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. 2019 Dec 18;14(12):e0224594.
doi: 10.1371/journal.pone.0224594. eCollection 2019.

Olfactory bulb volume changes associated with trans-sphenoidal pituitary surgery

Dino Podlesek  1 , Amir Zolal  2 , Matthias Kirsch  3 , Gabriele Schackert  1 , Thomas Pinzer  1 , Thomas Hummel  4
Affiliations

Olfactory bulb volume changes associated with trans-sphenoidal pituitary surgery

Dino Podlesek et al. PLoS One. .

Abstract

Objective: The trans-sphenoidal approach is most frequently used for pituitary adenoma (PA) enucleation. However, effects of this surgery on neighboring structures have received little attention so far. In particular, no investigations on olfactory bulb (OB) anatomy after trans-sphenoidal surgery have been reported. Because impairment of olfaction has been shown in small groups following trans-sphenoidal surgery we hypothesized that the transnasal approach is likely to alter OB volume which is associated with changes of olfactory function.

Methods: The study comprised 33 patients with pituitary adenoma (14 women and 19 men, mean age 50 years). Comprehensive assessment of olfactory function was conducted with the "Sniffin' Sticks" test kit. Based on magnetic resonance imaging scans OBs were measured before and approximately one year after trans-sphenoidal PA enucleation.

Results: Owing to postoperative non-compliance and MRI artifacts partly due to drill friction complete evaluation of "Sniffin' Sticks" in term of obtaining the TDI score was possible pre- and postoperatively in 21 patients whereas OB volumes were available in 32 patients. Approximately one year after surgery olfactory function was not significantly different from baseline. However, left- and right-sided OB volume in patients treated via trans-sphenoidal surgery decreased (p = 0.001). The side of the surgical approach did not affect OB volume in a side-specific manner. Changes in odor threshold were significantly correlated to changes in right-sided OB volume (r = 0.45, p = 0.024).

Conclusion: Overall olfactory performance one year after surgery was not significantly different from baseline. However, changes in OB volume are associated with changes in olfactory performance and OB volumes decreased in patients.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Segmented OB in a 60 years old female patient with pituicytoma pre- and postoperatively on the basis of T2 coronar images.
Postoperative volumetry was performed 13 months after transsphenoidal tumor enucleation. The protocol included T2-weighted 2D turbo spin echo (TSE) sequence in the coronal plane (matrix 256×256; field of view 120×120; slice thickness 2.0 mm; number of slices 30). Olfactory bulbs were smaller postoperatively.
Fig 2
Fig 2
A: OB volume (means, SEM) before and after surgery, separately for the left and right side; B: Correlation between the change of the right-sided OB volume and TDI score (r20 = 0.52, p = 0.018; for this display an outlier was removed–with the outlier the coefficient of correlation is slightly smaller: r21 = 0.48, p = 0.026). The graph shows that in 4 patients a slightly improved olfactory function is associated with an increased right-sided OB volume. The gravity of the changes, however, is on the side of smaller olfactory bulbs accompanied by decreased olfactory function.
See this image and copyright information in PMC

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