This document discusses using optic nerve sheath diameter (ONSD) measurements via ultrasound as a tool to assess increased intracranial pressure (ICP). It provides background on ONSD anatomy and evidence that ONSD changes mimic ICP changes. Studies show ONSD has high sensitivity and specificity for detecting elevated ICP compared to invasive monitoring. The document proposes a prospective study measuring ONSD in patients with conditions like end-stage liver disease, end-stage renal disease, and hypertensive crises to see if ONSD decreases after treatment and normalize, indicating reduced ICP. It suggests ONSD could help predict complications like dialysis disequilibrium syndrome.
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There have been significant developments in the diagnosis and management of ischaemic stroke.
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INTRODUCTION
TO DEFINE ICP
TO ENLIST FACTORS CAUSING INC ICP
TO ENLIST INDICATION ANDCONTRA INDICATION OF ICP MONITORING
TO BRIEF CONSIQUENCIES OF INC ICP
TO EXPLAIN ASSESSMENT OF INC ICP
TO BRIED WARNING SIGN OF ICPMONITORING
TO EXPLAIN VARIOUS INVASIVE AND NON INVASIVE METHOD OF ICP MONITORING
Assessment of increased intracranial pressureKrishna Gandhi
INTRODUCTION
TO DEFINE ICP
TO ENLIST FACTORS CAUSING INC ICP
TO ENLIST INDICATION ANDCONTRA INDICATION OF ICP MONITORING
TO BRIEF CONSIQUENCIES OF INC ICP
TO EXPLAIN ASSESSMENT OF INC ICP
TO BRIED WARNING SIGN OF ICPMONITORING
TO EXPLAIN VARIOUS INVASIVE AND NON INVASIVE METHOD OF ICP MONITORING
3. Why look at ONSD?
How do we currently assess EICP :
Non-specific signs and symptoms
Imaging CT scan/MRI
Pulsatliity index
Invasive monitoring
Papilledema
4. CT and ICP
Moving patients
Repeat for head CT one third of trauma
need repeat head CT looking for ICP .
Radiographic delay?
Initial head CTs of 100 head injured trauma
patients evaluated by group of 12
radiologists :
Sensitivity 83% , Specifity 78%
11. Outline
Basic anatomy of the Optic nerve and it’s sheath
How to measure ONSD?
Rationale and evidence for using the ONSD for Increased
intracerebral pressure ( ICP )
Uses and rationale in different clinical settings :
ESRD , ESLD ,HTN crises and altitude sickness
12. ONSD basic anatomy
Optic Nerve:
White matter tract direct extension of the CNS surrounded
by CSF
Sensitive to changes to CSF flow and intracerebral pressures
( ICP )
15. ONSD history
British opthalmologistHayreh
The mechanism of papiledema from increased ICP
Placed inflatable balloons in the brain of monkeys
16.
17.
18.
19. Rapid response ONSD
Hansen et al :
Infused NS into CSF
Changes in ONSD occurred within minutes
Mean change of 1.97mm or around 83% increase
Relieving pressure rapid decrease in size
Exception was with prolonged exposure to very high
pressures showed a delay in regression
Changes in ONSD mimics changes in ICP
Acta Ophthalmol. 2011 Sep;89(6):e528-32.
20. How do we measure the ONSD?
3-7.5Mhz Probe
Supine position at around 20 degrees phlebotactic axis
Perpendicular axis at 3mm behind ON entry point
2 reading on each eye
Probe applied directly over the eyelid
Cutoff 5mm or 5.7mm
27. ONSD evidence based approach
Most studies Trauma or neurosurgical patients
3 major studies on ONSD ( briefly )
28. ONSD evidence
Prospective study on 26 ED patients
ONSD cutoff > 0.5 cm
All had CT scans
Emer Med J published online August 15, 2010 ,Robert Major, Simon Girling and Adrian Boyleg
29. PPV100%
NPV95%
Sens 86%
Sepcificity 99% for
EICP
ONSD cutoff >5mm
31. Invasive and non-invasive
comparison
76 patients
Pulsatility index
26 Control 18 32
Moderate Severe
Invasive ICP
Moderate Marshall score I and GSC > 8 monitoring
Severe Marshall score >I and GCS < 8
32. 76 patients
Brain CT injury scale No CT done Normal CT Abnormal CT
18% 82%
ONSD cutoff 5.7mm
34. ROC :0.93
Sens : 74%
Spec: 99%
ONSD cutoff >
5.7mm
TheodorosSoldtos, Optic nerve sonography in the
diagnostic
Evaluation of adult brain injury, Critical care 2008;12
R 67
35. Prospective Blind observational
trial
31 ICU patients with severe TBI
GSC<8
16 EICP 15 Normal ICP
All patients underwent invasive
ICP monitoring
Intensive Care Med (2007) 33:1704–1711, T. Geeraerts () · Y. Launey · L. Martin ·J. Pottecher
· B. Vigué · J. Duranteau ·D. Benhamou
37. ROC: 0.96
Sens: 91%
Spec: 94%
Thomas Geerats M.D, Ultrasonography of Optic
nerve
Sheath may be useful in detecting raised ICP
After head trauma. Intensive care Medicine
2007, 33:1704-1711
38. ONSD evidence conclusion
Cutoff> 5.7mm for EICP
Sensitivity of around 93%
Specificity: 96%
5-5.7mm Sensitivity is maintained however Specificity
declines to 83%
Screening tool
Surrogate marker for EICP
40. Study
Prospective observational/descriptive analysis
Medicine patient admitted to general medicine floor , MICU
ESLD / ESRD / HTN crisis
No head / ocular trauma
No other cause for EICP
Comparing ONSD diameter of non-encephalopathy v/s
encephalopathy pre-treatment /24hrs post-treatment
Convenience sample
41. Hypothesis
Absolute value of ONSD would be high among the
encephalopathic group and would normalize after
treatment
Statistically significant change in ONSD pre and post
treatment
42. Definitions
EICP: - > 20 mmHg, If invasive monitoring available .
Radiographic evidence of raised ICP as determined by
CT
ONSD : cut-off of 5.7 mm to define enlarged ONSD ,
ESLD and Uremia straightforward
HTN encephalopathy ? Unclear and vague definition.
43. Method
7-12 MHz while patient is at 20 degree angle
2 measurements from each eye ( for a total of 4 per patient
)
Measurements will be taken both prior and within 24hrs
after treatment
44. ESLD and ICP
Fulminant hepatic failure 80% EICP
Ammonia and Manganese astrocyte edema
Chronic ESLD EICP only in stage IV hepatic
encephalopathy
45. N=24
No
Encephalopathy Encephalopathy
N=10 N=14
Stage I Stage II Stage III Stage IV
N=2 N=5 N=3 N=0
46. Pretreament ESLD
10 •Stage I
ONSD in mm
9 •Stage II
8 •Stage III
7
6
5.7mm
5
4
3
2
1
N= 14 N=10
0
Encephalopathy
No Encephalopathy With Encephalopathy
47. Post-treament ESLD
10
•Stage I
ONSD in mm
9 •Stage II
8 •Stage III
7
Relative decrease 57%
6
5.7mm
5
4
3
2
1
N= 14 N= 10
0
Encephalopathy
No Encephalopathy With Encephalopathy
48. Summary ESLD
Pretreatment Post-treatment
10 ONSD in mm 10 •Stage I
9 9
•Stage II
8 8
7 7
•Stage III
6 6 5.7mm
5 5
4 4
3 3
2 2
1 1
0 N= 8 0 N= 8
N= 14 N= 14
No Encephalopathy With No With
Encephalopathy Encephalopathy Encephalopathy
49. ESRD and ICP
Dialysis Dysequilibrium Syndrome
Very high BUN > 110
50. Pretreatment ESRD
Pretreatment Post-treatment
10
ONSD in mm
9
8
7
46 %decrease 63% decrease
6
5
4
3
2
N= 13 N= 4
1
No With No With
0
Encephalopathy Encephalopathy Encephalopathy Encephalopathy
yes No 1/9/02
51. Data analysis
Relative decrease in ONSD in both groups was significant
NO encephalopathy: - 46%
With Encephalopathy: - 63%
Other etiologies for increase ONSD :
Volume status
HTN
Utility in predicting DDS?
52. HTN crisis
Most common manifestation are neurologic :
44% with HTN emergency have neurologic manifestations
16% HTN encephalopathy
Clinically subtle
Pathophysiology Breakthrough autoregulation
CT head to r/o CVA helpful however in HTN
encephalopathy not so much
56. Data analysis
Uncontrolled HTN had rather high ONSD subclinical
EICP
Relative size decrease :
57% in Uncontrolled HTN
68% HTN emergency
57. High altitude sickness
No data yet
14er’s ONSD at base , peak , base
Symptoms of Altitude sickness
ONSD absolute value and change
58. Conclusion
ONSD: Reliable surrogate marker for EICP
Quick bedside evaluation that competes with CT scans
Reproducible results easy to learn
Large area of research
Downfalls: - Etiology