegrade flow in the venous sinus
Type 2a: retrograde flow in the venous sinus
Type 2b: retrograde flow with reflux into cortical vein
Type 3: Direct cortical drainage without venous ectasia
Type 4: Direct cortical drainage with venous ectasia
Type 4: Spinal venous drainage
Medial cranial nerve within the cavernous sinus
Abducens nerve VI
Serviceable hearing in acoustic neuroma
Less than 50dB in pure tone audiogram and greater than 50% in speech discrimination test
Circumventricular organs
Midline areas of increased permeability without the blood brain barrier.
7 in total
Sensory
Area postrema
Lamina terminalis
Subforniceal organ
Secretory:
Posterior pituitary
pineal gland
Subcommissural gland
Median eminence
Diastematomyelia
Disorder of gastrulation
Type 1: Hemicords in 2 separate dural scas separated by rigid osseous spur. Likely symptomatic with tethered cord, syrinx or scoliosis. Can require surgery
Type 2: Hemicords in a single dural sac. Likely asymptomatic. Associated with spina bifida
Parsonage-Turner syndrome
Brachial plexus neuritis
Causes shoulder and upper arm pain, and weakness
Spinal level targeted during spinal cord stimulation for failed back surgery syndrome
T8-T9
ASIA scale
A: Complete spinal cord injury
B: Incomplete spinal cord injury. No motor power below level but sacral sensation spared
C: Power less than 3/5 in more than 50% myotomes below level
D: Power 3/5 or better in more than 50% myotomes below level
E: Neurologically intact
Recurrent artery of Heubner
Arises from the proximal A2
Supplies the head of the caudate nucleus and anterior limb of internal capsule, anterior putamen and globus pallidus
Infarction causes contralateral hemiparesis, gaze neglect and dysarthria
Normal atlanto-dental interval
Adults < 3mm
Children < 5mm
Powers ratio
(Basion to posterior arch of C1)/ (Opisthion to anterior arch of C1)
Normal < 1
Atlanto-occipito dissociation > 1
McRae’s line
Basion to opisthion
If Odontoid peg crosses this line = basilar invagination
Chamberlain’s line
Hard palate to opisthion
Odontoid peg >3mm above the line = basilar invagination
McGregor’s line
Hard palate to caudal occipital bone
Odontoid peg >5mm above the line = basilar invagination
Klippel-Feil syndrome
Congenital fusion of 2 or more cervical vertebrae
Lesser petrosal nerve
Branch of Glossopharyngeal nerve IX
Arises from tympanic plexus in petrous bone
Passes through foramen ovale and synapses in the otic ganglion
Parasympathetic supply to the parotid gland
Fisher and modified fisher risks of vasospasm
Fisher
1: No blood visible on CT = 20% risk
2: SAH < 1mm thick = 25%
3: SAH > 1mm thick = 37%
4: IVH or ICH = 30%
Modified fisher
0: No blood visible on CT = 0%
1: Thin SAH and no IVH = 25%
2: Thin SAH and IVH = 33%
3: Thick SAH and no IVH = 33%
4: Thick SAH and IVH = 40%
Berger-Sanai classification
Insular gliomas
Separates the insula into 4 zones
Vertical is foramen of munro
Horizontal is sylvian fissure
Meyerding clasffification
Spondylolisthesis
grade I: 0-25%
grade II: 26-50%
grade III: 51-75%
grade IV: 76-100%
grade V (spondyloptosis): >100%
Name, location and function of dorsal columns
Fasciculus cuneatus is the lateral dorsal column which is for upper limb, above T6. For proprioception and fine touch sensation
Fasiculus gracilus is the medial dorsal column for lower limb, below T6. For proprioception and fine touch sensation
Is methylated or unmethylated MGMT better for prognosis in Glioblastoma?
Methylation of the promotor region will silence the MGMT gene. Therefore, the cancer cells will not be able to repair the DNA alkylation and will be sensitive to Temozolomide.
Methylated MGMT carries a better prognosis
Hypothalamic hamartomas cause
Gelastic seizures
Episodes of unprovoked laughter
Wallenberg syndrome pathophysiology
PICA infarct
Ipsilateral ataxia - inferior cerebellar peduncle
Ipsilateral facial sensory loss - trigeminal nucleus
Ipsilateral horners syndrome - descending sympathetic fibres
Contralateral loss of pain and temperature - spinothalamic tract
Vomiting and vertigo - vestibular nucleus VIII
Swallowing difficulties and hoarse voice - nucleus ambiguus/ glossopharyngeal nucleus IX and vagus X
Sensory nerve fibres
A-alpha: myelinated
Conduction speed 120m/s
Diameter 20micrometers
Proprioception
A-beta: myelinated
Conduction speed 75m/s
Diameter 12micrometers
Tactile sensation
A-delta: myelinated
Conduction speed 30m/s
Diameter 5micrometers
Pain
C: Unmyelinated
Conduction speed of 2m/s
Diameter 1micrometer
Pain
Genetic mutation in pilocytic astrocytoma
BRAF mutation
Chromosome 7
Oncogene which promotes cell proliferation
Trigeminal nucleus
Mesencephalic nucleus in midbrain - proprioception for jaw movements
Principle nucleus in pons - tactile sensation of the face
Spinal nucleus in upper cervical cord - pain and temperature (Also afferents from IX and X)
Motor nucleus in pons - mastication
Most common dermatome involved in trigeminal neuralgia
Right V2
Bill’s bar separates which 2 nerves
Facial VII anterior
Superior vestibular VIII posterior
Schwannomatosis
SMARCB1
tumour suppressor gene mutation on chromosone 22, normally regulates chromatin
Unilateral acoustic neuroma
Meningiomas
Do not get cataracts or spinal ependymomas
Brown-Sequard syndrome
Ipsilateral loss of motor power and proprioception
Contralateral loss of pain and temperature
Cavernous sinus inflow and outflow
Drain into the cavernous sinus:
Superior and inferior opthalmic veins
Superficial middle cerebral vein
Sphenoparietal sinus
Drain out of the cavernous sinus:
Inferior petrosal sinus to jugular bulb
Sperior petrosal sinus to the transverse sinus
Branches of external carotid
SALFOPSI
Superior thyroid
Ascending pharyngeal
Lingual
Facial
Occipital
Posterior auricular
Superficial temporal
Maxillary
Red nucleus
Ventral midbrain
III nerve fibres pass through it
Inhibits extensor tone
Projections to the rubrospinal tract which stimulates flexor muscles in the upper limbs
Persistent trigeminal artery
Cavernous ICA proximal to the menigohypophyseal trunk
Basilar artery between AICA and SCA
0.1-0.6% of cerebral angiograms
Usually unilateral
Persistent hypoglossal artery
Cervical segment of internal carotid artery
Basilar artery via the hypoglossal canal
0.02% of cerebral angiograms
Persistent otic artery
Petrous segment of internal carotid artery
Basilar artery via the internal acoustic meatus
Nerves within the annulus of zinn
Optic nerve II
Superior and inferior division of occulomotor nerve III
Nasociliary nerve of Opthalmic V1
Abducens VI
Nerves in the superior orbital fissure outside the annulus of zinn
Trochlear nerve IV
Frontal nerve of Opthalmic V1
Lacrimal nerve of Opthalmic V1
Solitary nucleus
Dorsomedial medulla
Receives afferents from VII, IX, X
Regulates autonomic nervous system
Mediates cough and gag reflex
Nucleus ambiguous
Ventrolateral medulla
Sends motor efferent fibres via the IX and X
for swallowing and voice
Segments of the internal carotid artery
C1 Cervical
C2 Petrous
C3 Lacerum
C4 Cavernous
C5 Clinoidal
C6 Supraclinoid
C7 Communicating
Artery arising from the Cavernous segment C5, of internal carotid artery
Meningohypophyseal artery
Gives rise to 3 branches:
inferior hypophyseal artery
Tentorial artery of Bernasconi and Cassirini
Dorsal clival artery
Arteries arising from the Supraclinoid segment C6, of internal carotid artery
Superior hypophyseal artery
Opthalmic artery
Arteries arising from the Communicating segment C7, of the internal carotid artery
Posterior communicating artery
Anterior choroidal artery
Anterior cerebral artery
A1 = proximal to ACom
Medial lenticulostriate
A2 = Distal to ACom
Recurrent artery of huebner
Orbitofrontal
Frontopolar
A3 = Once A2 divides into the callosal marginal and pericallosal
Middle cerebral artery
M1 = Sphenoidal
Anterior temporal artery
Lateral lenticulostriate
M2 = Insular
M3 = Opercular
M4 = cortical
Vertebral artery
V1 = Pre foraminol
Subclavian to C6
V2 = Foraminol
C6 to C2
V3 = Extradural
C2 to C1 and into dura
Posterior meningeal artery
V4 = Intracranial
PICA
Anterior and Posterior spinal arteries
PICA Segments
Origin to medullary olive = Anterior-medullary
Curves laterally around medulla supplying IX, X, XI = Lateral-medullary
Caudal loop, down to foramen magnum = Tonsillomedullary
Cranial loop/ choroid point, correlates with 4th ventricle = Telovelartonsillar
Hemispheric
Striae medullaris in rhomboid fossa
Part of auditory system
Separates the pons from the medulla
Evidence for treatment of ruptured aneurysms
Molyneux lancet 2002
n = 2,143
Primary end point: death or dependency/ mRS 3-6
Coiling 23%
Clipping 30%
Spinal arteries
2 paired posterior spinal arteries
1 single anterior spinal artery
Posterior supplied by multiple radicular arteries
Anterior supplied by segmental arterial supply
Watershed area is mid thoracic
Risk factors bleeding from a cerebral AVM
Previous haemorrhage
Flow aneurysm
Deep location
Deep venous drainage
Single draining vein
Diffuse morphology
Small nidus
Risk of intracranial haemmorhage for cerebral AVM
Annual risk 2-4%
After haemorrhage increases to 7-17% for 1 year
Grade of AVM size 4cm, located in the motor strip and drains into the straight sinus
Spetzler Martin:
<3cm = 1
3-6cm = 2
>6cm = 3
Non eloquent = 0
Eloquent = 1
Superficial venous drainage = 0
Deep venous drainage = 1
Galassi classification
1 limited to anterior part of middle fossa. No mass effect
2 extends into sylvian fissure and displaces the temporal lobe
3 occupies entire middle fossa, displaces parietal and frontal lobes, midline shift
Sensitivity
Odds a patient with the disease will test positive
= true positives/ (true positives+false negatives)
Specificity
Odds a patient without the disease will test negative
= true negatives/ (true negative+false positives)
Type 1 error
Rejecting the null hypothesis when it is in fact true.
p value is the probability of a type 1 error.
Type 1 error is reduced by lowering the significance level from 0.05 to 0.01
Type 2 error
Accept the null hypothesis that is in actual fact false.
Reducing the significance level from 0.05 to 0.01 increases the risk of a type 2 error.
Risk of type 2 error is minimised by increasing the sample size
Locus Coeruleus
Blue spot
Superior-lateral aspect of the rhomboid fossa
Produces noradrenaline
Musculocutaneous nerve
C5-C7
Lateral cord of brachial plexus
Motor: Biceps, Coracobrachalis, Brachalis
Sensory: lateral forearm
Axillary nerve
C5-C6
Posterior cord of brachial plexus
Motor: Teres minor, Deltoid
Sensory: Regimental badge area of arm
Radial nerve
C5-T1
Posterior cord of brachial plexus
Sensory: Posterior aspect of forearm, lateral aspect of dorsum of hand, dorsal surface of lateral 3.5 digits
Motor: Triceps and extensors in forearm
Median nerve
C6-T1
Medial and lateral cords of brachial plexus
Sensory: Palmar cutaneous nerve - lateral palm (does not pass through the carpal tunnel)
Digital cutaneous branch - lateral 3.5 digits palmar surface
Motor: Flexors of the forearm except flexor carpi ulnaris and medial aspect of flexor digitorum profundus.
Thenar muscles; opponens pollicis, flexor pollicis brevis, abductor pollicis brevis and lateral 2 lumbricals.
Ulnar nerve
C8-T1
Medial cord of brachial plexus
Sensory: Medial 1.5 fingers and medial palm
Motor: 2 flexors in forearm - Flexor carpi ulnaris and medial aspect flexor digitorum profundus
In hand - hypothenar, dorsal and palmar interossei, medial 2 lumbricals, adductor pollicus
Wartenberg’s sign
Ulnar nerve palsy
Involuntary abduction of 5th digit
Weakness of palmar interosseous muscles
Radial innervation of extensor digiti minimi is unnaposed
Pain terminology:
Dysethesia
Hyperpathia
Causalgia
Anaesthesia Dolorosa
Allodynia
Nociceptive pain
Dysethesia = unpleasant abnormal sensation, can be spontaneous or provoked
Hyperpathia = Exaggerated response to a painful stimulus, especially a repetitive painful stimulus
Causalgia = Complex regional pain syndrome type 2, results from nerve damage
Anaesthesia dolorosa = painful numbness
Allodynia = Non painful stimulus evokes pain
Nociceptive pain = damage to non neural tissue stimulates nociceptors
Osborne’s ligament
Fibrous band between the olecranon and medial epicondyle
Responsible for cubital tunnel syndrome
Meningioma
Whorling of cells
Whorling around an imaginary stem
Meningioma
Whorling of cells
Whorling around an imaginary stem
Acoustic neuroma
Antoni A = densely packed schwann cell area
Antoni B = Loosely packed schwann cell area with foamy macrophages
Acoustic neuroma
Antoni A = densely packed schwann cell area
Antoni B = Loosely packed schwann cell area with foamy macrophages
True ependymal rosettes surround an empty lumen
Perivascular rosettes surround a vessel
Both seen in Ependymoma
Hypercellular, angiogenesis, necrosis.
Glioblastoma
Microvascular proliferation is noticeable in this GBM
Microvascular proliferation is noticeable in this GBM
GBM with pseudopallisading necrosis
Verocay body pathognomonic of acoustic neuroma
Parallel rows of nuclear bodies
Verocay body pathognomonic of acoustic neuroma
Parallel rows of nuclear bodies
Array of nuclei surrounding necrosis
GBM
Incidence of craniosynostosis and proportion of different suture involvement
1 in 2,000 live births
Sagittal > Metopic > Unicoronal
Sagittal = 45-70% of cases
Metopic = 20-25%
Unicoronal = 15-20%
Lmabdoid = 1%
Most common gene mutation in craniosynostosis
FGFR
Fibroblast growth fractur receptors 1, 2, 3
Regulates osteoblast differentiation and function
Age that cranial sutures close
Metopic = 3 to 9 months
Others = adulthood
Clinical presentation in sagittal synostosis
Cranial index <75
Elongated head
Occipital bullet
Reversal of bregma/vertex ratio
Developmental delay, particularly speech and language
Raised intracranial pressure
Clinical presentation of unicoronal synostosis
Harlequin sign
Elevation of ipsilateral orbit due to superior displacement of greater wing of sphenoid
Strabismus
Forehead flattening with compensatory contralateral frontal bossing
Nasal displacement towards ipsilateral side
Ipsilateral ear displaced anteriorly
Harlequin sign
Unicoronal synostosis
Elevation of ipsilateral orbit
Gorlin syndrome
90% develops basal cell carcinoma of skin
5% develop Medulloblastoma
Tumour suppressor gene for Patched on Chromosome 9, regulates cell proliferation
Turcot syndrome
DNA mismatch repair cancer syndrome
Autosomal recessive
Familial polyposis of the colon associated with increased risk of colorectal cancer, Glioblastoma and Medulloblastoma
Evidence for Dexamethasone
Vecht Neurology 1994
RCT in 100 patients with brain metastases and oedema
No significant difference in KPS 4mg vs 16mg
Significantly more adverse effects with higher Dexamethasone dose
Mechanism of Dexamethasone
Binds to Glucocorticoid receptors which reduces inflammation
Decreases the permeability of the blood brain barrier
Half life of Dexamethasone
48 hours
Dose equivalents for Hydrocortisone, Prednisolone, Dexamethasone
Hydrocortisone 20mg
Prednisolone 5mg
=
Dexamethasone 0.75mg
Evidence for Nimodipine
Pickard 1989 BMJ
n = 550
Placebo versus Nimodipine within 96 hours of subarachnoid haemorrhage
Cerebral infarction 33% versus 22%
Poor outcome (GOS 1-3) at 3 months 33% versus 20%
No difference in re-bleeding
Mechanism of Nimodipine
Calcium channel blocker, acting on smooth muscle to cause vasodilation
Artery of Adamkiewicz
Largest radiculomedullary artery in the thoracolumbar region
anastamozes with the anterior spinal artery
Variable location
Most commonly left sided and anastamoses between T9-T12
Foix-Alajouanine syndrome
Neurological deterioration due to a spinal dural AV fistula causing venous hypertension and congestive myelopathy
Spetzler spinal vascular malformation
1 = Dural AV fistula
2 = AVM
3 = Neoplastic vascular lesion (Haemoangioblastoma or cavernoma)
Hypertensities within the anterior horn cells
cord ischaemia secondary to anterior spinal artery infarct
Obersteiner-Redlich zone
Myelin sheeth changes from glial in the central to schwann cell in the peripheral nervous system
The site of origin for acoustic neuroma
Acoustic neuroma
Rinnes positive
Air > bone conduction
Weber localises to the contralateral side
Unilateral facial weakness
Forehead movement = reduced
Asymmetry at rest = no
Eye closure = complete
House Brackman Grade II
Unilateral facial weakness
Forehead movement = minimal
Asymmetry at rest = no
Eye closure = complete
House Brackman III
Unilateral facial weakness
Forehead movement = None
Asymmetry at rest = no
Eye closure = incomplete
House Brackman IV
Unilateral facial weakness
Forehead movement = None
Asymmetry at rest = yes
Eye closure = incomplete
House Brackman V
Unilateral facial weakness
Total paralysis
House Brackman VI
Central neurocytoma
0.1% of primary brain tumours
Intraventricular, arising from the septum pellucidum
WHO grade II
Heterogenously enhancing
Synaptophysin, diagnostic in immunohistochemistry
Synaptophysin
Central neurocytoma
Colloid cyst risk score
High risk zone = 1
Age < 65 = 1
Headaches = 1
Hyperintense on FLAIR = 1
Axial diameter > 7mm = 1
Total 4+ indicates high risk of hydrocephalus and neurological deterioration
PHASES score
Population (Finish, Japanese or European/ American)
Hypertension
Age > or < 70 years
Aneurysm size
<7mm, 7-9mm, 10-19mm, >20mm
Previous aneurysmal subarachnoid haemorrhage
Location of aneurysm
ICA
MCA
ACA, PCOM, Posterior circulation
Calculates a 5 year risk of rupture. Based on data from over 8,000 patients
Functional MRI
Cortical activity increases the oxygen demand
Leading to increases cerebral blood flow and an increased ratio of oxyhaemaglobin to deoxyhaemaglobin
5 year recurrence rate for meningioma as per Simpson grading
Meningioma grade subtypes
Grade 1: Angiomatous, fibrous, Lymphoplasmacyte, secretory, metaplastic, Psammomatous, microcystic, meningothelial
Grade 2: Atypical, Choroid, Clear cell
Grade 3: Anaplastic, Rhabdoid, Papillary
Entry point for lumbar pedicle screws
Tokuhashi score
For metastatic spinal disease:
Performance status/ KPS
Number of extraspinal metastases
Number of vertebral metastases
Primary origin of cancer
Systemic metastases resectable
Neurological deficit/ Frankel
Score 0-8: Survival < 6 months
Score 9-11: Survival 6-12 months
Score 12-15: Survival >12 months
Intracranial branches of the facial nerve
Distal to the Geniculate ganglion
Greater Petrosal nerve = Lacrimal gland
Nerve to stapedius = Protected the inner ear from loud noise
Chorda Tympani = Anterior 2/3 tongue taste + parasympathetic supply to submandibular gland
Extracranial branches of the facial nerve
Stupp NEJM 2005
18-70 with histologically confirmed GBM, WHO performance 0-2
Radiotherapy alone versus Temozolomide + Radiotherapy
n = 570
Median survival 12.1 vs 14.6
months
Hazard ratio 0.63 (p<0.001)
2 years survival 10 vs 25%
7% had grade 3 or 4 haematological toxicity = Platelets < 50 or neutrophils < 1
Dome: neck 2+ favours coiling
Aspect ratio > 1.5 favours coiling
Neck width < 5mm favours coiling
Autoregulation in traumatic brain injury
Cerebral blood flow as per O2 and CO2
Define Cerebral blood flow, Cerebral perfusion pressure and Mean arterial pressure
CBF = CPP/CVR
CPP = MAP-ICP
MAP = DP + 1/3PP
Wilby Lancet 2021
Lumbar discectomy versus transforaminal epidural steroid injection
Adults with 6 weeks to 12 months of unilateral sciatica
Primary outcome was Oswestry Disability Questionnaire at 18 weeks
n = 163
No significant difference in ODQ scores
Mallucci Lancet 2019
Antibiotic vs Silver vs Silicone VP shunt
n = 1,605
Primary outcome VP shunt infection
2% vs 6% vs 6%
Shunt revised for other reason
22% vs 20 vs 18
Reduced gram positive but not gram negative infection
Save £13,500 per shunt infection avoided
Hazard ratio versus Odds ratio versus Risk ratio
Hazard ratio = Risk of an event in group 1 divided by risk of event in group 2 over a period of time
Used in clinical trials eg Survival analysis
Odds ratio = odds of event in group 1 divided by the odds of event in group 2
Used in retrospective case control studies
Risk ratio = risk of an event in group 1 divided by risk of event in group 2
Used in prospective cohort studies
Confidence interval
The outcome eg HR, RR, OR, or mean will be within this range 95 times if the study is repeated 100. If the confidence interval cross 1 in OR or HR then the result is not statistically significant.
CI becomes more narrow with increasing sample size
Knosp classication
Knosp grade 2
Knosp grade 3
Hook affect in Prolactinoma
If high number of prolactin, then the antibiodies become saturated, and therefore the antibody sandwich complex cannot be formed required in the immunoassay.
False negative.
Serial dilutions required to acquire a reliable result
Cabergoline
Dopamine agonist
Used for medical management of Prolactinoma
Normalises Prolactin levels and reduces tumour volume in 80-90% of patients
Bromocriptine not tolerated due to gastroentestinal side effects
Growth hormone increases with sleep, stress, exercise
Growth hormone decreases with hypoglyceamia
Excess growth hormone causes
Prior to closure of epiphyseal plates -> Gigantism
After closure of the epiphyseal plates -> Acromegaly
Biochemical diagnosis of Acromegaly
Oral glucose tolerance test
Performed in the morning, as exercise and stress increase growth hormone
Drink to cause hyperglycaemia which decreases growth hormone release
Measure serial growth hormone over 2 hours
Normal = Decreasing GH levels
Acromegaly + GH remains high
IGF-1 is more reliable for diagnosis acromegaly and assessing response to treatment. IGF-1 does not change with stress or exercise.
Medical treatment for Acromegaly
Somatostatin analogs
Octreotide, Lanreotide
Reduce GH and IGF-1 in 50-70%
Reduce tumour volume in 40-50%
Pterion formed by:
bones
sutures
Bones:
Greater wing of sphenoid, frontal, parietal, squamous part of temporal bone
Coronal, Squamous, sphenofrontal, sphenosquamous, sphenoparietal
Acetazolomide on ABG
Metabolic acidosis with respiratory compensation
Carbonic anhydrase inhibitor
Differentiate L5 motor deficit from a common peroneal nerve palsy
In common peroneal nerve palsy the patient can invert their foot
Ankle dorsiflexion = Deep peroneal nerve
Foot eversion = Superficial peroneal nerve
Foot inversion = Tibial nerve
Crash 3 Lancet 2019
n = 12,737
Tranexamic acid versus placebo within 3 hours of head injury
Tranexamic acid improved survival in mild-moderate head injury but not severe. The benefit was time related
Head injury related death: mild to moderate = 5-8%, severe = 39-41%
No difference in adverse events/ stroke
Meralgia Parasthetica
Lateral cutaneous nerve of the thigh
L2-L3
Sensory nerve, no motor innervation
Passes under the inguinal ligament, 2cm medial to the anterior superior iliac spine
More common in obesity
Ulnar paradox
Proximal ulnar nerve damage causes weakness of the medial half of flexor digitorum profundus
Distal ulnar nerve damage, at guyans canal, spares flexor digitorum profundus
Signs of Cushings Syndrome
Nelson Syndrome
A complication of bilateral adrenalectomy which was indicated to treat Cushings Disease
After adrenalectomy, the negative feedback on the pituitary is lost. Serum ACTH levels increase. This causes skin pigmentation and tumour progression/ increased invasiveness
Rare forms of trigeminal neuralgia
Exclusively V1 = 2%
Bilateral = 1%
C shape halo with temporal disc margin sparing
No elevation
No vessel obscuration
= Grade 1
Circumferential halo
Elevation of nasal border
No vessel obscuration
= Grade 2
Circumferential halo
Elevation of all borders
Obscuration of one vessel leaving the disc
= Grade 3
Circumferential halo
Complete elevation including the cup
Obscuration of a major vessel on the disc
= Grade 4
Circumferential halo
Complete elevation including the cup
Obscuration of all vessel on the disc and leaving the disc
= Grade 5
Papilloedema
Optic nerve sheath diameter less than 5mm is normal in adults
Occular Point of care ultrasound
Pupillary response, damage in mid brain versus pons
Types of aphasia
1) Expressive aphasia. Brocca’s area. Non-fluent. Comprehension intact.
2) Receptive aphasia. Wernicke’s area. Fluent. Comprehension impaired.
3) Conductive aphasia. Arcuate fasciculus. Fluent. Comprehension intact. Paraphasic speech and poor speech repetition.
4) Transcortical aphasia. Can be motor or sensory. Fluency and awareness of errors depends on type. Differentiated from Wernicke’s and Brocca’s aphasia as patient can repeat words.
Explain macular sparing
The occipital lobe has dual blood supply from the PCA and MCA
Parinaud’s syndrome
1) Impairment of upgaze
2) Light near dissociation. Dilated pupils that do not react to light but constrict on convergence
3) Convergence retraction nystagmus
Describe the light reflex
Inter nuclear ophthalmoplegia
Lesion within the medial longitudinal fasciculus
Unable to adduct the contralateral eye. Signal from VI nucleus to III nucleus impaired. Associated with nystagmus
Describe the course of the facial nerve
Motor examination of VII
Raise forehead - Temporal branch - Frontalis
Close eyes - Zygomatic branch - Obicularis occuli
Puff out cheeks - Buccal branch - Buccinator
Whistle - Buccal branch - Orbicularis oris
Show teeth - Buccal and Zygomatic branches - Zygomaticus major
Wrinkle chin - Marginal mandibular branch - Mentalis
Wrinkle neck - Cervical branch - Platysma
Pathophysiological mechanism for horners syndrome
Describe the different abnormalities of gait
1) Hemiplegic— spastic leg traces a semicircle due to fixed plantarflexion and extension at the knee
2) Diplegic— narrow-based, scissoring gait often due to cerebral palsy
3) Myelopathic— broad-based clumsy gait
4) Equine— high stepping gait seen in patients with foot drop due to L5 radiculopathy or common peroneal palsy
5) Myopathic— waddling gait with pelvis dropping on alternating sides 6) Parkinsonian— slow little steps marche à petits pas
7) Cerebellar— veering uncontrolled gait
8) Magnetic— feet seem to be stuck to the floor, seen in normal pressure hydrocephalus
Housefield units of different tissues
Acute blood 56 to 76
Air − 1000
Bone 1000 to 3000
Calcification 140 to 200 Cerebrospinal fluid 0
Fat − 30 to − 100
Grey matter 32 to 41
White matter (centrum semiovale) 23 to 34
Signal intensity of blood as per age, and name the products
Mechanism of floseal
Contains gelatin, calcium chloride and Thrombin
Gelatin swells and tamponades
Thrombin converts Fibrinogen into a fibrin clot
Mechanism of surgicel
Oxidised regenerated cellulose
Swells causing tamponade
Acts as a surface for platelet aggregation and fibrin deposition
Mechanism of anticoagulants
Epidemiology of diffuse low grade gliomas
DLGG are WHO grade 2 tumours including astrocytoma and oligodendroglioma
Incidence 1 in 100,000 per year
10% of all adult primary brain tumours
Median age at diagnosis is 35 years old
Clinical presentation of low grade glioma
Most commonly seizures.
Oligodendrogliomas are more likely to present with seizures
Focal deficits are rare
Absence of seizures is associated with worse prognosis
WHO grade 2: Astrocytoma
Hypercellular compared to white matter
Cellular pleomorphism
No necrosis or vascular proliferation
Monomorphic cells with uniform round nuclei surrounded by halos
Fried egg appearance
Histological artefact from formalin
How to classify low grade gliomas
Histology followed by IDH-1 and 1p19q status
Jakola Annals of Oncology 2017
Norway, 2 different regions
n = 153
Overall survival 5.8 versus 14.4 years
Classification of peripheral nerve injury
Class 1: Neuropraxia - Interruption of conduction without loss of axon continuity. Function recovers rapidly and returns to normal
Class 2: Axonotmesis - Loss of axon and myelin continuity but intact endoneurium. Variable prognosis
Class 3: Neurotmesis - Loss of all layers of nerve, severed. Prognosis poor and function unlikely to return to normal.
Gross motor function classification System GMFCS
McRae’s line runs across the foramen magnum from the basion to the opisthion, Chamberlain’s line runs from the back of
the hard palate to the posterior margin of the foramen magnum (opisthion). McGregor’s line is similar running from the palate to the lowest visible part of the occiput. The tip of the dens should be = < 3 mm above Chamberlain’s line, less than 4.5 mm above McGregor’s line and usually 5 mm below but not above McRae’s line.
Skull base angle of Boogard
Line from nasion to centre of sella joined by line from basion
Normal 125-143
Platybasia >143
Basilar kyphosis <125
Transthoracic approach for discectomy: Left or right?
High thoracic - right side approach avoids the aortic arch
T8 and below - a left sided approach avoids the liver and thoracic duct
Modic changes on MRI
MRI signal intensities for intradural extramedullary tumours
Nerve sheath tumour T1 hyper T2 hyper
Meningioma T1 iso T2 iso
Epemdymoma T1hypo T2 hyper
Myxopapillary edenymoma
Median age 35
90% of tumours arising at the conus medullaris
Upgraded in 2016 from WHO grade 1 to 2, due to high recurrence rate
Arises from filum terminale
Types of spinal lipomas
Dorsal - does not involve conus
Transitional - dorsal and involves the conus
Terminal - base of conus only, does not involve cord or nerve roots
Chaotic - ventral and dorsal with
Involvement of nerve roots
Fibromuscular dysplasia
Affects the cervical carotid in 75% and vertebrals in 15%. Disease is bilateral in 60%.
Angiography: “String of beads”
Perimesencephalic haemorrhage risk of aneurysm
5%
Haemangioblastoma blood results
Polycythaemia
Tumour secretes erythropoietin
Problem with paediatric radiotherapy in medulloblastoma
Can occur in patients younger than 3, where radiotherapy is innapropriate
Brainstem auditory evoked potential in acoustic neuroma
Delayed V wave latency on ipsilateral side
Ankylosing spondylitis
Incidence 1 in 20,000
Male: Female 3:1
90% are HLA-B27 +ve
Negative rheumatoid factor
Sacroiliitis on the X ray
Enthesopathy - inflammation of bone at the sites of ligament/ tendons/ capsule on bone. Leads to bamboo spine = bridging syndesmophyte
Schober test
Schober test
While patient standing mark a point at L5
Draw a line 10cm above and 5cm below
Patient then flexes there back to touch their toes
Normal = distance between two lines increases by 5cm+
Paget’s disease
Disorder of osteoclasts
Only 30% of Paget’s disease sites are symptomatic. Can cause bone pain or fracture
Pelvis > thoracic and lumbar spine > skull > femur
Ossification of posterior longitudinal ligament
More prevalent in Japanese (2-3%)
Hypervascular fibrosis and calcification extends into the dura
Annual growth rate of 0.6ml in AP and 4mm longitudinally
Cervical 70% Thoracic 20% lumbar 10%
Diffuse Idiopathic Skeletal Hyperostosis DISH
Usually idiopathic but can present with globus and dysphagia
Flowing osteophytic formation without degenerative changes
Sacroiliac joints are spared
Scheuermann’s kyphosis
Prevalence 1-8%. Diagnosed in ages 11-17
Anterior wedging 5+ degrees of 3+ adjacent thoracic vertebrae
Pain when thoracic kyphosis >50 degrees
Type 1: Thoracic spine only. Apex T7/T8
Type 2: Adult variation. Involves thoracolumbar spine. Scoliosis in 90%
Bertolotti’s syndrome
Hypertrophied L5 transverse process is fused with the sacrum
Prevalence 5%
Mechanism of Gamma Knife
201 Cobalt-60 sources of radiation
Principles of fractionated radiotherapy
Redistribution: Cells are most radiosensitive during M phase and are radioresistant during S phase.
Re-oxygenation: Cancer cells close to the oxygen source are killed first. Then cancer cells move from the hypoxic core towards the oxygen source, thereby increasing radiosensitivity. Indirect cytotoxic effects of ionizing radiation involves creation of reactive oxygen species.
Repair: Healthy cells repair DNA damage and therefore less likely to apoptosis. Cancer cells are less able to repair their DNA. Direct cytotoxic effect of ionizing radiation
Scalp block anatomical landmarks
Neuro toxoplasmosis
Protozoan parasite. Definitive host are cats.
Radiologically seen in basal ganglia and grey-white matter junction, often multifocal.
Diagnosis with serum IgG.
Treated medically with Sulfadiazine and Pyrimethamine.
Gradenigo’s syndrome
Otitis media, trigeminal neuralgia and VI nerve palsy
ATRT
Rhabdoid cells: Eosinophilic granular cytoplasm with eccentric nuclei
Development of rathke’s cleft cyst
Posterior pituitary forms from the neural ectoderm originating at the diencephalon.
Anterior pituitary forms from the oral ectodermal tissue called stomadeum, rathke’s pouch which migrates away from the oral cavity and then separates
Difference between pineoblastoma and pineocytoma
Pineoblastoma arise from primitive neuroectoderm, necrotic, CSF drop metastases, occur in young children, poor prognosis, hypercellular +/- rosettes, WHO grade IV
Pineocytoma arise from pineal parenchyma, don’t metastasis, solid core, occur in young adults, good prognosis, well differentiated pineocytes, WHO grade I
Anatomical risk factors for cervical cord injury in paediatrics
1 Absent uncinate processes
2 Higher water content of intervertebral discs
3 Increases stretch of ligaments
4 Proportionally larger head therefore higher fulcrum of movement
5 Odontoid is not ossified
6 Vertebral bodies are wedged
7 More horizontal orientated facets, less resistant to forward movements. In adults, facets are more oblique
8 Less muscle mass
Evidence for folic acid supplementation to prevent spina bifida
MRC study Lancet 1991
Multi national RCT
n 1,817
Women who had previously had a pregnancy with spina bifida
Folic acid = 6 cases
Placebo = 27 cases
72% relative risk reduction in mothers with previous Spina bifida pregnancy
41% relative risk reduction in first pregnancy spina bifida
Spina bifida prevention medical regime
400 micrograms of Folic Acid once daily.
Start 1 month prior to conception and continue through the 1st trimester
Trautmann triangle
Superior border = superior petrosal sinus
Posterior = sigmoid sinus
Anterior = semicircular canal
Dolenc triangle
Lateral = Occulomotor nerve
Medial = Optic nerve
Posterior = tentorial edge
Kawase triangle
Arcuate eminence (bony ridge on temporal bone which marks the superior semicircular canal)
Greater Superficial Petrosal nerve
Petrous ridge
Tolosa Hunt syndrome
Idiopathic inflammation of cavernous sinus
Painful ophthalmoplegia
Orbital pain with III, IV or VI palsy
Where does the gate control theory of pain occur
Substantia gelatinosa
The most epileptogenic primary brain tumour
DNET
DNET
Dysembryoplastic neuroepithelial tumour
WHO Grade 1
1% of primary brain tumours
Associated with cortical dysplasia
Median age 8 years old
90% present with seizures
Most commonly found in temporal lobe
Rolandic epilepsy
Consider benign. Not associated with learning difficulties
Familial
Occurs in childhood 8 years old, often resolves by adulthood
Focal seizures involving face, tongue, drooling or speech
Do not require surgery
Pathophysiology of Huntington’s disease
Huntington gene on chromosome 4
Inheritance is autosomal dominant
CAG repeats
Loss of neurons in the striatum
Reduced GABA
Excess of Dopamine
Substantia nigra
Pars reticula = GABAergic neurons = ventral
Pars compacta = Dopaminergic neurons = dorsal
STN versus GPi stimulation for Parkinson’s Disease
STN superior for rigidity, bradykinesia, tremor, off symptoms and medication reduction.
GPi superior for dyskinesia, dystonia, postural stability and mood.
Pedunculopontine nucleus DBS
Axial symptoms of Parkinson’s; gait freezing, postural instability
Gaze palsies
Lesion in the paramedian pontine reticular formation causes ipsilateral loss of eye abduction and contralateral eye adduction.
Lesion in the medial longitudinal fasciculus causes loss of ipsilateral lateral eye adduction and the contralateral eye abducts with nystagmus.
Lesion in both PPRF and MLF causes one and a half syndrome, loss of all lateral gaze movements except contralateral abduction.
How to diagnose Horner’s syndrome
Unilateral miosis, anhydrosis, ptosis.
Topical Cocaine eye drops.
Cocaine blocks reuptake or noradrenaline in the synapse, causing pupil mydriasis.
In Horner’s syndrome, there is loss of noradrenaline neruones. Therefore, the pupil does not dilate.
Adie’s syndrome
Tonic dilation of a pupil which does not react to like.
Associated with loss of tendon reflexes.
Viral infection causes damage to ciliary ganglion impairing parasympathetic supply to the eye, and also dorsal root ganglion.
Argyl Robertson syndrome
Bilaterally small pupils which do not react to like but constrict on accommodation.
Sign of neuro syphilis.
Noise induced hearing loss
Low frequency sensorineural loss - Menieres disease
High frequency sensorineural loss - presbyacusis
Superior and inferior vestibular nerve supplies
Brainstem auditory evoked potentials in acoustic neuroma
Delayed latencies, in wave V
Hitzelberger’s sign
Reduced sensation of posterior wall in external ear canal
Due to compression of the nervus intermedius of VII in acoustic neuroma
Grading haemorrhagic shock
Define ARDS
Pa02:FiO2 < 300mmHg
Ration of arterial oxygen to inspired oxygen is reduced.
Annual incidence of sudden unexpected death in epilepsy
Overall: 1 in 1,000
Medically refractory epilepsy: 1 in 200
Stereotactic radiosurgery dose for trigeminal neuralgia
90Gy to the dorsal root entry zone, near the pons
Maximum STRS dose when near the optic apparatus
Contraindicated when <3mm adjacent to optic nerve
Maximum marginal dose of 10Gy to the optic nerve
PCV chemotherapy
Procarbazine, Lomustine, Vincristine
Higher haematological toxicity than Temozolomide
Procarbazine = alkylating agent/ methylates guanine similar to Temozolamide
Lomustine = alkylating agent, causing DNA crosslinking
Vincristine is a Vinca Alkaloid, binds to tubulin. Therefore, chromosomes cannot be separated during metaphase
Identify central sulcus on sagittal MRI
cingulate sulcus joins with marginal sulcus
Marginal sulcus separates precuneus and paracentral lobule
Central sulcus is the next sulcus anterior to the marginal sulcus
Why do cerebellar lesions cause ipsilateral symptoms?
Dento-rubro-thalamic tract.
Dentate nucleus within the cerebellum sends afferent neurons via the superior cerebellar peduncle and decussate at the red nucleus and terminate in the contralateral ventral lateral nucleus of the thalamus to synapse with the corticospinal tract
Therefore, there is a double decussation
Identify the central sulcus on axial MRI brain
Superior frontal sulcus joins the precentral sulcus
The next sulcus posterior is the central sulcus
Describe the pineal tumour markers
Diagnostic criteria for brainstem death testing
Cerebellar nuclei
Lateral to medial
Dentate nucleus: Afferents to the Red nucleus and thalamus for motor function
Globose and Embiloform nuclei: coordinates agaonist/ anatagonist muscle pairs
Fastigial nucleus: Afferents to vestibular system
Gamma waves: Problem solving, higher level thinking
Beta waves: Alert, busy
Alpha waves: Calm and restful awakeness
Delta waves: REM sleep
Theta waves: Non-REM sleep, seen in infants and adults with severe brain dysfunction
Why would thoracic extrinsic cord compression cause ascending sensory loss starting at the toes?
The motor and sensory tracts are arranged somatotopically, with the sacral nerves more lateral to the thoracic nerves medially.
Clinical spinal level is T10
Radiological spinal level is T7
Explain
The spinal cord is 3 segments shorter than the spinal canal
Kernohan’s phenomenen
False lateralising sign.
Midline shift causes the contralateral cerebral peduncle to compress against the contralateral tentorium, producing a motor deficit ipsilateral to the lesion.
Nerve root compressed in paracentral versus far lateral lumbar disc herniation
Paracentral disc herniation compresses the traversing nerve root whereas the far lateral compresses the exiting nerve root
Spurling’s test
Lateral flexion, slight extension and axial load the neck to the ipsilateral side of the pain, will reproduce the radicular pain, by compressing the exiting foramen
Micturition reflexes damaged in cauda equina syndrome
Somatic control is lost: Pudendal nerve S2-S4, for voluntary control of the external urethral sphincter.
Parasympathetic control is lost: S2-S4, for parasympathetic control which contracts the detrusor and relaxes the internal urethral sphincter for bladder emptying.
Define ischaemic penumbra on CT perfusion
Parenchyma with mean transit time > 6 seconds but normal cerebral blood volume 2.2-4.2ml/100g.
Cerebral blood flow <10ml/100g/minute causes irreversible infarction
Difference between vasogenic and cytotoxic oedema on CT
Both = gyral enlargement
Vasogenic = hypoattenuation in white matter only
Cytotoxic = hypoattenuation involving white and grey matter/ loss of differentiation
Stroke causing hemiballismus
PCA territory infarct damaging the contralateral subthalamic nucleus
VIM DBS inserted for Parkinson’s complicated by paraesthesia
Electrode is in ventral posterior lateral nucleus which involves spinothalamic tract.
Reposition the lead anteriorly
Hering-Breuer reflex
Inflation and deflation reflexes mediated by vagus nerve X in the medulla
Contents of the inferior orbital fissure outside the annulus of Zinn
Inferior ophthalmic vein
Infraorbital nerve
Zygomatic nerve
Splanchnic nerves
Paired myelinated nerves that pass through the sympathetic chain.
Supply sympathetic innervation via the greater and lesser splanchnic nerves, to the coeliac and mesenteric ganglions
Autonomic ganglions receiving parasympathetic efferent input from cranial nerves
Cilliary ganglion: Receives efferent from III and stimulates pupillary constriction. From midbrain, Edinger Westphalt nucleus.
Sphenopalatine ganglion: Receives efferent from VII as greater superficial petrosal nerve, stimulates lacrimation
Submandibular ganglion: Receives efferent from VII as chorda tympani, stimulates salivation in submandibular gland
Otic ganglion: Receives efferent from IX as lesser petrosal nerve, stimulates parotid gland salivation
Nervi erigentes versus pudendal nerve
Nervi erigentes are pelvic splanchnic nerves providing parasympathetic innervation to the bladder, stimulating urination by contraction of detrusor muscle and inhibition of internal vesicular sphincter. S2-S4
Pudendal nerve are somatic nerves which provide voluntary control of urinary continence by stimulating the external vesicular sphincter. S2-S4
Branches of the basilar artery
1) Pontine perforators
2) AICA
3) SCA
4) Labarynthine artery
Segments of PCA
P1) Pre communicating
- Posterior thalamoperforators
- If present, artery of percheron
P2) Ambient
- Medial posterior choroidal
- Thalamogeniculate
P3) Quadrigeminal
- Lateral posterior choroidal
P4) Calcarine
- Parieto occipital artery which anastomoses with pericallosal
Blood supply to the basal ganglia
A) Medial striate artery - ACA/ A1
B) Lenticulostriate artery - MCA/ M1
C) Thalamoperforating artery - PCA/ P1
D) Medial posterior choroid artery - PCA/ P2
E) Thalamogeniculate artery - PCA/ P2
F) Anterior choroid artery - ICA/ C7
Cerebal fasciculi
A) Superior longitudinal fasciculus. Connects frontal lobe to parietal and temporal lobes via operculum, for motor, visuospatial and memory processing
D) - Arcuate fasciculus. Connects Brocca’s and Wernicke’s area for speech and language function
E) - Inferior fronto occipital fasciculus. Connects frontal to temporal and occipital lobes for somatic language control and executive function
G) Uncinate fasciulus. Connects frontal and temporal lobe for memory and social-emotional function
a, Labyrinthine segment;
b, Greater superficial petrosal nerve;
c, Cochlea;
d, Geniculate ganglion;
e, Stapes;
f, Malleus;
g, Incus;
h, Tympanic segment of facial nerve;
i, Vertical (mastoid) segment of facial nerve;
j, Stylomastoid foramen;
k, Horizontal (lateral) semicircular canal;
l, Posterior semicircular canal;
m, Superior semicircular canal;
n, Inferior vestibular nerve;
o, Superior vestibular nerve;
p, Internal auditory canal;
q, Facial nerve;
r, Meatal foramen.
a, Caudate nucleus;
b, Putamen;
c, Globus pallidus (External segment);
d, Globus pallidus (Internal segment);
e, Substantia innominate; - nucleus of meynert. Produces acetylcholine
f, Internal capsule;
g, External capsule;
h, Extreme capsule;
i, Claustrum; - involved in behaviour
j, Amygdala;
k, Hippocampus;
l, Thalamus.
a, Anterior nucleus;
b, Ventral anterior nucleus;
c, Lateral dorsal nucleus;
d, Ventral lateral nucleus (oral part);
e, Ventral lateral nucleus (caudal part);
f, Lateral posterior nucleus;
g, Ventral posterolateral and ventral posteromedial nuclei;
h, Dorsomedial nucleus (Magnocellular);
i, Dorsomedial nucleus (Parvicellular);
j, Pulvinar;
k, Medial geniculate nucleus;
l, Lateral geniculate nucleus.
a, Edinger-Westphal nucleus;
b, Oculomotor nucleus;
c, Trochlear nucleus;
d, Trigeminal motor nucleus;
e, Abducens nucleus;
f, Facial motor nucleus;
g, Salivatory nuclei (superior);
h, Salivatory nuclei (inferior);
i, Dorsal vagal motor nucleus;
j, Nucleus ambiguous;
k, Hypoglossal nucleus;
l, Trigeminal mesencephalic nucleus;
m, Trigeminal main sensory nucleus;
n, Trigeminal spinal nucleus;
o, Dorsal cochlear nucleus;
p, Nucleus of tractus solitaries.
a, Anterior medullary velum;
b, Middle cerebellar peduncle;
c, Median sulcus of rhomboid fossa;
d, Striae medullares;
e, Foramen of Luschka;
f, Hypoglossal trigone;
g, Vagal trigone;
h, Tela choroidea (cut edge);
i, Gracile tubercle;
j, Superior cerebellar peduncle;
k, Medial eminence of fourth ventricle;
l, Facial colliculus;
m, Superior fovea;
n, Vestibular area;
o, Lateral recess;
p, Sulcus limitans;
q, Restiform body;
r, Inferior fovea;
s, Cuneate tubercle.
Evan’s index
Callosal angle
Lundberg wave
All in Normal Pressure Hydrocephalus
Maximum frontal horn diameter/ maximum internal skull diameter
Ventriculomegally = Evan’s index>0.3
Callosal angle< 90 degrees
B waves on ICP monitoring during sleep
CSF outflow resistance indicative of normal pressure hydrocephalus
> 18mmHg/ml/min
Incidence of idiopathic intracranial hypertension
general public = 0.9 in 100,000
Obese women aged 20-44 = 19 in 100,000
Radiological signs of IIH
1) Empty sella
2) Enlarged peri optic subarachnoid space
3) Flattened posterior globe
4) Tortuous optic nerve
5) transverse sinus stenosis
Differential pressure versus flow regulated valves.
Orbis sigma valve exerts a variable resistance between 5-25mmHg enabling stabilisation of flow
Difference between syringomyelia and hydromyelia
Syrinx = cavitation within the spinal cord not lined by ependymal
Hydromyelia = dilation of the central canal, lined by ependymal
The 4 theories for syrinx formation
1) Gardner’s hydrodynamic water hammer theory - hindbrain malformation obstructs foramen of magendie causes pulsatile CSF flow through the obex
2) William’s craniospinal dissociation theory causes suck and slosh - hindbrain malformation causes ball and valve mechanism. High intracranial pressure and low pressure within the central canal causes suction of CSF down the pressure gradient. During valsalva. The CSF then rebounds off the caudal cord causing a slosh effect
3) Ball and Dayan - raised CSF pressure in the spinal canal during coughing causes CSF to move through virchow robin spaces into the spinal cord to form a cyst
4) Oldfield’s piston theory - During systole the cerebellar tonsils create a downward pulsation of CSF
Chiari 1.5
Chiari 1 plus descent of the medulla
Obex lies below the foramen magnum
No spina bifida
Epidemiology of head injury
Ratio of mild: moderate: severe TBI
22: 1.5: 1
UK annual incidence of head injury attendances at emergency department = 1,500 in 100,000 per year
UK annual death due to TBI = 1 in 10,000
Complications of concussion/ mild traumatic brain injury
Mild TBI GCS 13-15 has a mortality rate <1%
Post concussion syndrome: Headache, vertigo, neuropsychiatric disorder, BPPV. Lasts up to weeks to months
Second impact syndrome: Further head injury while still symptomatic from first head injury. Loss of cerebral autoregulation leads to cerebral oedema and raised intracranial pressure.
Chronic traumatic encephalopathy: Slowly progressive cognitive decline, impulsivity, depression. Years or decades after the head injury
Seizures: Risk after concussion is low.
Guideline on evacuating an extradural haematoma
Haematoma volume > 30cm3 to be removed regardless of GCS
Evidence for drains in CSDH
Santarius. Lancet. 2009
UK RCT comparing drain versus no drain
n = 215
Recurrence rate = 9% versus 24%
6 month mortality = 8.6% versus 18.1%
Transalar herniation
Brain tissue across the greater wing of sphenoid
Steroids in traumatic brain injury evidence
CRASH study Lancet 2004
International RCT
n=10,000
Age > 16 and GCS 14 or less
48 hours methylprednisolone versus placebo
2 week mortality 21% versus 18%
Facial nerve injury higher in transverse or longitudinal mastoid fractures
transverse mastoid fractures are more likely to cause facial nerve damage
Pressure reactivity index
Intact autoregulation: Increase in blood pressure causes cerebral vasoconstriction, and fall in ICP.
Disturbed autoregulation: Changes in blood pressure lead to passive changes to ICP.
Correlation coefficient between ABP and ICP is negative when autoregulation is intact and positive when autoregulation is disturbed.
Genetic disorders associated with cerebral aneurysms
Loeys-Dietz
Adult polycystic kidney disease
Marfans syndrome
Type IV Ehlers-Danlos
Neurofibromatosis type 1
number needed to treat to create 1 patient with mRS 3 or less in craniectomy for stroke
4
Molecular difference between primary and secondary glioblastoma
Primary GBM: EGFR overexpression
Secondary GMB: IDH1 mutation
DBS inserted into Globus Pallidus interna for dystonia, complicated by visual distrubance
Withdraw the electrode as the optic radiation is caudal to the GPi
DBS inserted into VIM for tremor complicated by dysarthria and ataxia
Withdraw the electrode as the dento-rubro-thalamic tract is caudal to the VIM
Differentiating glioblastoma pseudoprogression for disease progression
Pseudoprogression: Increased ADC values due to cell death. Reduced cerebral blood flow. Low FDG uptake due to lower glucose metabolism.
More common in patients receiving Temozolomide, with methylated MGMT. Pseudoprogression is associated with a better prognosis.
Advanced radiological characteristics of GBM
Elevated regional Cerebral blood volume on perfusion MRI
Decreased NAA and increased choline/ lipid/ lactate on MR spectroscopy
Increased 18F-fluorodeoxyglucose compared to normal grey matter on PET
18F-Fluorodeoxyglucose update on PET for gliomas
WHO Grade 2 = similar to white matter, less than grey matter
WHO grade 3 = greater than white matter, similar to grey matter
WHO grade 4 = greater than white and grey matter
Role of 18F-Fluorodeoxyglucose PET in gliomas
(1) Grading tumours and estimating prognosis;
(2) Localizing the optimum biopsy site,
(3) Defining target volumes for radiotherapy (RT),
(4) Assessing response to therapy, and
(5) Detecting tumour recurrence and distinguishing it from radionecrosis.
Difference between CRW and Leksel frame
Cosman-Roberts-Wells have 0 in the middle whereas Leksell has 0 in the upper, posterior, right corner and the middle is 1000m in the x, y and z axis
DBS inhibition and stimulation of neural tissue
High frequency inhibits
Low frequency stimulates
DBS stimulation of neuronal parts at low frequency
Activated at high frequency = cell body
Activated at lower frequency = axon
Larger axons are more easily activated than smaller axons
Axons with multiple branches are activated at lower stimulus
Conventional electrodes stimulate circumferentially around however directional electrodes can be configured to spare specific tissue adjacent to the target, such as the internal capsule which is lateral to the red nucleus
Summarise the Parkinson’s Disease pathophysiology
Loss of dopaminergic neurons in the substantia nigra pars compacta
Normally dopamine from SNpc stimulates D1 receptors in the direct pathway and inhibits D2 receptors in the indirect pathway
In Parkinson’s disease there is a net over inhibition of the thalamus and projecting cortical neurons
Diagnostic imaging in Parkinson’s Disease
DAT-SPECT
Dopamine transporter
Single Photon emission CT
Reveals reduced uptake in the Putamen
In Essential tremor and drug induced Parkinsonism this would be normal
Radionucleotide used in DAT SPECT
I-123 Ioflupane
Head impulse test suggestive of vestibulo-occular reflex dysfunction - peripheral vestibular dysfunction
Corrective saccades
IDH in glioma
Isocitrate dehydrogenase
IDH 1 gene is on chromosome 2
IDH 2 gene is on chromosome 15
IDH mutation carries a favourable prognosis
Mutations occur early in oligodendroglioma and astrocytoma, seen in secondary glioblastoma
1p19q
Longer progression free survival and improved chemotherapy responsiveness in oligodendroglioma
How many dentate ligaments are there?
21 pairs
Lateral projections of cord pia that anchors to the dura
Recovery rates by 12 months after traumatic spinal cord injury as per initial ASIA scale
ASIA A = 10% will improve to an incomplete spinal cord injury B+ and 2% will improve to D
ASIA C = 70% will improve to D or E
Probability of walking 1 year after complete spinal cord injury
Complete paraplegia = 5%
Complete quadriplegia = 0%
Cervical spine fractures
1 in 10,000 per year
10% associated with a neurological injury
Clinically clearing a patient of neck trauma
Jefferson’s fracture
C1 burst fracture
Mechanism is axial loading
Atlantodental distance predicts integrity of transverse ligament
ADI <3mm in adults and <5mm in children
If transverse ligament intact then hard collar
If transverse ligament torn then halo
Hangman fractures
Levine and Edwards
Odontoid peg fractures with highest rate of non-union
Anderson and D’Lonzo type 2 fractures
25% of non-union
Treat with anterior odontoid peg screws
Unilateral versus bilateral cervical facet joint dislocation
Flexion with distraction in road traffic accidents
Unilateral jumped facet is a rotational injury
Intact cord function but nerve root compression
Manage via closed reduction with cervical traction followed by halo
X ray shows 25% anterior subluxation
Bilateral jumped facet is not rotational. High energy trauma
Spinal cord is injured
X ray shows 50+% anterior subluxation
Manage via 360 fusion
Clay shoveler fracture
Avulsion fracture of the spinous process of C spine
Most commonly C7
Tear drop fracture
Fracture of anterior inferior vertebral body
Can miss an unstable injury
MRI may show ligamentous disruption
Lateral mass screw insertion
Aiming laterally avoids the vertebral artery
Aiming cranially avoids the nerve root
Magerl’s technique
20 degrees laterally and 25 degrees cranially
Thoracolumbar fractures
AO classification
B1 = chance fracture
B3 = common in ankylosing spondylitis
A1 = osteoporotic fracture
Define the spinal level in trauma
Sensory: Lowest level with intact tactile sensation to pin prick
Motor: Lowest level with power at least 3/5
Neurological: Most cephald of the motor and sensory levels
Acute systemic complications of traumatic spinal cord injury
Neurogenic shock: Peripheral vasodilation and bradycardia due to loss of sympathetic tone. Hypotension worsens cord perfusion and ischemia - Arterial line and inotropes
Respiratory dysfunction and hospital acquired pneumonia: Aim MAP > 90mmHg
Ileus causes abdominal distension which can splint the diaphragm - NG tube and IV fluids. Neurogenic bowl - Bowel regime to empty contents
In spinal shock the bladder becomes atonic there can overfly leading to vesiculoureteric reflux and infection - insert a urethral catheter
Pressure sores can be life threatening.
Muscle catabolism, muscle atrophy and loss of nitrogen - nutritional management
Chronic systemic complications of spinal cord injury
Autonomic dysreflexia:
Headaches, blurry vision, skin flushing about spinal level. Hypertension and bradycardia after stimulus such as bladder being full. If untreated can cause myocardial infarction, brain haemorrhage and death
Venous thromboembolism
Heterotopic ossification: Bone forms in soft tissues, adjacent to joints. Limits range of movement and rehabilitation. NSAIDs. Can be resected.
Neurogenic bladder - small volume with high tone. Suprapubic catheter with urine bypassing. Detrusor external sphincter dyssynergy. Intravesicular botulin injection. Supra pubic catheter avoids genital ulceration and infection
Spasticity. Baclofen. Contracture release surgery
Pelvic incidence
PI = Pelvic tilt + sacral slope
Used to estimate sagittal balance
Sagittal imbalance predicts poor outcome after spinal fusion
Assessing sagittal balance
Sagittal vertical axis:
Draw a plumb line from the middle of C7 to S1
This should line up with the posteriosuperior edge of the sacrum
Aberrant internal carotid artery
Congenital agenesis of the cervical segment of ICA
Inferior tympanic artery from ascending pharyngeal artery to the middle ear then to the petrous ICA via carototympanic artery
Associated with a persistent stapedial artery
Presented with tinnitus
5-ala mechanism in glioblastoma
Selectively fluoresces cancer cells as their mitochondria convert 5-ALA into protoporphyrin IX
Evidence for prenatal closure of myelomeningocele
MOMS trial
Adzick. NEJM. 2011
n = 158
VP shunt in prenatal repair group = 40% versus 82% in postnatal repair
Preterm group associated with higher prematurity and wound dehiscence at delivery
Pressure volume index
Change in volume required to cause a 10x increase in ICP
PVI = 25ml in teenagers but on 8ml in infants
Grading of IVH in prematurity
ETV success score
Kulkarni JNS 2009
n = 618
overall success rate 64%
ETV failure = death related to hydrocephalus or subsequent definitive CSF diversion within 6 months.
