High-resolution transbulbar ultrasonography helping differentiate intracranial hypertension in bilateral optic disc oedema patients

Abstract

Purpose: The enlargement of optic nerve sheath diameter (ONSD) has been proven to be related with raised intracranial pressure (ICP). No prospective study has been focused on utilizing retrobulbar ultrasonography in optic disc oedema patient presented to ophthalmologist.

Methods: High-resolution transbulbar ultrasonography was performed in a cohort of patient presented with bilateral optic disc oedema. The subarachnoid space of optic nerve (SAS), ONSD and optic nerve diameter (OND) was measured prior to other ancillaries including lumbar puncture. Subjects were classified into increased intracranial pressure (IIP) and normal intracranial pressure (NIP) group according to the open cerebrospinal fluid pressure more than 200 mm H₂ 0. The SAS, ONSD and OND were compared between groups and with normal control. The sensitivity of SAS or ONSD change for predicating intracranial hypertension was assessed.

Results: A total of 20 IIP, 25 NIP patients and 25 normal controls were evaluated. The mean SAS and ONSD measured in idiopathic intracranial hypertension group was significantly increased than that of NIP and controls (p < 0.001), whereas the OND showed no statistic difference between each group. The sensitivities using the SAS and ONSD for differentiating increased ICP in optic disc oedema patients were 0.99 and 0.97, respectively.

Conclusions: The enlarged SAS and ONSD measured by high-resolution transbulbar sonography are very sensitive parameters to predicate increased ICP in bilateral optic disc oedema patients.

Keywords: high-resolution ultrasonography; intracranial hypertension; optic disc oedema; optic nerve sheath diameter.