title: Structural olfactory nerve changes in patients suffering from idiopathic intracranial hypertension.
abstract: BACKGROUND
  Complications of idiopathic intracranial hypertension (IIH) are usually caused by elevated intracranial pressure (ICP). In a similar way as in the optic nerve, elevated ICP could also compromise the olfactory nerve system. On the other side, there is growing evidence that an extensive lymphatic network system around the olfactory nerves could be disturbed in cerebrospinal fluid disorders like IIH. The hypothesis that patients with IIH suffer from hyposmia has been suggested in the past. However, this has not been proven in clinical studies yet. This pilot study investigates whether structural changes of the olfactory nerve system can be detected in patients with IIH.
  
  
  RESULTS
  Twenty-three patients with IIH and 23 matched controls were included. Olfactory bulb volume (OBV) and sulcus olfactorius (OS) depth were calculated by magnetic resonance techniques. While mean values of total OBV (128.7±38.4 vs. 130.0±32.6 mm(3), p=0.90) and mean OS depth (8.5±1.2 vs. 8.6±1.1 mm, p=0.91) were similar in both groups, Pearson correlation showed that patients with a shorter medical history IIH revealed a smaller OBV (r=0.53, p<0.01). In untreated symptomatic patients (n=7), the effect was greater (r=0.76, p<0.05). Patients who suffered from IIH for less than one year (n=8), total OBV was significantly smaller than in matched controls (116.6±24.3 vs. 149.3±22.2 mm(3), p=0.01). IIH patients with visual disturbances (n=21) revealed a lower OS depth than patients without (8.3±0.9 vs. 10.8±1.0 mm, p<0.01).
  
  
  CONCLUSIONS
  The results suggest that morphological changes of the olfactory nerve system could be present in IIH patients at an early stage of disease.
authors.affiliation: Institute of Radiology, Charité-Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Schmidt
authors.forename: Edzard
authors.initials: E
authors.lastname: Wiener
authors.forename: Jan
authors.initials: J
authors.lastname: Hoffmann
authors.forename: Randolf
authors.initials: R
authors.lastname: Klingebiel
authors.forename: Felix
authors.initials: F
authors.lastname: Schmidt
authors.forename: Tobias
authors.initials: T
authors.lastname: Hofmann
authors.forename: Lutz
authors.initials: L
authors.lastname: Harms
authors.forename: Hagen
authors.initials: H
authors.lastname: Kunte
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D019586:Intracranial Hypertension / Q000150:complications / Q000473:pathology / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009830:Olfactory Bulb / Q000473:pathology / Q000503:physiopathology*; D009832:Olfactory Nerve / Q000473:pathology / Q000503:physiopathology*; D010865:Pilot Projects; D011559:Pseudotumor Cerebri / Q000150:complications / Q000473:pathology / Q000503:physiopathology*