Headache Flashcards
Which reflex regulates MAP by adjusting cardiac output and total peripheral resistance
baroreceptor reflex
if a patient has a blood pressure of 120/80 how would you estimate their MAP
MAP = 1/3 pulse pressure + diastolic pressure
1/3 (120-80) +80
13.3 +80
93.3 mmHg
what does CPP stand for
cerebral perfusion pressure
what does ICP stand for
intracranial pressure
how is ICP measured
by inserting a pressure transducer into brain parenchyma or a catheter into the lateral ventricle
what can a fall in cerebral perfusion pressure lead to
can result in cerebral ischaemia and eventually neuronal death
how is intracranial pressure measured
by inserting a pressure transducer into the brain parenchyma or a catheter into the lateral ventricle
what does the munro Kellie doctrine state
is that the sum of volumes of brain, CSF, and intracranial blood is constant. An increase in one should cause a decrease in one or both of the remaining two.
Some examples of the blood brain barrier and diseases that can affect it
eclampsia - makes the membrane more permeable and so results in pulmonary oedema
Meningitis - makes it more permeable to toxins and some antibiotics
HIV virus - thought to cross the barrier by hiding in monocytes to cause encephalitis
equation for CPP (Cerebral perfusion pressure)
CPP = MAP - ICP MAP = 1/3 pulse pressure + diastolic
in the context of trauma what can a decrease in MAP and increase in ICP result in
a catastrophic decrease in CPP
relationship between hyper/hypocapnia and cerebral perfusion
Hypercapnia induces cerebral vasodilation and increases cerebral blood flow (CBF), and hypocapnia induces cerebral vasoconstriction and decreases CBF.
what is the cerebral metabolic rate
The cerebral metabolic rate of oxygen (CMRO2) is the rate of oxygen consumption by the brain, and is thought to be a direct index of energy homeostasis and brain health.
What is autoregulation and how does it affect cerebral blood flow and ICP?
Autoregulation of cerebral blood flow is the ability of the brain to maintain relatively constant blood flow despite changes in perfusion pressure
how does a headache occur (nerves)
The headache occurs when the 5th cranial (trigeminal) nerve is stimulated. This nerve sends impulses (including pain impulses) from the eyes, scalp, forehead, upper eyelids, mouth, and jaw to the brain.
cerebral venous thrombosis (in terms of headache)
Cerebral venous thrombosis (CVT) is an uncommon cerebrovascular disease presenting with a remarkably wide spectrum of signs and mode of onset. In all series, headache is the most frequently occurring symptom at any time, present in over 80% of cases,1 and it is also the commonest initial symptom.
what is anopsia (aka anopia)
also known as blindness, is the absence of vision due to either a structural defect of the eye(s) or the lack of the eye(s) completely.
what is a scotoma
a partial loss of vision or blind spot in an otherwise normal visual field.
what does it mean if pupils are equal and reactive to light
that shining a light into the eye causes constriction of the ipsilateral pupil (direct reflex) and of the contralateral pupil (consensual reflex)
where is CSF produced
produced by the choroid plexus mainly in the lateral ventricles of the brain
(around 500mls a day)
composition of CSF
few cells
lower protein and glucose concentrations than in plasma
Brief description of CSF fluid flow
- through foramen of munro to third ventricle
- through aqueduct of Slyvius to the fourth ventricle
- through foramina of Luschka (lateral) and foramen of Magendie (midline) into the cisterna magna behind medulla and under the cerebellum
- Cisterna magna is continuous with subarachnoid space
- CSF flows upward over the brain and is reabsorbed by arachnoid granulations into venous sinus blood
Cushioning function of the CSF
brain and CSF have almost identical specific gravity
brain floats and is cushioned by CSF
minor blows to head cause skull and brain to move simultaneously so it doesn’t get bashed against a hard surface
metabolic function of CSF
- helps ,maintain a constant environment for brain cells
- drains unwanted metabolites from venous blood
- transports hormones from one side of the brain to the other
three (basic) causes of increased ICP
- Increase in brain volume : localised space occupying lesion (tumour, abscess), generalised brain oedema (hyponatremia, hypertensive encephalopathy)
- increase in blood volume: Intracerebral, subdural bleeding, vasodilation due to hypercapnia, decreased venous draining due to thrombosis , cough, head down tilt
- increase in CSF volume: hydrocephalus, meningitis
describe idiopathic intracranial hypertension
- cause unknown
- headaches worse on coughing or sneezing
- examination is normal apart from papilloedema
- refer to neurologist
- requires CT/MRI to exclude other causes of increase ICP
- lumbar puncture to measure opening pressure
brief description of hydrocephalus
what is non communicating due to? what is communicating due to?
- accumulation of CSF resulting in an increase in ICP
- Non communicating would be due to blockage somewhere between foramen of munro and foramina of Luschka and Magendie
- communicating would be due to failure to drain via the arachnoid granulations
features indicating rising ICP
- headache due to stretch receptors and nociceptors around intracranial vessels and with the dura mater, worse in the morning
- nausea and vomiting due to pressure on vomiting centres in brain stem
- visual disturbances due to raised pressure around the optic nerve
- seizure
- decreased level of consciousness from drowsy to eventual deep coma
- abnormal posturing ( decorticate and decerebrate)
- Cushing response
- Brain death when ICP exceed CPP
what is papilloedema
Papilledema is swelling of your optic nerve, which connects the eye and brain. This swelling is a reaction to a buildup of pressure in or around your brain that may have many causes.
Describe oculomotor palsy (CNIII)
A complete third nerve palsy causes a completely closed eyelid and deviation of the eye outward and downward. The eye cannot move inward or up, and the pupil is typically enlarged and does not react normally to light.
what does uncal herniation cause/what is it
herniation of part of the temporal lobe over the tentorium cerebelli and it causes ipsilateral CN III (oculomotor) palsy and a blown pupil
warning with doing a lumbar puncture in ICP
do not perform an LP in a patient with raised ICP unless they have idiopathic intracranial pressuree
describe decorticate posturing
indicates severe brain injury
flexor response spontaneously or in response to pain
M3 on glasgow coma scale
damage to upper midbrain
an abnormal posturing in which a person is stiff with bent arms, clenched fists, and legs held out straight.
describe decerebrate posturing
indicates severe brain injury
extensor response spontaneously or in response to pain
M2 on Glasgow coma scale
damage to upper pons
describe Cushing response/ reflex
- attempts to raise MAP to increase CPP and CBF
- triggered by brainstem ischaemia due to increase in ICP
- indicates that death may be imminent unless ICP reduced
- sympathetic activation causes a rise in TPR and hence increase in MAP and systolic pressure
- In response to increase in MAP the baroreceptor reflex causes a bradycardia through increased vagal parasympathetic tone
Cushings triad (in context of a head trauma)
- Decreased heart rate
- increased systolic blood pressure
- disordered breathing pattern with pattern of alternating apnoea and sighing
-get immediate senior help from anaesthetist, intensivist and neurosurgeon to decrease ICP
what is mononuclear vision loss and where is the lesion located
Loss of vision in one eye
Lesion is in optic nerve (right after the eye)
what is bitemporal hemianopia and where is the lesion located
visual loss of half in both eyes
For example: loss of left half in left eye and right half in right eye
lesion is in the optic chiasm - where the optic nerves meet
what is contralateral hemianopia and where is the lesion located
visual loss of half in both eyes
for example: loss of half left in left eye and half left in right eye
lesion can be in the optic tract ( after optic chiasm) or optic radiations
another name for idiopathic intracranial pressure
pseudotumour cerebri
difference between intracranial and intracerebral
The former refers to all bleeding occurring within the skull, while the latter indicates bleeding within the brain parenchyma.
difference between extradural, subdural and subarachnoid
extradural is on the outside of the natural covering of the brain (‘dura mater’)
subdural is on the inner surface of the dura
subarachnoid is under the arachnoid layer
stroke vs infarct
stroke is the sudden onset neurological onset whereas an infarct is what causes the stroke
what is an incidentaloma
victim of medical imaging technology
find something even when not looking for it
Saccular (berry) aneurysm
Berry (saccular) aneurysms are the most common type of intracranial aneurysm, representing 90% of cerebral aneurysms. Generally speaking, there is a ballooning arising from a weakened area in the wall of a blood vessel in the brain.
Saccular aneurysms are rounded berrylike outpouchings that arise from arterial bifurcation points, most commonly in the circle of Willis
Charcot-Bouchard aneurysm
Charcot-Bouchard aneurysms are minute aneurysms (microaneurysms) in the brain that occur in small penetrating blood vessels with a diameter that is less than 300 micrometers. The most common vessels involved are the lenticulostriate branches (LSA) of the middle cerebral artery (MCA).
examples of a intraparenchymal haemorrhage
stroke
contusion
clinical features of an intraparenchymal haemorrhage
Non-traumatic intraparenchymal hemorrhages typically present with a history of sudden onset of stroke symptoms including a headache, nausea, vomiting, focal neurologic deficits, lethargy, weakness, slurred speech, syncope, vertigo, or changes in sensation
clinical features of subarachnoid hemorrhage
A subarachnoid hemorrhage is bleeding in the space between your brain and the surrounding membrane (subarachnoid space). The primary symptom is a sudden, severe headache. The headache is sometimes associated with nausea, vomiting and a brief loss of consciousness.
clinical features of a subdural haemotoma
Headache that doesn't go away. ... Confusion and drowsiness. Nausea and vomiting. Slurred speech and changes in vision. Dizziness, loss of balance, difficulty walking. Weakness on one side of the body.
pathophysiology of a subdural haematoma
Bleeding in a SDH occurs from tearing of the bridging veins that cross from the cortex to the dural venous sinuses, which are vulnerable to deceleration injury. This subsequently leads to accumulation of blood between the dura and arachnoid and results in a gradual rise in intracranial pressure (ICP).
looks like a crescent shape on a CT
clinical features of a Extradural haematoma
typical symptoms of EDH include headache, nausea/vomiting, confusion and reduced level of consciousness. Typical clinical signs of EDH include confusion, cranial nerve deficits, motor or sensory deficits of the limbs, hyperreflexia, spasticity, upgoing plantar reflex and Cushing’s triad
pathophysiology of extradural haematoma
As the volume of blood leaking from the damaged blood vessel into the extradural space increases, it begins to strip the outer layer of the meninges, the dura mater, away from the skull. This often leads to the lemon-shaped haematoma, which is visible on CT and MRI imaging
clinical features of concussion
headache or “pressure” in head.
Nausea or vomiting.
Balance problems or dizziness, or double or blurry vision.
Bothered by light or noise.
Feeling sluggish, hazy, foggy, or groggy.
Confusion, or concentration or memory problems.
Just not “feeling right,” or “feeling down”.
clinical features of cerebral brain thrombosis
Patients with cerebral venous thrombosis (CVT) present with a remarkably wide spectrum of signs and symptoms. Most common are headaches (> 80%), seizures (approximately 40%), hemiparesis (approximately 40%), altered consciousness (15-20%), and papilledema (20-30%) [1–3].
what causes cerebral brain thrombosis
Collagen vascular diseases like lupus, Wegener’s granulomatosis, and Behcet syndrome. Obesity. Low blood pressure in the brain (intracranial hypotension) Inflammatory bowel disease like Crohn’s disease or ulcerative colitis.
define meningism
irritation of the meninges
-typically causes neck stiffness, photophobia and headache
define meningitis (presents with, caused by, which one is fatal)
inflammation of the meninges
- typically presents with fever, headache and meningism
- can be caused by bacteria, virus, fungi, parasites, non infective causes
- bacterial meningitis is fatal
define encephalitis
inflammation fo the brain parenchyma
what is meningio-encephalitis
inflammation of the brain substances and parenchyma
what is a cerebral abscess
focal collection within the brain parenchyma, which can arise as a complication of a variety of infections, trauma or surgery
what are the meninges
three connective tissue membranes that ensheath the CNS
- dura mater
- arachnoid mater
- pia mater
2 functions of the meninges
- provide a support framework for the cerebral and cranial vasculature
- acting with CSF to protect CNS from mechanical damage
viral CSF analysis (appearance, opening pressure, WBC count, glucose, protein, microbiology)
appearance - usually clear/turbid opening pressure - normal WBC - high, usually high lymphocyte glucose - high glucose protein - high microbiology - usually sterile
bacterial CSF analysis (appearance, opening pressure, WBC count, glucose, protein, microbiology)
appearance - turbid/purulent opening pressure - normal/elevated WBC - high, mainly polymorphs glucose - low protein - high microbiology - organism on gram stain
tuberculosis CSF analysis (appearance, opening pressure, WBC count, glucose, protein, microbiology)
appearance - turbid/viscous opening pressure - normal/elevated WBC - high, mainly lymphocytes glucose - low protein - high microbiology - positive Ziehls - Nielson stain
subarachnoid haemorrhage CSF analysis (appearance, opening pressure, WBC count, glucose, protein, microbiology)
appearance - blood stained (yellow) opening pressure - elevated WBC - normal/slightly increased glucose - normal protein - increased microbiology - sterile
effects of meningitis
- disrupts blood brain barrier
- increases entry of water soluble antibiotics
- raised ICP
- cerebral oedema
- increased CPP
- can lead to CSF obstruction and hydrocephalus
most common causes of meningitis in the UK
Neisseria Meningitidis
Streptococcus pnuemoniae
risk factors for community acquired meningitis
- > 65 age
- splenectomy
- complement deficiency
- alcohol excess
- HIV
- diabetes mellitus
- travel to endemic areas (Africa, Mecca)
two physically demonstrable symptoms of meningitis.
Kernig sign: Severe stiffness of the hamstrings causes an inability to straighten the leg when the hip is flexed to 90 degrees.
Brudzinski’s sign: Position the patients supine and passively flex their neck. This test is positive if this manoeuvre causes reflex flexion of the hip and knee.
contraindications to a lumbar puncture
- signs suggestive of raised ICP
- shock
- extensive or spreading purpura
- after convulsions stabilised
- clotting abnormalities
- local superficial infection at site of LP
- respiratory insufficiency
signs of raised ICP
- reduced or fluctuating levels of consciousness
- relative bradycardia and hypertension
- focal neurological signs
- abnormal posture or posturing
- unequal, dilated, or poorly responsive pupils
- abnormal “dolls eye” movement
where is LP preferentially performed
L4,5 or L3,4
what do you treat suspicion of meningiococcal infection with
benzylpenicillin or ceftriaxone
at what age is a meningiococcoal infection highest
<5 years or 15-19