Awake craniotomy in epilepsy surgery includes previously inoperable patients with preserved efficiency and safety.

Introduction: Whilst awake craniotomy has been widely used historically in epilepsy surgery, the safety and efficacy of this approach in epilepsy surgery has been sparsely investigated in controlled studies. The objective of this study is to investigate the safety and efficacy of awake resection in epilepsy surgery and focuses on the possibility to widen surgical indications with awake surgery. Methods: Fifteen patients operated with awake epilepsy surgery were compared to 30 matched controls undergoing conventional/asleep epilepsy surgery. The groups were compared with regard to neurological complications, seizure control and location of resection. Results: Regarding seizure control, 86% of patients in the awake group reached Engel grade 1-2 compared to 73% in the control group, operated with conventional/asleep surgery, not a statistically significant difference. Neither was there a statistical significant difference regarding postoperative neurological complications. However, there was a significant difference in location of the resection when comparing the two groups. Of the 15 patients operated with awake intraoperative mapping, four had previously been considered as non-operable by epilepsy surgery centres, due to vicinity to eloquent brain regions and predicted risk of post-operative neurological deficits. Discussion: The results show that awake epilepsy surgery yields similar level of seizure control when compared to conventional asleep surgery, with maintained safety in regard to neurological complications. Furthermore, the results indicate that awake craniotomy in epilepsy surgery is feasible and possible in patients otherwise regarded as inoperable with epileptigenic zone in proximity to eloquent brain structures.

Neural suppression in odor recognition memory.

Little is known about the neural basis of lower- and higher-order olfactory functions such as odor memory, compared with other sensory systems. The aim of this study was to explore neural networks and correlates associated with 3 functions: passive smelling (PS), odor encoding (OE), and in particular odor recognition memory (ORM). Twenty-six healthy participants were examined using functional magnetic resonance imaging conducted across 3 sessions, one for each function. Independent component analysis revealed a difference between sessions where a distinct ORM component incorporating hippocampus and posterior cingulate showed delayed triggering dissociated from odor stimulation and recognition. By contrasting Hit for ORM (target odors correctly recognized as old) and a combination of PS and detected odors from OE, we found significantly lower activations in amygdala, piriform cortex, insula, thalamus, and the inferior parietal lobule. Region of interest analysis including anterior insula, posterior cingulate gyrus, dentate gyrus, left middle frontal gyrus, amygdala, and piriform cortex demonstrated that Hit were associated with lower activations compared with other memory responses. In summary, our findings suggest that successful recognition of familiar odors (odor familiarity) is associated with neural suppression in the abovementioned regions of interest. Additionally, network including the hippocampus and posterior cingulate is engaged in a postrecognition process. This process may be related to incidental encoding of less familiar and more novel odors (odor novelty) and should be subject for future research.

Odor Recognition Memory in Parkinson's Disease: A Systematic Review.

Olfactory impairment is a central non-motor symptom in Parkinson's disease (PD). Previous studies have demonstrated that olfactory dysfunction is associated with mental illness and impaired cognition. The frequently investigated olfactory functions are odor detection, discrimination, and identification. However, few studies have focused on odor recognition memory (ORM). ORM tasks involves episodic memory which therefore can facilitate the detection of dementia among patients with PD and consequently adjust their treatment. Thus, the aim of this systematic review is to summarize the existing research on ORM in PD. Databases and reference lists were used for data collection. Studies were included in the review if they met the eligibility criteria derived from the PICOS-framework. Quality evaluation of the studies was based on the STROBE-statement. Six studies with small samples were included in the analysis which demonstrated the scarce research on the subject. The studies targeting ORM were heterogenous and involved two main tasks: odor recognition and odor matching. The synthesis of the data demonstrated that PD patients performed significantly lower than controls on both tasks, especially on odor matching task. Only the odor recognition task exhibited a difference between patients with PD vs. Alzheimer's disease (AD). PD patients performed significantly better than AD patients. The findings based on the available limited data support the notion that odor recognition task can be of importance in identifying Parkinson's disease dementia (PDD). To investigate this hypothesis, future research needs to include larger samples of PD, PDD and AD patients executing the same odor recognition task.