SD-OCT in monitoring intracranial pressure in patients with CSF shunts

Abstract

 

Purpose

 

To introduce a novel method of monitoring of CSF pressure in patients with CSF shunts using SD-OCT

 

Methods

 

Case review

 

Results

 

Case 1 was 24 year old female with idiopathic intracranial hypertension (IIH), optic atrophy and a ventriculo-peritoneal (VP) shunt. On follow up she developed headaches without changes in acuity or fields. Funduscopy showed optic atrophy and SD-OCT also failed to show any change in the RNFL thickness; however, the retinal pigmented epithelium (RPE) layer was inwardly deformed towards the vitreous. One month after shunt revision, symptoms resolved and the RPE layer returned to baseline shape(Figure 1). Case 2 was a 35 year old female with IIH and a lumboperitoneal (LP) shunt presented with worsening visual field. The patient had papilledema, thickening of the RNFL and inward deformation of the RPE layer on SD-OCT. 36 hours after the revision, the acuity, visual field, disc appearance and RNFL thickness remained unchanged but the RPE shape returned to baseline.

 

Conclusions

 

Inward deformation of the RPE layer toward the vitreous is a consequence of the translaminar pressure gradient between the CSF and intraocular pressure as well as the biomaterial properties of the underlying sclera. These two cases demonstrate that this deformation on the OCT can be used to indirectly assess the CSF pressure even in patients with optic atrophy (where the optic disc does not swell) and may show improvement before the disc edema resolves.

 

 

Figure 1:Baseline raster is shown (a). Note the deformation with shunt failure in (b) and then return to baseline in (c). Superimposed tracings of each raster is shown in (d). Note the absence of any significant change in RNFL thickness.

 

Keywords: 629 optic nerve • 550 imaging/image analysis: clinical