Phantosmias and Parkinson Disease

Abstract

Background: Impaired olfaction is a common, nonmotor manifestation of Parkinson disease (PD). However, to our knowledge, qualitative olfactory disturbances, such as odor distortions, have not been extensively reported in this condition. Objective: To describe 2 patients who reported positive olfactory symptoms preceding typical PD, which were consistent with olfactory hallucinations (phantosmias) in the absence of major smell deficit. Design: Case series. Setting: University hospital. Patients: We describe 2 patients, both seen in 2007, who reported pleasant olfactory hallucinations for several years. Main Outcome Measures: Iodine I 123-labeled ioflupane single-photon emission computed tomography and olfactometric testing results. Results: The 123 I-labeled ioflupane single-photon emission computed tomography showed reduced radiotracer uptake in both striatum more marked in the putamen and on the left side in patient 1 and reduced radiotracer uptake in both putamen more marked on the right side in patient 2. Olfactometric testing showed mild hyposmia in patient 1 and normal function in patient 2. The disappearance of the phantosmias in both patients coincided with the development of typical PD. Conclusion: We propose phantosmia as a new premotor manifestation of PD and suggest that qualitative abnormalities of olfaction, rather than the typical smell loss demonstrated in this condition, should be more carefully examined in the prodromal phase of PD.

Olfactory Loss in Parkinson's Disease

“…A number of case reports could show that some patients have experienced phantosmia very early in the course of the disease [35–37]. According to a recent study by Landis et al [38], however, idiopathic phantosmia as an early sign of PD remains probably a rather exceptional presentation whereas the overwhelming majority of people with idiopathic phantosmia will not develop PD.…”

Idiopathic Phantosmia: Outcome and Clinical Significance

“…Recent reports have shown that some patients who developed PD have experienced phantosmia very early in the course of the disease [3,20,21] . However, phantosmia seems to be rather rare in PD.…”

“…Several case reports identified idiopathic phantosmia to herald diseases such as tumors, chronic rhinosinusitis, intracranial hemorrhages, epilepsy, psychiatric conditions or, as recently suggested, Parkinson's disease (PD) [3] . In idiopathic hyposmia and anosmia, we could recently show that almost 10% of patients develop extrapyramidal symptoms or PD 4 years after initial presentation [4] .…”

Human Olfactory Perception

“…170 Two possible mechanisms have been suggested for phantosmia: either an altered inhibitory input from the primary olfactory neurons, or the presence of peripheral olfactory or trigeminal signals that 'trigger' a central perception. Olfactory perceptual disturbances can also be associated with temporal lobe epilepsy.…”