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Tuesday, August 4, 2015
Taste and Smell and the Basal Ganglia
I have had two brain MRI`s in the last five months, both done with gadolinium contrast. The MRI`s were performed by separate establishments and examined by different physicians trained to interpret MRI`s. In both cases, the physicians noted a "prominient perivascular space in the left inferior basal ganglia." The oval area on the MRI measured 8mm. However, since such a "Virchow-Robin" space is considered benign, the two MRI`s ultimately were classified as "normal." Here`s the problem: I suddenly lost much of my sense of taste and smell during the acute onset of several neurological symptoms that prompted these brain MRI`s. I understand that some portion of taste and smell interpretation is processed in the basal ganglia in addition to its primary function of handling motor functions. It is also a fact that many people suffering from Parkinson`s disease note a decreased ability to taste/smell early in the disease`s course. Could this "perivascular space" actually be the root cause of my taste/smell dysfunction --perhaps disrupting dopamine production and therefore dampening the ability of my brain to interpret taste and smell? While I understand these spaces are pretty common in older adults, wouldn`t it seem unusual for an 8mm space to show up in a 35-year-old? Of course, I don`t expect a diagnosis over the Internet, but any open speculation would be appreciated.
I am unable to answer directly to your specific case as only a thorough neurological and physical examination by your physician could define the source of your symptoms. In general, however, there has been more interest in recent years in the phenomenon of loss of smell seen in PD patients. With more research into this area, it is now largely believed that this is likely mediated through loss of nerve cell function outside of the basal ganglia area. Most likely there is some degeneration of function or cells in the olfactory bulb (area of brain for interpreting smell) or perhaps even in the area that processes memory of smells. These areas are not located in the basal ganglia or the "typical" striatal nigral pathway that is usually thought of as being the main areas effected in PD. Thus, it emphasizes that PD is a disease that truly effects more than just the basal ganglia circuitry.
Karen M Thomas, DO
College of Medicine
The Ohio State University