Personal Injury Law

Traumatic Brain Injury and Olfactory Deficits

By Bruce Stern

I just read a very interesting article which appeared in the January 2010 issue of Brain Injury.  The article entitled 'Traumatic Brain Injury and Olfactory Deficits: The Tale of Two Smell Tests!' by Fortin, Lefebvre and Ptito, from Montreal, Canada, compared two smell tests that are used in clinical setting.
 
It is well known that one of the sequelae of traumatic brain injury is the loss of smell and taste due to damage to the olfactory cranial nerve.  This damage occurs usually in a motor vehicle crash, where 'the brain moves in the skull and, since the fibers of the olfactory nerve pass through the cribriform plate, they are likely to be damaged due to sheering.  Damage can also be caused by compression of the olfactory bulbs or other olfactory-related critical structures because of traumatic contusion or hemorrhage of the orbitofrontal and anterior temporal lobes.  Research has demonstrated that approximately 45% of patients with olfactory impairments had frontal impact and 37.5% had occipital impact during the crash.
 
Not surprisingly, Green and Iverson suggest that there is 'an over-estimation of the prevalence of olfactory impairment in the TBI population because exaggeration or faking is usually not accounted for.'
 
The researchers used the two well known smell tests, The University of Pennsylvania Smell Identification Test (UPSIT) and the Alberta Smell Test.  Forty-nine TBI patients admitted to an out-patient rehabilitation program were used during the research.  The researchers found that the two smell tests 'were significantly correlated' and that 'both tests indicated that patients with frontal lesion performed significantly worse than patients with other types of lesion.'  The researchers found that 'mood and injury severity were not associated with olfactory impairment when age was taken into account.'  Finally, the researchers found that between 40-44% of the patients showing olfactory impairments were not even aware of their deficit.'  The researchers concluded that since a 'significant portion of the patients showing olfactory impairments were not aware of their deficit, it was recommended that clinicians systematically evaluate olfactory functions using the Alberta Smell Test.'  The researchers recommended that 'in order to refine their diagnosis that the UPSIT could also be used.'

Full post as published by Traumatic Brain Injury Law Blog on April 27, 2010 (boomark / email).