oprtic1.nerve sheath

Optic Nerve Sheath Diameter ( ONSD )

in Increased intracnial Pressures

( ICP ) A new tool in the Ultrasound Era

Causes of ICP

Mass effect:

Malignancy

CVA with edema

Cerebral contusions

subdural or epidural hematoma

abscess

Diffuse Encephalopathies:

Acute liver failure

Hypertensive Encephalopthy

High Altitude cerebral edema

Uremic Encephalopathy

PseudotumorCerebri

•Obstruction CSF flow and/or absorption :

•Hydrocephalus

•Extensive meningeal disease (e.g., infectious, carcinomatous, granulomatous )

•Superior sagittal sinus (decreased absorption)

•Increased CSF production :

•Meningitis

•Subarachnoid hemorrhage,

Why look at ONSD?

How do we currently assess EICP :

Non-specific signs and symptoms

Imaging CT scan/MRI

Pulsatliity index

Invasive monitoring

Papilledema

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%

Invasive ICP measurments

Gold standard External Ventricular Device

Comlipcated/ invasive procedure

Risks Infection, parenchymal injury , bleeding

Bleeding diasthesis

Gold standard for ICPExternal Ventricular Device ( EVD )

Papilledema

Operator dependant

Delayed manifestation: - 24 hrs

May persist for several days to weeks after treatment

Papilledema ?

Both are Normal

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

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 )

Intracranial CSF

Intra-orbital CSF

h

Optic Nerve

ONSD history

British opthalmologistHayreh

The mechanism of papiledema from increased ICP

Placed inflatable balloons in the brain of monkeys

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

Acta Ophthalmol. 2011 Sep;89(6):e528-32.

Changes in ONSD mimics changes in ICP

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

3mm

ONSD

3mm

ONSD

Lens

Vitreous

A-A 0.3cm

B-B 0.62 cm

ONSD False Positive

Emerg Med J 2007;24:251–254. doi: 10.1136/emj.2006.040931

Emerg Med J 2007;24:251–254. doi: 10.1136/emj.2006.040931 Abdullah SadikGirisgin, ErdalKalkan, SedatKocak, BasarCander, MehmetGul, Mustafa Semiz

Volume status

Reproducible results

54 patients:

28 confirmed EICP via CT scan

26 no evidence of EICP

ONSD evidence based approach

Most studies Trauma or neurosurgical patients

3 major studies on ONSD ( briefly )

ONSD evidence

Prospective study on 26 ED patients

ONSD cutoff > 0.5 cm

Emer Med J published online August 15, 2010 ,Robert Major, Simon Girling and Adrian Boyleg

All had CT scans

Sens 86% Sepcificity 99% for EICP

ONSD cutoff >5mm

PPV100%NPV95%

ONSD evidence

Small sample size

Non-trauma GSC: 8

Compared to CT scan

Invasive and non-invasive comparison

76 patients

26 Control 18Moderate

32Severe

Moderate Marshall score I and GSC > 8Severe Marshall score >I and GCS < 8

Pulsatility index

Invasive ICP monitoring

76 patients

Brain CT injury scale No CT done Normal CT Abnormal CT18% 82%

ONSD cutoff 5.7mm

Non-invasive monitoring

Invasive Monitoring

TheodorosSoldtos, Optic nerve sonography in the diagnostic Evaluation of adult brain injury, Critical care 2008;12 R 67

ROC :0.93Sens : 74%Spec: 99%

ONSD cutoff > 5.7mm

Intensive Care Med (2007) 33:1704–1711, T. Geeraerts () · Y. Launey · L. Martin ·J. Pottecher· B. Vigué · J. Duranteau ·D. Benhamou

31 ICU patients with severe TBIGSC<8

16 EICP 15 Normal ICP

Prospective Blind observational trial

All patients underwent invasive ICP monitoring

5.7 mm

Thomas Geerats M.D, Ultrasonography of Optic nerveSheath may be useful in detecting raised ICP After head trauma. Intensive care Medicine 2007, 33:1704-1711

ROC: 0.96Sens: 91%Spec: 94%

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

Diffuse Encephalopathies: ESLDESRDHypertensive EncephalopthyHigh Altitude cerebral edema

Obstruction CSF flow and/or absorption :

•Hydrocephalus

•Extensive meningeal disease (e.g., infectious, carcinomatous, granulomatous )

•Superior sagittal sinus (decreased absorption)

Increased CSF production :

•Meningitis

•Subarachnoid hemorrhage,

Mass effect:•Malignancy

•CVA with edema

•Cerebral contusions

•Subdural or epidural hematoma

•Abscess

ICP causes

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/sencephalopathy pre-treatment /24hrs post-treatment

Convenience sample

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

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.

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

ESLD and ICP

Fulminant hepatic failure 80% EICP

Ammonia and Manganese astrocyte edema

Chronic ESLD EICP only in stage IV hepatic encephalopathy

N=24

N=10

Stage I

N=2

Stage II

N=5

Stage III

N=3

Stage IV

N=0

N=14

EncephalopathyNo

Encephalopathy

Pretreament ESLD

0

1

2

3

4

5

6

7

8

9

10

No Encephalopathy With Encephalopathy

N= 14 N=10

Encephalopathy

ONSD in mm

5.7mm

•Stage I•Stage II•Stage III

Post-treament ESLD

0

1

2

3

4

5

6

7

8

9

10

No Encephalopathy With Encephalopathy

N= 14 N= 10

Encephalopathy

ONSD in mm

5.7mm

•Stage I•Stage II•Stage III

Relative decrease 57%

Summary ESLD

0

1

2

3

4

5

6

7

8

9

10

No Encephalopathy With Encephalopathy

N= 14 N= 8

ONSD in mm

5.7mm

•Stage I•Stage II•Stage III

0

1

2

3

4

5

6

7

8

9

10

No Encephalopathy

With Encephalopathy

N= 14 N= 8

Pretreatment Post-treatment

ESRD and ICP

Dialysis Dysequilibrium Syndrome

Very high BUN > 110

Pretreatment ESRD

0

1

2

3

4

5

6

7

8

9

10

yes No 1/9/02

No Encephalopathy

WithEncephalopathy

ONSD in mm

N= 4N= 13

No Encephalopathy

WithEncephalopathy

Pretreatment Post-treatment

46 %decrease 63% decrease

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?

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

HTN crisis

0

1

2

3

4

5

6

7

8

9

10

yes No 1/9/02

Uncontrolled HTN

HTN emergency

ONSD in mm

N= 5N= 11

Pretreatment Post-treatment

Uncontrolled HTN

HTN emergency

Encephalopathic

57% decrease 68% decrease

7.2mm5.2mm

Data analysis

Uncontrolled HTN had rather high ONSD subclinicalEICP

Relative size decrease :

57% in Uncontrolled HTN

68% HTN emergency

High altitude sickness

No data yet

14er’sONSD at base , peak , base

Symptoms of Altitude sickness

ONSD absolute value and change

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

Thank you