Traumatic brain injury and olfactory deficits: The tale of two smell tests!

Abstract

Since a significant proportion of the patients showing olfactory impairments were not aware of their deficit, it is recommended than clinicians systematically evaluate olfactory functions using the Alberta Smell test. To refine their diagnosis, the UPSIT can also be used.

Posttraumatic olfactory dysfunction

“…Other studies, but not all subsequent studies, have reported similar correlations between severity of injury and degree of olfactory dysfunction [28][29][30]. Interestingly Fortin et al found that 69% of 49 individuals admitted to an outpatient's rehabilitation program demonstrated impaired olfaction with no difference in rates according to TBI severity [31].…”

“…Unfortunately, no one single test has been accepted as the standard test of olfactory function, though several validated methods are commonly used [31,35,[48][49][50]. All tests involve odorant detection or odorant identification, though they can vary greatly in time of testing, cost, ease and manner of administration, supplies needed, and potential for self-administration.…”

“…The Alberta Smell Test uses scented markers inhaled into each nostril separately and is another example of a ''forced-choice'' test [31,53]. It is a good screening tool as the markers are reusable and therefore inexpensive, though patients with abnormal results should be tested with more comprehensive tests such as the UPSIT [54].…”

“…Many patients with posttraumatic olfactory dysfunction may be completely unaware of their loss [31,[34][35][36]. For those in whom the presence of olfactory disturbance is recognized, it may be days, weeks, or months after the traumatic event.…”

Implicit olfactory abilities in traumatic brain injured patients

“…Evidence from neuroimaging studies indicate that a damage at the level of eminent olfactory regions, such as entorhinal cortex or orbitofrontal cortex, is associated with poor performances at olfactory behavioral tasks (Atighechi, Salari, Baradarantar, Jafari, Karimi, & Mirjali, 2009;Bonanni et al, 2006;Fujiwara, Schwartz, Gao, Black, & Levine, 2008;Geisler, Schlotfeldt, Middleton, Dulay, & Murphy, 1999;Haxel, Grant, & Mackay-Sim, 2008;Mann & Vento, 2006;Roberts, Sheehan, Thurber, & Roberts, 2010;Sandford et al, 2006;Yousem, Geckle, Bilker, McKeown, & Doty, 1996). It must be said, however, that the present bulk of studies, as well as those only considering patients' performance at olfactory psychophysical tests (Callahan & Hinkebein, 1999De Kruiijk et al, 2003;Fortin, Lefebvre, & Ptito, 2010;Green & Iverson, 2001;Green, Rohling, Iverson, & Gervais, 2003;Landis et al, 2010;Sigurdardottir, Jerstad, Andelic, Roe, & Schanke, 2010;Swann, Bauza-Rodriguez, Currans, Riley, & Shukla, 2006), applied testing methods that require some specific cognitive functions to be intact. To date, to succeed in the completion of tests such as the University of Pennsylvania Smell Identification Test (UPSIT, Doty, Shaman, & Dann, 1984) and the Sniffin' Sticks Extended Test (Kobal et al, 1996), unharmed verbal and memory skills are needed (Olsson, Jonsson, & Faxbrink, 2002).…”