4.5 ICP measurement

Question 1

Symptoms

Answer 1

1. Headache
   - diffuse
   - worse mané
   - Worse lying flat / Valsalva
2. Visual field defects
   - Horizontal diplopia (CNVI)

Transient monocular field defects

Narrowed fields

Photophobia

3. Non specific
   Dizzy
   Nausea
   Vomiting

Tinnitus
Anosmia

Retrobulbar/ back / neck pain

Reduce LOC

Question 2

Sx

Answer 2

1. Bilaterally papilloedema
   - a/w macular oedema
2. CN palsy
   - usual VI + Horizontal nystagmus

Occasionally b/l

Trochlear 4 and Oculomotor 6

Cushing triad

HTN
Bradyardia
Irregular respiration

Question 3

ICP measurement methods

indirect

Answer 3

Indirect:

1 Imaging modalities (CT / MRI)

• sulcal effacement
• flattening of pit fossa
• slit like ventricles

2 orbital U/S - CSF ↑ volume around optic nerve

Question 4

ICP measures

Direc

Answer 4

1. Single shot
2. Extradural
3. Intraventricular device

Question 5

Single shot

Answer 5

LP or manometry

monitoring CSF following procedure

Question 6

Extradural

Answer 6

Codman pressure transducer

1. Strain gauge transducer
   tip of wire
   placed extradural (or intraparenchymal)
   to monitor ICP

Insertion via small burr hole
aseptic technique
relatively easy insert
allows continual monitoring

Question 7

Codman pressure systems

types

issues

Answer 7

Air referenced r fluid coupled systems
air ref avoid problems of damping traces

fluid systems flushing tip of transducer
displace debris
or clot causing inaccurate measure

Prone to drift
represent local rather than global tissue

Question 8

Intraventricular device

Answer 8

EVD

Aseptic blind insertion
Tube into anterior portion
lateral ventricle
similar approach to ICP transducer

Connect fluid filled set and transducer
similar to A line

Integrated to system
allows fluid drained off into reservoir
- Rx obstructive hydrocephalus

Represented higher infection risk
vs Codman and Camino

Question 9

Waveform of ICP Changes

Answer 9

Normal
P1 - Percussive wave
arterial pressure transmitted from choroid plexus

P2 - Tidal wave
amplitude varies w/ compliance

P3 - dichroic notch
Closure of aortic valve

Question 10

Pathological

Answer 10

A wave
Plateau waves 50-100mmHg
5-15min

Represent early herniation

Page 166

Question 11

Pathological

Answer 11

B wave
Small pressure oscillations
30-120s

Changes in respiration and gas changes

Question 12

Pathological

Answer 12

C wave
Low amplitude change up to 5 times a min
change in vasomotor tone

Health and injured brains