Heterogeneidad neuropsicológica en los pacientes con epilepsia del lóbulo temporal mesial

Semantic Processing Impairment in Patients with Temporal Lobe Epilepsy

The impairment in episodic memory system is the best-known cognitive deficit in patients with temporal lobe epilepsy (TLE). Recent studies have shown evidence of semantic disorders, but they have been less studied than episodic memory. The semantic dysfunction in TLE has various cognitive manifestations, such as the presence of language disorders characterized by defects in naming, verbal fluency, or remote semantic information retrieval, which affects the ability of patients to interact with their surroundings. This paper is a review of recent research about the consequences of TLE on semantic processing, considering neuropsychological, electrophysiological, and neuroimaging findings, as well as the functional role of the hippocampus in semantic processing. The evidence from these studies shows disturbance of semantic memory in patients with TLE and supports the theory of declarative memory of the hippocampus. Functional neuroimaging studies show an inefficient compensatory functional reorganization of semantic networks and electrophysiological studies show a lack of N400 effect that could indicate that the deficit in semantic processing in patients with TLE could be due to a failure in the mechanisms of automatic access to lexicon.

Postoperative neuropsychological outcome in patients with mesial temporal lobe epilepsy in Argentina

The aim of the present study is to compare pre- and postsurgical neuropsychological outcome in individuals suffering from mesial temporal lobe epilepsy (mTLE), in order to evaluate prognosis. The selected thirty-five patients had medically mTLE and had undergone an anterior temporal lobectomy (ATL). Neuropsychological evaluation was performed in three different stages: before ATL, 6 months after resection, and a year afterwards. Neuropsychological protocol evaluated attention, verbal memory, visual memory, executive function, language, intelligence, and handedness. There was a significant improvement (P = 0.030) in the group with visual memory deficit after surgery, whereas no changes were observed across patients with verbal memory deficit. No changes were observed in language after surgery. Executive function showed significant improvement 6 months after surgery (P = 0.035). Postoperative outcome of cognitive impairments depends on baseline neuropsychological status of the patients with TLE. In our case series, deficits found in patients with mTLE after ATL did not result in a subjective complaint.

Lateralizing value of memory tests in drug-resistant temporal lobe epilepsy

Our aim was to test the lateralizing value of a neuropsychological battery including several memory tests on a large sample of consecutive patients with drug-resistant temporal lobe epilepsy (TLE) evaluated for epilepsy surgery. We studied 73 right-handed patients (56% males, mean age 35.3 +/- 11.2 years, 49% left TLE) aged 16 years or older with normal IQ who underwent a preoperative neuropsychological assessment including several memory tests and were seizure-free after at least 1 year of follow-up. Forty-seven had TLE due to hippocampal sclerosis, whilst 26 had TLE secondary to tumors or other lesions. Receiver Operating Characteristic (ROC) analysis and discriminant function analysis were used to evaluate the lateralization value of selected tests and of the battery as a whole, respectively. In patients with TLE secondary to tumors or other lesions, no test showed significant lateralizing value. In patients with TLE due to hippocampal sclerosis, the immediate (P < 0.01) and delayed (P < 0.001) Rey Auditory Verbal Learning Test (RAVLT) displayed substantial discriminatory ability. The battery as a whole correctly classified 82% of patients with respect to side of epileptogenesis. Our findings suggest that a non-invasive, relatively short and unexpensive neuropsychological battery based on memory tests may profitably complement other well-established diagnostic procedures such as video-EEG or magnetic resonance imaging (MRI), at least in patients with drug-resistant TLE due to hippocampal sclerosis.