Week 3 Flashcards
What are the 2 layers of Dura in the brain?
Endosteal (Periosteal)
Meningeal
At what level does the dura matter end?
S2
What is the Falx Cerebri and what are its attachments?
Sickle-shaped extension of dura matter between cerebral hemispheres (longitudinal fissure)
Attached ant. to Crista Galli
Attached post. to Tentorium Cerebelli
The anastomoses of what 2 veins form the straight sinus?
Inf. sagittal sinus + great cerebral vein
What is the Tentorium Cerebelli?
Fold of dura matter that arches like a tent above post. cranial fossa, covering cerebellum.
Lifted up by Falx Cerebri.
Supports occipital lobes of cerebral hemispheres.
Tentorial notch is only connection between supra and infra tentorial compartments
What does the post. margin of Tentorium Cerebelli enclose?
Transverse Sinuses
What does the Tentorium Cerebelli enclose where it attaches to the upper border of the petrous temporal bone?
Superior Petrosal sinuses
What is an Epidural haemorrhage and what may cause it?
Haemorrhage into the epidural space. This will not cross suture lines due to the dura being tightly attached.
Caused by rupture of meningeal a.
Surgical emergency
What is an Uncal herniation and what may be a consequence of it?
Displacement of uncus of temporal lobe into the tentorial notch.
This will compress ipsilateral crus cerebri (contains corticospinal tract) leading to contralateral motor weakness.
What may cause an Uncal herniation?
Epidural haemorrhage
What is the Diaphragma Sellae?
Formed by the tentorium cerebelli on the roof of the sella turcica, covering hypophysis, with a central aperture for hypophyseal stalk
Name all structures that pass through the Cavernous sinus
CN’s III, IV, Vi, Vii, and VI
Sympathetic fibres
Int. Carotid a.
What makes up the walls of cavernous sinus?
Lateral Wall:
Continuation of meningeal layer of dura matter from the middle cranial fossa
Roof:
Diaphragma Sellae
What sensation can dura matter perceive?
Pressure and Stretch
What part of the dura is innervated by the Ophthalmic n.?
Ant. cranial fossa
Ant. Falx Cerebri
Tentorium Cerebelli
What part of the dura is innervated by recurrent meningeal branch of Maxillary n.?
Mid. cranial fossa
Mid region of the vault
Acute meningitis involving post. cranial fossa is associated with what symptoms?
Neck rigidity and often head retraction due to reflex contraction of the post. nuchal muscles, which are supplied by cervical nerves
What are Arachnoid granulations?
Pierce the dura and enter foveola granulares.
Absorb CSF and return it to venous system via sup. sagittal sinus
What structure is present in the Subdural space?
Bridging Veins
At what vertebral level does the dura and arachnoid matter end?
S2
What structures are present in the subarachnoid space?
Cerebral Arteries
CSF
What is a subdural haemorrhage and what is the cause?
Haemorrhage in the subdural space (may cross suture lines.
Rupture of bridging veins
What is the most common cause of a subarachnoid haemorrhage?
Ruptured berry aneurysm (85%) on circle of Willis
How will a subarachnoid haemorrhage appear on a CT scan?
Blood in basal cisterns, fissures and the depths of cortical sulci
What is the name of the ligaments formed by pia matter between roots of spinal nerves?
Denticulate ligaments
At what level does pia matter close, and what does it continue as afterwards?
L1/2
Continues as Filum Terminale to S2
What are the lateral ventricles located?
Cerebral hemispheres inferior to Corpus Callosum
What structure connects the two lateral ventricles and the 3rd ventricle?
Intraventricular foramen
Where is the 3rd ventricle located?
In the diencephalon between left and right Thalamus
What structure connects the 3rd and 4th ventricle?
Cerebral Aqueduct
Where is the 4th Ventricle located?
Between pons, medulla and cerebellum
CSF leaving the ventricles travel through what structure to reach the subarachnoid space?
Lateral apertures or the median aperture (both stem from 4th ventricle and exit at the cisterna magna)
CSF is produced in what structure?
Choroid Plexus
pia matter + ependymal cells + choroidal vessels
What is Communication hydrocephalus?
Flow of CSF blocked after exiting ventricles
OR
Reduced absorption of CSF
What is Non-communicating hydrocephalus?
Flow of CSF is blocked
What is a suboccipital puncture and where would it enter?
Needle inserted in to the Cisterna magna to obtain CSF or to administer drug/vaccine
What makes the BBB?
Astrocyte foot processes
Endothelial tight junctions
Basement membrane
In what structures are there no BBB?
Area Postrema
Neurohypophysis
Pineal Gland
What can pass the blood brain barrier?
Lipophilic, non-polar molecules
Gases, water, glucose and aa’s
For how long is the BBB defective for after injury?
2 to 3 Weeks
(can be taken advantage of with contrast agents for MRI scans)
Name structures
^^^
What structures make up the Pharyngeal Apparatus?
Pharyngeal arches
Pharyngeal clefts
Pharyngeal pouches
What is an old term that may be used interchangeably with the word “Pharyngeal”?
Branchial
What Pharyngeal arch is missing in humans?
5th (only in fish)
What are Epipharyngeal Placodes?
Ectodermal thickenings, contribute to cranial nerve ganglia
What hard tissues of the cranium does the Neural crest give rise to?
Viscerocranium, Frontal, Squamous Temporal
What hard tissues of the cranium does the Paraxial mesoderm give rise to?
Parietal, Petrous Temporal, Occipital
What hard tissues of the cranium does the Lateral plate mesoderm give rise to?
Laryngeal cartilages
What CN is associated with the 1st pharyngeal arch?
Viii (Mandibular division of Trigeminal n.)
What CN is associated with the 2nd pharyngeal arch?
VII (Facial)
What CN is associated with the 3rd pharyngeal arch?
IX (Glossopharyngeal)
What CN is associated with the 4th pharyngeal arch?
X (Superior laryngeal)
What CN is associated with the 6th pharyngeal arch?
X (Recurrent laryngeal)
What pharyngeal arches does the hyoid bone originate from?
2nd (lesser horn & sup. body)
&
3rd (greater horn & lower body)
What arteries stem from the 1st Pharyngeal arch?
Maxillary & external carotid arteries
What arteries stem from the 2nd Pharyngeal arch?
Hyoid & stapedial arteries
What arteries stem from the 3rd Pharyngeal arch?
Common carotid & first part of the int. carotid arteries
What arteries stem from the left side of the 4th Pharyngeal arch?
Arch of aorta from the left common carotid to the left subclavian arteries
What arteries stem from the right side of the 4th Pharyngeal arch?
Right subclavian artery (proximal portion)
What arteries stem from the left side of the 6th Pharyngeal arch?
Left Pulmonary artery & ductus arteriosus
What arteries stem from the right side of the 6th Pharyngeal arch?
Right pulmonary artery
What is the name of the 1st pharyngeal Pouch?
Tubotympanic recess
What is formed from the Tubotympanic recess?
Eustachian tube
Tubal tonsil
Middle ear cavity
Tympanic membrane
What is formed by the 2nd pharyngeal pouch?
Palatine tonsil
Tonsillar fossa
What is formed by the 3rd pharyngeal pouch?
Inf. parathyroid gland
Thymus (migrates inferiorly)
What is formed by the 4th pharyngeal pouch?
Sup. parathyroid gland
Ultimopharyngeal body (C cells of thyroid)
The remnants of clefts 2, 3 and 4 become what structure, and what does this structure do?
Become the Cervical sinus, which usually obliterates
What happens if the Cervical sinus doesn’t obliterate?
You get a Branchial (Lateral cervical) cyst and fistula
Cyst = no connection to int. or ext. surface
Fistula = connects either ext. or int.
Located ant. to SCM
What is the path of neural crest cells?
Originate from Hind brain region divisions called rhombomeres before migrating to the pharyngeal arches
What is the pattern of neural crest cells migrating to the pharyngeal arches?
R1/2 to arch 1
R4 to arch 2
R6/7 to arches 3,4,6
What are the odds of having a Craniofacial defect at birth?
1/500
Describe Treacher Collins syndrome
Autosomal Dom.
1st / 2nd arch syndrome
Defective protein called Treacle
Failure of formation of neural crest cells and migration into 1st and 2nd pharyngeal arches
List symptoms of Treacher Collins syndrome
Abnormal eye shape
Microganthia (underdeveloped jaw)
Conductive hearing loss
Underdeveloped zygoma
Malformed ears
Describe Di George syndrome
22q11 deletion
3rd & 4th pouches fail to develop = thalamus and parathyroids defective
List Symptoms of Di George syndrome
Cardiac abnormality (especially tetralogy of fallot)
Abnormal facies
Thymic aplasia - infection prone
Cleft palate
Hypocalcaemia
What is Craniosynostosis?
Range of syndromes where cranial sutures close prematurely
FGF receptor mutations cause imbalance in mesenchymal proliferation at sutures = premature closure
What do you get with inadequate and excessive SHH function?
Cyclopia and Diprosopus
What is the most common cause of Traumatic Brain Injury (TBI)?
Falls - 47%
What is the ratio of men/women for TBI’s?
M 1.5/1.0 F
What is the treatment for TBI?
No real treatment (only for secondary stuff)
When assessed pre admission, 50% of TBI cases will have what?
SpO2 < 90%
What are the GCS score catagories?
Mild 13-15
Moderate 9-12
Severe < 8
What 3 things are assessed in a GCS?
Eye opening
Verbal response
Motor response
How do you assess eye opening in a GCS?
1-4
4. Open spontaneously
3. Open to speech
2. Open in response to pressure
1. Do not open
NT. can’t assess
How do you assess verbal response in GCS?
1-5
5. Orientated
4. Confused
3. Inappropriate words
2. Incomprehensible sounds
1. No response to verbal and physical stimuli
NT. can’t be assess
How do you assess motor response in a GCS?
1-6
6. Obeys response
5. Localises to central pain
4. Normal flexion toward source of pain
3. Abnormal flexion
2. Extension to pain
1. No response to painful stimuli
What symptoms of TBI warrant going to hospital?
Under 5 / Over 65
Amnesia
Loss of consciousness
High energy injury
Vomiting
Seizure
Bleeding / Clotting disorders
What are examples of Secondary brain injuries in TBI?
Neurotransmitter release (glutamate)
Free radical generation
Calcium mediated damage
Inflammatory response
Mitochondrial dysfunction
Early gene activation
Define Secondary Brain Injuries in the context of TBI
Secondary processes which occur at the cell & molecular level to exacerbate neurological damage
How do you minimise secondary brain injury in TBI?
Optimise Oxygenation
Optimise Cerebral Perfusion
Blood glucose
Hypocapnia / Hypercapnia
Body temp
How do you calculate Cerebral Perfusion pressure?
Mean art. pressure - Intracranial pressure
What features suggest an individual is at risk of intracranial mass?
High impact injury
Significant retrograde amnesia
History of coagulopathy
Post traumatic seizure
GCS of 12/15 or less
Clinical signs of skull fracture
What is a sign of ant. cranial fossa fracture?
Peri-orbital bruising
What is a sign of Petrous temporal bone fracture?
Battle’s sign
When should you immediately request a CT scan in TBI?
GCS<13 on initial assessment
GCS<15 two hours after injury
Open or suspected depressed skull
Any sign of Basal skull injury
Post traumatic seizure
Vomiting
Amnesia for events over 30mins before event
What are common traits of an Extradural Haematoma?
Associated w/ skull fracture
Middle meningeal a. damage
1/3 due to venous bleeding
Biconvex on scan
What are common traits of a Subdural Haemorrhage?
20-30% of brain injuries
Rupture of bridging veins
Crescentic appearance on scan
What are common traits of a Subarachnoid Haemorrhage?
Assoc. w/ ruptured aneurysm of circle of willis
More commonly caused by head injury
What are common traits of an Intracerebral Haemorrhage?
Stretching & shearing injury
Impact on inside of skull
Often contrecoup injury
What are the clinical signs of herniation (in brain)?
Dilated or unreactive pupils
Extensor posturing
Decrease in GCS of 2 or more points
What are the most common headaches?
Migraine
Muscular tension
Analgesia overuse
Systemic illness
Cervicogenic
What are some of the most serious causes of headaches?
Subarachnoid haemorrhage
Raised intercranial pressure
Low intercranial pressure
Infection - Meningitis
Temporal Arteritis
Cerebral venous sinus thrombosis
What are some treatments for Tension headaches?
-Reassure the severity (or lack there of) to the patient
-Reduce analgesia (paracetamol / ibuprofen)
-Low dose amitriptyline (10-20mg)
What kind of headache is most associated with nausea?
Migraine
What other symptoms come along with Migraines?
Photophobia, phonophobia and gut symptoms
+/- Aura (visual issues around periphery ie. scotoma)
What are the two types of Scotoma, and what are they associated with?
Black and white - Migraine
Coloured - Epilepsy
What are thought to be causes of Migraines?
Vascular and neural theories (mechanisms unclear)
Treatments for Acute Migraine?
—Triptans—
(agonists at 5HT-1b and 5HT-1d receptors)
Aspirin, paracetamol, anti-nausea (metoclopramide)
Prophylaxis for Migraines
Beta blockers, low does amitriptyline, Pizotifen
ect.
What is an example of Migraine treatment that doesn’t use medication?
Botox injection (back of neck/head)
Acupuncture
What is contraindicated in women with migraines and aura, and why?
Oral contraceptive pill due to risk of stroke
A cluster headache is a common type of what?
Trigeminal Autonomic Cephalagia (TAC)
Symptoms of Cluster headache
Unilateral often around the eye
Striking circadian rhythm, same time of day
More common in males
Symptoms of Paroxysmal hemicrania (type of TAC)
More common in women
Shorter more frequent attacks
responds to indomethacin
Treatments of TACs
Triptans
Oxygen - high dose
High dose verapamil (up to 960mg/day)
What may cause a medication overuse headache?
Using too much simple analgesia >15 days/month
or
>10 days for other acute eg. triptans
What is a thunderclap headache?
Instant or rapid onset (<60 sec) very severe pain
Possible sub-arachnoid haemorrhage
CT head for blood immediately
Can be exertional (often during sex) due to migraine from vasospasm, quickly reversible
Give examples of early morning headaches
Cervicogenic + Sleep apnoea w/ CO2 retention
Causes of Cervicogenic headache
Poor posture when sleeping
Over exertion
Spinal degeneration
Usually muscular
Causes of Sleep apnoea w/ C02 retention
Obesity
History snoring - common w/ alcohol
Treated w/ +ve pressure Oxygen (mask)
What is the presentation of raised intracranial pressure and what may be a potential cause?
Headache (mild)
Diurnal variation
Often mild nausea
Abscess or CSF blockage
Presentation of meningitis?
Fever
Rash that doesn’t leave when pressed by glass
Photophobia
Treatment for Meningitis
Benzyl penicillin
Presentation of Temporal arteritis
Never below 50 y/o
Jaw claudication (jaw pain on chewing)
How to test for Temporal arteritis?
Palpate temporal arteries for tenderness (if not tender, probably not temp arteritis)
Treatment for Temporal arteritis
Use high dose steroids early (note it is hard to get them off as they enjoy them)
Presentation of Cerebral venous sinus thrombosis
Often F on oral contraceptive pill
Headache
Raised intercranial pressure
MRI of head shows haem bilaterally and empty delta sign
Cause of low intercranial pressure
Following lumbar puncture (not immediate)
due to CSF leakage through hole left in dura
Presentation of low intercranial pressure
Headache on standing, eased w/ lying
Can develop into fits as the brain is supported less
If left can cause death
Treatment of low intercranial pressure
Blood patch for post-LP headache - stops leaking
Name all strucures
^^^
What are the functions of the basal ganglia?
-Smooth movement
-Switching behaviour
-Reward system
-Linked to thalamus, cortex, limbic system
What is the neostriatum?
Caudate nuc. + Putamen
(dorsal striatum)
What are the 2 pathways of the Motor loop?
Direct & Indirect pathways
Stimulation of the direct pathway causes what?
Movement
Stimulation of the Indirect pathway causes what?
Inhibits Movement
What receptors are present in the striatal neurons on the Direct & Indirect pathway?
D1 - Direct
D2 - Indirect
(dopamine)
What specifically happens in the direct pathway of the basal ganglia?
Cortical excitation of neostriatum leads to disinhibition of thalamic nuc.
Movement follow activation of putamen by cortical areas
What specifically happens in the indirect pathway of the basal ganglia?
Cortical excitation of neostriatum leads to inhibition of inhibitory input to subthalamus.
Activation of indirect pathway leads to inhibition of cortical areas
Give examples of clinical problems with the Basal Ganglia
Parkinson’s disease (substantia pars compacta)
Huntington’s disease - chorea (caudate)
Hemiballism (subthalamic)
Wilson’s disease (lenticular)
What are some clinical features of Parkinson’s disease?
TRAP
Tremor at rest
cogwheel Rigidity
Akinesia
Postural instability
Describe the pathophysiology of Parkinson’s
Degeneration of dopaminergic neurons of substantia pars compacta means lack of inhibition of indirect pathway, and a lack of excitation of direct pathway.
What causes Huntington’s disease?
Autosomal dom
CAG triple repeat (>40 repeats)
What structural changes are associated with Huntington’s disease?
Caudate nuc. wasting leading to increase volume of lateral ventricles
What pathway is affected in Huntington’s disease and what are the symptoms caused by such?
Indirect is affected
Hyperkinesia, dyskinesia
Inappropriate or repetitive movement
What is used to treat Huntington’s disease?
Dopamine antagonist effective in reducing involuntary movement (Chlorpromazine)
What is Wilson’s disease?
Autosomal recessive
Abnormal copper accumulation (rings in eyes)
What is an example of first line treatment for Parkinson’s?
Levodopa
combined with a dopa decarboxylase inhibitor (lowers dose needed and peripheral system side effects such a HT and nausea)
What are some long term side effects of Levodopa?
Involuntary writhing (dyskinesia) may appear within 2 years on face and limbs
Rapid fluctuations in clinical state (doing well one day, then bad the next)
Give examples of Dopamine agonists used in Parkinson’s treatment
Ropinirole
Rotigotine (transdermal patch)
Apomorphine (injection)
What is the function of MAOI in Parkinson’s disease?
Inhibition of MAO-B protects dopamine from extra neuronal degradation therefore increasing conc of Dopamine
What antiviral may be used for Parkinson’s?
Amantadine
