Evaluation of optic nerve sheath diameter in comparison with cerebrospinal fluid pressure in children with idiopathic intracranial hypertension.

The purpose of this study is a non-invasive diagnosis of increasing the pressure of cerebrospinal fluid in patients involved in idiopathic intracranial hypertension (IIH) that is done with transbulbar sonography.

In this descriptive cross-sectional study all the non-toxic children under 18 who were referred to the neurology clinic of Loghman Hospital of Tehran from October 2017 to October 2018 with increased intracerebral pressure symptoms were studied. The increased intracerebral pressure symptoms were headache or vomiting or blurred vision or 6th nerve palsy and they had papillary edema. Also, if their diagnostic brain imaging measures were normal such as: Magnetic Resonance Imaging (MRI), Computed Tomography scan (CT scan) and in some cases Magnetic Resonance Venography (MRV), they were suspected to Idiopathic intracranial hypertension and were entered into the study consecutively. Their complete medical history and comorbidities and biographical information were recorded in the file. All patients were candidates for a lumbar puncture to measure cerebrospinal fluid pressure. After full explanation to the parents and obtaining written consent from them before performing a lumbar puncture, patients in coordination with the ultrasound unit without delay in performing a lumbar puncture, first underwent trans orbital ultrasound in supine position and were awakened with closed eyes. Opticians were implanted in both eyes by a skilled sonographer. And then sedated with sedatives (ketamine or midazolam) prescribed by an anesthesiologist. It was placed in a sterile position in a supine semi-flexion position and with lateral decubitus aligned with the body. Cerebrospinal fluid pressure to cm of water was recorded using a serum set in the lumber intervertebral space 4-5. Then a sample was sent for analysis and smear.

Out of 10 patients (age 2.5–14 year, mean 9 years) 10% were girls, 90% were boys, and mean BMI was 22.5 kg/m2. Their symptoms included: 80% Headache, 40% Vomiting, 40% Diplopia, 20% Blurred vision, 10% 6th nerve palsy, and 10% Tinnitus when being reffered. In All patients, CSF pressure was more than 25 cm H2o (mean 40 cm H2o), right and left eyes optic nerve sheath diameter (ONSD) was more than the cutoff point (ONSD≤4.5 mm), the mean right ONSD was 6.31 mm and left eye was 6.64 mm.

According to the findings of this study, the measuring of optic nerve sheath diameter in patients suspected of increasing the pressure of idiopathic intracranial hypertension can be helpful as a non–invasive diagnosis method.