The diagnosis of IIH is traditionally made if the clinical findings meet the modified Dandy criteria (5). Of the 606 patients, 3 (0.50%) (Patient P1, P2 and P3) met these criteria for IIH. This number does not include Patient P4 who declined lumbar puncture. All cases identified in the current study had very mild papilledema, which was not visually significant at the time of diagnosis. Whether these patients would have progressed to more severe papilledema is unknown.
Our study examined a large population of morbidly obese patients and found that none had papilledema with significant visual loss. Whether the 6 patients with suspicious optic nerves who were not evaluated in clinic could have undiagnosed IIH is unknown. However, all 6 of these patients had mild optic disc edema (stage 1) on screening photographs (Fig. 2); therefore, it seems unlikely that any cases of papilledema with significant visual loss were excluded. One interpretation of these data is that obesity alone is not a direct causal factor in the development of IIH. Because our study population comprised chronically obese patients, we are unable to assess if recent weight gain is a major risk factor for developing IIH. Previous studies suggest that if this is the case, then treatment with aggressive weight loss, including bariatric surgery, may be beneficial (2,25).
This study has several limitations. First, the large body habitus of our patients precluded in-office lumbar punctures in the lateral decubitus position. Normative data for opening pressures are known for the lateral decubitus position, but similar normative data do not exist for lumbar punctures performed in the prone position (26). Therefore, it is unclear how to interpret these opening pressure values. We did not analyze the comorbidities of our patients. Obesity is associated with numerous chronic medical conditions that may affect the development of IIH, including obstructive sleep apnea, hypertension, diabetes mellitus, and hypercoagulability. Further research into this area is ongoing. Finally, only 2 of the 4 patients with mild optic disc edema had magnetic resonance venograms. The magnetic resonance venogram for patient P1 was inconclusive. The other 2 patients had MRI only. It is possible that these imaging studies could have missed cerebral venous thromboses causing papilledema.
To our knowledge, this is the first prospective study evaluating the prevalence of previously undiagnosed IIH in morbidly obese patients. We found that, in this patient population, asymptomatic or previously undiagnosed papilledema with significant visual loss is extremely low. Based on our results, routine screening for papilledema with nonmydriatic fundus photographs for asymptomatic obese patients is likely not warranted. However, bariatric surgeons should be vigilant in screening for any symptoms consistent with IIH and refer these patients promptly for neuro-ophthalmic evaluation.
The authors thank Raymond Kong for his assistance with creating the figures.
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