Central Pathway of Taste: Clinical and MRI Study

Abstract

We present 3 cases of hemiageusia due to focal ischemic lesions in the brainstem. Clinical presentation with discrete localization of these lesions suggests that the central taste pathway in humans projects ipsilaterally from the solitary nucleus up to the level of the upper pontine or lower midbrain before decussation. Associated partial sensory disturbance of the face or limb with lack of evidence of medial lemniscus decussation at the upper brainstem suggests that the medial lemniscus may not directly convey taste sensation.

Clinical study of central taste disorders and discussion of the central gustatory pathway

“…In this study, ipsilateral [12][13][14]16], contralateral [2,7], and bilateral taste disorders [3,[14][15][16][17] were observed for lesional sites located above the midbrain. In previous reports, it was hypothesized that the pathway crosses and ascends contralaterally above the midbrain [7] or that the taste information from the right side of the tongue projects to the left insular cortex via the right insular cortex [14].…”

“…The other 25 cases were previously reported in the literature from 1983 to 2008 [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. The three cases we have already reported [2] were not included in these patients.…”

Taste Disorders in Acute Stroke

“…Considering the role of the hemispheres in gustatory processing, the current literature indicates that gustatory function has a bilateral representation. 4,11,27 Although this concept makes it difficult to understand how a unilateral lesion can produce general taste loss, examples of this have been reported previously. 31 Thus, apart from the bilaterally ascending pathways, interhemispheric transfer of gustatory function has to be considered, which may contribute significantly to overall gustatory function.…”

“…[1][2][3][4] Despite this significance there are only few reports on taste disorders in stroke patients. 3,[5][6][7][8][9][10][11] One reason for this lack of systematic investigations may be that until recently, there were no standardized, validated tests of natural gustatory function that would also be commercially available. 12 It is also important to note that detailed taste testing is time-consuming and, during the acute phase of stroke, concern about taste is overshadowed by the patient's other serious and even life-threatening medical problems.…”

Altered Food Preference after Cortical Infarction: Korean Style

“…In human beings, the presence of decussation of the secondary ascending taste pathway remains controversial. Although pontine lesions are usually associated with ipsilateral hemiageusia [9, 10, 11], suprapontine lesions have been shown to produce either ipsilateral [12, 13, 14]or contralateral [10, 15]hemiageusia. Our patients had bilaterally decreased bitter sensation in common, but whether or not abnormal perception of bitter taste is important in producing altered food preference remains unclear with the small number of patients reported here.…”