Predicting verbal memory decline following temporal lobe resection for epilepsy.

OBJECTIVES: The aim of the study was to develop a prediction model for verbal memory decline after temporal lobe resection (TLR) for epilepsy. The model will be used in the preoperative counselling of patients to give individualized information about risk for verbal memory decline. MATERIALS AND METHODS: A sample of 110 consecutive patients who underwent TLR for epilepsy at Sahlgrenska University Hospital between 1987 and 2011 constituted the basis for the prediction model. They had all gone through a formal neuropsychological assessment before surgery and 2 years after. Penalized regression and 20 × 10-fold cross-validation were used in order to build a reliable model for predicting individual risks. RESULTS: The final model included four predictors: side of surgery; inclusion or not of the hippocampus in the resection; preoperative verbal memory function; and presence/absence of focal to bilateral tonic-clonic seizures (TCS) the last year prior to the presurgical investigation. The impact of a history of TCS is a new finding which we interpret as a sign of a more widespread network disease which influences neuropsychological function and the cognitive reserve. The model correctly identified 82% of patients with post-operative decline in verbal memory, and the overall accuracy was 70%-85% depending on choice of risk thresholds. CONCLUSIONS: The model makes it possible to provide patients with individualized prediction regarding the risk of verbal memory decline following TLR. This will help them make more informed decisions regarding treatment, and it will also enable the epilepsy surgery team to prepare them better for the rehabilitation process.

Psychosocial status 10 years after temporal lobe resection for epilepsy, a longitudinal controlled study.

Knowledge about long-term psychosocial outcome of temporal lobe resection (TLR) for epilepsy is limited. The aims of this study were to describe vocational outcome 10 years after TLR and to analyze the effect on the vocational situation by seizures, laterality of resection, verbal memory, and mood. Fifty-one patients were prospectively followed 10 years after TLR. Psychosocial and neuropsychological data were ascertained at baseline and 10 years after surgery and at corresponding time points for 23 controls. Fewer patients worked 10 years post-operatively compared with controls (TLR patients: 61% and controls: 96%). However, seizure-free patients were more likely to retain employment (71%) than patients who had seizures (41%). The odds of working full-time were 9.5 times higher for patients with seizure freedom than for those with continuing seizures. There were no associations between working at 10 years and side of resection or mood, and impairment of verbal memory did not have an influence on vocational outcome.

Verbal memory decline is less frequent at 10 years than at 2 years after temporal lobe surgery for epilepsy.

We investigated individual short- and long-term verbal memory changes after temporal lobe resection for epilepsy. Fifty-one patients (23 operated on the speech-dominant temporal lobe, DTL and 28 on the non-dominant temporal lobe, NDTL) were tested on learning/immediate recall and delayed recall of word-list and word-pairs preoperatively, 2 years postoperatively and 10years postoperatively. Changes were defined using reliable change indices of 23 healthy controls assessed at corresponding intervals. Fewer patients had reliable declines at 10 years than at 2 years (DTL: 13-35% vs 35-44%; NDTL: 0-4% vs 7-21%). Four DTL patients (17%) had reliable declines in ≥2 tests at 10-year follow-up. More NDTL patients had improvement at 10 years than at 2 years (18-30% vs 4-22%). The only risk factor for decline both short and long term was DTL resection. In conclusion, most patients had stable verbal memory postoperatively. A few DTL patients had a lasting decline at long-term follow-up, but more patients showed partial recovery, especially in the NDTL group.

Cognitive outcome two years after frontal lobe resection for epilepsy--a prospective longitudinal study.

PURPOSE: To investigate cognitive outcomes after frontal lobe resection (FLR) for epilepsy in a consecutive single centre series. METHODS: Neuropsychological examinations were performed prior to and two years (mean test interval 2.5 years) after surgery in 30 consecutive patients who underwent FLR. Cognitive outcome was evaluated with particular consideration to the site of surgery (lateral, premotor/SMA [supplementary motor area], mesial/orbital). Cognitive domains assessed were speed, language, memory, attention, executive functions and intelligence. 25 healthy controls were assessed at corresponding time points (mean test interval 3.0 years). Analyses were made both at group and individual levels. RESULTS: At baseline the patients performed below controls in variables depending on speed, executive functions, global and verbal intelligence. Two years after surgery, the analyses at the subgroup level indicated that the lateral resection group had less improvement than the controls in global intelligence, FSIQ (p=.037). However, at the individual level, the majority of the change scores (74-100%) were classified as within the normal range for all but one variable. The exception was the variable "Comprehension" (measuring verbal reasoning ability) with reliable declines in 44% (8/18) of the patients. This pattern of decline was observed in the lateral (4/7 patients) and premotor/SMA (4/7 patients) resection groups. Seizure outcome and side of surgery did not influence these results. CONCLUSION: The main finding was cognitive stability at group level two years after FLR. A reliable decline in verbal reasoning ability was rather common at an individual level, but only in the lateral and premotor/SMA resection groups. The lateral resection group also had less improvement than the controls in global intelligence.

Cognitive outcome 10 years after temporal lobe epilepsy surgery: a prospective controlled study.

OBJECTIVE: To explore late effects of temporal lobe resection (TLR) for epilepsy on general cognitive level and memory. METHODS: Fifty-one patients who had undergone TLR (23 in the speech-dominant temporal lobe [DTL] and 28 in the nondominant temporal lobe [NDTL]) were assessed preoperatively and 2 and 10 years postoperatively. Twenty-three healthy controls were assessed at baseline and at corresponding intervals. A battery of standardized tests for assessment of general cognitive level and memory was analyzed using a linear mixed model of between-subjects treatment effect and within-subject time effect. RESULTS: The main result was cognitive stability from 2 to 10 years after TLR. The DTL group had declined in verbal memory at the 10-year follow-up compared to the NDTL group and to the controls. However, this decline was detected already 2 years postoperatively, with no further decline from 2 to 10 years. The memory decline was not related to seizure outcome or AED treatment. The NDTL group showed less improvement in performance IQ (PIQ) at the 10-year follow-up compared to the controls. The most important correlate to inferior PIQ scores was continuing seizures, which was more frequent in the NDTL group. CONCLUSIONS: In this study, the main finding was cognitive stability from 2 to 10 years after temporal lobe resection. There was no further decline in verbal memory from 2 to 10 years after surgery, lending no support to the notion of an ongoing progressive decline in verbal memory after temporal lobe resection. The verbal memory course was not dependent on seizure outcome or antiepileptic drug treatment.

Verbal cognition and attention deficits do not explain the verbal memory decline associated with pharmacoresistant partial epilepsy.

The aim of this study was to explore whether change in verbal memory with time in patients with epilepsy is influenced by performance on tasks assessing verbal cognition or attention/processing speed. Thirty-six patients and twenty-five healthy controls were tested twice with median retest intervals of 4.8 and 3.1 years, respectively. Aspects of verbal memory, verbal cognition, and attention/processing speed were assessed. Decline in one verbal memory variable (Cronholm-Molander Memory Test Paired Associates -- Delayed Recall) was the strongest correlate of epilepsy. The second strongest correlate was a decrease in one attention/processing speed variable (Digit Symbol). The relationship between decline in verbal memory and epilepsy was not influenced by the decline in attention/processing speed, and the results did not support the notion that limited mental reserves as reflected in impaired verbal cognition or attention/processing speed can explain the relationship between verbal memory and epilepsy.

Serial cognitive change patterns across time after temporal lobe resection for epilepsy.

Longitudinal cognitive outcome with respect to general cognitive status and memory at the group and individual levels was studied 10 years after temporal lobe resection for epilepsy. Twenty-five patients who had undergone a medium-term follow-up (T2, median = 2.7 years) also underwent a long-term follow-up (T3, median = 9.8 years). At the group level, there was a significant increment across time, partly due to practice, in IQ (P value from 0.049 to <0.0001) but not in memory variables. On the basis of the normative interval of reassessed matched controls, the analysis at the individual level of change from baseline to T2 disclosed decrements in 12-29% of the patients and increments in 8-21%. These proportions diminished at T3 (0-12 and 0-16%) and the dominating pattern of Performance IQ and verbal memory was a return toward baseline. These findings make the interpretation of an initial (T2) postoperative increment or decrement more problematic and underline the need for a comprehensive evaluation across time, including both at the group and individual levels.

Non-parametric evaluation of memory changes at group and individual level following temporal lobe resection for pharmaco-resistant partial epilepsy.

Group versus individual verbal and visuospatial memory outcome following epilepsy surgery was evaluated by a non-parametric method in 25 left and 29 right temporal lobectomy patients. Twenty-five controls were assessed twice. Analyses of change at an individual level evaluated by this statistical approach based on paired-ranks were compared to results with a method based on distances (Reliable Change). The left temporal lobectomy group deteriorated in the two verbal memory variables (p < 0.01 and 0.05). High levels of individual changes unexplained by group patterns were disclosed in the three memory variables analyzed in the patients. Significant individual change, although less pronounced, also occurred in the controls. Group versus individual outcome was adequately distinguished by the non-parametric method. To properly analyze memory change after epilepsy surgery, evaluation at group and individual level ought to combined.

Verbal memory decline and adverse effects on cognition in adult patients with pharmacoresistant partial epilepsy: a longitudinal controlled study of 36 patients.

The aim of this study was to delineate possible longitudinal cognitive changes in adult patients with a long history of pharmacoresistant partial epilepsy. Thirty-six patients and thirty healthy controls were investigated at baseline. A reassessment was conducted, with median test intervals of 4.8 years for the patients and 3.1 years for controls. A standardized battery was used for assessment of general cognitive level and memory. At baseline, patients performed at a significantly lower level on general cognition, immediate recall of pairs of associated words, and retention of learned words and visuospatial stimuli, compared with controls. Analyses of change over time in the patients disclosed significant verbal memory decline in retention of pairs of associated words. Group comparisons of change over time revealed adverse effects in the performance aspect of general cognition on the patients. Also, group comparisons indicated impaired performance across time for the patients in retention of pairs of associated words and retention of visuospatial stimuli. The adverse effect on memory and general cognition in this patient group over the period was clear-cut when compared with the longitudinal changes in an adequate control group.