Cognitive outcomes following vagus nerve stimulation, responsive neurostimulation and deep brain stimulation for epilepsy: A systematic review.

BACKGROUND: The cognitive impacts of resective surgery for epilepsy have been well-studied. While seizure outcomes for less invasive, neuromodulatory treatments are promising, there is a paucity of data for cognitive outcomes. METHODS: Medline, EMBASE, and the Cochrane Library were searched on November 2019. Inclusion criteria were studies reporting cognitive outcomes following chronic (>6 months) vagus nerve stimulation (VNS), deep brain stimulation (DBS) and responsive neurostimulation (RNS) for epilepsy in at least five patients. Studies reporting acute on-off effects of stimulation were also included. Studies were screened, extracted of data, and assessed for bias using the Joanna Briggs Institute Critical Appraisal Tools by two independent reviewers. Prospero ID: CRD42020184432. RESULTS: Of 8443 studies screened, 29 studies were included. Nineteen investigated the effects of chronic stimulation (11 VNS, 6 DBS, 2 RNS): 10 (53 %) reported no change compared to preoperative baseline; 8 (42 %) reported some improvement in one or more cognitive domain; 1 (5%) reported decline. Ten investigated the effects of acute stimulation (5 VNS, 5 DBS): 3 (30 %) reported no change; 4 reported improvement (40 %); 3 (30 %) reported decline. Eight (28 %) did not report statistical analysis. CONCLUSIONS: Long-term cognitive outcomes are at least stable following VNS, DBS and RNS. Acute effects of stimulation are less clear. However, data are limited by number, size, and quality. More robust evidence is needed to properly assess the cognitive effects of each of these treatments.

Repetitive Behaviors in Frontotemporal Dementia: Compulsions or Impulsions?

OBJECTIVE: The presence of repetitive behaviors is one of the core criteria for behavioral variant frontotemporal dementia (bvFTD). Patients with bvFTD often have perseverative, stereotyped, or compulsive-ritualistic behavior as an early aspect of their disorder. It is unclear whether such behaviors are related to compulsions, as in obsessive-compulsive disorder (OCD), or are part of the impulse disorder spectrum. METHODS: The authors investigated early (within 3 years) repetitive behaviors among 93 well-characterized patients who met International Consensus Criteria for clinically probable bvFTD and compared the results with the literature on OCD. The most common repetitive behaviors among 59 (63.4%) bvFTD patients were stereotypies of speech (35.5%), simple repetitive movements (15.2%-18.6%), hoarding and collecting (16.9%), and excessive or unnecessary trips to the bathroom (13.5%). RESULTS: Only hoarding and collecting was significantly common in both bvFTD and OCD; otherwise, the bvFTD patients had very low frequencies of the common OCD behaviors of checking, cleaning, counting, and ordering. The repetitive behaviors in bvFTD were not associated with verbalized anxiety, obsessional ideation, or reports of relief after completing the act. In contrast, these behaviors were often triggered by environmental stimuli and could be temporarily prevented from completion without undue distress. Finally, among the bvFTD patients, the repetitive behaviors were always associated with impulsive or disinhibited behaviors, such as inappropriate verbal or physical behavior. CONCLUSIONS: These findings suggest that the repetitive behaviors in bvFTD are repetitive impulsions, possibly from specific involvement of frontostriatal-anterior temporal pathology.

Screening for Emotional Expression in Frontotemporal Dementia: A Pilot Study.

OBJECTIVE: Although emotional blunting is a core feature of behavioral variant frontotemporal dementia (bvFTD), there are no practical clinical measures of emotional expression for the early diagnosis of bvFTD. METHOD: Three age-matched groups (bvFTD, Alzheimer's disease (AD), and healthy controls (HC)) of eight participants each were presented with real-life vignettes varying in emotional intensity (high versus low) with either negative or positive outcomes. This study evaluated verbal (self-reports of distress) and visual (presence or absence of facial affect) measures of emotional expression during the vignettes. RESULTS: The bvFTD patients did not differ from the AD and HC groups in reported distress or in the amount of facial affect during vignettes with high emotional intensity or type of outcome. However, the bvFTD patients reported significantly less distress and had correspondingly few facial affective expressions when compared on vignettes of low intensity. CONCLUSIONS: Patients with bvFTD require a high intensity of emotional stimulus and are significantly hyporesponsive to low-intensity stimuli. Simple screening or observations of verbal and facial responsiveness to mildly arousing stimuli may aid in differentiating bvFTD from normal subjects and patients with other dementias. Future studies can investigate whether delivering information with high emotional intensity can facilitate communication with patients with bvFTD.

Skin Conduction Levels Differentiate Frontotemporal Dementia From Alzheimer's Disease.

Patients with behavioral variant frontotemporal dementia (bvFTD) and Alzheimer's disease (AD) differ in basic emotional tone. Skin conduction levels (SCLs), a measure of sympathetic tone, may be a sensitive test for discriminating these two dementias early in their course. Previous research has shown differences in resting SCLs between patients with bvFTD and AD, but no study has evaluated the discriminability of SCLs during different environmental conditions. The authors compared bvFTD patients (N=8), AD patients (N=10), and healthy control subjects (N=9) on SCL measures pertaining to real-life vignettes or scenarios differing in valence and emotional intensity. The SCLs among the bvFTD patients were decreased across all conditions, whereas the SCLs among the AD patients were increased compared with control participants. On analysis, the SCLs in response to emotional stimuli differentiated bvFTD from AD with an area under the receiver operator characteristic curve of 95.3%. At a cutoff ≤0.77 µS, emotional vignettes distinguished bvFTD from AD with a sensitivity of 86% and a specificity of 96%. These preliminary results indicate the potential utility of SCLs for differentiating bvFTD from AD early in their course, regardless of environmental condition.