Olfactory abnormalities in temporal lobe epilepsy

Desai, Maya; Agadi, JB; Karthik, N.; Praveen-kumar, S.; Netto, Archana B

doi:10.1016/j.jocn.2015.03.035

Cited by 34 publications

(23 citation statements)

References 19 publications

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“…More recently, Jones-Gotman et al [30] and Haehner et al [21] found poorer bilateral odor identification in TLR patients, with poorest performance on the resected side. Other investigators have found no differences between left- and right-side foci and/or resections on bilaterally-administered olfactory tests, including tests of identification, odor memory, and discrimination [9, 18, 19, 27, 29, 42, 49]. In the pre- and post-operative study by Martinez et al [32], odor discrimination was lower only following right-side resection, with improvement occurring on the left side.…”

Section: Introductionmentioning

confidence: 96%

Influences of temporal lobe epilepsy and temporal lobe resection on olfaction

et al. 2018

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Although temporal lobe epilepsy (TLE) and resection (TLR) impact olfactory eloquent brain structures, their influences on olfaction remain enigmatic. We sought to more definitively assess the influences of TLE and TLR on olfaction using three well-validated olfactory tests and measuring the tests' associations with the volume of numerous temporal lobe brain structures. The University of Pennsylvania Smell Identification Test and an odor detection threshold test were administered to 71 TLE patients and 71 age- and sex-matched controls; 69 TLE patients and controls received an odor discrimination/memory test. Fifty-seven patients and 57 controls were tested on odor identification and threshold before and after TLR; 27 patients and 27 controls were similarly tested for odor detection/discrimination. Scores were compared using analysis of variance and correlated with pre- and post-operative volumes of the target brain structures. TLE was associated with bilateral deficits in all test measures. TLR further decreased function on the side ipsilateral to resection. The hippocampus and other structures were smaller on the focus side of the TLE subjects. Although post-operative volumetric decreases were evident in most measured brain structures, modest contralateral volumetric increases were observed in some cases. No meaningful correlations were evident pre- or post-operatively between the olfactory test scores and the structural volumes. In conclusion, we demonstrate that smell dysfunction is clearly a key element of both TLE and TLR, impacting odor identification, detection, and discrimination/memory. Whether our novel finding of significant post-operative increases in the volume of brain structures contralateral to the resection side reflects plasticity and compensatory processes requires further study.

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Section: Introductionmentioning

confidence: 96%

Influences of temporal lobe epilepsy and temporal lobe resection on olfaction

et al. 2018

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“…With an estimated prevalence of up to 21.6% of the general population, 1 it is more common than blindness or profound deafness 2,3 and can have significant impact on quality of life. [4][5][6] Furthermore, olfactory dysfunction has been linked with multiple etiologies, including neurodegenerative 7-10 and psychiatric conditions 11 as well as epilepsy, 12,13 stroke, 14 and sinonasal disease. 15 Olfactory function is assessed clinically using psychophysical testing.…”

Section: Introductionmentioning

confidence: 99%

Patterns of olfactory impairment reflect underlying disease etiology

et al. 2016

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“…In temporal lobe epilepsy associated with hippocampal sclerosis, olfactory auras are not prognostic for surgical outcome of mesial temporal lobectomy (Dupont et al ., ). Olfactory impairment is found in patients with either left or right temporal lobe epilepsy, and is unrelated to the duration of epilepsy, frequency of seizures, and/or medications administered (Desai et al ., ). Olfactory auras are difficult to confirm in infants and young children because they require verbal description, though they might be inferred by a facial grimace, wrinkling of the nose, or wiping the hand across the nose (Sarnat, ; Sarnat and Flores‐Sarnat, a).…”

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confidence: 99%

Might the olfactory bulb be an origin of olfactory auras in focal epilepsy?

Sarnat¹,

Flores‐Sarnat²

2016

Epileptic Disorders

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Olfactory auras (phantosmia) are an infrequent phenomenon in complex focal seizures generated in the mesial temporal lobe. It is generally assumed that all such auras arise from epileptic foci in the entorhinal cortex, amygdala or rostral insula, all of which have major afferent projections from the olfactory bulb or mainly from its relay, the anterior olfactory nucleus. The histological morphology, synaptic circuitry, and foetal development of the olfactory bulb are unique. The olfactory system is the only special sensory system that does not project to the thalamus because its bulb and tract incorporate an intrinsic thalamic equivalent: axonless granular and periglomerular neurons and the anterior olfactory nucleus. The olfactory bulb exhibits continuous synaptic turnover throughout life. Other brain structures with synaptic plasticity (neocortex, hippocampus, and amygdala) are epileptogenic; synaptically stable structures (brainstem, cerebellum, and basal ganglia) are not epileptogenic. Electrophysiological and neuropathological data of the olfactory bulb in epilepsy are sparse. We propose an alternative hypothesis, first hinted in 1954 by Penfield and Jasper, that some epileptic olfactory auras are primarily generated by the olfactory bulb and secondarily mediated by the amygdala and entorhinal cortex.

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Olfactory abnormalities in temporal lobe epilepsy

Cited by 34 publications

References 19 publications

Influences of temporal lobe epilepsy and temporal lobe resection on olfaction

Influences of temporal lobe epilepsy and temporal lobe resection on olfaction

Patterns of olfactory impairment reflect underlying disease etiology

Might the olfactory bulb be an origin of olfactory auras in focal epilepsy?

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