Purchase this article with an account.
K. G. Kapoor, D. M. Grzybowski, S. E. Katz; Odor Sensitivity Threshold in Patients With Pseudotumor Cerebri. Invest. Ophthalmol. Vis. Sci. 2007;48(13):951.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Pseudotumor cerebri (PTC) is a disease associated with increased intracranial pressure. Compression of the endoneurial sheath around the optic nerve in these patients can lead to visual deficits and even blindness. We hypothesize that compression of the endoneurial sheath surrounding the olfactory nerve can also lead to hyposmia in PTC. The purpose of this project is to determine if there is a statistically significant difference between the odor sensitivity threshold in PTC patients and age/weight matched controls.
Patients that presented with symptoms suggestive of PTC were selected from a neuroophthalmology practice at The Ohio State University Medical Center. These patients’ odor sensitivity was measured prior to diagnostic lumbar puncture using the "Sniffin’ Sticks" instrument by St. Croix Sensory, Inc. This test kit includes fourteen pen-like devices that have felt tips impregnated with increasing concentrations of the odorous agent n-butanol, and blank pens with no odor. Patients were blindfolded and presented pens in a sequence of increasing concentrations and asked to differentiate from the odorless pens. After multiple trials, the average point at which the patient was able to differentiate the pen with n-butanol from the odorless pens determined that patient's odor sensitivity.
Eight female patients between the ages of 18-40 with symptoms suggestive of PTC have been evaluated at this point. Odor sensitivity was graded on a scale of 0 (no odor sensitivity) to 15 (highest odor sensitivity). Odor sensitivity of these patients ranged from 0 to 7, with an average of 4.19. Patients determined to have PTC after diagnostic lumbar puncture had an average odor sensitivity of 2.38, and patients without PTC had an average odor sensitivity of 6.00. The difference in odor sensitivities of the two groups was statistically significant with a p-value <.05 (p=.045).
These results support our hypothesis that the endoneurial sheath surrounding the olfactory nerve is compressed in the PTC population. Due to greater drainage of cerebrospinal fluid (CSF) along the endoneurial sheath of the olfactory nerve, smell may be even more compromised than vision, possibly escaping clinical detection. This would further confirm our current model of CSF drainage and alter our understanding of PTC to a pathologic state with a larger family of systemic symptoms than previously believed. Also, depending on the sensitivity of this test, improved non-invasive methods of detecting PTC can be developed.
This PDF is available to Subscribers Only