Lateralization of Deficit in Self-Awareness of Memory in Patients with Intractable Epilepsy

Self-awareness and underestimation of cognitive abilities in patients with adult temporal lobe epilepsy after surgical treatment

INTRODUCTION

Self-awareness of cognitive, emotional, functional, and social performance is critical for compliance with treatment. However, few studies have investigated self-awareness and the associated effects on other cognitive variables in patients with temporal lobe epilepsy (TLE) after surgical treatment.

AIM

This study was designed to investigate the prevalence of impaired self-awareness (ISA) in patients with TLE who have undergone surgical treatment. Associated correlations with clinical variables (frequency of seizures before surgery, time elapsed since the epilepsy diagnosis, depression, and anxiety) and verbal and visual episodic memory function and differences between patients with right and left TLE were also investigated.

METHOD

Twenty-three adults with TLE after surgical treatment were assessed with the Patient Competency Rating Scale (PCRS-R-BR), the Rey Auditory Verbal Learning Task (RAVLT), and the Modified Ruche Visuospatial Learning Test (RUCHE-M). Patients were considered to have memory dysfunction if delayed recall as assessed with the RUCHE-M or RAVLT was at or below the 25th percentile. Patients were considered to have ISA if PCRS-R-BR discrepancy scores were at or above the 75th percentile. Underestimated cognitive ability (UCA) was defined as a PCRS-R-BR discrepancy percentile score ≤25. Results were analyzed using frequency, Spearman correlation, regression analyses, and the Mann-Whitney test.

RESULTS

Frequency analysis of the total sample indicated ISA in 39.13% of patients (n = 9), UCA in 39.13% of patients (n = 9), and impaired verbal and/or visual memory performance in 69.56% of patients (n = 16). Moderate positive correlations were found between the frequency of seizures before surgical treatment and relatives' reports, as well as between the duration of time that had elapsed since the epilepsy diagnosis and patient reports. Negative and moderate correlations were found between the frequency of seizures and the discrepancy score, as well as between depression and patient reports. No differences in PCRS-R-BR were found between patients with right vs. left TLE. No clinical variables significantly predicted self-report or self-awareness.

CONCLUSION

Patients with TLE exhibit various patterns of ISA and negative effects on cognitive function after surgical treatment. Emotional factors and relatives' reports must be considered when assessing these patients.

Anaesthetic interventions for prevention of awareness during surgery

BACKGROUND

General anaesthesia is usually associated with unconsciousness. 'Awareness' is when patients have postoperative recall of events or experiences during surgery. 'Wakefulness' is when patients become conscious during surgery, but have no postoperative recollection of the period of consciousness.

OBJECTIVES

To evaluate the efficacy of two types of anaesthetic interventions in reducing clinically significant awareness:- anaesthetic drug regimens; and- intraoperative anaesthetic depth monitors.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, ISSUE 4 2016); PubMed from 1950 to April 2016; MEDLINE from 1950 to April 2016; and Embase from 1980 to April 2016. We contacted experts to identify additional studies. We performed a handsearch of the citations in the review. We did not search trial registries.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) of either anaesthetic regimens or anaesthetic depth monitors. We excluded volunteer studies, studies of patients prior to skin incision, intensive care unit studies, and studies that only randomized different word presentations for memory tests (not anaesthetic interventions).Anaesthetic drug regimens included studies of induction or maintenance, or both. Anaesthetic depth monitors included the Bispectral Index monitor, M-Entropy, Narcotrend monitor, cerebral function monitor, cerebral state monitor, patient state index, and lower oesophageal contractility monitor. The use of anaesthetic depth monitors allows the titration of anaesthetic drugs to maintain unconsciousness.

DATA COLLECTION AND ANALYSIS

At least two authors independently scanned abstracts, extracted data from the studies, and evaluated studies for risk of bias. We made attempts to contact all authors for additional clarification. We performed meta-analysis statistics in packages of the R language.

MAIN RESULTS

We included 160 studies with 54,109 enrolled participants; 53,713 participants started the studies and 50,034 completed the studies or data analysis (or both). We could not use 115 RCTs in meta-analytic comparisons because they had zero awareness events. We did not merge 27 of the remaining 45 studies because they had excessive clinical and methodological heterogeneity. We pooled the remaining 18 eligible RCTs in meta-analysis. There are 10 studies awaiting classification which we will process when we update the review.The meta-analyses included 18 trials with 36,034 participants. In the analysis of anaesthetic depth monitoring (either Bispectral Index or M-entropy) versus standard clinical and electronic monitoring, there were nine trials with 34,744 participants. The overall event rate was 0.5%. The effect favoured neither anaesthetic depth monitoring nor standard clinical and electronic monitoring, with little precision in the odds ratio (OR) estimate (OR 0.98, 95% confidence interval (CI) 0.59 to 1.62).In a five-study subset of Bispectral Index monitoring versus standard clinical and electronic monitoring, with 34,181 participants, 503 participants gave awareness reports to a blinded, expert panel who adjudicated or judged the outcome for each patient after reviewing the questionnaires: no awareness, possible awareness, or definite awareness. Experts judged 351 patient awareness reports to have no awareness, 87 to have possible awareness, and 65 to have definite awareness. The effect size favoured neither Bispectral Index monitoring nor standard clinical and electronic monitoring, with little precision in the OR estimate for the combination of definite and possible awareness (OR 0.96, 95% CI 0.35 to 2.65). The effect size favoured Bispectral Index monitoring for definite awareness, but with little precision in the OR estimate (OR 0.60, 95% CI 0.13 to 2.75).We performed three smaller meta-analyses of anaesthetic drugs. There were nine studies with 1290 participants. Wakefulness was reduced by ketamine and etomidate compared to thiopental. Wakefulness was more frequent than awareness. Benzodiazepines reduces awareness compared to thiopental, ketamine, and placebo., Also, higher doses of inhaled anaesthetics versus lower doses reduced the risk of awareness.We graded the quality of the evidence as low or very low in the 'Summary of findings' tables for the five comparisons.Most of the secondary outcomes in this review were not reported in the included RCTs.

AUTHORS' CONCLUSIONS

Anaesthetic depth monitors may have similar effects to standard clinical and electrical monitoring on the risk of awareness during surgery. In older studies comparing anaesthetics in a smaller portion of the patient sample, wakefulness occurred more frequently than awareness. Use of etomidate and ketamine lowered the risk of wakefulness compared to thiopental. Benzodiazepines compared to thiopental and ketamine, or higher doses of inhaled anaesthetics versus lower doses, reduced the risk of awareness.

Subjective memory evaluation before and after temporal lobe epilepsy surgery

Subjective memory (SM), a self-evaluation of memory, in contrast to objective memory (OM) measured by neuropsychological testing, is less well studied in patients with epilepsy. We assessed SM before and after temporal lobectomy. The Frequency of Forgetting 10 scale (FOF-10), developed to evaluate SM in dementia, was given before and one year after temporal lobectomy. Reliability and validity for use in epilepsy were first assessed. Measures of depression (CES-D) and neuroticism (PANAS) were done before and after surgery as well as complete neuropsychological assessment of OM. Correlation analysis between FOF-10 results and all the other variables was implemented. In 48 patients the FOF-10 was reliable and valid showing high internal consistency in all items (Cronbach's alpha >0.82) and high reproducibility (p<0.01). The FOF-10 also correlated with the memory assessment clinics self rating scale (MAC-S) (p<0.01). FOF-10 scores improved or were unchanged postoperatively in 28 patients (58%) and worsened in 20 (42%). The FOF-10 did not significantly correlate with memory scores from neuropsychological testing but did correlate with perceived word finding difficulty (p<0.001) and postoperative depression (p<0.05). A reduction in number of antiepileptic drugs (AEDs) after surgery distinguished those with improved postoperative SM. No correlation was found between SM and neuroticism, side of surgery or number of seizures. The FOF-10 is a brief and reliable measure of subjective memory in patients with epilepsy. Perceived memory impairment reflects more emotional state, language problems and quantity of AEDs than actual defects in memory function. These results would potentially be useful in presurgical counselling and management of memory issues after temporal lobe surgery.

Group administration influences design but not written word fluency testing

Quicker assessments of right and left frontal lobe function, such as the examination of performance on design and language fluency tasks, respectively, lend themselves to a group administration setting. However, the influence of social facilitation factors on a dissociation model in these group settings is not well understood. One hundred college students (71 women) completed design and written word fluency tasks while sitting beside a faster or slower working confederate. Questionnaires related to trait worry, emotion regulation, state depression, anxiety and stress were completed following these tasks. Students in the fast condition produced significantly more unique designs, but there was no condition difference on written word fluency. This finding indicated that performance on a design task, which requires relative right frontal activation, may decrease if the subject is paired with a slow working confederate. High trait worriers demonstrated reduced performance on the design task (as indicated by higher design error ratios) but preserved performance on the word task. This supported a single dissociation in that performance on these tasks indicates compromised right hemisphere function and preserved left hemisphere function, respectively, in high trait worriers.

Everyday prospective memory and executive function deficits associated with exposure to second-hand smoke

This study explored whether exposure to second-hand smoke (SHS) has a detrimental impact upon everyday memory in two groups of non-smokers; one which reported regular exposure to SHS and one that reported never having been exposed to SHS. Thirty-four non-smokers who reported having been regularly exposed to SHS (SHS group) and 34 non-smokers who reported never having been exposed to SHS (non-SHS group) were compared on self-reports of prospective memory (PM: remembering future intentions and/or activities) and executive function (EF: those processes involved in attention, multitasking and decision-making). The Prospective and Retrospective Memory Questionnaire (PRMQ) assessed everyday PM lapses; the Executive Function Questionnaire (EFQ) assessed self-reported problems in EF; a drug-use questionnaire and a mood questionnaire were also administered. Two univariate ANCOVAs were applied to the PM and EF data, controlling for between-group differences in age, weekly alcohol use, anxiety and depression scores, and self-reported retrospective memory scores. The SHS group reported significantly more lapses on the PRMQ and more deficits on the EFQ than the non-SHS group. These findings provide new insights into PM and EF deficits associated with prolonged exposure to SHS in a group of non-smokers. Possible explanations and suggestions for future research are also considered.

Neural response to eye contact and paroxetine treatment in generalized social anxiety disorder

Generalized social anxiety disorder (GSAD) is characterized by excessive fears of scrutiny and negative evaluation, but neural circuitry related to scrutiny in GSAD has been little studied. In this study, 16 unmedicated adults with GSAD and 16 matched healthy comparison (HC) participants underwent functional magnetic resonance imaging to assess neural response to viewed images of faces simulating movement into eye contact versus away from eye contact. GSAD patients were then treated for 8 weeks with paroxetine, and 15 patients were re-imaged. At baseline, GSAD patients had elevated neural response to eye contact in parahippocampal cortex, inferior parietal lobule, supramarginal gyrus, posterior cingulate and middle occipital cortex. During paroxetine treatment, symptomatic improvement was associated with decreased neural response to eye contact in regions including inferior and middle frontal gyri, anterior cingulate, posterior cingulate, precuneus and inferior parietal lobule. Both the magnitude of GSAD symptom reduction with paroxetine treatment and the baseline comparison of GSAD vs. HCs were associated with neural processing of eye contact in distributed networks that included regions involved in self-referential processing. These findings demonstrate that eye contact in GSAD engages neurocircuitry consistent with the heightened self-conscious emotional states known to characterize GSAD patients during scrutiny.

An rTMS study into self-face recognition using video-morphing technique

Self-face recognition is a sign of higher order self-awareness. Research into the neuronal network argues that the visual pathway of recognizing one's own face differs from recognizing others. The present study aimed at investigating the cortical network of self-other discrimination by producing virtual lesions over the temporo-parietal junction and the prefrontal cortex using low-frequency repetitive transcranial magnetic stimulation (rTMS) in a sham-controlled design. Frontal and parietal areas were stimulated separately in consecutive sessions one week apart in 10 healthy subjects. We designed a video-task comprising morphings of famous, unfamiliar and the subjects' own faces that transformed into each other over a time period of six seconds. Reaction time (RT) was measured by pushing a mouse-button once a change of identity was recognized. rTMS over the right temporo-parietal junction led to a decrease in RT when a subject's own face emerged from a familiar face; a similar effect was observed after rTMS over right-prefrontal and left-parietal cortices, when the subjects' ratings of own likeability were taken into account. The transition from an unfamiliar face to one's own face indicated a left frontal lateralization.

rTMS to the right inferior parietal lobule disrupts self-other discrimination

Self-other discrimination is fundamental to social interaction, however, little is known about the neural systems underlying this ability. In a previous functional magnetic resonance imaging study, we demonstrated that a right fronto-parietal network is activated during viewing of self-faces as compared with the faces of familiar others. Here we used image-guided repetitive transcranial magnetic stimulation (rTMS) to create a 'virtual lesion' over the parietal component of this network to test whether this region is necessary for discriminating self-faces from other familiar faces. The current results indeed show that 1 Hz rTMS to the right inferior parietal lobule (IPL) selectively disrupts performance on a self-other discrimination task. Applying 1 Hz rTMS to the left IPL had no effect. It appears that activity in the right IPL is essential to the task, thus providing for the first time evidence for a causal relation between a human brain area and this high-level cognitive capacity.

How can cognitive status predispose to psychological impairment?

A significant proportion of people report cognitive impairments, in particular memory problems, and express concern that these impairments will worsen with the passage of time. Unfortunately, the lack of well-designed studies has meant that disentangling the relative influences of factors likely important in the development and course of neuropsychological impairment has proved problematic. In addition to experiencing neuropsychological difficulties, people with epilepsy have to manage the psychosocial sequalae often associated with epilepsy. A diagnosis of epilepsy can have negative implications for quality of life and be associated with an increased risk of psychosocial problems; and individuals with epilepsy do not all experience its impact equally. The impacts of neuropsychological functioning on quality of life have only been rarely investigated, but there is some evidence to suggest that quality of life may correlate better with self-perceived cognitive difficulties than with scores on formal tests of cognitive functioning.

Selective impairment of self body-parts processing in right brain-damaged patients

To investigate whether the processing of the visual appearance of one's own body, that is the corporeal self is a unified or modular function we submitted eight right brain-damaged (RBD) patients and a group of fourteen age-matched neurologically healthy subjects, to a visual matching-to-sample task testing for corporeal self processing. If corporeal self processing is a unique function (i.e., body- and face-parts are processed by the same network), patients impaired in self body-parts (i.e., showing no self-advantage) should be impaired also in self face-parts; alternatively, if corporeal self processing is a modular function (i.e., body- and face-parts are processed by different networks), patients impaired in self body-parts should be unimpaired in self face-parts, unless the face-module is also damaged by the lesion. Results showed that healthy participants were more accurate in processing pictures representing their own as compared to other people's body- and face-parts, showing the so-called self-advantage. The patients' findings revealed a simple dissociation, in that patients who were impaired in the processing of self-related body-parts showed a preserved self-advantage when processing self-related face-parts, thus providing initial evidence of a modular representation of the corporeal self.

Self-reported memory problems in everyday activities in patients with epilepsy treated with antiepileptic drugs

OBJECTIVE

The goal of this study was to assess everyday memory complaints in a large cohort of patients with epilepsy treated with antiepileptic drugs and to determine demographic, clinical, and emotional state factors associated with patients' self-perception of memory disturbances.

METHODS

This cross-sectional epidemiological study was carried out in routine clinical practice using the Questionnaire of Memory Efficiency (QME) and the Hospital Anxiety and Depression Scale (HADS).

RESULTS

Six hundred sixty-one patients were recruited. The time since epilepsy diagnosis was 17.3 years (SD=12.5); the number of seizures in the past year 13.8 (SD=4.8); the proportion of patients free of seizures in the last year 42.5%; the proportion of patients with partial seizures 73.2%; and the proportion of patients on monotherapy 56.3%. Total QME score was 110.0 (SD=18.6). Depression and anxiety scores and polytherapy explained 38.7% of the QME variance.

CONCLUSIONS

Subjective memory functioning in this cohort of patients with epilepsy was relatively good. Complaints expressed by these patients are explained mainly by the presence of depressive and anxiety symptoms.

Update on epilepsy and cerebral localization

The field of epilepsy has contributed significantly to localization of neurologic function, particularly in the neocortex. Methodologies such as cortical stimulation, positron emission tomography, functional MRI, trans-cranial magnetic stimulation, surgical resection, and magnetoencephalography have been used successfully in patients with epilepsy to locate specific functions, primarily for the purpose of defining eloquent cortex before surgical resections. The left hemisphere serves language-related functions and verbal memory in most people, whereas the right hemisphere serves some language function in addition to perceiving most components of music and other forms of nonverbal material. Both hemispheres cooperate in understanding spatial relationships. Studies in patients with developmental abnormalities have enriched our understanding of localization of function within the cortex. Future studies may help us understand the sequence in which specific regions are activated during specific tasks and determine which regions are necessary for tasks and which are supplementary. The ability to predict preoperatively the effect of removal of specific tissues would benefit surgical planning for all patients who undergo cortical resections, including those with epilepsy.

Short-term prospective memory deficits in chronic back pain patients

OBJECTIVE

Chronic pain, particularly low back pain, is widespread. Although a great deal is known about the impact that this has on quality of life and physical activity, relatively little has been established regarding the more cognitive effects of pain. This study aims to find out whether individuals with chronic pain experience memory deficits in prospective memory (PM), the process of remembering to do things at some future point in time. Examples of PM include remembering to keep an appointment, such as a visit to a clinic, or to perform a particular task, such as paying a bill on time.

METHODS

The PM of 50 participants with chronic pain was compared with 50 pain-free participants. Each participant completed the Prospective Memory Questionnaire, which assesses three aspects of prospective memory (short-term habitual, long-term episodic, and internally cued), and records the use of strategies to aid remembering.

RESULTS

In comparison to those not in pain, participants with chronic pain had significantly impaired short-term prospective memory, an effect which was evident even after co-varying use of analgesics and other drugs.

CONCLUSIONS

These findings provide new insights into prospective memory dysfunction in people with chronic pain. Possible mechanisms for this dysfunction are discussed and suggestions for future research given.

Measurement of remote memory pre- and post-temporal lobectomy: a longitudinal case study

There is evidence that remote memory is affected by temporal lobe epilepsy (TLE) and by temporal lobectomy (TL) for the relief of epilepsy. However, remote memory is not routinely assessed when patients with epilepsy undergo neuropsychological testing either pre- or postsurgery. We present a literature review and detailed longitudinal case study of a woman (A.Z.) who had right TLE and fears about deterioration of her remote memory following right TL. Remote memory was assessed by conventional methods (remote memory questionnaire for public events) and by a novel method of seeking vividness ratings for elicited autobiographical memories with A.Z.'s partner acting as the control. A.Z.'s level of memory for remote/recent public events and her rate of forgetting were the same as her partner's, both before and after surgery. A.Z.'s vividness ratings for her own autobiographical memories were similar to her partner's ratings for his memories. Her vividness ratings for her partner's memories that involved events common to both of them were slightly lower than his. A.Z.'s rate of forgetting of her own and her partner's memories was the same as that of her partner, both before and after surgery. There are two principal conclusions. First, this assessment method of measuring remote memory is easy to use and captured the patient's clinical concerns. Second, applying the methodology in this single case suggested that right-sided unilateral TLE and TL may pose no threat to remote memory.

Epilepsy surgery in professional musicians: subjective and objective reports of three cases

We describe a small series of three professional musicians who had right (two patients) and left (one patient) temporal lobe epilepsy surgery with the histological diagnoses of hippocampal sclerosis (two patients) and benign tumor (one patient, xanthoastrocytoma). The musicians were asked to complete a questionnaire about their musical abilities before and after surgery with respect to special musical skills like melody processing, musical memory, rhythm, meter, harmony/dissonance, timbre, concentration and endurance, emotionality, and absolute pitch. In addition, the musicians submitted reports of their experiences. Surgical outcome was excellent with respect to seizures and professional skills. The two patients with right temporal lobe epilepsy reported improvements of specific musical abilities. Vocational development was very positive in all three patients. We conclude that epilepsy surgery can be safe and rewarding in professional musicians and propose initiating a database on epilepsy surgery in this special group of patients.

Right-hemisphere motor facilitation by self-descriptive personality-trait words

The emergent picture from the literature on the processing of self-related information suggests that in addition to the neural mechanisms involved in recognizing one's own face, there may also be neural representations of the self that are modality independent and favour the right hemisphere. We used focal, single-pulse transcranial magnetic stimulation in human subjects to assess cortical excitability during covert reading of self-descriptive personality-trait words. We hypothesized that the right hemisphere would show a greater overall facilitation to personality-trait words than the left hemisphere. Overall, personality-trait words led to significantly greater motor facilitation in the right hemisphere than in the left hemisphere. In addition, words rated as 'never' self-characteristic yielded significant right hemisphere facilitation, and words rated as 'always' self-characteristic showed a similar trend. The results are discussed in terms of the notion that the right hemisphere plays a dominant role in both self-relevant processing and the processing of affective stimuli.