intracranial hypotension

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Diagnostic value of the optic nerve sheath subarachnoid space in patients with

intracranial hypotension syndrome

Clinical article Nobuyasu Takeuchi, M.D., Toru Horikoshi, M.D., Hiroyuki

Kinouchi, M.D., Ph.D., Arata Watanabe, M.D., Takashi Yagi, M.D., Kentaro

Mitsuka, M.D., Ph.D., and Nobuo Senbokuya, M.D. [...]

Journal of Neurosurgery 1-6 (Volume publication date: June 2012) DOI:

10.3171/2012.5.JNS1271

ABSTRACT

Object

The size of the subarachnoid space in the optic nerve sheath (ONS) on MR images

is thought to reflect intracranial pressure. The diagnostic value of this space

was investigated in patients with spontaneous intracranial hypotension (SIH)

syndrome.

Methods

Coronal fat-saturated T2-weighted MRI of the orbit was performed in 15 patients

with SIH fulfilling the diagnostic criteria for headache caused by low CSF

pressure of the International Classification of Headache Disorders or the

criteria for spontaneous spinal CSF leaks and intracranial hypotension. The size

of the subarachnoid space in the ONS was measured in 2 slices behind the

eyeballs. The images were compared before and after treatment. The CSF pressure

was measured by lumbar puncture.

Results

Before treatment, the diameter of the ONS subarachnoid space ranged from 2.58 to

4.21 mm (mean 3.34 mm) and the thickness from 0 to 0.48 mm (mean 0.15 mm). Both

measurements showed significant correlations with CSF opening pressure, and 8

patients had no CSF space before treatment. The size of CSF space increased in

many patients after effective treatment.

Conclusions

Disappearance of the CSF space in the ONS was frequently observed in patients

with SIH. This characteristic finding may be useful in the diagnosis of SIH as

well as in the evaluation of treatment effectiveness.

Abbreviations used in this paper:

EBP = epidural blood patch; ONS = optic nerve sheath; SIH = spontaneous

intracranial hypotension.