Hello, my name is Tyler Cho, and I am a second year medical student at The Ohio State University College of Medicine. I will be presenting on the resource utilization and radiation exposure in patients with idiopathic intracranial hypertension that I had the pleasure of studying with Dr. Dan Kreatsoulis, Dr. Luciano Prevedello, and Dr. Douglas Hardesty. There were no conflicts of interest in this study. Idiopathic intracranial hypertension, or as I will refer to it as IIH, was historically called pseudotumor cerebri and is a condition characterized by elevated intracranial hypertension without an identifiable cause. IIH has a high incidence in patients that are female, Caucasian, obese, and of childbearing age. Patients with IIH present with a range of symptoms, most commonly chronic debilitating headaches and in severe cases, permanent vision loss. Patients include lifestyle modifications such as weight loss and medications like acetosolamide. More severe cases are often treated with cerebrospinal fluid diversions such as ventricular peritoneal or lumboperitoneal shunts. However, surgical approaches are rarely curative, with many patients with persistent refractory symptoms despite successful CSF diversion. As such, many of these patients utilize healthcare resources at a high frequency, especially emergency departments. Given their symptoms, such as headache and vision loss, it is understandable that assessment of patients with IIH include the use of imaging modalities, often including a combination of CT imaging, shunt series x-ray, and MRI. And so factoring in the persistent nature of IIH, the high frequency of which patients with IIH utilize healthcare resources, and the typical workup consisting of numerous imaging studies, we asked the question of just how much are these patients being exposed to ionizing radiation as a result of their condition. Furthermore, wanted to assess just how clinically and diagnostically useful imaging studies were in patients with IIH. In our study, we retrospectively reviewed 100 randomly selected patients with IIH and a prior CSF diversion procedure treated at our institution between July 2010 and August 2018. Demographics, patient characteristics, healthcare utilization data, imaging utilization data, and estimated radiation exposures were collected. CTs, shunt series x-rays, and MRIs ordered in the emergency department were reviewed for the rationale for the order and their diagnostic findings. For healthcare encounters and imaging studies, we looked solely at those pertaining to IIH. For example, primary care visits or visits to other specialists for concurrent medical conditions were not included. Firstly, our cohort was consistent with published epidemiological data of patients with IIH. In our study, 90% of our patients were female, 75% Caucasian, of childbearing age with an average age at baseline of 33.4 years old, and obese with an average BMI of 40.62. Treatment-wise, by their last encounter in the study period, there was a variety in the type of CSF diversion used to treat their condition, with VP and LP shunts the most common. Prior to baseline, 21 patients had a history of shunt revision surgery, with a further 56 patients undergoing revision surgery during the study period. Of those 56 patients, there was an average of 2.6 revision surgeries performed during the study period. Additionally, almost every patient had prior treatment with either optic nerve fenestration or the use of orodiuretic or anticonvulsive medication. As for healthcare utilization, the average length of follow-up for IIH-related complaints within our study period was 4.8 years. In that time, our cohort averaged 33.4 total healthcare encounters, consisting of, on average, 12.4 emergency department encounters, 4.6 inpatient admissions, and 16.3 office visits. As you can see, there are a number of patients that utilize healthcare resources at an extremely high rate, particularly in the emergency department. Those numbers are likely underestimates, as they only include encounters at our institution and does not factor in encounters at other institutions. Moving on to imaging studies, our cohort averaged 23.8 total imaging studies across our study period, consisting of, on average, 9 head CTs, 0.2 CT angiograms, 4.3 brain MRIs, and 10.3 shunt series x-rays. Using values of 2 mSv per head CT, 4 mSv per CT angiogram, and 0.267 mSv for shunt series x-rays, we were able to calculate the estimated ionizing radiation exposure as a result of imaging studies. Our cohort averaged 21.4 mSv of radiation. As you can see in the figure below, a majority of patients received less than 20 mSv, but there are a number of patients with high levels of radiation exposure, with some greater than 50 mSv. Just as the number of healthcare encounters, these numbers pertaining to imaging studies and cumulative radiation exposure are likely underestimates, as they only include those at our institution and does not factor in imaging studies possibly ordered at other institutions. In the emergency department, there were 748 imaging studies ordered for IIH-related complaints. Rationales and diagnostic findings of those imaging studies are shown here. Of those 748 imaging studies, 263 were CTs, 436 were shunt series x-rays, and 49 were MRIs. The three most common reasons for ordering an imaging study were headaches at 92.6% of the time, nausea and vomiting at 52.5% of the time, and vision changes at 47.3% of the time. Diagnostic findings were initially separated by presence or lack of an actionable finding, which is a finding that could suggest further treatment or a change in course of treatment. Of the 748 total imaging studies, 91% demonstrated no significant findings. Specifically, absence of significant findings was shown in 82.5% of CTs, 97.5% of shunt series x-rays, and 79.6% of MRIs. Of the 9% of imaging studies that showed actionable findings, the most common pathologies found were evidence of over-shunting and decreased ventricles at 2.4%, effects of increased intracranial pressure at 1.7%, and sinus disease at 1.5%. We also explored potential racial disparities in patients with IIH. We compared the rates of healthcare utilization, rates of imaging studies, and shunt revision surgeries between Caucasian and African-American patients. Of these, we found that inpatient admissions, number of MRIs ordered, and the average number of revision surgeries were significantly lower in African-Americans compared to Caucasian patients. Our studies showed that patients with IIH truly utilize healthcare resources at a high rate for persistent refractory symptoms, and as a result, undergo frequent imaging studies and are exposed to considerable levels of ionizing radiation. Furthermore, imaging studies showed actionable findings less than 10% of the time, bringing into question their diagnostic and clinical usefulness. Patients with IIH, as well as patients of other chronic conditions that require numerous imaging studies, may benefit from alternative modalities of imaging, such as limited-sequence head CTs or ultrasound, to minimize unnecessary radiation exposure. Finally, our studies suggest possible racial disparities in patients with IIH and in the field of neurosurgery, and as such, deserves further attention and further research. Thank you for your time. If you have questions, I can be reached at the email provided.

idiopathic intracranial hypertension

resource utilization

radiation exposure

emergency department

racial disparities