Background. Measurement of CSF pressure is the only known way to confirm the diagnosis of intracranial hypotension. We aimed to assess colour doppler flow imaging (CDFI) for measurement of blood flow of the superior ophthalmic vein for the diagnosis of intracranial hypotension. Methods. We enrolled 25 consecutive patients with orthostatic headache who had clinical features of intracranial hypotension. We defined low-pressure headache as cerebrospinal-fluid pressure below 60 mm H2O. We used CDFI to measure the diameter and maximum flow velocity of the superior ophthalmic vein in all patients. Magnetic resonance imaging of the brain and lumbar puncture with measurement of cerebrospinal-fluid pressure within 24 h were also done after sonographic examination. The control group comprised 13 healthy individuals of a similar age; in addition, those patients who had orthostatic headache without low pressure served as a control group for the patients. Findings. Of the 25 patients recruited for this study, 13 satisfied the criteria for low-pressure headache. The remaining 12 patients with normal cerebrospinal-fluid pressure had transformed migraine (five patients) or chronic tension-type headache (seven patients), and therefore served as the control group for the patients. The mean diameter of the superior ophthalmic vein was substantially larger in the patients with intracranial hypotension (3.9 [SD 0.2] mm) than in the healthy controls (2.6 [0.4] mm) and the controls from the patients' group (2.7 [0.2] mm) (p < 0.0001). The mean maximum flow velocity was significantly higher in the intracranial-hypotension group (7.9 [SD 3.4] cm/s) than in the healthy controls (7.9 [1.1] cm/s) and the other patients (7.3 [1.7] cm/s) (p < 0.0001). Seven patients with intracranial hypotension were reassessed after treatment with epidural blood patch. After this treatment the clinical symptoms were relieved and there was a striking reversal of the superior ophthalmic vein flow. Interpretation. CDFI to measure blood flow of the superior ophthalmic vein provides a practical, simple, and non-invasive diagnostic method for suspected intracranial hypotension.
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