Cognition in adult patients with newly diagnosed non-lesional temporal lobe epilepsy

Abstract

Objective: To evaluate whether cognitive performance is affected in newly diagnosed temporal lobe epilepsy (TLE) and to determine the most vulnerable cognitive domains. Methods: In this baseline longitudinal study, differences in memory and non-memory cognitive functions were assessed using comprehensive neuropsychological test batteries in 21 adult patients with newly diagnosed non-lesional TLE and individually matched controls. In addition, the analyses included ratings of self-perceived emotional status. Results: The patients performed more poorly than the control group regarding delayed visual memory (p = 0.013) and executive function tasks related to switching (Trail Making Test and verbal fluency shifting; p = 0.025 and p = 0.03, respectively). We found no differences in verbal learning and memory, attention/working memory/processing speed, and other executive functions. Significance: Our results show that patients with TLE often have specific cognitive deficits at time of diagnosis, even in the absence of structural brain abnormalities. This supports the hypothesis that memory dysfunction is linked to an underlying pathology rather than to the effect of recurrent seizures, longterm use of anti-seizure medication, or other epilepsy-related factors. As certain executive functions are affected at an early stage, the pathology may involve brain regions beyond the temporal lobe and may comprise larger brain networks. These results indicate the need for greater awareness of cognition at the time of diagnosis of TLE and before initiation of treatment, and integration of neuropsychological assessment into early routine clinical care.

Episodic Memory Dysfunction and Effective Connectivity in Adult Patients With Newly Diagnosed Nonlesional Temporal Lobe Epilepsy

“…In a previous study, we recently found slight cognitive deficits at the time of diagnosis in the same cohort of patients as utilized in the present study ( 26 ). Reduced scores on some of the executive function tests led us to suspect that extratemporal or network dysfunction might be present at an early stage.…”

“… * Four patients and one control subject have several abnormalities. For details of these mainly clinically insignificant findings, see Bjørke et al ( 26 ) for details . ** Four patients have both nonspecific and epileptiform abnormalities .…”

“…Since most recruited participants during inclusion were found to be nonlesional and no one appeared to have mesial temporal sclerosis, only patients with nonlesional TLE were included. The clinical diagnosis in each case was made by the same group of the experienced epileptologists, according to the seizure semiology, interictal EEG recordings, and qualitative assessment of structural MRI data according to ILAE definitions (see Table 1 ) ( 26 ). The MRI scans were acquired on a 3T whole-body scanner (Philips Ingenia®, Best, The Netherlands).…”

“…Patients were examined by the experienced neurologists, neuropsychologists, and neurophysiologists at the Oslo University Hospital, Rikshospitalet, Oslo, Norway as part of the ProTLE study. ProTLE is a longitudinal study that aims to follow newly diagnosed patients with TLE and their matched controls for a period of 10 years ( 26 ). Patients arrived for a full day of testing at the hospital, participating in the clinical neurological assessment and neuropsychological testing, in addition to MRI and EEG.…”

The use of rodent models to better characterize the relationship among epilepsy, sleep, and memory

“…Using only these patients, however, makes it difficult to determine how memory naturally deteriorates as the disease progresses. Bjørke et al (2021) 12 evaluated cognition in patients newly diagnosed with TLE and found that these patients often display cognitive deficits, despite the absence of structural brain abnormalities in some patients. These findings support the association of memory impairment to an underlying pathology.…”