Artikel
Ultrasound of the optic nerve sheath diameter before and after microsurgical closure of a dural CSF-fistula as discriminator in spontaneous intracranial hypotension
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Veröffentlicht: | 8. Juni 2016 |
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Objective: Spontaneous intracranial hypotension (SIH) is caused by spinal cerebrospinal fluid (CSF) leaking. Sonographic, two-fold assessment (supine vs. upright position) of the optic nerve sheath is able to show a collapse of the optic nerve sheath in patients with SIH and orthostatic headaches. We wanted to test whether the collapse of the optic nerve sheath in the upright positon is related to the presence of an open fistula with current CSF leaking.
Method: We included patients with SIH with a proven CSF leak and refractory clinical symptoms from 2013 to May 2015. The systematic spinal diagnostic work-up included: dynamic ultrasound of the optic nerve sheath, fluid sensitive thin slice MRI of the spinal axis, MRI with intrathecal gadolinium, dynamic myelography, post myelography CT including delayed films, and microsurgical exploration. Microsurgical sealing of the CSF leak was aimed at in all cases.
Results: There were 15 patients with an proven (evidence of CSF leakage on CT/MRI and/or fluoroscopy) CSF fistula. One patient declined surgery. CSF leaking was verified at the time of microsurgical exploration in all cases. After sealing, the dural CSF leakage stopped and symptoms of SIH resolved in all cases. Before surgery, in an active state of SIH, mean ONSD was significantly different between supine (5.13 ± 0.77mm) and upright position (4.67 ± 0.79mm, p=0.002; Wilcoxon rank sum test). After surgery with symptoms resolved, the mean ONSD was not significantly different between supine (5.32 ± 0.63mm) and upright position (5.33 ± 0.73mm p=0.94). Comparing the mean changes (delta) in ONSD from supine to upright position, there was a significant difference in the same group of patients before (-0.46 ± 0.35mm) and after (0.01 ± 0.16mm; p=0.004) surgery.
Conclusions: Sonographic two-fold assessment of the optic nerve sheath diameter can discern open from closed spinal CSF fistulas in spontaneous intracranial hypotension. The findings also correlate with the clinical resolution of symptoms. Transorbital ultrasound of the optic nerve sheath diameter may be utilized as a non-invasive tool for follow-up examinations in patients with SIH.