Use of Ultrasonography in Neurological diseases of the eye

1. Use of Ultrasonography in
Neurological diseases of the eye:
Dr.Roopchand PS
Senior Resident Academic
Department of Neurology

2. Introduction:
• Settings used in USS eye
– B-mode – transmit frequency 14 MHz, mechanical
index (MI) = 0.23, single focal zone at 2.5 cm,
bandwidth 74 dB;
– C-mode – transmit frequency 10 MHz, MI = 0.23,
color scale optimized for low velocities, no wall
filter
– pw-Mode – transmit frequency 2 MHz, MI = <0.23
(<0.44*) .

3. • During the examination the patient lies in
supine position with the eyes closed.
• A layer of acoustic gel is applied to the closed
lids, the transducer is placed on the upper and
slightly lateral eye-lids with the examiner’s
hand resting on the orbital margin to minimize
pressure on the globe.

5. ICP Monitoring:
• Raised Intracranial Pressure (ICP) is a dreaded
complication of neurological disease.
• Invasive measurement by an intraventricular
or intra-parenchymal catheter is the gold
standard.
• It may not be feasible in a heterogenous group
of medical patients.

6. • The optic nerve sheath is an anatomical
extension of the duramater
• The subarachnoid space around the optic
nerve is continuous with the intracranial
subarachnoid space.
• Any pressure rise within the intracranial
compartment impacts on the optic nerve head
as swelling of the optic disc and papilledema.

7. • Requiring a skilled observer for precise
identification.
• May develop late or may evolve.
• Dilatation of the optic nerve sheath has been
shown to be a much earlier manifestation of
ICP rise.
• B Mode USS can be used to measure optic
nerve sheath.

8. • Using cut-off values of 4.6 mm for females,
and 4.8 mm for males-high level of sensitivity
and specificity for the diagnosis of intracranial
hypertension as evident on CT or MRI imaging.
• Can be used for early detection aswell as
monitoring of ICP.

10. Papilledema
The mean depth measurements ranged from 0.68 to 2.01 mm (1.17 +/-
0.38 mm)

11. Vascular diagnostics:
• It can greatly aid in the diagnosis of visual loss
due to CRAO and Temporal Arteritis.
• B mode scan, Spectral Doppler with colour
mode are used.
Orbital vessel Mean ± SD Blood Flow, cm/s (Range)
Central retinal artery 10.3 ± 2.1 (6.4-17.2)
Central retinal vein 2.9 ± 0.73 (1.9-5.4)
Ophthalmic artery 31.4 ± 4.2 (23.5-39.8)
Posterior ciliary artery 12.4 ± 4.8 (1.4-22.7)

12. Normal:

13. • CRAO a hyperechoic structure might be
depicted in the optic nerve head, representing
a fresh cholesterol embolus - termed “spot
sign

15. Pseudopapilledema:
• A common cause for pseudopapilledema are
optic disc drusen.
B-mode sonography: calcific dispositions in the optic nerve head representing optic
disc drusen. (b) Fundoscopy: nasally located superficial drusen, blurred rim of optic
disc, optic disc edema and hyperemia