Neuropsychological Significance of Anosmia following Traumatic Brain Injury

Abstract

Anosmia is a common sequela of TBI, although only a minority of patients are aware of this deficit. Further, anosmics demonstrated greater impairment in a variety of frontal-lobe mediated executive functions, as well as greater functional disability.

Posttraumatic olfactory dysfunction

“…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).…”

Olfactory and executive dysfunctions following orbito-basal lesions in traumatic brain injury

“…The increasingly accepted relationship between post-traumatic anosmia and frontal lobe involvement is further supported by the difficulties that patients with anosmia exhibit in executive functions [19] and affective states [20]. In fact, these functions rely on the same regions as olfactory processing-frontal regions for executive functions and limbic regions for emotions [21].…”