Efficacy of optic nerve sheath diameter by ultrasound as a non-invasive
method to determine elevated intracranial pressure in Indian population.
Year : 2019 | Volume : 7 | Issue : 2 Page : 38-42
Mhatre M1, Baviskar A2Dongre H3, Rajpal D4
*Address for correspondence:: Dr Ajit Baviskar, Department of Emergency Medicine, Dr. D.Y. Patil Medical College, Navi Mumbai.
E mail ID: - drbaviskar@gmail.com
Abstract
Introduction:
It is important to assess use of Optic Nerve
sheath Diameter (ONSD) measurement by point of care
ultrasonography (POCUS) as a non-invasive method for
detecting elevated Intracranial Pressure (ICP) and to compare
with Brain Computed Tomography (CT) findings of Elevated
ICP in Indian population
Methods:
This study was a Prospective Observational
Study done in emergency Department of a tertiary care hospital
in western India .Adult patients within 18-60 years age group,
with Head trauma presenting with headache, vomiting,
convulsions, loss of consciousness, and altered sensorium were
included in the study.Non-trauma patients with focal
neurological changes and history suggestive of possible
spontaneous intracranial hemorrhage were also included. Data
was recorded after stabilizing patients as per standard trauma
and non-trauma protocol.
Patients underwent a POCUS study to measure the
ONSD. Based on clinical judgment and ONSD measurement
above the expected cut-off range, medical management for
Elevated ICP was started. A Plain Brain CT Scan was obtained.
Definitive treatment was planned after confirming on CT scan.
ONSD measurement more than 6mm was suggestive
of Elevated ICP
Results:
108 patients were studied. A normal range of
ONSD found was 3.5mm – 5.4mm.
26 patients had CT results consistent with Elevated ICP.
All cases of CT-determined Elevated ICP were correctly
predicted by ONSD. The sensitivity and specificity of this study
is 98.75 % and 92.86% respectively.
Conclusion: POCUS has the advantages of cost, time
effective, non-invasive and reproducibility. It can be used as
an additional diagnostic tool.
Keywords:
Optic nerve sheath diameter, Point of care
Ultrasound, Intracranial pressure
INTRODUCTION
Traumatic Brain Injury (TBI) is defined as impairment in
brain function as a result of mechanical force. The dysfunction
can be temporary or permanent, and may or may not result in
underlying structural changes in the brain. [
1] Any changes to
the volume of the intracranial contents affect the Intracranial
Pressure (ICP). Normal ICP is <15 mm Hg and is determined by
the volume of the three intracranial compartments: the brain
parenchyma (1300 ml), cerebrospinal fluid (CSF) (100 to 150
ml), and intravascular blood (100 to 150 ml). When one
compartment expands, there is a compensatory reduction in
the volume of another and/or the baseline ICP will increase
(Monroe Kellie Hypothesis).[
2] Rapid rises in ICP may lead to a
phenomenon known as the Cushing Reflex (hypertension,
bradycardia, and respiratory irregularity). This triad is classic
for an acute rise in ICP. [
3]
If ICP rises to the level of the systemic arterial pressure,
cerebral brain perfusion ceases and brain death occurs.
Uncontrollable ICP is defined as an ICP of 20 mm Hg or higher
refractory to treatment. If ICP is not controlled, herniation
syndromes can occur, resulting in brainstem compression and
subsequent cardiorespiratory arrest. [
4]
Of the various traditional means of detecting EICP in
an acutely ill patient, none except physical examination can
be performed rapidly and non-invasively at bedside. However,
the physical examination has significant limitations if the
patient is unconscious or intubated and paralyzed. Papilledema
from EICP is delayed in its appearance from Intracranial
Pressure Elevation, by up to several hours. Performing a lumbar
puncture to measure pressure on a patient with potentially
EICP may be dangerous. Thus, for most patients in the
Emergency Department setting, Head Contrast Tomography
scanning is often the best option available for the detection of
EICP.
In situations like a disaster scene where multiple
casualties are being triaged, and the ability to detect EICP in
one out of several critical patients may help select the patient
requiring the most rapid care also in times of scarce resources,
when a decision has to be made regarding which trauma victim
is most likely to survive.[
5]
Ultrasound is a readily available imaging modality in
most critical care areas, and examination of the optic nerve
sheath by bedside ultrasound allows detection of changes in
diameter which may indicate intracranial hypertension.[
6]
Elevated ICP is a common emergency following brain injury,
with prompt diagnosis having a significant impact on morbidity
![](table12.png)
mm. The sensitivity and specificity for ONSD, when compared
with CT results, were 100% and 95%, respectively.
In Geeraerts et al [15] study the largest ONSD value was
significantly higher in EICP patients. There was a significant
relationship between the largest ONSD and ICP at admission.
The largest ONSD was a suitable predictor of high ICP.ONSD
was well prognosticated with treatment modalities. The
sensitivity was 100%.
In Claire Shevlin et al [
4] study of ONSD values greater
than 5 mm, and certainly greater than 5.8 mm, have been
shown to be highly specific and sensitive for the presence of
EICP. EICP should be considered in the presence of an ONSD
greater than 5mm, and if greater than 5.5 mm urgent
consideration should be given to medical management.
Tayal et al[7], 59 patients were selected for the study,
cutoff was kept to be 5 mm. Patients with EICP had ONSD > 5.5
mm. 8 patients with an ONSD of 5 mm or more had CT findings
suggestive of EICP. Sensitivity 100%, specificity 63%.
Altered sensorium and focal neurological signs also
showed significance with clinical correlation.92.31% patients
having bradycardia had increased ONSD and abnormal CT
findings.
51.02% patients having Irregular respiratory pattern had
increased ONSD and abnormal CT findings.100% patients
having a poor GCS between 3-8, had increased ONSD and
abnormal CT findings.76.92% patients having a Moderate GCS
between 9-12, had increased ONSD and abnormal CT findings.
CONCLUSION:
92.86% patients had ONSD >/=6 mm and abnormal CT
Brain findings.
100%patients had ONSD between 5.5 to 5.9 mm and
abnormal CT findings.
There were no patients having ONSD in ranges between
3.5 to 4.4 mm and 4.5 to 5.4 mm with abnormal CT findings
(0.00%).
Elevated ICP should be considered in the presence of
an ONSD greater than 5.5 mm, and if greater than 6 mm, urgent
consideration should be given to medical management pending
further diagnostic workup.
A poor GCS at the time of presentation to the ED is
associated with Elevated ICP and has Increased ONSD with
abnormal CT findings.
Bradycardia, Hypertension and Irregular breathing
pattern are associated with Elevated ICP with Increased ONSD
and abnormal CT findings. This defines the Cushings Reflex.
93.10% patients who had Increased ONSD and were
started on Medical Management had EICP confirmed on CT
Brain and Definitive treatment given.
ONSD value can thus be prognosticated with Treatment.
Thus Increased ONSD and Abnormal findings on CT scan
Brain are statistically significant with Elevated ICP.
Bedside ultrasound has the advantages of Expense,
time-effective, non-invasive and does not require moving a
critical patient from the ED. In acute care settings, Ultrasound
can be used for early detection and to prioritize patients in
the setting of trauma. It is a rapid and reproducible modality
and the method could be applied as an additional diagnostic
tool in Emergency and Intensive care settings.
List of Figures;
1. Proper transducer placement to obtain transverse &
saggital
2. Measured increased ONSD
List of Tables:
1. ONSD range correlated to ONSD and Ct findings
2. Medical Management vs Definitive Treatment
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How to cite this article : Mhatre M, Baviskar A, Dongre H,
Rajpal D. Efficacy of optic nerve sheath diameter by
ultrasound as a non-invasive method to determine elevated
intracranial pressure in Indian population. Perspectives in
Medical Research 2019; 7(2):38-42
Sources of Support: Nil,Conflict of interest:None declared