CSF, Hydrocephalus, Lumbar Puncture Flashcards
1
Q
What is hydrocephalus?
A
Refers to general condition where there is an excess cerebrospinal fluid (CSF) within the intracranial space, and specifically the intraventricular spaces which cause dilation of the ventricles
2
Q
What does CSF stand for?
A
Cerebro-spinal fluid
3
Q
What does an excess of CSF cause to the ventricles in the brain?
A
Dilation
4
Q
What is majority of CSF produced by?
A
Choroid plexus
5
Q
Is the production of CSF a passive process?
A
No, is a metabolic process and requires ATP:
- Sodium is pumped into the subarachnoid space, and water follows from the blood vessels
6
Q
Where is the choroid plexus primarily located?
A
Choroid plexus is primarily located in the lateral ventricles (temporal horn roofs, and floors of bodies), posterior 3rd ventricle roof and caudal 4th ventricle roof
7
Q
How much CSF does the adult brain produce every day?
A
450-600cc’s
Normal production is the same as reabsorption
8
Q
How does normal production of CSF compare to reabsorption?
A
The same
9
Q
How if CSF distributed at any given moment?
A
At any given moment, there is about 150cc’s of CSF present in the average adult, with about 25cc of this being in the brain ventricles
So the CSF volume turns over 3 to 4 times everyday
10
Q
Describe the steps of the CSF pathway?
A
- Begins in lateral ventricle (remember there is one at each side)
- Travels through foramen of Monro into the 3rd ventricle
- Passes through the cerebral aqueduct of Sylvius into the 4th ventricle
- Passes through either of two foramina of Luschka or the single foramen of Magendie
- Flows through subarachnoid space over and around the brain and spinal cord
- Reabsorbed into venous system through numerous arachnoid granulations along the dural venous sinuses
11
Q
In what ventricle does CSF begin?
A
Lateral ventricle
12
Q
What does CSF travel through to get from the lateral ventricles to the III ventricle?
A
Foramen of Monro
13
Q
What does CSF travel through to get from III ventricle to IV ventricle?
A
Cerebral aquaduct of Sylvius
14
Q
What does CSF travel through to get from IV ventricle to subarachnoid space?
A
Either of two foramina of Luschka or single foramen of Magendie
15
Q
What is CSF reabsorbed through and into?
A
- Reabsorbed into venous system through numerous arachnoid granulations along the dural venous sinuses
16
Q
What do arachnoid granulations contain to assist with reabsorption of CSF?
A
Arachnoid granulations contain arachnoid villi which function as pressure-dependent one way valves that open when the ICP is about 3-5cm H2O greater than dural venous sinus pressure
17
Q
When do valves open to allow CSF reaborption?
A
When the ICP is about 3-5cm H2O greater than dural venous sinus pressure
18
Q
Is CSF reabsorption a passive process?
A
Yes, is driven by pressure gradient between intracranial space (ICP) and the venous system (about CVP)
19
Q
What are the two major types of hydrocephalus?
A
- Communicating hydrocephalus (CoH)
- Also known as non-obstructive hydrocephalus
- Non-communicating hydrocephalus (NCH)
- Also known as obstructive hydrocephalus
20
Q
What is communicating hydrocephalus also called?
A
Non-obstructive hydrocephalus
21
Q
What is non-communicating hydrocephalus also called?
A
Obstructive hydrocephalus
22
Q
What does CoH stand for?
A
Communicating hydrocephalus
23
Q
What does NCH stand for?
A
Non-communicating hydrocephalus
24
Q
What is a consequence of the CSF pathway being open from start to finish?
A
CSF can travel freely from the choroid plexus to the arachnoid granulations, so no obstruction and communicating hydrocephalus
25
What is the cause of communicating hydrocephalus in vast majority of cases?
Problem with CSF reabsorption (reabsorption cannot keep pace with production)
26
How does CSF production compare to reabsorption in communicating hydrocephalus?
CSF production \> resorption
27
What is the immediate consequence of CSF production being greater than reabsorption in communicating hydrocephalus?
Ventricles dilate uniformly and ICP rises
28
Most of the time communicating hydrocephalus is due to CSF production \> reabsorption, but what can be the cause sometimes?
Very rarely, overproduction of CSF (rather than under absorption) leads to disruption of the balance and development of communicating hydrocephalus
This is rare, but Choroid Plexus Papillomas have been known to present in this way
29
What is a example of a disease that causes communicating hydrocephalus due to overproduction of CSF rather than under absorption?
Choroid plexus papillomas
30
What is the presentation of communicating hydrocephalus in children?
* In young children whose cranial sutures have not yet fused can see disproportional increase in head circumference to the rest of the body or failure to thrive
* In children with fused sutures/adults manifests with symptoms of increased intracranial pressure
* Papilledema
* Gait disturbance
* 6th cranial nerve palsy
* Upgaze difficulty
31
What is the aetiology of communicating hydrocephalus?
* Infection (incidence after bacterial meningitis can approach 30%)
* Subarachnoid haemorrhage (blood and blood breakdown products cause scarring of arachnoid granulations)
* Post-operative
* Head trauma
32
What kind of infection commonly causes communicating hydrocephalus?
Bacterial meningitis
33
How can a subarachnoid haemorrhage cause communicating hydrocephalus?
Blood and blood breakdown products cause scarring of arachnoid granulations
34
How does the severity of communicating hydrocephalus vary?
Communicating hydrocephalus is thought of as a gentle disruption between production and resorption of CSF that occurs over time, sometimes there is a sizable insult that causes acute disruption of balance and CSF resorption is suddenly and dramatically reduced
35
What happens to patients when communicating hydrocephalus develops quickly such as due to a rupture aneurysm impairing a significant number of arachnoid granulations?
Neurological decline can be rapid with patients becoming sleepy then obtunded, then requiring intubation
36
When does non-communicating hydrocephalus occur?
Occurs whenever there is any physical obstruction to normal flow of CSF before it leaves the ventricles
37
What is the aetiology of non-communicating hydrocephalus?
* Aqueductal stenosis
* Tumours/cancers/masses
* Cysts
* Infection
* Haemorrhage/haematoma
* Congenital malformations/conditions
38
What typically causes gradual development of non-communicating hydrocephalus and what causes acute development?
Gradual - processes that have developed over time
Acute - intraventricular bleed
39
In terms of mental status, what is acute hydrocephalus associated with?
Rapid mental status decline
40
What can be seen in a radiography for hydrocephalus?
Earliest finding is dilation of temporal horns of the lateral ventricles
In most younger patients these should be almost invisible
The third ventricle will become ballooned
Lateral ventricle size increase
Peripheral sulci effaced
41
What evans ratio indicates hydrocephalus?
30% (0.3)
42
What ventricular index indicates hydrocephalus?
\>50
43
What is Evans ratio?
Ratio of the maximum width of the anterior horns of the lateral ventricles to the maximum width of the calvarium at the same level of the foramen of Monro
44
An Evans ratio of what indicates ventriculomegaly?
0.3
45
What is the general treatment for hydrocephalus?
Surgery
46
What is the treatment of acute hydrocephalus (whether communicating or non-communicating) usually?
Placement of an external ventricular drain (EVD) which is a catheter passes through the patients scalp and skull into lateral ventricle
47
What does EVD stand for?
External ventricular drain
48
Explain how a EVD works?
Drains CSF to collection system next to patients bed
49
Is EVD a permanent solution to hydrocephalus?
* EVD cannot be maintained indefinitely, a permanent shunt may be required
50
Risk of what is high with EVD?
Infection risk during EVD is high
51
What is the main treatment for communicating hydrocephalus?
Shunt placement
52
What are the different kinds of shunt placement for hydrocephalus?
* Venticulo-peritoneal is most used
* Lumbar-peritoneal sometimes used though over drainage is a problem
* Ventriculo-atrial can also be considered in cases of peritoneal failure
53
What kind of shunt placement is most common for communicating hydrocephalus?
Ventriculo-peritoneal
54
What is step 1 and 2 of managing communicating hydrocephalus?
1) EVD
2) Shunt
55
What is the treatment for non-communicating hydrocephalus?
Non-communicating hydrocephalus is surgical but sometimes shunt can be avoided by removing the obstructing lesion
56
What are some examples of obstructions causing non-communicating hydrocephalus?
* Colloid cyst at anterior 3rd ventricle causing ball/valve obstruction of foramen of monro
* Pineal region tumour causing compression of cerebral aqueduct
* Ependymoma blocking 4th ventricular CSF outlets
57
What often causes obstruction at anterior 3rd ventricle?
Colloid cyst causing obstruction of foramen of Monro
58
What often causes compression of cerebral aqueduct?
Pineal region tumour
59
What often blocks 4th ventricular CSF outlets?
Ependymoma
60
Other than surgery, what is another treatment option for non-communicating hydrocephalus?
Another option for NCH is third ventriculostomy:
* Often performed in conjuction with VP shunt placement
* Hole is surgically opened in floor of 3rd ventricle so CSF flows out into the interpeduncular cistern and pre-pontine space
61
Describe venticulostomy?
* Hole is surgically opened in floor of 3rd ventricle so CSF flows out into the interpeduncular cistern and pre-pontine space
62
What is incidence of shunt failure?
Incidence of shunt failure is 40% in the first year and 5% per year after the first year
50% of shunts fail by 5 years of placement
63
What are different reasons that shunts fail?
* Mechanical failure from occlusion/disconnection
* Migration
* Over drainage/underdrainage
* Infection
* Skin erosion
64
Other than communicating and non-communicating hydrocephalus, what is another kind?
Normal pressure hydrocephalus
65
What is normal pressure hydrocephalus a rare and preventable cause of?
Is a rare and preventable cause of dementia:
* Under recognition leads to patients with NPH to be diagnosed with Alzheimer’s and they never seek treatment
66
What are symptoms of normal pressure hydrocephalus?
* Hakim-Adams triad
* Urinary incontinence
* Gait disturbance
* Quickly progressive dementia
67
What does the Hakim-Adams triad consist of?
Gait deviation, dementia, and urinary incontinence
68
What investigations are done for normal pressure hydrocephalus?
* Communicating hydrocephalus on CT/MRI
* Lumbar puncture
* Symptoms improve with CSF removal
* Gait assessment
* MMSE
69
What is the treatment for normal pressure hydrocephalus?
* Programmable VP shunt placement
70
Why is LP shunt not often used to treat normal pressure hydrocephalus?
LP shunt tends to over drain and are difficult to assess
71
What is the prognosis of normal pressure hydrocephalus?
* Most likely symptoms to improve with treatment are gait, then incontinence then memory
72
What are indications for lumbar puncture?
* To obtain CSF fluid for the diagnosis of
* Meningitis
* Meningoencephalitis
* Subarachnoid haemorrhage
* Malignancy
* Diagnosis and treatment
* Idiopathic intracranial hypertension
* Other neurological syndromes
Infusion of drugs or contrast
73
What does LP stand for?
Lumbar puncture
74
What are contraindications for lumbar puncture?
* Unstable patient with CVS or respiratory instability
* Localised skin/soft tissue infection over puncture site
* Evidence of unstable bleeding disorder
* Platelets \<50000 or clotting factor deficiency
* Increased intracranial pressure
* Head CT before study if focal neurologic findings present to rule out impending cerebral mass herniation
* Do not delay antibiotics to obtain imaging studies when bacterial meningitis is strongly suspected
* Neurologic determination can occur if LP is done below level of a complete spinal subarachnoid block
* Caution in patients with Chiari malformations
75
What equipment is used for a LP?
* Anaesthetic such as
* Topical (EMLA, Elamax, Zylocaine cream)
* Lidocaine 1% with 25 gauge needle and syringe
* Povidone-iodine solution and sponge wand
* Drapes, gauze and bandages
* Manometer, stopcock and tubing in non-infant kits
* Spinal needle usually 22 gauge
* 1.5 inches for \<1 year
* 2.5 inches for 1 year to middle childhood
* 3.5 inches for older children and adolescents
* Larger for larger adolescents
* Atraumatic needles cause less spinal headaches
76
What size of spinal needle is used for a LP for someone younger than 1?
1.5 inches
77
What size of spinal needle is used for a LP for someone aged 1 to middle childhood?
2.5 inches
78
What size of spinal needle is used for a LP for older children and adolescents?
3.5 inches
79
What position is used for LP?
The position used is the lateral decubitus position:
* Apply topical anaesthetic 30-45 mins prior to procedure
* Spinal cord usually ends at L1-L2 (check) so sites for puncture are located at L3-L4 or L4-L5
* Restrain patient in lateral decubitus position
* Maximally flex spine without compromising airway
* Keep alignment of feet, knees and hips
* Position head to left if right handed or vice versa
80
What anaesthetics are used for LP?
* Anaesthetic such as
* Topical (EMLA, Elamax, Zylocaine cream)
* Lidocaine 1% with 25 gauge needle and syringe
81
Were does the spinal cord normally terminate?
L1-L2
82
What spinal level is LP normally done?
L3-L4 or L4-L5
83
Describe the lateral decubitus position?
* Maximally flex spine without compromising airway
* Keep alignment of feet, knees and hips
* Position head to left if right handed or vice versa
84
Describe the LP procedure?
1. Cleanse skin with povidone iodine from puncture site radially out to 10cm and allow to dry
2. Drape below patient and around site with fenestrated drape
3. Anesthetise with lidocaine if topical not used by
1. Intradermally raising a wheal at needle insertion site
2. Advance needle through wheal to desired interspace
1. Careful not to inject into a blood vessel or spinal canal
4. Insert needle and keep cutting edge parallel with nerve and ligament fibres
5. Aim towards umbilicus directing needle slightly cephalad
6. ‘Pop’ of sudden decrease in resistance indicates that ligamentum flavum and dura are puncture
7. Remove stylet and check for slow of spinal fluid
8. If no fluid then rotate 90o and reinsert stylet and advance needle slowly checking frequently for CSF
85
What is the skin cleansed with before a LP?
Povidone iodine radially out to 10cm
86
What do you do if you remove a LP to find there is no fluid present?
1. If no fluid then rotate 90o and reinsert stylet and advance needle slowly checking frequently for CSF
87
What can increase CSF in low flow situations during LP?
Jugular vein compression
88
What do you do if you perform an LP and blood fluid that does not clear or that clots results?
Withdraw, and reattempt at a different interspace
89
What do you do if you perform an LP and bony resistance is felt deeply?
Withdraw needle to skin surface and redirect more cephalad and increase patient flexion
90
What do you do if you perform an LP and bony resistance is felt superficially?
You are not in spinal interspace so withdraw
91
How much CSF should be collected in a LP?
1. Collect 1ml of CSF in each of 3 vials for
1. Tube 1 – culture and gram stain
2. Tube 2 – glucose and protein
3. Tube 3 – cell count and differential
4. And extra CSF if desired for other lab tests
92
What position is used for LP for infants?
1. Restrain infant in seated position with maximal spinal flexion
1. Hold hands between flexed legs with one hand and flex head with other hand
2. Drape patient below buttocks and fenestrated drape opening along puncture ite
3. Insert needle so bevel is parallel to spinal cord
93
Can pressure be measured in all positions for LP?
No, only in lateral decubitus position
94
When is the paramediun (lateral) approach used for LP?
Patients who have calcifications from repeated LPs or anatomic abnormalities:
95
Describe the paramedian (lateral) approach for LP?
* Needle passes through erector spinae muscles and ligamentum flavum
* Bypasses supraspinal and interspinal ligament
* * Less incidence of spinal headache
96
What are some potential complications of LP?
* Headache (most common)
* Apnea
* Back pain
* Bleeding or fluid leak around spinal cord
* Infection, pain, haematoma
* Subarachnoid epidermal cyst
* Ocular muscle palsy
* Nerve trauma
* Brainstem herniation
* Epidermal inclusion cyst
97
What is the most common complication with LP?
Headache
98
What are risk factors for headache complication with LP?
* Female
* Age 18-30
* Lower BMI
* History of HA
99
What is the treatment for people who get a headache after LP?
* Put in supine position for at least 2 hours
* Hydration
* Caffeine either PO or IV
* Epidural blood patch
100
What can be done to prevent the complication of a headache after a LP?
* Passing needle bavel parallel to longitudinal fibres of dura
* Replacing stylet before removing needle
* Using small diameter needles
* Using atraumatic needles
101
What treatment can be done for the nerve trauma complication of LP if it persists?
* If pain or motor weakness persists, start corticosteroids
* Electromyogram/nerve conduction velocity studies should be scheduled if pain persists
102
What does a brainstem hernitation complication of LP manifest as?
* Manifests as altered mental status, followed by cranial nerve abnormalities and Cushing triad
103
What is the treatment for brainstem herniation complication in LP?
* Immediately remove needle and raise the head of bed to 30-45o to improve venous return from brain
* Mannitol or 3% saline
* Intubate patient and hyperventilate
* Emergent neurosurgical consult
104
What alternatives can be done if LP procedure fails and sample of CSF is critical?
* Have someone else try
* From anaesthesia or neurology
* Bedside ultrasound for difficult LPS
* Radiographic guided procedure
* Fluoroscopy
* Ultrasound
* CT
* Cisterna Magna tap
105
What things are checked in a LP?
Colour
Opening pressure
Protein level
Glucose level
WCC
Culture and gram staining
