ICHD-2 Criteria for Diagnosis of Intracranial Hypotension:
- orthostatic headache (starts 15 minutes to hours after upright positioning, improves 15-30 minutes after lying down)
- PLUS at least 1 of the following:
- neck stiffness, tinnitus, hyperacusia, photophobia, nausea
- CSF opening pressure <6cm H20, observation of CSF leakage on imaging, MR imaging features of IHS
Classic Imaging Findings in IHS:
- diffuse dural enhancement, 85%
- brain descent on sagittal, 40-50%
- Caudal displacement of tonsils, 25-75%
- bilateral subdural fluid collections, 15%
Other MRI findings:
- thickening and enhancement of dura
- pituitary enlargement
- subdural effusion (hematocele)
- venous engorgement
Brain MRI (below). (a) Diffuse dural thickening, (b) herniation of the cerebellar amygdalae, (c) bilateral fronto-temporal subdural collections, (d) diffuse cerebral edema.
Quantitative Indicators: In patients with IHS, the pontomesencephalic angle and mamillo-pointine distance may help in diagnosing this syndrome more accurately.
- mamillopontine distance
- inferior margin of mammillary bodies to superior margin of pons
- 6.4mm (Sn and Sp of 73.1%)
- pontomesencephalic angle
- angle between a line drawn along the anterior margin of the midbrain and the anterosuperior margin of the pons
- 51.7 deg (Sn 76.9% and Sp 96.2%)
Other MRI Findings:
Anvekar, Dr. “Neuroradiology Cases: Intracranial Hypotension MRI”. Neuroradiologycases.com. N.p., 2011. Web. 14 Jan. 2016.
Quintero, Iván Fernando et al. “Intracranial Hypotension Syndrome: A Post Dural Puncture Headache?”. Colombian Journal of Anesthesiology 41.1 (2013): 57-60. Web. 14 Jan. 2016.
Screencast.com,. N.p., 2016. Web. 14 Jan. 2016. http://www.screencast.com/users/OckerARRS/folders/Exhibits/media/fd674437-2a9a-43f4-9472-587eb544aba9/embed
Tian, Weizhong et al. “A Quantitative Study Of Intracranial Hypotensive Syndrome By Magnetic Resonance”. Clinical Neurology and Neurosurgery 141 (2016): 71-76. Web. 14 Jan. 2016.