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Systems: Neurology AB > CSF, Hydrocephalus and Lumbar Puncture > Flashcards

CSF, Hydrocephalus and Lumbar Puncture Flashcards

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1
Q

What is hydrocephalus?

A

A general condition whereby there is excess Cerebro-Spinal Fluid (CSF) within the intracranial space and, specifically, the intraventricular spaces within the brain…causing dilation of the ventricles, and a wide range of symptoms.

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2
Q

How is CSF produced?

A

The majority of CSF is produced by the choroid plexus within the brain through a metabolically active process (i.e. requires ATP) whereby sodium is pumped into the subarachnoid space, and water follows from the blood vessels.

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3
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.

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4
Q

How much CSF is produced each day?

A

The average adult brain produces between 450 and 600 cc’s of CSF every day.

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5
Q

What is the turn over of CSF each day?

A

So, the CSF volume turns over three to four times every day, with only a very small fraction of the CSF being in the ventricles at any given time, even though the majority of it is produced there

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6
Q

How much CSF is there in the body?

A

At any given moment, there is only ~150 cc’s of CSF present in the average adult; of this, only ~25 cc’s is within the brain ventricles

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7
Q

What is the pathway of CSF flow?

A
  • From the lateral ventricle, CSF travels through the foramen of Monro into the 3rd ventricle (midline), then passes through the Cerebral Aqueduct [of Sylvius] into the 4th ventricle.
  • It then exits the 4th ventricle through either of two Foramina of Luschka (“L” is for Lateral/Luschka) or the single Foramen of Magendie (“M” is for Midline/Magendie).
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8
Q

Where is the CSF reabsorbed?

A

After exiting the 4th ventricle, the CSF flows through the subarachnoid space over and around the brain and spinal cord, and is eventually reabsorbed into the venous system through numerous arachnoid granulations along the dural venous sinuses (especially the superior sagittal sinus).

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9
Q

What do the arachnoid granulations contain?

A

Arachnoid granulations contain arachnoid villi, which function as pressure-dependent one-way valves that open when the ICP is ~3 to 5 cm H20 greater than dural venous sinus pressure.

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10
Q

What kind of process is CSF production?

A

CSF production is a metabolically active process which uses ATP

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11
Q

What kind of process is CSF reabsorption?

A

CSF resorption is a passive process

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12
Q

What drives CSF reabsorption?

A

It is driven by the pressure gradient between the intracranial space (ICP) and the venous system (~CVP

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13
Q

What are the distinct types of hydrocephalus?

A
  • Communicating hydrocephalus (CoH)

- Non-communicating hydrocephalus (NCH)

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14
Q

What is communicating hydrocephalus also known as?

A

Non-obstructive hydrocephalus

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15
Q

What is non-communicating hydrocephalus also known as?

A

Obstructive hydrocephalus

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16
Q

When is hydrocephalus communicating hydrocephalus?

A

If the CSF pathway is “open from start to finish,” meaning CSF can travel freely from the choroid plexus to the arachnoid granulations, then you have “no obstruction” and a communicating hydrocephalus.

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17
Q

When is hydrocephalus non-communicating hydrocephalus?

A

If the CSF can’t travel freely from start to finish, then you’ve got an “obstruction” and non-communicating hydrocephalus.

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18
Q

What is normally the problem in communicating hydrocephalus?

A

In the vast, vast majority of cases, this represents a problem with CSF resorption; simply put, it cannot keep the pace with CSF production.

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19
Q

What does CSF production> resorption result in?

A

As a result, the ventricular system dilates uniformly, and ICP rises.

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20
Q

What is a rare cause of CoH?

A

Very rarely, there is overproduction of CSF (rather than under-absorption) which leads to disruption of this balance, and development of communicating hydrocephalus.

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21
Q

What can cause overproduction of CSF?

A

Choroid plexus papillomas

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22
Q

What are the signs and symptoms of CoH in young children?

A

In young children whose cranial sutures have not yet fused, you can see disproportional increase in head circumference compared to the rest of the face/body or failure to thrive

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23
Q

What are the signs and symptoms of CoH in older children?

A

In children with fused sutures/adults, hydrocephalus manifests with symptoms of increased intracranial pressure;
-H/A, N/V, papilledema, gait disturbance, 6th cranial nerve palsy, upgaze difficulty, etc.

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24
Q

What is the aetiology of CoH?

A
  • Infection (incidence after bacterial meningitis can approach 30%)
  • Subarachnoid Hemorrhage (blood and blood breakdown products cause scarring of arachnoid granulations)
  • Post-operative
  • Head trauma
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25
When can hydrocephalus develop very quickly?
Sometimes there can be a sizeable insult that causes an acute disruption of the balance, and CSF resorption is suddenly (and dramatically) reduced
26
How can patients present with acute (emeregency) CoH hydrocephalus?
Neurological decline can be rapid, with patients becoming sleepy, then obtunded, then requiring intubation.
27
When does NCH occur?
Non-communicating hydrocephalus occurs whenever there is ANY physical obstruction to the normal flow of CSF before it leaves the ventricles.
28
What can cause NCH?
- Aqueductal stenosis - Tumors/Cancers/Masses - Cysts - Infection - Hemorrhage/hematoma - Congenital malformations/conditions - Etc.
29
Where can NCH occur
Non-communicating hydrocephalus can result from CSF flow obstruction at any point along the intraventricular pathway.
30
What cause gradual symptoms of NCH?
Processes that have developed over longer periods of time (i.e. masses, etc) usually cause gradual development of symptoms.
31
How do acute processes present in NCH?
Acute processes (i.e. intraventricular bleed) can cause acute obstruction with rapid mental status decline.
32
What is the earliest consistent radio graphical indicative development of hydrocephalus?
Dilation of the temporal horns of the lateral ventricles. In most younger and middle-aged patients, these should be almost invisible.
33
What can be seen on radiology of hydrocephalus?
- The third ventricle will become ballooned - Lateral ventricle size increase - Peripheral sulci effaced - Evans Ratio ->30% /Ventricular index >50%
34
What is the mode of treatment for hydrocephalus?
Surgical
35
How is acute hydrocephalus treated?
Acute hydrocephalus, whether communicating or not, usually necessitates urgent or emergent placement of an External Ventricular Drain (EVD - catheter passed through the patient’s scalp and skull into lateral ventricle, that drains CSF to a collection system kept at the patient’s bedside).
36
What can EVD be replaced with?
EVD cannot be maintained indefinitely; usually, if the patient is unable to tolerate weaning/clamping of the EVD prior to removal, a permanent shunt will be required.
37
What is the infection risk of EVD?
High
38
What is the mainstay of treatment for CoH?
For communicating hydrocephalus, the mainstay of treatment is shunt placement.
39
What types of shunts can be used to treat CoH?
- Ventriculo-peritoneal is most used. - Lumbar-peritoneal sometimes utilized, though overdrainage is a problem. - Ventriculo-atrial can also be considered in cases of peritoneal failure
40
How can a small number of acute CoH patients by managed?
Acute communicating hydrocephalus patients (i.e. SAH) can sometimes be managed with EVD with successful weaning and no shunt placement, but a significant number of these patients eventually need shunt placement weeks or months later.
41
How is NCH treated?
NCH treatment also surgical, but sometimes shunt can be avoided by removing the obstructing lesion.
42
Give examples of lesions which can be removed in NCH?
- Colloid cyst at anterior 3rd ventricle causing ball/valve obstruction of Foramen of Monro. - Pineal region tumor causing compression of cerebral aqueduct. - Ependymoma blocking 4th ventricular CSF outlets.
43
What s ventriculostomy often performed in conjunction with?
Often performed in conjunction with VP shunt placement.
44
How is ventricuolstomy carried out?
Hole is surgically opened in floor of third ventricle so CSF flows out into the interpeduncular cistern and pre-pontine space (bypasses cerebral aqueduct).
45
What should you note about a patient with a known shunt who presents with headache?
Take note: Every patient with a history of VP shunt placement who presents with a headache is NOT automatically having a shunt malfunction/infection.
46
What percentage of shunts fail?
- The incidence of shunt failure is as much as 40% the first year (most in the first few months), and then 5% per year after the first year. - 50% of shunts fail by 5 years from placement.
47
Why may shunt fail?
- Mechanical failure from occlusion/disconnection - Migration - Overdrainage/underdrainage - Infection - Skin erosion
48
What is a rare preventable and/or reversible cause of dementia?
Normal pressure hydrocephalus (NPH)
49
What is the classic triad of NPH?
Hakim-Adams Triad: Wet, wobbly and wacky - Urinary incontinence - Gait disturbance (usually the first symptom to present) – wide stance; short, shuffling steps - Rather quickly-progressive dementia
50
How does NP present on CT/MRI?
CoH
51
What is found on LP of NPH?
- Normal opening pressure | - Symptoms improve with CSF removal
52
How is NPH treated?
Procedure of choice for patients felt to be suffering from NPH is Programmable VP shunt placement.
53
What improves outcome in NPH?
Chance of outcome is improved if symptoms have been present for shorter period of time
54
What is the least likely symptom of NPH to improve?
Dementia
55
What is the most likely symptom of NPH to improve?
Gait
56
What can LP help in the diagnosis of?
- Meningitis - Meningoencephalitis - Subarachnoid hemorrhage - Malignancy – diagnosis and treatment - Idiopathic Intracranial Hypertension - Other neurologic syndromes - Infusion of Drugs or contrast
57
What are the contraindications of LP?
- Unstable patient with cardiovascular or respiratory instability - Localized skin/soft tissue infection over puncture site - Evidence of unstable bleeding disorder - Increase intracranial pressure
58
What is evidence of an unstable bleeding disorder?
Platelets < 50,000 or clotting factor deficiency
59
What should be done before LP to rule out impending cerebral mass herniation?
Head CT before study if focal neurologic findings present to rule out impending cerebral mass herniation
60
What can happen if LP is done below the level of complete spinal subarachnoid block?
Neurologic deterioration can occur if LP is done below the level of a complete spinal subarachnoid block
61
What patients should extra caution be taken in with LP?
People with Chiara malformation
62
What equipment do most CSF trays come with?
- Anesthetic such as: Topical - EMLA, Elamax, Zylocaine cream and/or Lidocaine 1% with 25 gauge needle and syringe - Povidone-iodine solution & sponge wand - Drapes, gauze, and bandages - Manometer, stopcock and tubing in non-infant kits
63
What type of needles are used for LP?
Spinal needle, usually 22 gauge - 1.5 in for < 1 yr - 2.5 in for 1 year to middle childhood - 3.5 in for older children and adolescents - Larger for large adolescents
64
What type of needle can decrease the incidence of spinal headache following LP?
Atraumatic needles
65
What position should LP be carried out 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
66
Where is LP usually carried out?
Spinal cord usually ends at L1-L2(check!), so sites for puncture are located at L3-L4 or L4-L5
67
What should happen 30-45 minutes before LP?
Apply topical anesthetic 30-45 min prior to procedure
68
How should the patient be prepped for LP?
Cleanse skin with povidone iodine from puncture site radially out to 10 cm and ALLOW TO DRY Drape below patient and around site with fenestrated drape
69
How should lidocaine be administered in LP?
- Anesthetize with lidocaine if topical not used by: - Intradermally raising a wheal at needle insertion site - Advance needle through wheal to desired interspace - Careful not to inject into a blood vessel or spinal canal
70
How should the spinal needle be inserted in LP?
Insert spinal needle with stylet with bevel up to keep cutting edge parallel with nerve and ligament fibers
71
Where should you aim the needle in LP?
Aim towards umbilicus directing needle slightly cephalad
72
What does a pop of sudden decrease in resistance indicate in LP?
A “pop” of sudden decrease in resistance indicates that ligamentum flavum and dura are punctured
73
When you remove the stylet during LP, what should you check?
Spinal fluid
74
What should you do if there is no fluid in LP?
- Rotate needle 90° | - Reinsert stylet and advance needle slowly checking frequently for CSF
75
What can increase CSF pressure in low flow situations?
Jugular vein compression can increase CSF pressure in low flow situations
76
What should you do if bony resistance is felt deeply during LP?
If bony resistance is felt deeply, then withdraw needle to the skin surface and redirect more cephalad and increase patient flexion
77
What does immediate bony resistance indicated during LP?
If bony resistance is felt immediately then you are not in the spinal interspace
78
What should you do if the fluid is bloody, is not clear or clots in LP?
If bloody fluid that does not clear or that clots results, then withdraw needle and reattempt at a different interspace
79
How is the opening pressure of LP obtained?
When CSF flows, attach manometer to obtain opening pressure if desired
80
When can pressure be accurately measured during LP?
Pressure can only be accurately measured in lateral decubitus position and in the relaxed patient
81
When should you attach a manometer during LP?
Attach manometer with a 3-way stopcock when free flow of CSF is obtained
82
How should manometry results be recorded?
Read column when highest level is achieved and respiratory variation is noted
83
What samples should be collected during LP?
Collect 1ml of CSF in each of 3 vials for: - Tube 1: culture & gram stain - Tube 2: glucose, protein - Tube 3: cell count & differential - And extra CSF if desired for other lab tests
84
How is an LP exam concluded after samples collected?
- Check closing pressure with manometer, if desired - Reinsert stylet and remove needle in one quick motion - Cleanse back and cover puncture site
85
How is LP carried out in the seated position?
- Restrain infant in the seated position with maximal spinal flexion - Hold infant’s hands between flexed legs with one hand and flex head with the other hand - Drape patient below buttocks and fenestrated drape opening over puncture site
86
How is the needle inserted in a seated LP?
Insert needle so bevel is parallel to spinal cord (Bevel left or right)
87
What is the disadvantage of a seated LP?
Cannot measure pressure accurately in this position
88
Who should the paramedian (lateral) approach for LP be used in?
Use for patients who have calcifications from repeated LPs or anatomic abnormalities
89
What does the needle pass through in the paramedian (lateral) approach to LP
- Needle passes through erector spinae muscles, and ligamentum flavum - Bypasses supraspinal and interspinal ligaments
90
What does the paramedian (lateral) LP approach decrease the incidence of?
Spinal headache
91
What are the possible complications of LP?
- Headache - Apnea (central or obstructive) - Back pain - Bleeding or fluid leak around spinal cord - Infection, pain, hematoma - Subarachnoid epidermal cyst - Ocular muscle palsy (transient) - Nerve Trauma - Brainstem herniation
92
Who is post LP headache uncommon in?
Uncommon in < 10 y/o
93
What is the most common complication of LP?
Spinal headahce
94
What are the risk factors for spinal headache?
- Female - Aged 18-30 - Lower BMI - History of HA - Prior spinal HA
95
How is spinal headache managed?
- Bilateral HA, improves when supine - Can last hours to weeks - Supine position for at least 2 hours - Hydration - Caffeine either PO or IV - Epidural blood patch
96
How can spinal headache by avoided?
- Passing needle bevel parallel to longitudinal fibers of dura - Replacing stylet before removing needle - Using small diameter needles - Using atraumatic needles
97
What does not reduce the incidence of spinal headache?
Bed rest or PO intake after LP does not reduce incidence of headache
98
How can nerve root trauma/ irritation present?
- Can feel electric shocks or dysesthesias | - Back pain can persist for months
99
How should nerve root trauma/irritation be treated?
- Withdraw needle immediately - If pain or motor weakness persists, start corticosteroids - Electromyogram/nerve conduction velocity studies should be scheduled if pain persists
100
How does herniation manifest in LP?
Manifests initially as altered mental status, followed by cranial nerve abnormalities and Cushing triad
101
How should herniation be treated in LP?
- Immediately remove needle and raise the head of bed to 30-45° improve venous return from the brain. - Mannitol or 3% Saline - Intubate patient and hyperventilate - Emergent neurosurgical consult
102
What is a rare complication of LP related to the use of the stylet?
Epidermal inclusion cyst
103
When do epidermal inclusion cysts occur?
Occurs when a core of skin is driven into spinal or paraspinal space with hollow needle
104
How can epidermal inclusion cysts be prevented?
Do not remove stylet until through the skin
105
Failure of LP: If sample of CSF is critical, what alternatives are available?
- Have someone else try - Bedside ultrasound for difficult LPs - Radiographic guided procedure - Cisterna Magna tap
106
If sending LP sample for xanthochromia how should it be sent?
If sending for Xanthochromia put sample in a brown paper envelope
107
What should you send with LP sample if looking for OCB?
Remember to send glucose sample and paired blood sample if looking for OCB
108
What is venticulostomy an option in the treatment of?
NCH

Systems: Neurology AB (51 decks)

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